text: /*
   * Copyright (C) 2005 Junio C Hamano
   */
  #include "cache.h"
  #include "quote.h"
  #include "diff.h"
  #include "diffcore.h"
  #include "delta.h"
  #include "xdiff-interface.h"
  #include "color.h"
  #include "attr.h"
  #include "run-command.h"
  #include "utf8.h"
  #include "userdiff.h"
  #include "sigchain.h"
  #include "submodule.h"
  #include "ll-merge.h"
  #include "string-list.h"
  #include "argv-array.h"
  
  #ifdef NO_FAST_WORKING_DIRECTORY
  #define FAST_WORKING_DIRECTORY 0
  #else
  #define FAST_WORKING_DIRECTORY 1
  #endif
  
  static int diff_detect_rename_default;
  static int diff_rename_limit_default = 400;
  static int diff_suppress_blank_empty;
  static int diff_use_color_default = -1;
  static int diff_context_default = 3;
  static const char *diff_word_regex_cfg;
  static const char *external_diff_cmd_cfg;
  static const char *diff_order_file_cfg;
  int diff_auto_refresh_index = 1;
  static int diff_mnemonic_prefix;
  static int diff_no_prefix;
  static int diff_stat_graph_width;
  static int diff_dirstat_permille_default = 30;
  static struct diff_options default_diff_options;
  static long diff_algorithm;
  
  static char diff_colors[][COLOR_MAXLEN] = {
  	GIT_COLOR_RESET,
  	GIT_COLOR_NORMAL,	/* CONTEXT */
  	GIT_COLOR_BOLD,		/* METAINFO */
  	GIT_COLOR_CYAN,		/* FRAGINFO */
  	GIT_COLOR_RED,		/* OLD */
  	GIT_COLOR_GREEN,	/* NEW */
  	GIT_COLOR_YELLOW,	/* COMMIT */
  	GIT_COLOR_BG_RED,	/* WHITESPACE */
  	GIT_COLOR_NORMAL,	/* FUNCINFO */
  };
  
  static int parse_diff_color_slot(const char *var)
  {
  	if (!strcasecmp(var, "context") || !strcasecmp(var, "plain"))
  		return DIFF_CONTEXT;
  	if (!strcasecmp(var, "meta"))
  		return DIFF_METAINFO;
  	if (!strcasecmp(var, "frag"))
  		return DIFF_FRAGINFO;
  	if (!strcasecmp(var, "old"))
  		return DIFF_FILE_OLD;
  	if (!strcasecmp(var, "new"))
  		return DIFF_FILE_NEW;
  	if (!strcasecmp(var, "commit"))
  		return DIFF_COMMIT;
  	if (!strcasecmp(var, "whitespace"))
  		return DIFF_WHITESPACE;
  	if (!strcasecmp(var, "func"))
  		return DIFF_FUNCINFO;
  	return -1;
  }
  
  static int parse_dirstat_params(struct diff_options *options, const char *params_string,
  				struct strbuf *errmsg)
  {
  	char *params_copy = xstrdup(params_string);
  	struct string_list params = STRING_LIST_INIT_NODUP;
  	int ret = 0;
  	int i;
  
  	if (*params_copy)
  		string_list_split_in_place(&params, params_copy, ',', -1);
  	for (i = 0; i < params.nr; i++) {
  		const char *p = params.items[i].string;
  		if (!strcmp(p, "changes")) {
  			DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
  			DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
  		} else if (!strcmp(p, "lines")) {
  			DIFF_OPT_SET(options, DIRSTAT_BY_LINE);
  			DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
  		} else if (!strcmp(p, "files")) {
  			DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
  			DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
  		} else if (!strcmp(p, "noncumulative")) {
  			DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
  		} else if (!strcmp(p, "cumulative")) {
  			DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
  		} else if (isdigit(*p)) {
  			char *end;
  			int permille = strtoul(p, &end, 10) * 10;
  			if (*end == '.' && isdigit(*++end)) {
  				/* only use first digit */
  				permille += *end - '0';
  				/* .. and ignore any further digits */
  				while (isdigit(*++end))
  					; /* nothing */
  			}
  			if (!*end)
  				options->dirstat_permille = permille;
  			else {
  				strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%s'\n"),
  					    p);
  				ret++;
  			}
  		} else {
  			strbuf_addf(errmsg, _("  Unknown dirstat parameter '%s'\n"), p);
  			ret++;
  		}
  
  	}
  	string_list_clear(&params, 0);
  	free(params_copy);
  	return ret;
  }
  
  static int parse_submodule_params(struct diff_options *options, const char *value)
  {
  	if (!strcmp(value, "log"))
  		DIFF_OPT_SET(options, SUBMODULE_LOG);
  	else if (!strcmp(value, "short"))
  		DIFF_OPT_CLR(options, SUBMODULE_LOG);
  	else
  		return -1;
  	return 0;
  }
  
  static int git_config_rename(const char *var, const char *value)
  {
  	if (!value)
  		return DIFF_DETECT_RENAME;
  	if (!strcasecmp(value, "copies") || !strcasecmp(value, "copy"))
  		return  DIFF_DETECT_COPY;
  	return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
  }
  
  long parse_algorithm_value(const char *value)
  {
  	if (!value)
  		return -1;
  	else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
  		return 0;
  	else if (!strcasecmp(value, "minimal"))
  		return XDF_NEED_MINIMAL;
  	else if (!strcasecmp(value, "patience"))
  		return XDF_PATIENCE_DIFF;
  	else if (!strcasecmp(value, "histogram"))
  		return XDF_HISTOGRAM_DIFF;
  	return -1;
  }
  
  /*
   * These are to give UI layer defaults.
   * The core-level commands such as git-diff-files should
   * never be affected by the setting of diff.renames
   * the user happens to have in the configuration file.
   */
  int git_diff_ui_config(const char *var, const char *value, void *cb)
  {
  	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
  		diff_use_color_default = git_config_colorbool(var, value);
  		return 0;
  	}
  	if (!strcmp(var, "diff.context")) {
  		diff_context_default = git_config_int(var, value);
  		if (diff_context_default < 0)
  			return -1;
  		return 0;
  	}
  	if (!strcmp(var, "diff.renames")) {
  		diff_detect_rename_default = git_config_rename(var, value);
  		return 0;
  	}
  	if (!strcmp(var, "diff.autorefreshindex")) {
  		diff_auto_refresh_index = git_config_bool(var, value);
  		return 0;
  	}
  	if (!strcmp(var, "diff.mnemonicprefix")) {
  		diff_mnemonic_prefix = git_config_bool(var, value);
  		return 0;
  	}
  	if (!strcmp(var, "diff.noprefix")) {
  		diff_no_prefix = git_config_bool(var, value);
  		return 0;
  	}
  	if (!strcmp(var, "diff.statgraphwidth")) {
  		diff_stat_graph_width = git_config_int(var, value);
  		return 0;
  	}
  	if (!strcmp(var, "diff.external"))
  		return git_config_string(&external_diff_cmd_cfg, var, value);
  	if (!strcmp(var, "diff.wordregex"))
  		return git_config_string(&diff_word_regex_cfg, var, value);
  	if (!strcmp(var, "diff.orderfile"))
  		return git_config_pathname(&diff_order_file_cfg, var, value);
  
  	if (!strcmp(var, "diff.ignoresubmodules"))
  		handle_ignore_submodules_arg(&default_diff_options, value);
  
  	if (!strcmp(var, "diff.submodule")) {
  		if (parse_submodule_params(&default_diff_options, value))
  			warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
  				value);
  		return 0;
  	}
  
  	if (!strcmp(var, "diff.algorithm")) {
  		diff_algorithm = parse_algorithm_value(value);
  		if (diff_algorithm < 0)
  			return -1;
  		return 0;
  	}
  
  	if (git_color_config(var, value, cb) < 0)
  		return -1;
  
  	return git_diff_basic_config(var, value, cb);
  }
  
  int git_diff_basic_config(const char *var, const char *value, void *cb)
  {
  	const char *name;
  
  	if (!strcmp(var, "diff.renamelimit")) {
  		diff_rename_limit_default = git_config_int(var, value);
  		return 0;
  	}
  
  	if (userdiff_config(var, value) < 0)
  		return -1;
  
  	if (skip_prefix(var, "diff.color.", &name) ||
  	    skip_prefix(var, "color.diff.", &name)) {
  		int slot = parse_diff_color_slot(name);
  		if (slot < 0)
  			return 0;
  		if (!value)
  			return config_error_nonbool(var);
  		return color_parse(value, diff_colors[slot]);
  	}
  
  	/* like GNU diff's --suppress-blank-empty option  */
  	if (!strcmp(var, "diff.suppressblankempty") ||
  			/* for backwards compatibility */
  			!strcmp(var, "diff.suppress-blank-empty")) {
  		diff_suppress_blank_empty = git_config_bool(var, value);
  		return 0;
  	}
  
  	if (!strcmp(var, "diff.dirstat")) {
  		struct strbuf errmsg = STRBUF_INIT;
  		default_diff_options.dirstat_permille = diff_dirstat_permille_default;
  		if (parse_dirstat_params(&default_diff_options, value, &errmsg))
  			warning(_("Found errors in 'diff.dirstat' config variable:\n%s"),
  				errmsg.buf);
  		strbuf_release(&errmsg);
  		diff_dirstat_permille_default = default_diff_options.dirstat_permille;
  		return 0;
  	}
  
  	if (starts_with(var, "submodule."))
  		return parse_submodule_config_option(var, value);
  
  	return git_default_config(var, value, cb);
  }
  
  static char *quote_two(const char *one, const char *two)
  {
  	int need_one = quote_c_style(one, NULL, NULL, 1);
  	int need_two = quote_c_style(two, NULL, NULL, 1);
  	struct strbuf res = STRBUF_INIT;
  
  	if (need_one + need_two) {
  		strbuf_addch(&res, '"');
  		quote_c_style(one, &res, NULL, 1);
  		quote_c_style(two, &res, NULL, 1);
  		strbuf_addch(&res, '"');
  	} else {
  		strbuf_addstr(&res, one);
  		strbuf_addstr(&res, two);
  	}
  	return strbuf_detach(&res, NULL);
  }
  
  static const char *external_diff(void)
  {
  	static const char *external_diff_cmd = NULL;
  	static int done_preparing = 0;
  
  	if (done_preparing)
  		return external_diff_cmd;
  	external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
  	if (!external_diff_cmd)
  		external_diff_cmd = external_diff_cmd_cfg;
  	done_preparing = 1;
  	return external_diff_cmd;
  }
  
  static struct diff_tempfile {
  	const char *name; /* filename external diff should read from */
  	char hex[41];
  	char mode[10];
  	char tmp_path[PATH_MAX];
  } diff_temp[2];
  
  typedef unsigned long (*sane_truncate_fn)(char *line, unsigned long len);
  
  struct emit_callback {
  	int color_diff;
  	unsigned ws_rule;
  	int blank_at_eof_in_preimage;
  	int blank_at_eof_in_postimage;
  	int lno_in_preimage;
  	int lno_in_postimage;
  	sane_truncate_fn truncate;
  	const char **label_path;
  	struct diff_words_data *diff_words;
  	struct diff_options *opt;
  	int *found_changesp;
  	struct strbuf *header;
  };
  
  static int count_lines(const char *data, int size)
  {
  	int count, ch, completely_empty = 1, nl_just_seen = 0;
  	count = 0;
  	while (0 < size--) {
  		ch = *data++;
  		if (ch == '\n') {
  			count++;
  			nl_just_seen = 1;
  			completely_empty = 0;
  		}
  		else {
  			nl_just_seen = 0;
  			completely_empty = 0;
  		}
  	}
  	if (completely_empty)
  		return 0;
  	if (!nl_just_seen)
  		count++; /* no trailing newline */
  	return count;
  }
  
  static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
  {
  	if (!DIFF_FILE_VALID(one)) {
  		mf->ptr = (char *)""; /* does not matter */
  		mf->size = 0;
  		return 0;
  	}
  	else if (diff_populate_filespec(one, 0))
  		return -1;
  
  	mf->ptr = one->data;
  	mf->size = one->size;
  	return 0;
  }
  
  /* like fill_mmfile, but only for size, so we can avoid retrieving blob */
  static unsigned long diff_filespec_size(struct diff_filespec *one)
  {
  	if (!DIFF_FILE_VALID(one))
  		return 0;
  	diff_populate_filespec(one, CHECK_SIZE_ONLY);
  	return one->size;
  }
  
  static int count_trailing_blank(mmfile_t *mf, unsigned ws_rule)
  {
  	char *ptr = mf->ptr;
  	long size = mf->size;
  	int cnt = 0;
  
  	if (!size)
  		return cnt;
  	ptr += size - 1; /* pointing at the very end */
  	if (*ptr != '\n')
  		; /* incomplete line */
  	else
  		ptr--; /* skip the last LF */
  	while (mf->ptr < ptr) {
  		char *prev_eol;
  		for (prev_eol = ptr; mf->ptr <= prev_eol; prev_eol--)
  			if (*prev_eol == '\n')
  				break;
  		if (!ws_blank_line(prev_eol + 1, ptr - prev_eol, ws_rule))
  			break;
  		cnt++;
  		ptr = prev_eol - 1;
  	}
  	return cnt;
  }
  
  static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
  			       struct emit_callback *ecbdata)
  {
  	int l1, l2, at;
  	unsigned ws_rule = ecbdata->ws_rule;
  	l1 = count_trailing_blank(mf1, ws_rule);
  	l2 = count_trailing_blank(mf2, ws_rule);
  	if (l2 <= l1) {
  		ecbdata->blank_at_eof_in_preimage = 0;
  		ecbdata->blank_at_eof_in_postimage = 0;
  		return;
  	}
  	at = count_lines(mf1->ptr, mf1->size);
  	ecbdata->blank_at_eof_in_preimage = (at - l1) + 1;
  
  	at = count_lines(mf2->ptr, mf2->size);
  	ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
  }
  
  static void emit_line_0(struct diff_options *o, const char *set, const char *reset,
  			int first, const char *line, int len)
  {
  	int has_trailing_newline, has_trailing_carriage_return;
  	int nofirst;
  	FILE *file = o->file;
  
  	fputs(diff_line_prefix(o), file);
  
  	if (len == 0) {
  		has_trailing_newline = (first == '\n');
  		has_trailing_carriage_return = (!has_trailing_newline &&
  						(first == '\r'));
  		nofirst = has_trailing_newline || has_trailing_carriage_return;
  	} else {
  		has_trailing_newline = (len > 0 && line[len-1] == '\n');
  		if (has_trailing_newline)
  			len--;
  		has_trailing_carriage_return = (len > 0 && line[len-1] == '\r');
  		if (has_trailing_carriage_return)
  			len--;
  		nofirst = 0;
  	}
  
  	if (len || !nofirst) {
  		fputs(set, file);
  		if (!nofirst)
  			fputc(first, file);
  		fwrite(line, len, 1, file);
  		fputs(reset, file);
  	}
  	if (has_trailing_carriage_return)
  		fputc('\r', file);
  	if (has_trailing_newline)
  		fputc('\n', file);
  }
  
  static void emit_line(struct diff_options *o, const char *set, const char *reset,
  		      const char *line, int len)
  {
  	emit_line_0(o, set, reset, line[0], line+1, len-1);
  }
  
  static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line, int len)
  {
  	if (!((ecbdata->ws_rule & WS_BLANK_AT_EOF) &&
  	      ecbdata->blank_at_eof_in_preimage &&
  	      ecbdata->blank_at_eof_in_postimage &&
  	      ecbdata->blank_at_eof_in_preimage <= ecbdata->lno_in_preimage &&
  	      ecbdata->blank_at_eof_in_postimage <= ecbdata->lno_in_postimage))
  		return 0;
  	return ws_blank_line(line, len, ecbdata->ws_rule);
  }
  
  static void emit_line_checked(const char *reset,
  			      struct emit_callback *ecbdata,
  			      const char *line, int len,
  			      enum color_diff color,
  			      unsigned ws_error_highlight,
  			      char sign)
  {
  	const char *set = diff_get_color(ecbdata->color_diff, color);
  	const char *ws = NULL;
  
  	if (ecbdata->opt->ws_error_highlight & ws_error_highlight) {
  		ws = diff_get_color(ecbdata->color_diff, DIFF_WHITESPACE);
  		if (!*ws)
  			ws = NULL;
  	}
  
  	if (!ws)
  		emit_line_0(ecbdata->opt, set, reset, sign, line, len);
  	else if (sign == '+' && new_blank_line_at_eof(ecbdata, line, len))
  		/* Blank line at EOF - paint '+' as well */
  		emit_line_0(ecbdata->opt, ws, reset, sign, line, len);
  	else {
  		/* Emit just the prefix, then the rest. */
  		emit_line_0(ecbdata->opt, set, reset, sign, "", 0);
  		ws_check_emit(line, len, ecbdata->ws_rule,
  			      ecbdata->opt->file, set, reset, ws);
  	}
  }
  
  static void emit_add_line(const char *reset,
  			  struct emit_callback *ecbdata,
  			  const char *line, int len)
  {
  	emit_line_checked(reset, ecbdata, line, len,
  			  DIFF_FILE_NEW, WSEH_NEW, '+');
  }
  
  static void emit_del_line(const char *reset,
  			  struct emit_callback *ecbdata,
  			  const char *line, int len)
  {
  	emit_line_checked(reset, ecbdata, line, len,
  			  DIFF_FILE_OLD, WSEH_OLD, '-');
  }
  
  static void emit_context_line(const char *reset,
  			      struct emit_callback *ecbdata,
  			      const char *line, int len)
  {
  	emit_line_checked(reset, ecbdata, line, len,
  			  DIFF_CONTEXT, WSEH_CONTEXT, ' ');
  }
  
  static void emit_hunk_header(struct emit_callback *ecbdata,
  			     const char *line, int len)
  {
  	const char *context = diff_get_color(ecbdata->color_diff, DIFF_CONTEXT);
  	const char *frag = diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO);
  	const char *func = diff_get_color(ecbdata->color_diff, DIFF_FUNCINFO);
  	const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
  	static const char atat[2] = { '@', '@' };
  	const char *cp, *ep;
  	struct strbuf msgbuf = STRBUF_INIT;
  	int org_len = len;
  	int i = 1;
  
  	/*
  	 * As a hunk header must begin with "@@ -<old>, +<new> @@",
  	 * it always is at least 10 bytes long.
  	 */
  	if (len < 10 ||
  	    memcmp(line, atat, 2) ||
  	    !(ep = memmem(line + 2, len - 2, atat, 2))) {
  		emit_line(ecbdata->opt, context, reset, line, len);
  		return;
  	}
  	ep += 2; /* skip over @@ */
  
  	/* The hunk header in fraginfo color */
  	strbuf_addstr(&msgbuf, frag);
  	strbuf_add(&msgbuf, line, ep - line);
  	strbuf_addstr(&msgbuf, reset);
  
  	/*
  	 * trailing "\r\n"
  	 */
  	for ( ; i < 3; i++)
  		if (line[len - i] == '\r' || line[len - i] == '\n')
  			len--;
  
  	/* blank before the func header */
  	for (cp = ep; ep - line < len; ep++)
  		if (*ep != ' ' && *ep != '\t')
  			break;
  	if (ep != cp) {
  		strbuf_addstr(&msgbuf, context);
  		strbuf_add(&msgbuf, cp, ep - cp);
  		strbuf_addstr(&msgbuf, reset);
  	}
  
  	if (ep < line + len) {
  		strbuf_addstr(&msgbuf, func);
  		strbuf_add(&msgbuf, ep, line + len - ep);
  		strbuf_addstr(&msgbuf, reset);
  	}
  
  	strbuf_add(&msgbuf, line + len, org_len - len);
  	emit_line(ecbdata->opt, "", "", msgbuf.buf, msgbuf.len);
  	strbuf_release(&msgbuf);
  }
  
  static struct diff_tempfile *claim_diff_tempfile(void) {
  	int i;
  	for (i = 0; i < ARRAY_SIZE(diff_temp); i++)
  		if (!diff_temp[i].name)
  			return diff_temp + i;
  	die("BUG: diff is failing to clean up its tempfiles");
  }
  
  static int remove_tempfile_installed;
  
  static void remove_tempfile(void)
  {
  	int i;
  	for (i = 0; i < ARRAY_SIZE(diff_temp); i++) {
  		if (diff_temp[i].name == diff_temp[i].tmp_path)
  			unlink_or_warn(diff_temp[i].name);
  		diff_temp[i].name = NULL;
  	}
  }
  
  static void remove_tempfile_on_signal(int signo)
  {
  	remove_tempfile();
  	sigchain_pop(signo);
  	raise(signo);
  }
  
  static void print_line_count(FILE *file, int count)
  {
  	switch (count) {
  	case 0:
  		fprintf(file, "0,0");
  		break;
  	case 1:
  		fprintf(file, "1");
  		break;
  	default:
  		fprintf(file, "1,%d", count);
  		break;
  	}
  }
  
  static void emit_rewrite_lines(struct emit_callback *ecb,
  			       int prefix, const char *data, int size)
  {
  	const char *endp = NULL;
  	static const char *nneof = " No newline at end of file\n";
  	const char *reset = diff_get_color(ecb->color_diff, DIFF_RESET);
  
  	while (0 < size) {
  		int len;
  
  		endp = memchr(data, '\n', size);
  		len = endp ? (endp - data + 1) : size;
  		if (prefix != '+') {
  			ecb->lno_in_preimage++;
  			emit_del_line(reset, ecb, data, len);
  		} else {
  			ecb->lno_in_postimage++;
  			emit_add_line(reset, ecb, data, len);
  		}
  		size -= len;
  		data += len;
  	}
  	if (!endp) {
  		const char *context = diff_get_color(ecb->color_diff,
  						     DIFF_CONTEXT);
  		putc('\n', ecb->opt->file);
  		emit_line_0(ecb->opt, context, reset, '\\',
  			    nneof, strlen(nneof));
  	}
  }
  
  static void emit_rewrite_diff(const char *name_a,
  			      const char *name_b,
  			      struct diff_filespec *one,
  			      struct diff_filespec *two,
  			      struct userdiff_driver *textconv_one,
  			      struct userdiff_driver *textconv_two,
  			      struct diff_options *o)
  {
  	int lc_a, lc_b;
  	const char *name_a_tab, *name_b_tab;
  	const char *metainfo = diff_get_color(o->use_color, DIFF_METAINFO);
  	const char *fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
  	const char *reset = diff_get_color(o->use_color, DIFF_RESET);
  	static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
  	const char *a_prefix, *b_prefix;
  	char *data_one, *data_two;
  	size_t size_one, size_two;
  	struct emit_callback ecbdata;
  	const char *line_prefix = diff_line_prefix(o);
  
  	if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
  		a_prefix = o->b_prefix;
  		b_prefix = o->a_prefix;
  	} else {
  		a_prefix = o->a_prefix;
  		b_prefix = o->b_prefix;
  	}
  
  	name_a += (*name_a == '/');
  	name_b += (*name_b == '/');
  	name_a_tab = strchr(name_a, ' ') ? "\t" : "";
  	name_b_tab = strchr(name_b, ' ') ? "\t" : "";
  
  	strbuf_reset(&a_name);
  	strbuf_reset(&b_name);
  	quote_two_c_style(&a_name, a_prefix, name_a, 0);
  	quote_two_c_style(&b_name, b_prefix, name_b, 0);
  
  	size_one = fill_textconv(textconv_one, one, &data_one);
  	size_two = fill_textconv(textconv_two, two, &data_two);
  
  	memset(&ecbdata, 0, sizeof(ecbdata));
  	ecbdata.color_diff = want_color(o->use_color);
  	ecbdata.found_changesp = &o->found_changes;
  	ecbdata.ws_rule = whitespace_rule(name_b);
  	ecbdata.opt = o;
  	if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
  		mmfile_t mf1, mf2;
  		mf1.ptr = (char *)data_one;
  		mf2.ptr = (char *)data_two;
  		mf1.size = size_one;
  		mf2.size = size_two;
  		check_blank_at_eof(&mf1, &mf2, &ecbdata);
  	}
  	ecbdata.lno_in_preimage = 1;
  	ecbdata.lno_in_postimage = 1;
  
  	lc_a = count_lines(data_one, size_one);
  	lc_b = count_lines(data_two, size_two);
  	fprintf(o->file,
  		"%s%s--- %s%s%s\n%s%s+++ %s%s%s\n%s%s@@ -",
  		line_prefix, metainfo, a_name.buf, name_a_tab, reset,
  		line_prefix, metainfo, b_name.buf, name_b_tab, reset,
  		line_prefix, fraginfo);
  	if (!o->irreversible_delete)
  		print_line_count(o->file, lc_a);
  	else
  		fprintf(o->file, "?,?");
  	fprintf(o->file, " +");
  	print_line_count(o->file, lc_b);
  	fprintf(o->file, " @@%s\n", reset);
  	if (lc_a && !o->irreversible_delete)
  		emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
  	if (lc_b)
  		emit_rewrite_lines(&ecbdata, '+', data_two, size_two);
  	if (textconv_one)
  		free((char *)data_one);
  	if (textconv_two)
  		free((char *)data_two);
  }
  
  struct diff_words_buffer {
  	mmfile_t text;
  	long alloc;
  	struct diff_words_orig {
  		const char *begin, *end;
  	} *orig;
  	int orig_nr, orig_alloc;
  };
  
  static void diff_words_append(char *line, unsigned long len,
  		struct diff_words_buffer *buffer)
  {
  	ALLOC_GROW(buffer->text.ptr, buffer->text.size + len, buffer->alloc);
  	line++;
  	len--;
  	memcpy(buffer->text.ptr + buffer->text.size, line, len);
  	buffer->text.size += len;
  	buffer->text.ptr[buffer->text.size] = '\0';
  }
  
  struct diff_words_style_elem {
  	const char *prefix;
  	const char *suffix;
  	const char *color; /* NULL; filled in by the setup code if
  			    * color is enabled */
  };
  
  struct diff_words_style {
  	enum diff_words_type type;
  	struct diff_words_style_elem new, old, ctx;
  	const char *newline;
  };
  
  static struct diff_words_style diff_words_styles[] = {
  	{ DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
  	{ DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
  	{ DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
  };
  
  struct diff_words_data {
  	struct diff_words_buffer minus, plus;
  	const char *current_plus;
  	int last_minus;
  	struct diff_options *opt;
  	regex_t *word_regex;
  	enum diff_words_type type;
  	struct diff_words_style *style;
  };
  
  static int fn_out_diff_words_write_helper(FILE *fp,
  					  struct diff_words_style_elem *st_el,
  					  const char *newline,
  					  size_t count, const char *buf,
  					  const char *line_prefix)
  {
  	int print = 0;
  
  	while (count) {
  		char *p = memchr(buf, '\n', count);
  		if (print)
  			fputs(line_prefix, fp);
  		if (p != buf) {
  			if (st_el->color && fputs(st_el->color, fp) < 0)
  				return -1;
  			if (fputs(st_el->prefix, fp) < 0 ||
  			    fwrite(buf, p ? p - buf : count, 1, fp) != 1 ||
  			    fputs(st_el->suffix, fp) < 0)
  				return -1;
  			if (st_el->color && *st_el->color
  			    && fputs(GIT_COLOR_RESET, fp) < 0)
  				return -1;
  		}
  		if (!p)
  			return 0;
  		if (fputs(newline, fp) < 0)
  			return -1;
  		count -= p + 1 - buf;
  		buf = p + 1;
  		print = 1;
  	}
  	return 0;
  }
  
  /*
   * '--color-words' algorithm can be described as:
   *
   *   1. collect a the minus/plus lines of a diff hunk, divided into
   *      minus-lines and plus-lines;
   *
   *   2. break both minus-lines and plus-lines into words and
   *      place them into two mmfile_t with one word for each line;
   *
   *   3. use xdiff to run diff on the two mmfile_t to get the words level diff;
   *
   * And for the common parts of the both file, we output the plus side text.
   * diff_words->current_plus is used to trace the current position of the plus file
   * which printed. diff_words->last_minus is used to trace the last minus word
   * printed.
   *
   * For '--graph' to work with '--color-words', we need to output the graph prefix
   * on each line of color words output. Generally, there are two conditions on
   * which we should output the prefix.
   *
   *   1. diff_words->last_minus == 0 &&
   *      diff_words->current_plus == diff_words->plus.text.ptr
   *
   *      that is: the plus text must start as a new line, and if there is no minus
   *      word printed, a graph prefix must be printed.
   *
   *   2. diff_words->current_plus > diff_words->plus.text.ptr &&
   *      *(diff_words->current_plus - 1) == '\n'
   *
   *      that is: a graph prefix must be printed following a '\n'
   */
  static int color_words_output_graph_prefix(struct diff_words_data *diff_words)
  {
  	if ((diff_words->last_minus == 0 &&
  		diff_words->current_plus == diff_words->plus.text.ptr) ||
  		(diff_words->current_plus > diff_words->plus.text.ptr &&
  		*(diff_words->current_plus - 1) == '\n')) {
  		return 1;
  	} else {
  		return 0;
  	}
  }
  
  static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
  {
  	struct diff_words_data *diff_words = priv;
  	struct diff_words_style *style = diff_words->style;
  	int minus_first, minus_len, plus_first, plus_len;
  	const char *minus_begin, *minus_end, *plus_begin, *plus_end;
  	struct diff_options *opt = diff_words->opt;
  	const char *line_prefix;
  
  	if (line[0] != '@' || parse_hunk_header(line, len,
  			&minus_first, &minus_len, &plus_first, &plus_len))
  		return;
  
  	assert(opt);
  	line_prefix = diff_line_prefix(opt);
  
  	/* POSIX requires that first be decremented by one if len == 0... */
  	if (minus_len) {
  		minus_begin = diff_words->minus.orig[minus_first].begin;
  		minus_end =
  			diff_words->minus.orig[minus_first + minus_len - 1].end;
  	} else
  		minus_begin = minus_end =
  			diff_words->minus.orig[minus_first].end;
  
  	if (plus_len) {
  		plus_begin = diff_words->plus.orig[plus_first].begin;
  		plus_end = diff_words->plus.orig[plus_first + plus_len - 1].end;
  	} else
  		plus_begin = plus_end = diff_words->plus.orig[plus_first].end;
  
  	if (color_words_output_graph_prefix(diff_words)) {
  		fputs(line_prefix, diff_words->opt->file);
  	}
  	if (diff_words->current_plus != plus_begin) {
  		fn_out_diff_words_write_helper(diff_words->opt->file,
  				&style->ctx, style->newline,
  				plus_begin - diff_words->current_plus,
  				diff_words->current_plus, line_prefix);
  		if (*(plus_begin - 1) == '\n')
  			fputs(line_prefix, diff_words->opt->file);
  	}
  	if (minus_begin != minus_end) {
  		fn_out_diff_words_write_helper(diff_words->opt->file,
  				&style->old, style->newline,
  				minus_end - minus_begin, minus_begin,
  				line_prefix);
  	}
  	if (plus_begin != plus_end) {
  		fn_out_diff_words_write_helper(diff_words->opt->file,
  				&style->new, style->newline,
  				plus_end - plus_begin, plus_begin,
  				line_prefix);
  	}
  
  	diff_words->current_plus = plus_end;
  	diff_words->last_minus = minus_first;
  }
  
  /* This function starts looking at *begin, and returns 0 iff a word was found. */
  static int find_word_boundaries(mmfile_t *buffer, regex_t *word_regex,
  		int *begin, int *end)
  {
  	if (word_regex && *begin < buffer->size) {
  		regmatch_t match[1];
  		if (!regexec(word_regex, buffer->ptr + *begin, 1, match, 0)) {
  			char *p = memchr(buffer->ptr + *begin + match[0].rm_so,
  					'\n', match[0].rm_eo - match[0].rm_so);
  			*end = p ? p - buffer->ptr : match[0].rm_eo + *begin;
  			*begin += match[0].rm_so;
  			return *begin >= *end;
  		}
  		return -1;
  	}
  
  	/* find the next word */
  	while (*begin < buffer->size && isspace(buffer->ptr[*begin]))
  		(*begin)++;
  	if (*begin >= buffer->size)
  		return -1;
  
  	/* find the end of the word */
  	*end = *begin + 1;
  	while (*end < buffer->size && !isspace(buffer->ptr[*end]))
  		(*end)++;
  
  	return 0;
  }
  
  /*
   * This function splits the words in buffer->text, stores the list with
   * newline separator into out, and saves the offsets of the original words
   * in buffer->orig.
   */
  static void diff_words_fill(struct diff_words_buffer *buffer, mmfile_t *out,
  		regex_t *word_regex)
  {
  	int i, j;
  	long alloc = 0;
  
  	out->size = 0;
  	out->ptr = NULL;
  
  	/* fake an empty "0th" word */
  	ALLOC_GROW(buffer->orig, 1, buffer->orig_alloc);
  	buffer->orig[0].begin = buffer->orig[0].end = buffer->text.ptr;
  	buffer->orig_nr = 1;
  
  	for (i = 0; i < buffer->text.size; i++) {
  		if (find_word_boundaries(&buffer->text, word_regex, &i, &j))
  			return;
  
  		/* store original boundaries */
  		ALLOC_GROW(buffer->orig, buffer->orig_nr + 1,
  				buffer->orig_alloc);
  		buffer->orig[buffer->orig_nr].begin = buffer->text.ptr + i;
  		buffer->orig[buffer->orig_nr].end = buffer->text.ptr + j;
  		buffer->orig_nr++;
  
  		/* store one word */
  		ALLOC_GROW(out->ptr, out->size + j - i + 1, alloc);
  		memcpy(out->ptr + out->size, buffer->text.ptr + i, j - i);
  		out->ptr[out->size + j - i] = '\n';
  		out->size += j - i + 1;
  
  		i = j - 1;
  	}
  }
  
  /* this executes the word diff on the accumulated buffers */
  static void diff_words_show(struct diff_words_data *diff_words)
  {
  	xpparam_t xpp;
  	xdemitconf_t xecfg;
  	mmfile_t minus, plus;
  	struct diff_words_style *style = diff_words->style;
  
  	struct diff_options *opt = diff_words->opt;
  	const char *line_prefix;
  
  	assert(opt);
  	line_prefix = diff_line_prefix(opt);
  
  	/* special case: only removal */
  	if (!diff_words->plus.text.size) {
  		fputs(line_prefix, diff_words->opt->file);
  		fn_out_diff_words_write_helper(diff_words->opt->file,
  			&style->old, style->newline,
  			diff_words->minus.text.size,
  			diff_words->minus.text.ptr, line_prefix);
  		diff_words->minus.text.size = 0;
  		return;
  	}
  
  	diff_words->current_plus = diff_words->plus.text.ptr;
  	diff_words->last_minus = 0;
  
  	memset(&xpp, 0, sizeof(xpp));
  	memset(&xecfg, 0, sizeof(xecfg));
  	diff_words_fill(&diff_words->minus, &minus, diff_words->word_regex);
  	diff_words_fill(&diff_words->plus, &plus, diff_words->word_regex);
  	xpp.flags = 0;
  	/* as only the hunk header will be parsed, we need a 0-context */
  	xecfg.ctxlen = 0;
  	xdi_diff_outf(&minus, &plus, fn_out_diff_words_aux, diff_words,
  		      &xpp, &xecfg);
  	free(minus.ptr);
  	free(plus.ptr);
  	if (diff_words->current_plus != diff_words->plus.text.ptr +
  			diff_words->plus.text.size) {
  		if (color_words_output_graph_prefix(diff_words))
  			fputs(line_prefix, diff_words->opt->file);
  		fn_out_diff_words_write_helper(diff_words->opt->file,
  			&style->ctx, style->newline,
  			diff_words->plus.text.ptr + diff_words->plus.text.size
  			- diff_words->current_plus, diff_words->current_plus,
  			line_prefix);
  	}
  	diff_words->minus.text.size = diff_words->plus.text.size = 0;
  }
  
  /* In "color-words" mode, show word-diff of words accumulated in the buffer */
  static void diff_words_flush(struct emit_callback *ecbdata)
  {
  	if (ecbdata->diff_words->minus.text.size ||
  	    ecbdata->diff_words->plus.text.size)
  		diff_words_show(ecbdata->diff_words);
  }
  
  static void diff_filespec_load_driver(struct diff_filespec *one)
  {
  	/* Use already-loaded driver */
  	if (one->driver)
  		return;
  
  	if (S_ISREG(one->mode))
  		one->driver = userdiff_find_by_path(one->path);
  
  	/* Fallback to default settings */
  	if (!one->driver)
  		one->driver = userdiff_find_by_name("default");
  }
  
  static const char *userdiff_word_regex(struct diff_filespec *one)
  {
  	diff_filespec_load_driver(one);
  	return one->driver->word_regex;
  }
  
  static void init_diff_words_data(struct emit_callback *ecbdata,
  				 struct diff_options *orig_opts,
  				 struct diff_filespec *one,
  				 struct diff_filespec *two)
  {
  	int i;
  	struct diff_options *o = xmalloc(sizeof(struct diff_options));
  	memcpy(o, orig_opts, sizeof(struct diff_options));
  
  	ecbdata->diff_words =
  		xcalloc(1, sizeof(struct diff_words_data));
  	ecbdata->diff_words->type = o->word_diff;
  	ecbdata->diff_words->opt = o;
  	if (!o->word_regex)
  		o->word_regex = userdiff_word_regex(one);
  	if (!o->word_regex)
  		o->word_regex = userdiff_word_regex(two);
  	if (!o->word_regex)
  		o->word_regex = diff_word_regex_cfg;
  	if (o->word_regex) {
  		ecbdata->diff_words->word_regex = (regex_t *)
  			xmalloc(sizeof(regex_t));
  		if (regcomp(ecbdata->diff_words->word_regex,
  			    o->word_regex,
  			    REG_EXTENDED | REG_NEWLINE))
  			die ("Invalid regular expression: %s",
  			     o->word_regex);
  	}
  	for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
  		if (o->word_diff == diff_words_styles[i].type) {
  			ecbdata->diff_words->style =
  				&diff_words_styles[i];
  			break;
  		}
  	}
  	if (want_color(o->use_color)) {
  		struct diff_words_style *st = ecbdata->diff_words->style;
  		st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
  		st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
  		st->ctx.color = diff_get_color_opt(o, DIFF_CONTEXT);
  	}
  }
  
  static void free_diff_words_data(struct emit_callback *ecbdata)
  {
  	if (ecbdata->diff_words) {
  		diff_words_flush(ecbdata);
  		free (ecbdata->diff_words->opt);
  		free (ecbdata->diff_words->minus.text.ptr);
  		free (ecbdata->diff_words->minus.orig);
  		free (ecbdata->diff_words->plus.text.ptr);
  		free (ecbdata->diff_words->plus.orig);
  		if (ecbdata->diff_words->word_regex) {
  			regfree(ecbdata->diff_words->word_regex);
  			free(ecbdata->diff_words->word_regex);
  		}
  		free(ecbdata->diff_words);
  		ecbdata->diff_words = NULL;
  	}
  }
  
  const char *diff_get_color(int diff_use_color, enum color_diff ix)
  {
  	if (want_color(diff_use_color))
  		return diff_colors[ix];
  	return "";
  }
  
  const char *diff_line_prefix(struct diff_options *opt)
  {
  	struct strbuf *msgbuf;
  	if (!opt->output_prefix)
  		return "";
  
  	msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
  	return msgbuf->buf;
  }
  
  static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
  {
  	const char *cp;
  	unsigned long allot;
  	size_t l = len;
  
  	if (ecb->truncate)
  		return ecb->truncate(line, len);
  	cp = line;
  	allot = l;
  	while (0 < l) {
  		(void) utf8_width(&cp, &l);
  		if (!cp)
  			break; /* truncated in the middle? */
  	}
  	return allot - l;
  }
  
  static void find_lno(const char *line, struct emit_callback *ecbdata)
  {
  	const char *p;
  	ecbdata->lno_in_preimage = 0;
  	ecbdata->lno_in_postimage = 0;
  	p = strchr(line, '-');
  	if (!p)
  		return; /* cannot happen */
  	ecbdata->lno_in_preimage = strtol(p + 1, NULL, 10);
  	p = strchr(p, '+');
  	if (!p)
  		return; /* cannot happen */
  	ecbdata->lno_in_postimage = strtol(p + 1, NULL, 10);
  }
  
  static void fn_out_consume(void *priv, char *line, unsigned long len)
  {
  	struct emit_callback *ecbdata = priv;
  	const char *meta = diff_get_color(ecbdata->color_diff, DIFF_METAINFO);
  	const char *context = diff_get_color(ecbdata->color_diff, DIFF_CONTEXT);
  	const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
  	struct diff_options *o = ecbdata->opt;
  	const char *line_prefix = diff_line_prefix(o);
  
  	if (ecbdata->header) {
  		fprintf(ecbdata->opt->file, "%s", ecbdata->header->buf);
  		strbuf_reset(ecbdata->header);
  		ecbdata->header = NULL;
  	}
  	*(ecbdata->found_changesp) = 1;
  
  	if (ecbdata->label_path[0]) {
  		const char *name_a_tab, *name_b_tab;
  
  		name_a_tab = strchr(ecbdata->label_path[0], ' ') ? "\t" : "";
  		name_b_tab = strchr(ecbdata->label_path[1], ' ') ? "\t" : "";
  
  		fprintf(ecbdata->opt->file, "%s%s--- %s%s%s\n",
  			line_prefix, meta, ecbdata->label_path[0], reset, name_a_tab);
  		fprintf(ecbdata->opt->file, "%s%s+++ %s%s%s\n",
  			line_prefix, meta, ecbdata->label_path[1], reset, name_b_tab);
  		ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
  	}
  
  	if (diff_suppress_blank_empty
  	    && len == 2 && line[0] == ' ' && line[1] == '\n') {
  		line[0] = '\n';
  		len = 1;
  	}
  
  	if (line[0] == '@') {
  		if (ecbdata->diff_words)
  			diff_words_flush(ecbdata);
  		len = sane_truncate_line(ecbdata, line, len);
  		find_lno(line, ecbdata);
  		emit_hunk_header(ecbdata, line, len);
  		if (line[len-1] != '\n')
  			putc('\n', ecbdata->opt->file);
  		return;
  	}
  
  	if (len < 1) {
  		emit_line(ecbdata->opt, reset, reset, line, len);
  		if (ecbdata->diff_words
  		    && ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN)
  			fputs("~\n", ecbdata->opt->file);
  		return;
  	}
  
  	if (ecbdata->diff_words) {
  		if (line[0] == '-') {
  			diff_words_append(line, len,
  					  &ecbdata->diff_words->minus);
  			return;
  		} else if (line[0] == '+') {
  			diff_words_append(line, len,
  					  &ecbdata->diff_words->plus);
  			return;
  		} else if (starts_with(line, "\\ ")) {
  			/*
  			 * Eat the "no newline at eof" marker as if we
  			 * saw a "+" or "-" line with nothing on it,
  			 * and return without diff_words_flush() to
  			 * defer processing. If this is the end of
  			 * preimage, more "+" lines may come after it.
  			 */
  			return;
  		}
  		diff_words_flush(ecbdata);
  		if (ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN) {
  			emit_line(ecbdata->opt, context, reset, line, len);
  			fputs("~\n", ecbdata->opt->file);
  		} else {
  			/*
  			 * Skip the prefix character, if any.  With
  			 * diff_suppress_blank_empty, there may be
  			 * none.
  			 */
  			if (line[0] != '\n') {
  			      line++;
  			      len--;
  			}
  			emit_line(ecbdata->opt, context, reset, line, len);
  		}
  		return;
  	}
  
  	switch (line[0]) {
  	case '+':
  		ecbdata->lno_in_postimage++;
  		emit_add_line(reset, ecbdata, line + 1, len - 1);
  		break;
  	case '-':
  		ecbdata->lno_in_preimage++;
  		emit_del_line(reset, ecbdata, line + 1, len - 1);
  		break;
  	case ' ':
  		ecbdata->lno_in_postimage++;
  		ecbdata->lno_in_preimage++;
  		emit_context_line(reset, ecbdata, line + 1, len - 1);
  		break;
  	default:
  		/* incomplete line at the end */
  		ecbdata->lno_in_preimage++;
  		emit_line(ecbdata->opt,
  			  diff_get_color(ecbdata->color_diff, DIFF_CONTEXT),
  			  reset, line, len);
  		break;
  	}
  }
  
  static char *pprint_rename(const char *a, const char *b)
  {
  	const char *old = a;
  	const char *new = b;
  	struct strbuf name = STRBUF_INIT;
  	int pfx_length, sfx_length;
  	int pfx_adjust_for_slash;
  	int len_a = strlen(a);
  	int len_b = strlen(b);
  	int a_midlen, b_midlen;
  	int qlen_a = quote_c_style(a, NULL, NULL, 0);
  	int qlen_b = quote_c_style(b, NULL, NULL, 0);
  
  	if (qlen_a || qlen_b) {
  		quote_c_style(a, &name, NULL, 0);
  		strbuf_addstr(&name, " => ");
  		quote_c_style(b, &name, NULL, 0);
  		return strbuf_detach(&name, NULL);
  	}
  
  	/* Find common prefix */
  	pfx_length = 0;
  	while (*old && *new && *old == *new) {
  		if (*old == '/')
  			pfx_length = old - a + 1;
  		old++;
  		new++;
  	}
  
  	/* Find common suffix */
  	old = a + len_a;
  	new = b + len_b;
  	sfx_length = 0;
  	/*
  	 * If there is a common prefix, it must end in a slash.  In
  	 * that case we let this loop run 1 into the prefix to see the
  	 * same slash.
  	 *
  	 * If there is no common prefix, we cannot do this as it would
  	 * underrun the input strings.
  	 */
  	pfx_adjust_for_slash = (pfx_length ? 1 : 0);
  	while (a + pfx_length - pfx_adjust_for_slash <= old &&
  	       b + pfx_length - pfx_adjust_for_slash <= new &&
  	       *old == *new) {
  		if (*old == '/')
  			sfx_length = len_a - (old - a);
  		old--;
  		new--;
  	}
  
  	/*
  	 * pfx{mid-a => mid-b}sfx
  	 * {pfx-a => pfx-b}sfx
  	 * pfx{sfx-a => sfx-b}
  	 * name-a => name-b
  	 */
  	a_midlen = len_a - pfx_length - sfx_length;
  	b_midlen = len_b - pfx_length - sfx_length;
  	if (a_midlen < 0)
  		a_midlen = 0;
  	if (b_midlen < 0)
  		b_midlen = 0;
  
  	strbuf_grow(&name, pfx_length + a_midlen + b_midlen + sfx_length + 7);
  	if (pfx_length + sfx_length) {
  		strbuf_add(&name, a, pfx_length);
  		strbuf_addch(&name, '{');
  	}
  	strbuf_add(&name, a + pfx_length, a_midlen);
  	strbuf_addstr(&name, " => ");
  	strbuf_add(&name, b + pfx_length, b_midlen);
  	if (pfx_length + sfx_length) {
  		strbuf_addch(&name, '}');
  		strbuf_add(&name, a + len_a - sfx_length, sfx_length);
  	}
  	return strbuf_detach(&name, NULL);
  }
  
  struct diffstat_t {
  	int nr;
  	int alloc;
  	struct diffstat_file {
  		char *from_name;
  		char *name;
  		char *print_name;
  		unsigned is_unmerged:1;
  		unsigned is_binary:1;
  		unsigned is_renamed:1;
  		unsigned is_interesting:1;
  		uintmax_t added, deleted;
  	} **files;
  };
  
  static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
  					  const char *name_a,
  					  const char *name_b)
  {
  	struct diffstat_file *x;
  	x = xcalloc(1, sizeof(*x));
  	ALLOC_GROW(diffstat->files, diffstat->nr + 1, diffstat->alloc);
  	diffstat->files[diffstat->nr++] = x;
  	if (name_b) {
  		x->from_name = xstrdup(name_a);
  		x->name = xstrdup(name_b);
  		x->is_renamed = 1;
  	}
  	else {
  		x->from_name = NULL;
  		x->name = xstrdup(name_a);
  	}
  	return x;
  }
  
  static void diffstat_consume(void *priv, char *line, unsigned long len)
  {
  	struct diffstat_t *diffstat = priv;
  	struct diffstat_file *x = diffstat->files[diffstat->nr - 1];
  
  	if (line[0] == '+')
  		x->added++;
  	else if (line[0] == '-')
  		x->deleted++;
  }
  
  const char mime_boundary_leader[] = "------------";
  
  static int scale_linear(int it, int width, int max_change)
  {
  	if (!it)
  		return 0;
  	/*
  	 * make sure that at least one '-' or '+' is printed if
  	 * there is any change to this path. The easiest way is to
  	 * scale linearly as if the alloted width is one column shorter
  	 * than it is, and then add 1 to the result.
  	 */
  	return 1 + (it * (width - 1) / max_change);
  }
  
  static void show_name(FILE *file,
  		      const char *prefix, const char *name, int len)
  {
  	fprintf(file, " %s%-*s |", prefix, len, name);
  }
  
  static void show_graph(FILE *file, char ch, int cnt, const char *set, const char *reset)
  {
  	if (cnt <= 0)
  		return;
  	fprintf(file, "%s", set);
  	while (cnt--)
  		putc(ch, file);
  	fprintf(file, "%s", reset);
  }
  
  static void fill_print_name(struct diffstat_file *file)
  {
  	char *pname;
  
  	if (file->print_name)
  		return;
  
  	if (!file->is_renamed) {
  		struct strbuf buf = STRBUF_INIT;
  		if (quote_c_style(file->name, &buf, NULL, 0)) {
  			pname = strbuf_detach(&buf, NULL);
  		} else {
  			pname = file->name;
  			strbuf_release(&buf);
  		}
  	} else {
  		pname = pprint_rename(file->from_name, file->name);
  	}
  	file->print_name = pname;
  }
  
  int print_stat_summary(FILE *fp, int files, int insertions, int deletions)
  {
  	struct strbuf sb = STRBUF_INIT;
  	int ret;
  
  	if (!files) {
  		assert(insertions == 0 && deletions == 0);
  		return fprintf(fp, "%s\n", " 0 files changed");
  	}
  
  	strbuf_addf(&sb,
  		    (files == 1) ? " %d file changed" : " %d files changed",
  		    files);
  
  	/*
  	 * For binary diff, the caller may want to print "x files
  	 * changed" with insertions == 0 && deletions == 0.
  	 *
  	 * Not omitting "0 insertions(+), 0 deletions(-)" in this case
  	 * is probably less confusing (i.e skip over "2 files changed
  	 * but nothing about added/removed lines? Is this a bug in Git?").
  	 */
  	if (insertions || deletions == 0) {
  		strbuf_addf(&sb,
  			    (insertions == 1) ? ", %d insertion(+)" : ", %d insertions(+)",
  			    insertions);
  	}
  
  	if (deletions || insertions == 0) {
  		strbuf_addf(&sb,
  			    (deletions == 1) ? ", %d deletion(-)" : ", %d deletions(-)",
  			    deletions);
  	}
  	strbuf_addch(&sb, '\n');
  	ret = fputs(sb.buf, fp);
  	strbuf_release(&sb);
  	return ret;
  }
  
  static void show_stats(struct diffstat_t *data, struct diff_options *options)
  {
  	int i, len, add, del, adds = 0, dels = 0;
  	uintmax_t max_change = 0, max_len = 0;
  	int total_files = data->nr, count;
  	int width, name_width, graph_width, number_width = 0, bin_width = 0;
  	const char *reset, *add_c, *del_c;
  	const char *line_prefix = "";
  	int extra_shown = 0;
  
  	if (data->nr == 0)
  		return;
  
  	line_prefix = diff_line_prefix(options);
  	count = options->stat_count ? options->stat_count : data->nr;
  
  	reset = diff_get_color_opt(options, DIFF_RESET);
  	add_c = diff_get_color_opt(options, DIFF_FILE_NEW);
  	del_c = diff_get_color_opt(options, DIFF_FILE_OLD);
  
  	/*
  	 * Find the longest filename and max number of changes
  	 */
  	for (i = 0; (i < count) && (i < data->nr); i++) {
  		struct diffstat_file *file = data->files[i];
  		uintmax_t change = file->added + file->deleted;
  
  		if (!file->is_interesting && (change == 0)) {
  			count++; /* not shown == room for one more */
  			continue;
  		}
  		fill_print_name(file);
  		len = strlen(file->print_name);
  		if (max_len < len)
  			max_len = len;
  
  		if (file->is_unmerged) {
  			/* "Unmerged" is 8 characters */
  			bin_width = bin_width < 8 ? 8 : bin_width;
  			continue;
  		}
  		if (file->is_binary) {
  			/* "Bin XXX -> YYY bytes" */
  			int w = 14 + decimal_width(file->added)
  				+ decimal_width(file->deleted);
  			bin_width = bin_width < w ? w : bin_width;
  			/* Display change counts aligned with "Bin" */
  			number_width = 3;
  			continue;
  		}
  
  		if (max_change < change)
  			max_change = change;
  	}
  	count = i; /* where we can stop scanning in data->files[] */
  
  	/*
  	 * We have width = stat_width or term_columns() columns total.
  	 * We want a maximum of min(max_len, stat_name_width) for the name part.
  	 * We want a maximum of min(max_change, stat_graph_width) for the +- part.
  	 * We also need 1 for " " and 4 + decimal_width(max_change)
  	 * for " | NNNN " and one the empty column at the end, altogether
  	 * 6 + decimal_width(max_change).
  	 *
  	 * If there's not enough space, we will use the smaller of
  	 * stat_name_width (if set) and 5/8*width for the filename,
  	 * and the rest for constant elements + graph part, but no more
  	 * than stat_graph_width for the graph part.
  	 * (5/8 gives 50 for filename and 30 for the constant parts + graph
  	 * for the standard terminal size).
  	 *
  	 * In other words: stat_width limits the maximum width, and
  	 * stat_name_width fixes the maximum width of the filename,
  	 * and is also used to divide available columns if there
  	 * aren't enough.
  	 *
  	 * Binary files are displayed with "Bin XXX -> YYY bytes"
  	 * instead of the change count and graph. This part is treated
  	 * similarly to the graph part, except that it is not
  	 * "scaled". If total width is too small to accommodate the
  	 * guaranteed minimum width of the filename part and the
  	 * separators and this message, this message will "overflow"
  	 * making the line longer than the maximum width.
  	 */
  
  	if (options->stat_width == -1)
  		width = term_columns() - options->output_prefix_length;
  	else
  		width = options->stat_width ? options->stat_width : 80;
  	number_width = decimal_width(max_change) > number_width ?
  		decimal_width(max_change) : number_width;
  
  	if (options->stat_graph_width == -1)
  		options->stat_graph_width = diff_stat_graph_width;
  
  	/*
  	 * Guarantee 3/8*16==6 for the graph part
  	 * and 5/8*16==10 for the filename part
  	 */
  	if (width < 16 + 6 + number_width)
  		width = 16 + 6 + number_width;
  
  	/*
  	 * First assign sizes that are wanted, ignoring available width.
  	 * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
  	 * starting from "XXX" should fit in graph_width.
  	 */
  	graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
  	if (options->stat_graph_width &&
  	    options->stat_graph_width < graph_width)
  		graph_width = options->stat_graph_width;
  
  	name_width = (options->stat_name_width > 0 &&
  		      options->stat_name_width < max_len) ?
  		options->stat_name_width : max_len;
  
  	/*
  	 * Adjust adjustable widths not to exceed maximum width
  	 */
  	if (name_width + number_width + 6 + graph_width > width) {
  		if (graph_width > width * 3/8 - number_width - 6) {
  			graph_width = width * 3/8 - number_width - 6;
  			if (graph_width < 6)
  				graph_width = 6;
  		}
  
  		if (options->stat_graph_width &&
  		    graph_width > options->stat_graph_width)
  			graph_width = options->stat_graph_width;
  		if (name_width > width - number_width - 6 - graph_width)
  			name_width = width - number_width - 6 - graph_width;
  		else
  			graph_width = width - number_width - 6 - name_width;
  	}
  
  	/*
  	 * From here name_width is the width of the name area,
  	 * and graph_width is the width of the graph area.
  	 * max_change is used to scale graph properly.
  	 */
  	for (i = 0; i < count; i++) {
  		const char *prefix = "";
  		struct diffstat_file *file = data->files[i];
  		char *name = file->print_name;
  		uintmax_t added = file->added;
  		uintmax_t deleted = file->deleted;
  		int name_len;
  
  		if (!file->is_interesting && (added + deleted == 0))
  			continue;
  
  		/*
  		 * "scale" the filename
  		 */
  		len = name_width;
  		name_len = strlen(name);
  		if (name_width < name_len) {
  			char *slash;
  			prefix = "...";
  			len -= 3;
  			name += name_len - len;
  			slash = strchr(name, '/');
  			if (slash)
  				name = slash;
  		}
  
  		if (file->is_binary) {
  			fprintf(options->file, "%s", line_prefix);
  			show_name(options->file, prefix, name, len);
  			fprintf(options->file, " %*s", number_width, "Bin");
  			if (!added && !deleted) {
  				putc('\n', options->file);
  				continue;
  			}
  			fprintf(options->file, " %s%"PRIuMAX"%s",
  				del_c, deleted, reset);
  			fprintf(options->file, " -> ");
  			fprintf(options->file, "%s%"PRIuMAX"%s",
  				add_c, added, reset);
  			fprintf(options->file, " bytes");
  			fprintf(options->file, "\n");
  			continue;
  		}
  		else if (file->is_unmerged) {
  			fprintf(options->file, "%s", line_prefix);
  			show_name(options->file, prefix, name, len);
  			fprintf(options->file, " Unmerged\n");
  			continue;
  		}
  
  		/*
  		 * scale the add/delete
  		 */
  		add = added;
  		del = deleted;
  
  		if (graph_width <= max_change) {
  			int total = scale_linear(add + del, graph_width, max_change);
  			if (total < 2 && add && del)
  				/* width >= 2 due to the sanity check */
  				total = 2;
  			if (add < del) {
  				add = scale_linear(add, graph_width, max_change);
  				del = total - add;
  			} else {
  				del = scale_linear(del, graph_width, max_change);
  				add = total - del;
  			}
  		}
  		fprintf(options->file, "%s", line_prefix);
  		show_name(options->file, prefix, name, len);
  		fprintf(options->file, " %*"PRIuMAX"%s",
  			number_width, added + deleted,
  			added + deleted ? " " : "");
  		show_graph(options->file, '+', add, add_c, reset);
  		show_graph(options->file, '-', del, del_c, reset);
  		fprintf(options->file, "\n");
  	}
  
  	for (i = 0; i < data->nr; i++) {
  		struct diffstat_file *file = data->files[i];
  		uintmax_t added = file->added;
  		uintmax_t deleted = file->deleted;
  
  		if (file->is_unmerged ||
  		    (!file->is_interesting && (added + deleted == 0))) {
  			total_files--;
  			continue;
  		}
  
  		if (!file->is_binary) {
  			adds += added;
  			dels += deleted;
  		}
  		if (i < count)
  			continue;
  		if (!extra_shown)
  			fprintf(options->file, "%s ...\n", line_prefix);
  		extra_shown = 1;
  	}
  	fprintf(options->file, "%s", line_prefix);
  	print_stat_summary(options->file, total_files, adds, dels);
  }
  
  static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
  {
  	int i, adds = 0, dels = 0, total_files = data->nr;
  
  	if (data->nr == 0)
  		return;
  
  	for (i = 0; i < data->nr; i++) {
  		int added = data->files[i]->added;
  		int deleted= data->files[i]->deleted;
  
  		if (data->files[i]->is_unmerged ||
  		    (!data->files[i]->is_interesting && (added + deleted == 0))) {
  			total_files--;
  		} else if (!data->files[i]->is_binary) { /* don't count bytes */
  			adds += added;
  			dels += deleted;
  		}
  	}
  	fprintf(options->file, "%s", diff_line_prefix(options));
  	print_stat_summary(options->file, total_files, adds, dels);
  }
  
  static void show_numstat(struct diffstat_t *data, struct diff_options *options)
  {
  	int i;
  
  	if (data->nr == 0)
  		return;
  
  	for (i = 0; i < data->nr; i++) {
  		struct diffstat_file *file = data->files[i];
  
  		fprintf(options->file, "%s", diff_line_prefix(options));
  
  		if (file->is_binary)
  			fprintf(options->file, "-\t-\t");
  		else
  			fprintf(options->file,
  				"%"PRIuMAX"\t%"PRIuMAX"\t",
  				file->added, file->deleted);
  		if (options->line_termination) {
  			fill_print_name(file);
  			if (!file->is_renamed)
  				write_name_quoted(file->name, options->file,
  						  options->line_termination);
  			else {
  				fputs(file->print_name, options->file);
  				putc(options->line_termination, options->file);
  			}
  		} else {
  			if (file->is_renamed) {
  				putc('\0', options->file);
  				write_name_quoted(file->from_name, options->file, '\0');
  			}
  			write_name_quoted(file->name, options->file, '\0');
  		}
  	}
  }
  
  struct dirstat_file {
  	const char *name;
  	unsigned long changed;
  };
  
  struct dirstat_dir {
  	struct dirstat_file *files;
  	int alloc, nr, permille, cumulative;
  };
  
  static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
  		unsigned long changed, const char *base, int baselen)
  {
  	unsigned long this_dir = 0;
  	unsigned int sources = 0;
  	const char *line_prefix = diff_line_prefix(opt);
  
  	while (dir->nr) {
  		struct dirstat_file *f = dir->files;
  		int namelen = strlen(f->name);
  		unsigned long this;
  		char *slash;
  
  		if (namelen < baselen)
  			break;
  		if (memcmp(f->name, base, baselen))
  			break;
  		slash = strchr(f->name + baselen, '/');
  		if (slash) {
  			int newbaselen = slash + 1 - f->name;
  			this = gather_dirstat(opt, dir, changed, f->name, newbaselen);
  			sources++;
  		} else {
  			this = f->changed;
  			dir->files++;
  			dir->nr--;
  			sources += 2;
  		}
  		this_dir += this;
  	}
  
  	/*
  	 * We don't report dirstat's for
  	 *  - the top level
  	 *  - or cases where everything came from a single directory
  	 *    under this directory (sources == 1).
  	 */
  	if (baselen && sources != 1) {
  		if (this_dir) {
  			int permille = this_dir * 1000 / changed;
  			if (permille >= dir->permille) {
  				fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
  					permille / 10, permille % 10, baselen, base);
  				if (!dir->cumulative)
  					return 0;
  			}
  		}
  	}
  	return this_dir;
  }
  
  static int dirstat_compare(const void *_a, const void *_b)
  {
  	const struct dirstat_file *a = _a;
  	const struct dirstat_file *b = _b;
  	return strcmp(a->name, b->name);
  }
  
  static void show_dirstat(struct diff_options *options)
  {
  	int i;
  	unsigned long changed;
  	struct dirstat_dir dir;
  	struct diff_queue_struct *q = &diff_queued_diff;
  
  	dir.files = NULL;
  	dir.alloc = 0;
  	dir.nr = 0;
  	dir.permille = options->dirstat_permille;
  	dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
  
  	changed = 0;
  	for (i = 0; i < q->nr; i++) {
  		struct diff_filepair *p = q->queue[i];
  		const char *name;
  		unsigned long copied, added, damage;
  		int content_changed;
  
  		name = p->two->path ? p->two->path : p->one->path;
  
  		if (p->one->sha1_valid && p->two->sha1_valid)
  			content_changed = hashcmp(p->one->sha1, p->two->sha1);
  		else
  			content_changed = 1;
  
  		if (!content_changed) {
  			/*
  			 * The SHA1 has not changed, so pre-/post-content is
  			 * identical. We can therefore skip looking at the
  			 * file contents altogether.
  			 */
  			damage = 0;
  			goto found_damage;
  		}
  
  		if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE)) {
  			/*
  			 * In --dirstat-by-file mode, we don't really need to
  			 * look at the actual file contents at all.
  			 * The fact that the SHA1 changed is enough for us to
  			 * add this file to the list of results
  			 * (with each file contributing equal damage).
  			 */
  			damage = 1;
  			goto found_damage;
  		}
  
  		if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
  			diff_populate_filespec(p->one, 0);
  			diff_populate_filespec(p->two, 0);
  			diffcore_count_changes(p->one, p->two, NULL, NULL, 0,
  					       &copied, &added);
  			diff_free_filespec_data(p->one);
  			diff_free_filespec_data(p->two);
  		} else if (DIFF_FILE_VALID(p->one)) {
  			diff_populate_filespec(p->one, CHECK_SIZE_ONLY);
  			copied = added = 0;
  			diff_free_filespec_data(p->one);
  		} else if (DIFF_FILE_VALID(p->two)) {
  			diff_populate_filespec(p->two, CHECK_SIZE_ONLY);
  			copied = 0;
  			added = p->two->size;
  			diff_free_filespec_data(p->two);
  		} else
  			continue;
  
  		/*
  		 * Original minus copied is the removed material,
  		 * added is the new material.  They are both damages
  		 * made to the preimage.
  		 * If the resulting damage is zero, we know that
  		 * diffcore_count_changes() considers the two entries to
  		 * be identical, but since content_changed is true, we
  		 * know that there must have been _some_ kind of change,
  		 * so we force all entries to have damage > 0.
  		 */
  		damage = (p->one->size - copied) + added;
  		if (!damage)
  			damage = 1;
  
  found_damage:
  		ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
  		dir.files[dir.nr].name = name;
  		dir.files[dir.nr].changed = damage;
  		changed += damage;
  		dir.nr++;
  	}
  
  	/* This can happen even with many files, if everything was renames */
  	if (!changed)
  		return;
  
  	/* Show all directories with more than x% of the changes */
  	qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
  	gather_dirstat(options, &dir, changed, "", 0);
  }
  
  static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *options)
  {
  	int i;
  	unsigned long changed;
  	struct dirstat_dir dir;
  
  	if (data->nr == 0)
  		return;
  
  	dir.files = NULL;
  	dir.alloc = 0;
  	dir.nr = 0;
  	dir.permille = options->dirstat_permille;
  	dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
  
  	changed = 0;
  	for (i = 0; i < data->nr; i++) {
  		struct diffstat_file *file = data->files[i];
  		unsigned long damage = file->added + file->deleted;
  		if (file->is_binary)
  			/*
  			 * binary files counts bytes, not lines. Must find some
  			 * way to normalize binary bytes vs. textual lines.
  			 * The following heuristic assumes that there are 64
  			 * bytes per "line".
  			 * This is stupid and ugly, but very cheap...
  			 */
  			damage = (damage + 63) / 64;
  		ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
  		dir.files[dir.nr].name = file->name;
  		dir.files[dir.nr].changed = damage;
  		changed += damage;
  		dir.nr++;
  	}
  
  	/* This can happen even with many files, if everything was renames */
  	if (!changed)
  		return;
  
  	/* Show all directories with more than x% of the changes */
  	qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
  	gather_dirstat(options, &dir, changed, "", 0);
  }
  
  static void free_diffstat_info(struct diffstat_t *diffstat)
  {
  	int i;
  	for (i = 0; i < diffstat->nr; i++) {
  		struct diffstat_file *f = diffstat->files[i];
  		if (f->name != f->print_name)
  			free(f->print_name);
  		free(f->name);
  		free(f->from_name);
  		free(f);
  	}
  	free(diffstat->files);
  }
  
  struct checkdiff_t {
  	const char *filename;
  	int lineno;
  	int conflict_marker_size;
  	struct diff_options *o;
  	unsigned ws_rule;
  	unsigned status;
  };
  
  static int is_conflict_marker(const char *line, int marker_size, unsigned long len)
  {
  	char firstchar;
  	int cnt;
  
  	if (len < marker_size + 1)
  		return 0;
  	firstchar = line[0];
  	switch (firstchar) {
  	case '=': case '>': case '<': case '|':
  		break;
  	default:
  		return 0;
  	}
  	for (cnt = 1; cnt < marker_size; cnt++)
  		if (line[cnt] != firstchar)
  			return 0;
  	/* line[1] thru line[marker_size-1] are same as firstchar */
  	if (len < marker_size + 1 || !isspace(line[marker_size]))
  		return 0;
  	return 1;
  }
  
  static void checkdiff_consume(void *priv, char *line, unsigned long len)
  {
  	struct checkdiff_t *data = priv;
  	int marker_size = data->conflict_marker_size;
  	const char *ws = diff_get_color(data->o->use_color, DIFF_WHITESPACE);
  	const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
  	const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
  	char *err;
  	const char *line_prefix;
  
  	assert(data->o);
  	line_prefix = diff_line_prefix(data->o);
  
  	if (line[0] == '+') {
  		unsigned bad;
  		data->lineno++;
  		if (is_conflict_marker(line + 1, marker_size, len - 1)) {
  			data->status |= 1;
  			fprintf(data->o->file,
  				"%s%s:%d: leftover conflict marker\n",
  				line_prefix, data->filename, data->lineno);
  		}
  		bad = ws_check(line + 1, len - 1, data->ws_rule);
  		if (!bad)
  			return;
  		data->status |= bad;
  		err = whitespace_error_string(bad);
  		fprintf(data->o->file, "%s%s:%d: %s.\n",
  			line_prefix, data->filename, data->lineno, err);
  		free(err);
  		emit_line(data->o, set, reset, line, 1);
  		ws_check_emit(line + 1, len - 1, data->ws_rule,
  			      data->o->file, set, reset, ws);
  	} else if (line[0] == ' ') {
  		data->lineno++;
  	} else if (line[0] == '@') {
  		char *plus = strchr(line, '+');
  		if (plus)
  			data->lineno = strtol(plus, NULL, 10) - 1;
  		else
  			die("invalid diff");
  	}
  }
  
  static unsigned char *deflate_it(char *data,
  				 unsigned long size,
  				 unsigned long *result_size)
  {
  	int bound;
  	unsigned char *deflated;
  	git_zstream stream;
  
  	git_deflate_init(&stream, zlib_compression_level);
  	bound = git_deflate_bound(&stream, size);
  	deflated = xmalloc(bound);
  	stream.next_out = deflated;
  	stream.avail_out = bound;
  
  	stream.next_in = (unsigned char *)data;
  	stream.avail_in = size;
  	while (git_deflate(&stream, Z_FINISH) == Z_OK)
  		; /* nothing */
  	git_deflate_end(&stream);
  	*result_size = stream.total_out;
  	return deflated;
  }
  
  static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two,
  				  const char *prefix)
  {
  	void *cp;
  	void *delta;
  	void *deflated;
  	void *data;
  	unsigned long orig_size;
  	unsigned long delta_size;
  	unsigned long deflate_size;
  	unsigned long data_size;
  
  	/* We could do deflated delta, or we could do just deflated two,
  	 * whichever is smaller.
  	 */
  	delta = NULL;
  	deflated = deflate_it(two->ptr, two->size, &deflate_size);
  	if (one->size && two->size) {
  		delta = diff_delta(one->ptr, one->size,
  				   two->ptr, two->size,
  				   &delta_size, deflate_size);
  		if (delta) {
  			void *to_free = delta;
  			orig_size = delta_size;
  			delta = deflate_it(delta, delta_size, &delta_size);
  			free(to_free);
  		}
  	}
  
  	if (delta && delta_size < deflate_size) {
  		fprintf(file, "%sdelta %lu\n", prefix, orig_size);
  		free(deflated);
  		data = delta;
  		data_size = delta_size;
  	}
  	else {
  		fprintf(file, "%sliteral %lu\n", prefix, two->size);
  		free(delta);
  		data = deflated;
  		data_size = deflate_size;
  	}
  
  	/* emit data encoded in base85 */
  	cp = data;
  	while (data_size) {
  		int bytes = (52 < data_size) ? 52 : data_size;
  		char line[70];
  		data_size -= bytes;
  		if (bytes <= 26)
  			line[0] = bytes + 'A' - 1;
  		else
  			line[0] = bytes - 26 + 'a' - 1;
  		encode_85(line + 1, cp, bytes);
  		cp = (char *) cp + bytes;
  		fprintf(file, "%s", prefix);
  		fputs(line, file);
  		fputc('\n', file);
  	}
  	fprintf(file, "%s\n", prefix);
  	free(data);
  }
  
  static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two,
  			     const char *prefix)
  {
  	fprintf(file, "%sGIT binary patch\n", prefix);
  	emit_binary_diff_body(file, one, two, prefix);
  	emit_binary_diff_body(file, two, one, prefix);
  }
  
  int diff_filespec_is_binary(struct diff_filespec *one)
  {
  	if (one->is_binary == -1) {
  		diff_filespec_load_driver(one);
  		if (one->driver->binary != -1)
  			one->is_binary = one->driver->binary;
  		else {
  			if (!one->data && DIFF_FILE_VALID(one))
  				diff_populate_filespec(one, CHECK_BINARY);
  			if (one->is_binary == -1 && one->data)
  				one->is_binary = buffer_is_binary(one->data,
  						one->size);
  			if (one->is_binary == -1)
  				one->is_binary = 0;
  		}
  	}
  	return one->is_binary;
  }
  
  static const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespec *one)
  {
  	diff_filespec_load_driver(one);
  	return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
  }
  
  void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
  {
  	if (!options->a_prefix)
  		options->a_prefix = a;
  	if (!options->b_prefix)
  		options->b_prefix = b;
  }
  
  struct userdiff_driver *get_textconv(struct diff_filespec *one)
  {
  	if (!DIFF_FILE_VALID(one))
  		return NULL;
  
  	diff_filespec_load_driver(one);
  	return userdiff_get_textconv(one->driver);
  }
  
  static void builtin_diff(const char *name_a,
  			 const char *name_b,
  			 struct diff_filespec *one,
  			 struct diff_filespec *two,
  			 const char *xfrm_msg,
  			 int must_show_header,
  			 struct diff_options *o,
  			 int complete_rewrite)
  {
  	mmfile_t mf1, mf2;
  	const char *lbl[2];
  	char *a_one, *b_two;
  	const char *meta = diff_get_color_opt(o, DIFF_METAINFO);
  	const char *reset = diff_get_color_opt(o, DIFF_RESET);
  	const char *a_prefix, *b_prefix;
  	struct userdiff_driver *textconv_one = NULL;
  	struct userdiff_driver *textconv_two = NULL;
  	struct strbuf header = STRBUF_INIT;
  	const char *line_prefix = diff_line_prefix(o);
  
  	if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
  			(!one->mode || S_ISGITLINK(one->mode)) &&
  			(!two->mode || S_ISGITLINK(two->mode))) {
  		const char *del = diff_get_color_opt(o, DIFF_FILE_OLD);
  		const char *add = diff_get_color_opt(o, DIFF_FILE_NEW);
  		show_submodule_summary(o->file, one->path ? one->path : two->path,
  				line_prefix,
  				one->sha1, two->sha1, two->dirty_submodule,
  				meta, del, add, reset);
  		return;
  	}
  
  	if (DIFF_OPT_TST(o, ALLOW_TEXTCONV)) {
  		textconv_one = get_textconv(one);
  		textconv_two = get_textconv(two);
  	}
  
  	diff_set_mnemonic_prefix(o, "a/", "b/");
  	if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
  		a_prefix = o->b_prefix;
  		b_prefix = o->a_prefix;
  	} else {
  		a_prefix = o->a_prefix;
  		b_prefix = o->b_prefix;
  	}
  
  	/* Never use a non-valid filename anywhere if at all possible */
  	name_a = DIFF_FILE_VALID(one) ? name_a : name_b;
  	name_b = DIFF_FILE_VALID(two) ? name_b : name_a;
  
  	a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
  	b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
  	lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
  	lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
  	strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, meta, a_one, b_two, reset);
  	if (lbl[0][0] == '/') {
  		/* /dev/null */
  		strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
  		if (xfrm_msg)
  			strbuf_addstr(&header, xfrm_msg);
  		must_show_header = 1;
  	}
  	else if (lbl[1][0] == '/') {
  		strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
  		if (xfrm_msg)
  			strbuf_addstr(&header, xfrm_msg);
  		must_show_header = 1;
  	}
  	else {
  		if (one->mode != two->mode) {
  			strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
  			strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
  			must_show_header = 1;
  		}
  		if (xfrm_msg)
  			strbuf_addstr(&header, xfrm_msg);
  
  		/*
  		 * we do not run diff between different kind
  		 * of objects.
  		 */
  		if ((one->mode ^ two->mode) & S_IFMT)
  			goto free_ab_and_return;
  		if (complete_rewrite &&
  		    (textconv_one || !diff_filespec_is_binary(one)) &&
  		    (textconv_two || !diff_filespec_is_binary(two))) {
  			fprintf(o->file, "%s", header.buf);
  			strbuf_reset(&header);
  			emit_rewrite_diff(name_a, name_b, one, two,
  						textconv_one, textconv_two, o);
  			o->found_changes = 1;
  			goto free_ab_and_return;
  		}
  	}
  
  	if (o->irreversible_delete && lbl[1][0] == '/') {
  		fprintf(o->file, "%s", header.buf);
  		strbuf_reset(&header);
  		goto free_ab_and_return;
  	} else if (!DIFF_OPT_TST(o, TEXT) &&
  	    ( (!textconv_one && diff_filespec_is_binary(one)) ||
  	      (!textconv_two && diff_filespec_is_binary(two)) )) {
  		if (!one->data && !two->data &&
  		    S_ISREG(one->mode) && S_ISREG(two->mode) &&
  		    !DIFF_OPT_TST(o, BINARY)) {
  			if (!hashcmp(one->sha1, two->sha1)) {
  				if (must_show_header)
  					fprintf(o->file, "%s", header.buf);
  				goto free_ab_and_return;
  			}
  			fprintf(o->file, "%s", header.buf);
  			fprintf(o->file, "%sBinary files %s and %s differ\n",
  				line_prefix, lbl[0], lbl[1]);
  			goto free_ab_and_return;
  		}
  		if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
  			die("unable to read files to diff");
  		/* Quite common confusing case */
  		if (mf1.size == mf2.size &&
  		    !memcmp(mf1.ptr, mf2.ptr, mf1.size)) {
  			if (must_show_header)
  				fprintf(o->file, "%s", header.buf);
  			goto free_ab_and_return;
  		}
  		fprintf(o->file, "%s", header.buf);
  		strbuf_reset(&header);
  		if (DIFF_OPT_TST(o, BINARY))
  			emit_binary_diff(o->file, &mf1, &mf2, line_prefix);
  		else
  			fprintf(o->file, "%sBinary files %s and %s differ\n",
  				line_prefix, lbl[0], lbl[1]);
  		o->found_changes = 1;
  	} else {
  		/* Crazy xdl interfaces.. */
  		const char *diffopts = getenv("GIT_DIFF_OPTS");
  		const char *v;
  		xpparam_t xpp;
  		xdemitconf_t xecfg;
  		struct emit_callback ecbdata;
  		const struct userdiff_funcname *pe;
  
  		if (must_show_header) {
  			fprintf(o->file, "%s", header.buf);
  			strbuf_reset(&header);
  		}
  
  		mf1.size = fill_textconv(textconv_one, one, &mf1.ptr);
  		mf2.size = fill_textconv(textconv_two, two, &mf2.ptr);
  
  		pe = diff_funcname_pattern(one);
  		if (!pe)
  			pe = diff_funcname_pattern(two);
  
  		memset(&xpp, 0, sizeof(xpp));
  		memset(&xecfg, 0, sizeof(xecfg));
  		memset(&ecbdata, 0, sizeof(ecbdata));
  		ecbdata.label_path = lbl;
  		ecbdata.color_diff = want_color(o->use_color);
  		ecbdata.found_changesp = &o->found_changes;
  		ecbdata.ws_rule = whitespace_rule(name_b);
  		if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
  			check_blank_at_eof(&mf1, &mf2, &ecbdata);
  		ecbdata.opt = o;
  		ecbdata.header = header.len ? &header : NULL;
  		xpp.flags = o->xdl_opts;
  		xecfg.ctxlen = o->context;
  		xecfg.interhunkctxlen = o->interhunkcontext;
  		xecfg.flags = XDL_EMIT_FUNCNAMES;
  		if (DIFF_OPT_TST(o, FUNCCONTEXT))
  			xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
  		if (pe)
  			xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
  		if (!diffopts)
  			;
  		else if (skip_prefix(diffopts, "--unified=", &v))
  			xecfg.ctxlen = strtoul(v, NULL, 10);
  		else if (skip_prefix(diffopts, "-u", &v))
  			xecfg.ctxlen = strtoul(v, NULL, 10);
  		if (o->word_diff)
  			init_diff_words_data(&ecbdata, o, one, two);
  		xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
  			      &xpp, &xecfg);
  		if (o->word_diff)
  			free_diff_words_data(&ecbdata);
  		if (textconv_one)
  			free(mf1.ptr);
  		if (textconv_two)
  			free(mf2.ptr);
  		xdiff_clear_find_func(&xecfg);
  	}
  
   free_ab_and_return:
  	strbuf_release(&header);
  	diff_free_filespec_data(one);
  	diff_free_filespec_data(two);
  	free(a_one);
  	free(b_two);
  	return;
  }
  
  static void builtin_diffstat(const char *name_a, const char *name_b,
  			     struct diff_filespec *one,
  			     struct diff_filespec *two,
  			     struct diffstat_t *diffstat,
  			     struct diff_options *o,
  			     struct diff_filepair *p)
  {
  	mmfile_t mf1, mf2;
  	struct diffstat_file *data;
  	int same_contents;
  	int complete_rewrite = 0;
  
  	if (!DIFF_PAIR_UNMERGED(p)) {
  		if (p->status == DIFF_STATUS_MODIFIED && p->score)
  			complete_rewrite = 1;
  	}
  
  	data = diffstat_add(diffstat, name_a, name_b);
  	data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
  
  	if (!one || !two) {
  		data->is_unmerged = 1;
  		return;
  	}
  
  	same_contents = !hashcmp(one->sha1, two->sha1);
  
  	if (diff_filespec_is_binary(one) || diff_filespec_is_binary(two)) {
  		data->is_binary = 1;
  		if (same_contents) {
  			data->added = 0;
  			data->deleted = 0;
  		} else {
  			data->added = diff_filespec_size(two);
  			data->deleted = diff_filespec_size(one);
  		}
  	}
  
  	else if (complete_rewrite) {
  		diff_populate_filespec(one, 0);
  		diff_populate_filespec(two, 0);
  		data->deleted = count_lines(one->data, one->size);
  		data->added = count_lines(two->data, two->size);
  	}
  
  	else if (!same_contents) {
  		/* Crazy xdl interfaces.. */
  		xpparam_t xpp;
  		xdemitconf_t xecfg;
  
  		if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
  			die("unable to read files to diff");
  
  		memset(&xpp, 0, sizeof(xpp));
  		memset(&xecfg, 0, sizeof(xecfg));
  		xpp.flags = o->xdl_opts;
  		xecfg.ctxlen = o->context;
  		xecfg.interhunkctxlen = o->interhunkcontext;
  		xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
  			      &xpp, &xecfg);
  	}
  
  	diff_free_filespec_data(one);
  	diff_free_filespec_data(two);
  }
  
  static void builtin_checkdiff(const char *name_a, const char *name_b,
  			      const char *attr_path,
  			      struct diff_filespec *one,
  			      struct diff_filespec *two,
  			      struct diff_options *o)
  {
  	mmfile_t mf1, mf2;
  	struct checkdiff_t data;
  
  	if (!two)
  		return;
  
  	memset(&data, 0, sizeof(data));
  	data.filename = name_b ? name_b : name_a;
  	data.lineno = 0;
  	data.o = o;
  	data.ws_rule = whitespace_rule(attr_path);
  	data.conflict_marker_size = ll_merge_marker_size(attr_path);
  
  	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
  		die("unable to read files to diff");
  
  	/*
  	 * All the other codepaths check both sides, but not checking
  	 * the "old" side here is deliberate.  We are checking the newly
  	 * introduced changes, and as long as the "new" side is text, we
  	 * can and should check what it introduces.
  	 */
  	if (diff_filespec_is_binary(two))
  		goto free_and_return;
  	else {
  		/* Crazy xdl interfaces.. */
  		xpparam_t xpp;
  		xdemitconf_t xecfg;
  
  		memset(&xpp, 0, sizeof(xpp));
  		memset(&xecfg, 0, sizeof(xecfg));
  		xecfg.ctxlen = 1; /* at least one context line */
  		xpp.flags = 0;
  		xdi_diff_outf(&mf1, &mf2, checkdiff_consume, &data,
  			      &xpp, &xecfg);
  
  		if (data.ws_rule & WS_BLANK_AT_EOF) {
  			struct emit_callback ecbdata;
  			int blank_at_eof;
  
  			ecbdata.ws_rule = data.ws_rule;
  			check_blank_at_eof(&mf1, &mf2, &ecbdata);
  			blank_at_eof = ecbdata.blank_at_eof_in_postimage;
  
  			if (blank_at_eof) {
  				static char *err;
  				if (!err)
  					err = whitespace_error_string(WS_BLANK_AT_EOF);
  				fprintf(o->file, "%s:%d: %s.\n",
  					data.filename, blank_at_eof, err);
  				data.status = 1; /* report errors */
  			}
  		}
  	}
   free_and_return:
  	diff_free_filespec_data(one);
  	diff_free_filespec_data(two);
  	if (data.status)
  		DIFF_OPT_SET(o, CHECK_FAILED);
  }
  
  struct diff_filespec *alloc_filespec(const char *path)
  {
  	int namelen = strlen(path);
  	struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
  
  	memset(spec, 0, sizeof(*spec));
  	spec->path = (char *)(spec + 1);
  	memcpy(spec->path, path, namelen+1);
  	spec->count = 1;
  	spec->is_binary = -1;
  	return spec;
  }
  
  void free_filespec(struct diff_filespec *spec)
  {
  	if (!--spec->count) {
  		diff_free_filespec_data(spec);
  		free(spec);
  	}
  }
  
  void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
  		   int sha1_valid, unsigned short mode)
  {
  	if (mode) {
  		spec->mode = canon_mode(mode);
  		hashcpy(spec->sha1, sha1);
  		spec->sha1_valid = sha1_valid;
  	}
  }
  
  /*
   * Given a name and sha1 pair, if the index tells us the file in
   * the work tree has that object contents, return true, so that
   * prepare_temp_file() does not have to inflate and extract.
   */
  static int reuse_worktree_file(const char *name, const unsigned char *sha1, int want_file)
  {
  	const struct cache_entry *ce;
  	struct stat st;
  	int pos, len;
  
  	/*
  	 * We do not read the cache ourselves here, because the
  	 * benchmark with my previous version that always reads cache
  	 * shows that it makes things worse for diff-tree comparing
  	 * two linux-2.6 kernel trees in an already checked out work
  	 * tree.  This is because most diff-tree comparisons deal with
  	 * only a small number of files, while reading the cache is
  	 * expensive for a large project, and its cost outweighs the
  	 * savings we get by not inflating the object to a temporary
  	 * file.  Practically, this code only helps when we are used
  	 * by diff-cache --cached, which does read the cache before
  	 * calling us.
  	 */
  	if (!active_cache)
  		return 0;
  
  	/* We want to avoid the working directory if our caller
  	 * doesn't need the data in a normal file, this system
  	 * is rather slow with its stat/open/mmap/close syscalls,
  	 * and the object is contained in a pack file.  The pack
  	 * is probably already open and will be faster to obtain
  	 * the data through than the working directory.  Loose
  	 * objects however would tend to be slower as they need
  	 * to be individually opened and inflated.
  	 */
  	if (!FAST_WORKING_DIRECTORY && !want_file && has_sha1_pack(sha1))
  		return 0;
  
  	len = strlen(name);
  	pos = cache_name_pos(name, len);
  	if (pos < 0)
  		return 0;
  	ce = active_cache[pos];
  
  	/*
  	 * This is not the sha1 we are looking for, or
  	 * unreusable because it is not a regular file.
  	 */
  	if (hashcmp(sha1, ce->sha1) || !S_ISREG(ce->ce_mode))
  		return 0;
  
  	/*
  	 * If ce is marked as "assume unchanged", there is no
  	 * guarantee that work tree matches what we are looking for.
  	 */
  	if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
  		return 0;
  
  	/*
  	 * If ce matches the file in the work tree, we can reuse it.
  	 */
  	if (ce_uptodate(ce) ||
  	    (!lstat(name, &st) && !ce_match_stat(ce, &st, 0)))
  		return 1;
  
  	return 0;
  }
  
  static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
  {
  	int len;
  	char *data = xmalloc(100), *dirty = "";
  
  	/* Are we looking at the work tree? */
  	if (s->dirty_submodule)
  		dirty = "-dirty";
  
  	len = snprintf(data, 100,
  		       "Subproject commit %s%s\n", sha1_to_hex(s->sha1), dirty);
  	s->data = data;
  	s->size = len;
  	s->should_free = 1;
  	if (size_only) {
  		s->data = NULL;
  		free(data);
  	}
  	return 0;
  }
  
  /*
   * While doing rename detection and pickaxe operation, we may need to
   * grab the data for the blob (or file) for our own in-core comparison.
   * diff_filespec has data and size fields for this purpose.
   */
  int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
  {
  	int size_only = flags & CHECK_SIZE_ONLY;
  	int err = 0;
  	/*
  	 * demote FAIL to WARN to allow inspecting the situation
  	 * instead of refusing.
  	 */
  	enum safe_crlf crlf_warn = (safe_crlf == SAFE_CRLF_FAIL
  				    ? SAFE_CRLF_WARN
  				    : safe_crlf);
  
  	if (!DIFF_FILE_VALID(s))
  		die("internal error: asking to populate invalid file.");
  	if (S_ISDIR(s->mode))
  		return -1;
  
  	if (s->data)
  		return 0;
  
  	if (size_only && 0 < s->size)
  		return 0;
  
  	if (S_ISGITLINK(s->mode))
  		return diff_populate_gitlink(s, size_only);
  
  	if (!s->sha1_valid ||
  	    reuse_worktree_file(s->path, s->sha1, 0)) {
  		struct strbuf buf = STRBUF_INIT;
  		struct stat st;
  		int fd;
  
  		if (lstat(s->path, &st) < 0) {
  			if (errno == ENOENT) {
  			err_empty:
  				err = -1;
  			empty:
  				s->data = (char *)"";
  				s->size = 0;
  				return err;
  			}
  		}
  		s->size = xsize_t(st.st_size);
  		if (!s->size)
  			goto empty;
  		if (S_ISLNK(st.st_mode)) {
  			struct strbuf sb = STRBUF_INIT;
  
  			if (strbuf_readlink(&sb, s->path, s->size))
  				goto err_empty;
  			s->size = sb.len;
  			s->data = strbuf_detach(&sb, NULL);
  			s->should_free = 1;
  			return 0;
  		}
  		if (size_only)
  			return 0;
  		if ((flags & CHECK_BINARY) &&
  		    s->size > big_file_threshold && s->is_binary == -1) {
  			s->is_binary = 1;
  			return 0;
  		}
  		fd = open(s->path, O_RDONLY);
  		if (fd < 0)
  			goto err_empty;
  		s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
  		close(fd);
  		s->should_munmap = 1;
  
  		/*
  		 * Convert from working tree format to canonical git format
  		 */
  		if (convert_to_git(s->path, s->data, s->size, &buf, crlf_warn)) {
  			size_t size = 0;
  			munmap(s->data, s->size);
  			s->should_munmap = 0;
  			s->data = strbuf_detach(&buf, &size);
  			s->size = size;
  			s->should_free = 1;
  		}
  	}
  	else {
  		enum object_type type;
  		if (size_only || (flags & CHECK_BINARY)) {
  			type = sha1_object_info(s->sha1, &s->size);
  			if (type < 0)
  				die("unable to read %s", sha1_to_hex(s->sha1));
  			if (size_only)
  				return 0;
  			if (s->size > big_file_threshold && s->is_binary == -1) {
  				s->is_binary = 1;
  				return 0;
  			}
  		}
  		s->data = read_sha1_file(s->sha1, &type, &s->size);
  		if (!s->data)
  			die("unable to read %s", sha1_to_hex(s->sha1));
  		s->should_free = 1;
  	}
  	return 0;
  }
  
  void diff_free_filespec_blob(struct diff_filespec *s)
  {
  	if (s->should_free)
  		free(s->data);
  	else if (s->should_munmap)
  		munmap(s->data, s->size);
  
  	if (s->should_free || s->should_munmap) {
  		s->should_free = s->should_munmap = 0;
  		s->data = NULL;
  	}
  }
  
  void diff_free_filespec_data(struct diff_filespec *s)
  {
  	diff_free_filespec_blob(s);
  	free(s->cnt_data);
  	s->cnt_data = NULL;
  }
  
  static void prep_temp_blob(const char *path, struct diff_tempfile *temp,
  			   void *blob,
  			   unsigned long size,
  			   const unsigned char *sha1,
  			   int mode)
  {
  	int fd;
  	struct strbuf buf = STRBUF_INIT;
  	struct strbuf template = STRBUF_INIT;
  	char *path_dup = xstrdup(path);
  	const char *base = basename(path_dup);
  
  	/* Generate "XXXXXX_basename.ext" */
  	strbuf_addstr(&template, "XXXXXX_");
  	strbuf_addstr(&template, base);
  
  	fd = git_mkstemps(temp->tmp_path, PATH_MAX, template.buf,
  			strlen(base) + 1);
  	if (fd < 0)
  		die_errno("unable to create temp-file");
  	if (convert_to_working_tree(path,
  			(const char *)blob, (size_t)size, &buf)) {
  		blob = buf.buf;
  		size = buf.len;
  	}
  	if (write_in_full(fd, blob, size) != size)
  		die_errno("unable to write temp-file");
  	close(fd);
  	temp->name = temp->tmp_path;
  	strcpy(temp->hex, sha1_to_hex(sha1));
  	temp->hex[40] = 0;
  	sprintf(temp->mode, "%06o", mode);
  	strbuf_release(&buf);
  	strbuf_release(&template);
  	free(path_dup);
  }
  
  static struct diff_tempfile *prepare_temp_file(const char *name,
  		struct diff_filespec *one)
  {
  	struct diff_tempfile *temp = claim_diff_tempfile();
  
  	if (!DIFF_FILE_VALID(one)) {
  	not_a_valid_file:
  		/* A '-' entry produces this for file-2, and
  		 * a '+' entry produces this for file-1.
  		 */
  		temp->name = "/dev/null";
  		strcpy(temp->hex, ".");
  		strcpy(temp->mode, ".");
  		return temp;
  	}
  
  	if (!remove_tempfile_installed) {
  		atexit(remove_tempfile);
  		sigchain_push_common(remove_tempfile_on_signal);
  		remove_tempfile_installed = 1;
  	}
  
  	if (!S_ISGITLINK(one->mode) &&
  	    (!one->sha1_valid ||
  	     reuse_worktree_file(name, one->sha1, 1))) {
  		struct stat st;
  		if (lstat(name, &st) < 0) {
  			if (errno == ENOENT)
  				goto not_a_valid_file;
  			die_errno("stat(%s)", name);
  		}
  		if (S_ISLNK(st.st_mode)) {
  			struct strbuf sb = STRBUF_INIT;
  			if (strbuf_readlink(&sb, name, st.st_size) < 0)
  				die_errno("readlink(%s)", name);
  			prep_temp_blob(name, temp, sb.buf, sb.len,
  				       (one->sha1_valid ?
  					one->sha1 : null_sha1),
  				       (one->sha1_valid ?
  					one->mode : S_IFLNK));
  			strbuf_release(&sb);
  		}
  		else {
  			/* we can borrow from the file in the work tree */
  			temp->name = name;
  			if (!one->sha1_valid)
  				strcpy(temp->hex, sha1_to_hex(null_sha1));
  			else
  				strcpy(temp->hex, sha1_to_hex(one->sha1));
  			/* Even though we may sometimes borrow the
  			 * contents from the work tree, we always want
  			 * one->mode.  mode is trustworthy even when
  			 * !(one->sha1_valid), as long as
  			 * DIFF_FILE_VALID(one).
  			 */
  			sprintf(temp->mode, "%06o", one->mode);
  		}
  		return temp;
  	}
  	else {
  		if (diff_populate_filespec(one, 0))
  			die("cannot read data blob for %s", one->path);
  		prep_temp_blob(name, temp, one->data, one->size,
  			       one->sha1, one->mode);
  	}
  	return temp;
  }
  
  static void add_external_diff_name(struct argv_array *argv,
  				   const char *name,
  				   struct diff_filespec *df)
  {
  	struct diff_tempfile *temp = prepare_temp_file(name, df);
  	argv_array_push(argv, temp->name);
  	argv_array_push(argv, temp->hex);
  	argv_array_push(argv, temp->mode);
  }
  
  /* An external diff command takes:
   *
   * diff-cmd name infile1 infile1-sha1 infile1-mode \
   *               infile2 infile2-sha1 infile2-mode [ rename-to ]
   *
   */
  static void run_external_diff(const char *pgm,
  			      const char *name,
  			      const char *other,
  			      struct diff_filespec *one,
  			      struct diff_filespec *two,
  			      const char *xfrm_msg,
  			      int complete_rewrite,
  			      struct diff_options *o)
  {
  	struct argv_array argv = ARGV_ARRAY_INIT;
  	struct argv_array env = ARGV_ARRAY_INIT;
  	struct diff_queue_struct *q = &diff_queued_diff;
  
  	argv_array_push(&argv, pgm);
  	argv_array_push(&argv, name);
  
  	if (one && two) {
  		add_external_diff_name(&argv, name, one);
  		if (!other)
  			add_external_diff_name(&argv, name, two);
  		else {
  			add_external_diff_name(&argv, other, two);
  			argv_array_push(&argv, other);
  			argv_array_push(&argv, xfrm_msg);
  		}
  	}
  
  	argv_array_pushf(&env, "GIT_DIFF_PATH_COUNTER=%d", ++o->diff_path_counter);
  	argv_array_pushf(&env, "GIT_DIFF_PATH_TOTAL=%d", q->nr);
  
  	if (run_command_v_opt_cd_env(argv.argv, RUN_USING_SHELL, NULL, env.argv))
  		die(_("external diff died, stopping at %s"), name);
  
  	remove_tempfile();
  	argv_array_clear(&argv);
  	argv_array_clear(&env);
  }
  
  static int similarity_index(struct diff_filepair *p)
  {
  	return p->score * 100 / MAX_SCORE;
  }
  
  static void fill_metainfo(struct strbuf *msg,
  			  const char *name,
  			  const char *other,
  			  struct diff_filespec *one,
  			  struct diff_filespec *two,
  			  struct diff_options *o,
  			  struct diff_filepair *p,
  			  int *must_show_header,
  			  int use_color)
  {
  	const char *set = diff_get_color(use_color, DIFF_METAINFO);
  	const char *reset = diff_get_color(use_color, DIFF_RESET);
  	const char *line_prefix = diff_line_prefix(o);
  
  	*must_show_header = 1;
  	strbuf_init(msg, PATH_MAX * 2 + 300);
  	switch (p->status) {
  	case DIFF_STATUS_COPIED:
  		strbuf_addf(msg, "%s%ssimilarity index %d%%",
  			    line_prefix, set, similarity_index(p));
  		strbuf_addf(msg, "%s\n%s%scopy from ",
  			    reset,  line_prefix, set);
  		quote_c_style(name, msg, NULL, 0);
  		strbuf_addf(msg, "%s\n%s%scopy to ", reset, line_prefix, set);
  		quote_c_style(other, msg, NULL, 0);
  		strbuf_addf(msg, "%s\n", reset);
  		break;
  	case DIFF_STATUS_RENAMED:
  		strbuf_addf(msg, "%s%ssimilarity index %d%%",
  			    line_prefix, set, similarity_index(p));
  		strbuf_addf(msg, "%s\n%s%srename from ",
  			    reset, line_prefix, set);
  		quote_c_style(name, msg, NULL, 0);
  		strbuf_addf(msg, "%s\n%s%srename to ",
  			    reset, line_prefix, set);
  		quote_c_style(other, msg, NULL, 0);
  		strbuf_addf(msg, "%s\n", reset);
  		break;
  	case DIFF_STATUS_MODIFIED:
  		if (p->score) {
  			strbuf_addf(msg, "%s%sdissimilarity index %d%%%s\n",
  				    line_prefix,
  				    set, similarity_index(p), reset);
  			break;
  		}
  		/* fallthru */
  	default:
  		*must_show_header = 0;
  	}
  	if (one && two && hashcmp(one->sha1, two->sha1)) {
  		int abbrev = DIFF_OPT_TST(o, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
  
  		if (DIFF_OPT_TST(o, BINARY)) {
  			mmfile_t mf;
  			if ((!fill_mmfile(&mf, one) && diff_filespec_is_binary(one)) ||
  			    (!fill_mmfile(&mf, two) && diff_filespec_is_binary(two)))
  				abbrev = 40;
  		}
  		strbuf_addf(msg, "%s%sindex %s..", line_prefix, set,
  			    find_unique_abbrev(one->sha1, abbrev));
  		strbuf_addstr(msg, find_unique_abbrev(two->sha1, abbrev));
  		if (one->mode == two->mode)
  			strbuf_addf(msg, " %06o", one->mode);
  		strbuf_addf(msg, "%s\n", reset);
  	}
  }
  
  static void run_diff_cmd(const char *pgm,
  			 const char *name,
  			 const char *other,
  			 const char *attr_path,
  			 struct diff_filespec *one,
  			 struct diff_filespec *two,
  			 struct strbuf *msg,
  			 struct diff_options *o,
  			 struct diff_filepair *p)
  {
  	const char *xfrm_msg = NULL;
  	int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
  	int must_show_header = 0;
  
  
  	if (DIFF_OPT_TST(o, ALLOW_EXTERNAL)) {
  		struct userdiff_driver *drv = userdiff_find_by_path(attr_path);
  		if (drv && drv->external)
  			pgm = drv->external;
  	}
  
  	if (msg) {
  		/*
  		 * don't use colors when the header is intended for an
  		 * external diff driver
  		 */
  		fill_metainfo(msg, name, other, one, two, o, p,
  			      &must_show_header,
  			      want_color(o->use_color) && !pgm);
  		xfrm_msg = msg->len ? msg->buf : NULL;
  	}
  
  	if (pgm) {
  		run_external_diff(pgm, name, other, one, two, xfrm_msg,
  				  complete_rewrite, o);
  		return;
  	}
  	if (one && two)
  		builtin_diff(name, other ? other : name,
  			     one, two, xfrm_msg, must_show_header,
  			     o, complete_rewrite);
  	else
  		fprintf(o->file, "* Unmerged path %s\n", name);
  }
  
  static void diff_fill_sha1_info(struct diff_filespec *one)
  {
  	if (DIFF_FILE_VALID(one)) {
  		if (!one->sha1_valid) {
  			struct stat st;
  			if (one->is_stdin) {
  				hashcpy(one->sha1, null_sha1);
  				return;
  			}
  			if (lstat(one->path, &st) < 0)
  				die_errno("stat '%s'", one->path);
  			if (index_path(one->sha1, one->path, &st, 0))
  				die("cannot hash %s", one->path);
  		}
  	}
  	else
  		hashclr(one->sha1);
  }
  
  static void strip_prefix(int prefix_length, const char **namep, const char **otherp)
  {
  	/* Strip the prefix but do not molest /dev/null and absolute paths */
  	if (*namep && **namep != '/') {
  		*namep += prefix_length;
  		if (**namep == '/')
  			++*namep;
  	}
  	if (*otherp && **otherp != '/') {
  		*otherp += prefix_length;
  		if (**otherp == '/')
  			++*otherp;
  	}
  }
  
  static void run_diff(struct diff_filepair *p, struct diff_options *o)
  {
  	const char *pgm = external_diff();
  	struct strbuf msg;
  	struct diff_filespec *one = p->one;
  	struct diff_filespec *two = p->two;
  	const char *name;
  	const char *other;
  	const char *attr_path;
  
  	name  = p->one->path;
  	other = (strcmp(name, p->two->path) ? p->two->path : NULL);
  	attr_path = name;
  	if (o->prefix_length)
  		strip_prefix(o->prefix_length, &name, &other);
  
  	if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
  		pgm = NULL;
  
  	if (DIFF_PAIR_UNMERGED(p)) {
  		run_diff_cmd(pgm, name, NULL, attr_path,
  			     NULL, NULL, NULL, o, p);
  		return;
  	}
  
  	diff_fill_sha1_info(one);
  	diff_fill_sha1_info(two);
  
  	if (!pgm &&
  	    DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
  	    (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
  		/*
  		 * a filepair that changes between file and symlink
  		 * needs to be split into deletion and creation.
  		 */
  		struct diff_filespec *null = alloc_filespec(two->path);
  		run_diff_cmd(NULL, name, other, attr_path,
  			     one, null, &msg, o, p);
  		free(null);
  		strbuf_release(&msg);
  
  		null = alloc_filespec(one->path);
  		run_diff_cmd(NULL, name, other, attr_path,
  			     null, two, &msg, o, p);
  		free(null);
  	}
  	else
  		run_diff_cmd(pgm, name, other, attr_path,
  			     one, two, &msg, o, p);
  
  	strbuf_release(&msg);
  }
  
  static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
  			 struct diffstat_t *diffstat)
  {
  	const char *name;
  	const char *other;
  
  	if (DIFF_PAIR_UNMERGED(p)) {
  		/* unmerged */
  		builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, p);
  		return;
  	}
  
  	name = p->one->path;
  	other = (strcmp(name, p->two->path) ? p->two->path : NULL);
  
  	if (o->prefix_length)
  		strip_prefix(o->prefix_length, &name, &other);
  
  	diff_fill_sha1_info(p->one);
  	diff_fill_sha1_info(p->two);
  
  	builtin_diffstat(name, other, p->one, p->two, diffstat, o, p);
  }
  
  static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
  {
  	const char *name;
  	const char *other;
  	const char *attr_path;
  
  	if (DIFF_PAIR_UNMERGED(p)) {
  		/* unmerged */
  		return;
  	}
  
  	name = p->one->path;
  	other = (strcmp(name, p->two->path) ? p->two->path : NULL);
  	attr_path = other ? other : name;
  
  	if (o->prefix_length)
  		strip_prefix(o->prefix_length, &name, &other);
  
  	diff_fill_sha1_info(p->one);
  	diff_fill_sha1_info(p->two);
  
  	builtin_checkdiff(name, other, attr_path, p->one, p->two, o);
  }
  
  void diff_setup(struct diff_options *options)
  {
  	memcpy(options, &default_diff_options, sizeof(*options));
  
  	options->file = stdout;
  
  	options->line_termination = '\n';
  	options->break_opt = -1;
  	options->rename_limit = -1;
  	options->dirstat_permille = diff_dirstat_permille_default;
  	options->context = diff_context_default;
  	options->ws_error_highlight = WSEH_NEW;
  	DIFF_OPT_SET(options, RENAME_EMPTY);
  
  	/* pathchange left =NULL by default */
  	options->change = diff_change;
  	options->add_remove = diff_addremove;
  	options->use_color = diff_use_color_default;
  	options->detect_rename = diff_detect_rename_default;
  	options->xdl_opts |= diff_algorithm;
  
  	options->orderfile = diff_order_file_cfg;
  
  	if (diff_no_prefix) {
  		options->a_prefix = options->b_prefix = "";
  	} else if (!diff_mnemonic_prefix) {
  		options->a_prefix = "a/";
  		options->b_prefix = "b/";
  	}
  }
  
  void diff_setup_done(struct diff_options *options)
  {
  	int count = 0;
  
  	if (options->set_default)
  		options->set_default(options);
  
  	if (options->output_format & DIFF_FORMAT_NAME)
  		count++;
  	if (options->output_format & DIFF_FORMAT_NAME_STATUS)
  		count++;
  	if (options->output_format & DIFF_FORMAT_CHECKDIFF)
  		count++;
  	if (options->output_format & DIFF_FORMAT_NO_OUTPUT)
  		count++;
  	if (count > 1)
  		die("--name-only, --name-status, --check and -s are mutually exclusive");
  
  	/*
  	 * Most of the time we can say "there are changes"
  	 * only by checking if there are changed paths, but
  	 * --ignore-whitespace* options force us to look
  	 * inside contents.
  	 */
  
  	if (DIFF_XDL_TST(options, IGNORE_WHITESPACE) ||
  	    DIFF_XDL_TST(options, IGNORE_WHITESPACE_CHANGE) ||
  	    DIFF_XDL_TST(options, IGNORE_WHITESPACE_AT_EOL))
  		DIFF_OPT_SET(options, DIFF_FROM_CONTENTS);
  	else
  		DIFF_OPT_CLR(options, DIFF_FROM_CONTENTS);
  
  	if (DIFF_OPT_TST(options, FIND_COPIES_HARDER))
  		options->detect_rename = DIFF_DETECT_COPY;
  
  	if (!DIFF_OPT_TST(options, RELATIVE_NAME))
  		options->prefix = NULL;
  	if (options->prefix)
  		options->prefix_length = strlen(options->prefix);
  	else
  		options->prefix_length = 0;
  
  	if (options->output_format & (DIFF_FORMAT_NAME |
  				      DIFF_FORMAT_NAME_STATUS |
  				      DIFF_FORMAT_CHECKDIFF |
  				      DIFF_FORMAT_NO_OUTPUT))
  		options->output_format &= ~(DIFF_FORMAT_RAW |
  					    DIFF_FORMAT_NUMSTAT |
  					    DIFF_FORMAT_DIFFSTAT |
  					    DIFF_FORMAT_SHORTSTAT |
  					    DIFF_FORMAT_DIRSTAT |
  					    DIFF_FORMAT_SUMMARY |
  					    DIFF_FORMAT_PATCH);
  
  	/*
  	 * These cases always need recursive; we do not drop caller-supplied
  	 * recursive bits for other formats here.
  	 */
  	if (options->output_format & (DIFF_FORMAT_PATCH |
  				      DIFF_FORMAT_NUMSTAT |
  				      DIFF_FORMAT_DIFFSTAT |
  				      DIFF_FORMAT_SHORTSTAT |
  				      DIFF_FORMAT_DIRSTAT |
  				      DIFF_FORMAT_SUMMARY |
  				      DIFF_FORMAT_CHECKDIFF))
  		DIFF_OPT_SET(options, RECURSIVE);
  	/*
  	 * Also pickaxe would not work very well if you do not say recursive
  	 */
  	if (options->pickaxe)
  		DIFF_OPT_SET(options, RECURSIVE);
  	/*
  	 * When patches are generated, submodules diffed against the work tree
  	 * must be checked for dirtiness too so it can be shown in the output
  	 */
  	if (options->output_format & DIFF_FORMAT_PATCH)
  		DIFF_OPT_SET(options, DIRTY_SUBMODULES);
  
  	if (options->detect_rename && options->rename_limit < 0)
  		options->rename_limit = diff_rename_limit_default;
  	if (options->setup & DIFF_SETUP_USE_CACHE) {
  		if (!active_cache)
  			/* read-cache does not die even when it fails
  			 * so it is safe for us to do this here.  Also
  			 * it does not smudge active_cache or active_nr
  			 * when it fails, so we do not have to worry about
  			 * cleaning it up ourselves either.
  			 */
  			read_cache();
  	}
  	if (options->abbrev <= 0 || 40 < options->abbrev)
  		options->abbrev = 40; /* full */
  
  	/*
  	 * It does not make sense to show the first hit we happened
  	 * to have found.  It does not make sense not to return with
  	 * exit code in such a case either.
  	 */
  	if (DIFF_OPT_TST(options, QUICK)) {
  		options->output_format = DIFF_FORMAT_NO_OUTPUT;
  		DIFF_OPT_SET(options, EXIT_WITH_STATUS);
  	}
  
  	options->diff_path_counter = 0;
  
  	if (DIFF_OPT_TST(options, FOLLOW_RENAMES) && options->pathspec.nr != 1)
  		die(_("--follow requires exactly one pathspec"));
  }
  
  static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)
  {
  	char c, *eq;
  	int len;
  
  	if (*arg != '-')
  		return 0;
  	c = *++arg;
  	if (!c)
  		return 0;
  	if (c == arg_short) {
  		c = *++arg;
  		if (!c)
  			return 1;
  		if (val && isdigit(c)) {
  			char *end;
  			int n = strtoul(arg, &end, 10);
  			if (*end)
  				return 0;
  			*val = n;
  			return 1;
  		}
  		return 0;
  	}
  	if (c != '-')
  		return 0;
  	arg++;
  	eq = strchrnul(arg, '=');
  	len = eq - arg;
  	if (!len || strncmp(arg, arg_long, len))
  		return 0;
  	if (*eq) {
  		int n;
  		char *end;
  		if (!isdigit(*++eq))
  			return 0;
  		n = strtoul(eq, &end, 10);
  		if (*end)
  			return 0;
  		*val = n;
  	}
  	return 1;
  }
  
  static int diff_scoreopt_parse(const char *opt);
  
  static inline int short_opt(char opt, const char **argv,
  			    const char **optarg)
  {
  	const char *arg = argv[0];
  	if (arg[0] != '-' || arg[1] != opt)
  		return 0;
  	if (arg[2] != '\0') {
  		*optarg = arg + 2;
  		return 1;
  	}
  	if (!argv[1])
  		die("Option '%c' requires a value", opt);
  	*optarg = argv[1];
  	return 2;
  }
  
  int parse_long_opt(const char *opt, const char **argv,
  		   const char **optarg)
  {
  	const char *arg = argv[0];
  	if (!skip_prefix(arg, "--", &arg))
  		return 0;
  	if (!skip_prefix(arg, opt, &arg))
  		return 0;
  	if (*arg == '=') { /* stuck form: --option=value */
  		*optarg = arg + 1;
  		return 1;
  	}
  	if (*arg != '\0')
  		return 0;
  	/* separate form: --option value */
  	if (!argv[1])
  		die("Option '--%s' requires a value", opt);
  	*optarg = argv[1];
  	return 2;
  }
  
  static int stat_opt(struct diff_options *options, const char **av)
  {
  	const char *arg = av[0];
  	char *end;
  	int width = options->stat_width;
  	int name_width = options->stat_name_width;
  	int graph_width = options->stat_graph_width;
  	int count = options->stat_count;
  	int argcount = 1;
  
  	if (!skip_prefix(arg, "--stat", &arg))
  		die("BUG: stat option does not begin with --stat: %s", arg);
  	end = (char *)arg;
  
  	switch (*arg) {
  	case '-':
  		if (skip_prefix(arg, "-width", &arg)) {
  			if (*arg == '=')
  				width = strtoul(arg + 1, &end, 10);
  			else if (!*arg && !av[1])
  				die("Option '--stat-width' requires a value");
  			else if (!*arg) {
  				width = strtoul(av[1], &end, 10);
  				argcount = 2;
  			}
  		} else if (skip_prefix(arg, "-name-width", &arg)) {
  			if (*arg == '=')
  				name_width = strtoul(arg + 1, &end, 10);
  			else if (!*arg && !av[1])
  				die("Option '--stat-name-width' requires a value");
  			else if (!*arg) {
  				name_width = strtoul(av[1], &end, 10);
  				argcount = 2;
  			}
  		} else if (skip_prefix(arg, "-graph-width", &arg)) {
  			if (*arg == '=')
  				graph_width = strtoul(arg + 1, &end, 10);
  			else if (!*arg && !av[1])
  				die("Option '--stat-graph-width' requires a value");
  			else if (!*arg) {
  				graph_width = strtoul(av[1], &end, 10);
  				argcount = 2;
  			}
  		} else if (skip_prefix(arg, "-count", &arg)) {
  			if (*arg == '=')
  				count = strtoul(arg + 1, &end, 10);
  			else if (!*arg && !av[1])
  				die("Option '--stat-count' requires a value");
  			else if (!*arg) {
  				count = strtoul(av[1], &end, 10);
  				argcount = 2;
  			}
  		}
  		break;
  	case '=':
  		width = strtoul(arg+1, &end, 10);
  		if (*end == ',')
  			name_width = strtoul(end+1, &end, 10);
  		if (*end == ',')
  			count = strtoul(end+1, &end, 10);
  	}
  
  	/* Important! This checks all the error cases! */
  	if (*end)
  		return 0;
  	options->output_format |= DIFF_FORMAT_DIFFSTAT;
  	options->stat_name_width = name_width;
  	options->stat_graph_width = graph_width;
  	options->stat_width = width;
  	options->stat_count = count;
  	return argcount;
  }
  
  static int parse_dirstat_opt(struct diff_options *options, const char *params)
  {
  	struct strbuf errmsg = STRBUF_INIT;
  	if (parse_dirstat_params(options, params, &errmsg))
  		die(_("Failed to parse --dirstat/-X option parameter:\n%s"),
  		    errmsg.buf);
  	strbuf_release(&errmsg);
  	/*
  	 * The caller knows a dirstat-related option is given from the command
  	 * line; allow it to say "return this_function();"
  	 */
  	options->output_format |= DIFF_FORMAT_DIRSTAT;
  	return 1;
  }
  
  static int parse_submodule_opt(struct diff_options *options, const char *value)
  {
  	if (parse_submodule_params(options, value))
  		die(_("Failed to parse --submodule option parameter: '%s'"),
  			value);
  	return 1;
  }
  
  static const char diff_status_letters[] = {
  	DIFF_STATUS_ADDED,
  	DIFF_STATUS_COPIED,
  	DIFF_STATUS_DELETED,
  	DIFF_STATUS_MODIFIED,
  	DIFF_STATUS_RENAMED,
  	DIFF_STATUS_TYPE_CHANGED,
  	DIFF_STATUS_UNKNOWN,
  	DIFF_STATUS_UNMERGED,
  	DIFF_STATUS_FILTER_AON,
  	DIFF_STATUS_FILTER_BROKEN,
  	'\0',
  };
  
  static unsigned int filter_bit['Z' + 1];
  
  static void prepare_filter_bits(void)
  {
  	int i;
  
  	if (!filter_bit[DIFF_STATUS_ADDED]) {
  		for (i = 0; diff_status_letters[i]; i++)
  			filter_bit[(int) diff_status_letters[i]] = (1 << i);
  	}
  }
  
  static unsigned filter_bit_tst(char status, const struct diff_options *opt)
  {
  	return opt->filter & filter_bit[(int) status];
  }
  
  static int parse_diff_filter_opt(const char *optarg, struct diff_options *opt)
  {
  	int i, optch;
  
  	prepare_filter_bits();
  
  	/*
  	 * If there is a negation e.g. 'd' in the input, and we haven't
  	 * initialized the filter field with another --diff-filter, start
  	 * from full set of bits, except for AON.
  	 */
  	if (!opt->filter) {
  		for (i = 0; (optch = optarg[i]) != '\0'; i++) {
  			if (optch < 'a' || 'z' < optch)
  				continue;
  			opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
  			opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
  			break;
  		}
  	}
  
  	for (i = 0; (optch = optarg[i]) != '\0'; i++) {
  		unsigned int bit;
  		int negate;
  
  		if ('a' <= optch && optch <= 'z') {
  			negate = 1;
  			optch = toupper(optch);
  		} else {
  			negate = 0;
  		}
  
  		bit = (0 <= optch && optch <= 'Z') ? filter_bit[optch] : 0;
  		if (!bit)
  			return optarg[i];
  		if (negate)
  			opt->filter &= ~bit;
  		else
  			opt->filter |= bit;
  	}
  	return 0;
  }
  
  static void enable_patch_output(int *fmt) {
  	*fmt &= ~DIFF_FORMAT_NO_OUTPUT;
  	*fmt |= DIFF_FORMAT_PATCH;
  }
  
  static int parse_one_token(const char **arg, const char *token)
  {
  	const char *rest;
  	if (skip_prefix(*arg, token, &rest) && (!*rest || *rest == ',')) {
  		*arg = rest;
  		return 1;
  	}
  	return 0;
  }
  
  static int parse_ws_error_highlight(struct diff_options *opt, const char *arg)
  {
  	const char *orig_arg = arg;
  	unsigned val = 0;
  	while (*arg) {
  		if (parse_one_token(&arg, "none"))
  			val = 0;
  		else if (parse_one_token(&arg, "default"))
  			val = WSEH_NEW;
  		else if (parse_one_token(&arg, "all"))
  			val = WSEH_NEW | WSEH_OLD | WSEH_CONTEXT;
  		else if (parse_one_token(&arg, "new"))
  			val |= WSEH_NEW;
  		else if (parse_one_token(&arg, "old"))
  			val |= WSEH_OLD;
  		else if (parse_one_token(&arg, "context"))
  			val |= WSEH_CONTEXT;
  		else {
  			error("unknown value after ws-error-highlight=%.*s",
  			      (int)(arg - orig_arg), orig_arg);
  			return 0;
  		}
  		if (*arg)
  			arg++;
  	}
  	opt->ws_error_highlight = val;
  	return 1;
  }
  
  int diff_opt_parse(struct diff_options *options, const char **av, int ac)
  {
  	const char *arg = av[0];
  	const char *optarg;
  	int argcount;
  
  	/* Output format options */
  	if (!strcmp(arg, "-p") || !strcmp(arg, "-u") || !strcmp(arg, "--patch")
  	    || opt_arg(arg, 'U', "unified", &options->context))
  		enable_patch_output(&options->output_format);
  	else if (!strcmp(arg, "--raw"))
  		options->output_format |= DIFF_FORMAT_RAW;
  	else if (!strcmp(arg, "--patch-with-raw")) {
  		enable_patch_output(&options->output_format);
  		options->output_format |= DIFF_FORMAT_RAW;
  	} else if (!strcmp(arg, "--numstat"))
  		options->output_format |= DIFF_FORMAT_NUMSTAT;
  	else if (!strcmp(arg, "--shortstat"))
  		options->output_format |= DIFF_FORMAT_SHORTSTAT;
  	else if (!strcmp(arg, "-X") || !strcmp(arg, "--dirstat"))
  		return parse_dirstat_opt(options, "");
  	else if (skip_prefix(arg, "-X", &arg))
  		return parse_dirstat_opt(options, arg);
  	else if (skip_prefix(arg, "--dirstat=", &arg))
  		return parse_dirstat_opt(options, arg);
  	else if (!strcmp(arg, "--cumulative"))
  		return parse_dirstat_opt(options, "cumulative");
  	else if (!strcmp(arg, "--dirstat-by-file"))
  		return parse_dirstat_opt(options, "files");
  	else if (skip_prefix(arg, "--dirstat-by-file=", &arg)) {
  		parse_dirstat_opt(options, "files");
  		return parse_dirstat_opt(options, arg);
  	}
  	else if (!strcmp(arg, "--check"))
  		options->output_format |= DIFF_FORMAT_CHECKDIFF;
  	else if (!strcmp(arg, "--summary"))
  		options->output_format |= DIFF_FORMAT_SUMMARY;
  	else if (!strcmp(arg, "--patch-with-stat")) {
  		enable_patch_output(&options->output_format);
  		options->output_format |= DIFF_FORMAT_DIFFSTAT;
  	} else if (!strcmp(arg, "--name-only"))
  		options->output_format |= DIFF_FORMAT_NAME;
  	else if (!strcmp(arg, "--name-status"))
  		options->output_format |= DIFF_FORMAT_NAME_STATUS;
  	else if (!strcmp(arg, "-s") || !strcmp(arg, "--no-patch"))
  		options->output_format |= DIFF_FORMAT_NO_OUTPUT;
  	else if (starts_with(arg, "--stat"))
  		/* --stat, --stat-width, --stat-name-width, or --stat-count */
  		return stat_opt(options, av);
  
  	/* renames options */
  	else if (starts_with(arg, "-B") || starts_with(arg, "--break-rewrites=") ||
  		 !strcmp(arg, "--break-rewrites")) {
  		if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
  			return error("invalid argument to -B: %s", arg+2);
  	}
  	else if (starts_with(arg, "-M") || starts_with(arg, "--find-renames=") ||
  		 !strcmp(arg, "--find-renames")) {
  		if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
  			return error("invalid argument to -M: %s", arg+2);
  		options->detect_rename = DIFF_DETECT_RENAME;
  	}
  	else if (!strcmp(arg, "-D") || !strcmp(arg, "--irreversible-delete")) {
  		options->irreversible_delete = 1;
  	}
  	else if (starts_with(arg, "-C") || starts_with(arg, "--find-copies=") ||
  		 !strcmp(arg, "--find-copies")) {
  		if (options->detect_rename == DIFF_DETECT_COPY)
  			DIFF_OPT_SET(options, FIND_COPIES_HARDER);
  		if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
  			return error("invalid argument to -C: %s", arg+2);
  		options->detect_rename = DIFF_DETECT_COPY;
  	}
  	else if (!strcmp(arg, "--no-renames"))
  		options->detect_rename = 0;
  	else if (!strcmp(arg, "--rename-empty"))
  		DIFF_OPT_SET(options, RENAME_EMPTY);
  	else if (!strcmp(arg, "--no-rename-empty"))
  		DIFF_OPT_CLR(options, RENAME_EMPTY);
  	else if (!strcmp(arg, "--relative"))
  		DIFF_OPT_SET(options, RELATIVE_NAME);
  	else if (skip_prefix(arg, "--relative=", &arg)) {
  		DIFF_OPT_SET(options, RELATIVE_NAME);
  		options->prefix = arg;
  	}
  
  	/* xdiff options */
  	else if (!strcmp(arg, "--minimal"))
  		DIFF_XDL_SET(options, NEED_MINIMAL);
  	else if (!strcmp(arg, "--no-minimal"))
  		DIFF_XDL_CLR(options, NEED_MINIMAL);
  	else if (!strcmp(arg, "-w") || !strcmp(arg, "--ignore-all-space"))
  		DIFF_XDL_SET(options, IGNORE_WHITESPACE);
  	else if (!strcmp(arg, "-b") || !strcmp(arg, "--ignore-space-change"))
  		DIFF_XDL_SET(options, IGNORE_WHITESPACE_CHANGE);
  	else if (!strcmp(arg, "--ignore-space-at-eol"))
  		DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL);
  	else if (!strcmp(arg, "--ignore-blank-lines"))
  		DIFF_XDL_SET(options, IGNORE_BLANK_LINES);
  	else if (!strcmp(arg, "--patience"))
  		options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
  	else if (!strcmp(arg, "--histogram"))
  		options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
  	else if ((argcount = parse_long_opt("diff-algorithm", av, &optarg))) {
  		long value = parse_algorithm_value(optarg);
  		if (value < 0)
  			return error("option diff-algorithm accepts \"myers\", "
  				     "\"minimal\", \"patience\" and \"histogram\"");
  		/* clear out previous settings */
  		DIFF_XDL_CLR(options, NEED_MINIMAL);
  		options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
  		options->xdl_opts |= value;
  		return argcount;
  	}
  
  	/* flags options */
  	else if (!strcmp(arg, "--binary")) {
  		enable_patch_output(&options->output_format);
  		DIFF_OPT_SET(options, BINARY);
  	}
  	else if (!strcmp(arg, "--full-index"))
  		DIFF_OPT_SET(options, FULL_INDEX);
  	else if (!strcmp(arg, "-a") || !strcmp(arg, "--text"))
  		DIFF_OPT_SET(options, TEXT);
  	else if (!strcmp(arg, "-R"))
  		DIFF_OPT_SET(options, REVERSE_DIFF);
  	else if (!strcmp(arg, "--find-copies-harder"))
  		DIFF_OPT_SET(options, FIND_COPIES_HARDER);
  	else if (!strcmp(arg, "--follow"))
  		DIFF_OPT_SET(options, FOLLOW_RENAMES);
  	else if (!strcmp(arg, "--no-follow"))
  		DIFF_OPT_CLR(options, FOLLOW_RENAMES);
  	else if (!strcmp(arg, "--color"))
  		options->use_color = 1;
  	else if (skip_prefix(arg, "--color=", &arg)) {
  		int value = git_config_colorbool(NULL, arg);
  		if (value < 0)
  			return error("option `color' expects \"always\", \"auto\", or \"never\"");
  		options->use_color = value;
  	}
  	else if (!strcmp(arg, "--no-color"))
  		options->use_color = 0;
  	else if (!strcmp(arg, "--color-words")) {
  		options->use_color = 1;
  		options->word_diff = DIFF_WORDS_COLOR;
  	}
  	else if (skip_prefix(arg, "--color-words=", &arg)) {
  		options->use_color = 1;
  		options->word_diff = DIFF_WORDS_COLOR;
  		options->word_regex = arg;
  	}
  	else if (!strcmp(arg, "--word-diff")) {
  		if (options->word_diff == DIFF_WORDS_NONE)
  			options->word_diff = DIFF_WORDS_PLAIN;
  	}
  	else if (skip_prefix(arg, "--word-diff=", &arg)) {
  		if (!strcmp(arg, "plain"))
  			options->word_diff = DIFF_WORDS_PLAIN;
  		else if (!strcmp(arg, "color")) {
  			options->use_color = 1;
  			options->word_diff = DIFF_WORDS_COLOR;
  		}
  		else if (!strcmp(arg, "porcelain"))
  			options->word_diff = DIFF_WORDS_PORCELAIN;
  		else if (!strcmp(arg, "none"))
  			options->word_diff = DIFF_WORDS_NONE;
  		else
  			die("bad --word-diff argument: %s", arg);
  	}
  	else if ((argcount = parse_long_opt("word-diff-regex", av, &optarg))) {
  		if (options->word_diff == DIFF_WORDS_NONE)
  			options->word_diff = DIFF_WORDS_PLAIN;
  		options->word_regex = optarg;
  		return argcount;
  	}
  	else if (!strcmp(arg, "--exit-code"))
  		DIFF_OPT_SET(options, EXIT_WITH_STATUS);
  	else if (!strcmp(arg, "--quiet"))
  		DIFF_OPT_SET(options, QUICK);
  	else if (!strcmp(arg, "--ext-diff"))
  		DIFF_OPT_SET(options, ALLOW_EXTERNAL);
  	else if (!strcmp(arg, "--no-ext-diff"))
  		DIFF_OPT_CLR(options, ALLOW_EXTERNAL);
  	else if (!strcmp(arg, "--textconv"))
  		DIFF_OPT_SET(options, ALLOW_TEXTCONV);
  	else if (!strcmp(arg, "--no-textconv"))
  		DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
  	else if (!strcmp(arg, "--ignore-submodules")) {
  		DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
  		handle_ignore_submodules_arg(options, "all");
  	} else if (skip_prefix(arg, "--ignore-submodules=", &arg)) {
  		DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
  		handle_ignore_submodules_arg(options, arg);
  	} else if (!strcmp(arg, "--submodule"))
  		DIFF_OPT_SET(options, SUBMODULE_LOG);
  	else if (skip_prefix(arg, "--submodule=", &arg))
  		return parse_submodule_opt(options, arg);
  	else if (skip_prefix(arg, "--ws-error-highlight=", &arg))
  		return parse_ws_error_highlight(options, arg);
  
  	/* misc options */
  	else if (!strcmp(arg, "-z"))
  		options->line_termination = 0;
  	else if ((argcount = short_opt('l', av, &optarg))) {
  		options->rename_limit = strtoul(optarg, NULL, 10);
  		return argcount;
  	}
  	else if ((argcount = short_opt('S', av, &optarg))) {
  		options->pickaxe = optarg;
  		options->pickaxe_opts |= DIFF_PICKAXE_KIND_S;
  		return argcount;
  	} else if ((argcount = short_opt('G', av, &optarg))) {
  		options->pickaxe = optarg;
  		options->pickaxe_opts |= DIFF_PICKAXE_KIND_G;
  		return argcount;
  	}
  	else if (!strcmp(arg, "--pickaxe-all"))
  		options->pickaxe_opts |= DIFF_PICKAXE_ALL;
  	else if (!strcmp(arg, "--pickaxe-regex"))
  		options->pickaxe_opts |= DIFF_PICKAXE_REGEX;
  	else if ((argcount = short_opt('O', av, &optarg))) {
  		options->orderfile = optarg;
  		return argcount;
  	}
  	else if ((argcount = parse_long_opt("diff-filter", av, &optarg))) {
  		int offending = parse_diff_filter_opt(optarg, options);
  		if (offending)
  			die("unknown change class '%c' in --diff-filter=%s",
  			    offending, optarg);
  		return argcount;
  	}
  	else if (!strcmp(arg, "--abbrev"))
  		options->abbrev = DEFAULT_ABBREV;
  	else if (skip_prefix(arg, "--abbrev=", &arg)) {
  		options->abbrev = strtoul(arg, NULL, 10);
  		if (options->abbrev < MINIMUM_ABBREV)
  			options->abbrev = MINIMUM_ABBREV;
  		else if (40 < options->abbrev)
  			options->abbrev = 40;
  	}
  	else if ((argcount = parse_long_opt("src-prefix", av, &optarg))) {
  		options->a_prefix = optarg;
  		return argcount;
  	}
  	else if ((argcount = parse_long_opt("dst-prefix", av, &optarg))) {
  		options->b_prefix = optarg;
  		return argcount;
  	}
  	else if (!strcmp(arg, "--no-prefix"))
  		options->a_prefix = options->b_prefix = "";
  	else if (opt_arg(arg, '\0', "inter-hunk-context",
  			 &options->interhunkcontext))
  		;
  	else if (!strcmp(arg, "-W"))
  		DIFF_OPT_SET(options, FUNCCONTEXT);
  	else if (!strcmp(arg, "--function-context"))
  		DIFF_OPT_SET(options, FUNCCONTEXT);
  	else if (!strcmp(arg, "--no-function-context"))
  		DIFF_OPT_CLR(options, FUNCCONTEXT);
  	else if ((argcount = parse_long_opt("output", av, &optarg))) {
  		options->file = fopen(optarg, "w");
  		if (!options->file)
  			die_errno("Could not open '%s'", optarg);
  		options->close_file = 1;
  		return argcount;
  	} else
  		return 0;
  	return 1;
  }
  
  int parse_rename_score(const char **cp_p)
  {
  	unsigned long num, scale;
  	int ch, dot;
  	const char *cp = *cp_p;
  
  	num = 0;
  	scale = 1;
  	dot = 0;
  	for (;;) {
  		ch = *cp;
  		if ( !dot && ch == '.' ) {
  			scale = 1;
  			dot = 1;
  		} else if ( ch == '%' ) {
  			scale = dot ? scale*100 : 100;
  			cp++;	/* % is always at the end */
  			break;
  		} else if ( ch >= '0' && ch <= '9' ) {
  			if ( scale < 100000 ) {
  				scale *= 10;
  				num = (num*10) + (ch-'0');
  			}
  		} else {
  			break;
  		}
  		cp++;
  	}
  	*cp_p = cp;
  
  	/* user says num divided by scale and we say internally that
  	 * is MAX_SCORE * num / scale.
  	 */
  	return (int)((num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale));
  }
  
  static int diff_scoreopt_parse(const char *opt)
  {
  	int opt1, opt2, cmd;
  
  	if (*opt++ != '-')
  		return -1;
  	cmd = *opt++;
  	if (cmd == '-') {
  		/* convert the long-form arguments into short-form versions */
  		if (skip_prefix(opt, "break-rewrites", &opt)) {
  			if (*opt == 0 || *opt++ == '=')
  				cmd = 'B';
  		} else if (skip_prefix(opt, "find-copies", &opt)) {
  			if (*opt == 0 || *opt++ == '=')
  				cmd = 'C';
  		} else if (skip_prefix(opt, "find-renames", &opt)) {
  			if (*opt == 0 || *opt++ == '=')
  				cmd = 'M';
  		}
  	}
  	if (cmd != 'M' && cmd != 'C' && cmd != 'B')
  		return -1; /* that is not a -M, -C, or -B option */
  
  	opt1 = parse_rename_score(&opt);
  	if (cmd != 'B')
  		opt2 = 0;
  	else {
  		if (*opt == 0)
  			opt2 = 0;
  		else if (*opt != '/')
  			return -1; /* we expect -B80/99 or -B80 */
  		else {
  			opt++;
  			opt2 = parse_rename_score(&opt);
  		}
  	}
  	if (*opt != 0)
  		return -1;
  	return opt1 | (opt2 << 16);
  }
  
  struct diff_queue_struct diff_queued_diff;
  
  void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
  {
  	ALLOC_GROW(queue->queue, queue->nr + 1, queue->alloc);
  	queue->queue[queue->nr++] = dp;
  }
  
  struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
  				 struct diff_filespec *one,
  				 struct diff_filespec *two)
  {
  	struct diff_filepair *dp = xcalloc(1, sizeof(*dp));
  	dp->one = one;
  	dp->two = two;
  	if (queue)
  		diff_q(queue, dp);
  	return dp;
  }
  
  void diff_free_filepair(struct diff_filepair *p)
  {
  	free_filespec(p->one);
  	free_filespec(p->two);
  	free(p);
  }
  
  /* This is different from find_unique_abbrev() in that
   * it stuffs the result with dots for alignment.
   */
  const char *diff_unique_abbrev(const unsigned char *sha1, int len)
  {
  	int abblen;
  	const char *abbrev;
  	if (len == 40)
  		return sha1_to_hex(sha1);
  
  	abbrev = find_unique_abbrev(sha1, len);
  	abblen = strlen(abbrev);
  	if (abblen < 37) {
  		static char hex[41];
  		if (len < abblen && abblen <= len + 2)
  			sprintf(hex, "%s%.*s", abbrev, len+3-abblen, "..");
  		else
  			sprintf(hex, "%s...", abbrev);
  		return hex;
  	}
  	return sha1_to_hex(sha1);
  }
  
  static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
  {
  	int line_termination = opt->line_termination;
  	int inter_name_termination = line_termination ? '\t' : '\0';
  
  	fprintf(opt->file, "%s", diff_line_prefix(opt));
  	if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
  		fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
  			diff_unique_abbrev(p->one->sha1, opt->abbrev));
  		fprintf(opt->file, "%s ", diff_unique_abbrev(p->two->sha1, opt->abbrev));
  	}
  	if (p->score) {
  		fprintf(opt->file, "%c%03d%c", p->status, similarity_index(p),
  			inter_name_termination);
  	} else {
  		fprintf(opt->file, "%c%c", p->status, inter_name_termination);
  	}
  
  	if (p->status == DIFF_STATUS_COPIED ||
  	    p->status == DIFF_STATUS_RENAMED) {
  		const char *name_a, *name_b;
  		name_a = p->one->path;
  		name_b = p->two->path;
  		strip_prefix(opt->prefix_length, &name_a, &name_b);
  		write_name_quoted(name_a, opt->file, inter_name_termination);
  		write_name_quoted(name_b, opt->file, line_termination);
  	} else {
  		const char *name_a, *name_b;
  		name_a = p->one->mode ? p->one->path : p->two->path;
  		name_b = NULL;
  		strip_prefix(opt->prefix_length, &name_a, &name_b);
  		write_name_quoted(name_a, opt->file, line_termination);
  	}
  }
  
  int diff_unmodified_pair(struct diff_filepair *p)
  {
  	/* This function is written stricter than necessary to support
  	 * the currently implemented transformers, but the idea is to
  	 * let transformers to produce diff_filepairs any way they want,
  	 * and filter and clean them up here before producing the output.
  	 */
  	struct diff_filespec *one = p->one, *two = p->two;
  
  	if (DIFF_PAIR_UNMERGED(p))
  		return 0; /* unmerged is interesting */
  
  	/* deletion, addition, mode or type change
  	 * and rename are all interesting.
  	 */
  	if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
  	    DIFF_PAIR_MODE_CHANGED(p) ||
  	    strcmp(one->path, two->path))
  		return 0;
  
  	/* both are valid and point at the same path.  that is, we are
  	 * dealing with a change.
  	 */
  	if (one->sha1_valid && two->sha1_valid &&
  	    !hashcmp(one->sha1, two->sha1) &&
  	    !one->dirty_submodule && !two->dirty_submodule)
  		return 1; /* no change */
  	if (!one->sha1_valid && !two->sha1_valid)
  		return 1; /* both look at the same file on the filesystem. */
  	return 0;
  }
  
  static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
  {
  	if (diff_unmodified_pair(p))
  		return;
  
  	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
  	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
  		return; /* no tree diffs in patch format */
  
  	run_diff(p, o);
  }
  
  static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
  			    struct diffstat_t *diffstat)
  {
  	if (diff_unmodified_pair(p))
  		return;
  
  	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
  	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
  		return; /* no useful stat for tree diffs */
  
  	run_diffstat(p, o, diffstat);
  }
  
  static void diff_flush_checkdiff(struct diff_filepair *p,
  		struct diff_options *o)
  {
  	if (diff_unmodified_pair(p))
  		return;
  
  	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
  	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
  		return; /* nothing to check in tree diffs */
  
  	run_checkdiff(p, o);
  }
  
  int diff_queue_is_empty(void)
  {
  	struct diff_queue_struct *q = &diff_queued_diff;
  	int i;
  	for (i = 0; i < q->nr; i++)
  		if (!diff_unmodified_pair(q->queue[i]))
  			return 0;
  	return 1;
  }
  
  #if DIFF_DEBUG
  void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
  {
  	fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
  		x, one ? one : "",
  		s->path,
  		DIFF_FILE_VALID(s) ? "valid" : "invalid",
  		s->mode,
  		s->sha1_valid ? sha1_to_hex(s->sha1) : "");
  	fprintf(stderr, "queue[%d] %s size %lu\n",
  		x, one ? one : "",
  		s->size);
  }
  
  void diff_debug_filepair(const struct diff_filepair *p, int i)
  {
  	diff_debug_filespec(p->one, i, "one");
  	diff_debug_filespec(p->two, i, "two");
  	fprintf(stderr, "score %d, status %c rename_used %d broken %d\n",
  		p->score, p->status ? p->status : '?',
  		p->one->rename_used, p->broken_pair);
  }
  
  void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
  {
  	int i;
  	if (msg)
  		fprintf(stderr, "%s\n", msg);
  	fprintf(stderr, "q->nr = %d\n", q->nr);
  	for (i = 0; i < q->nr; i++) {
  		struct diff_filepair *p = q->queue[i];
  		diff_debug_filepair(p, i);
  	}
  }
  #endif
  
  static void diff_resolve_rename_copy(void)
  {
  	int i;
  	struct diff_filepair *p;
  	struct diff_queue_struct *q = &diff_queued_diff;
  
  	diff_debug_queue("resolve-rename-copy", q);
  
  	for (i = 0; i < q->nr; i++) {
  		p = q->queue[i];
  		p->status = 0; /* undecided */
  		if (DIFF_PAIR_UNMERGED(p))
  			p->status = DIFF_STATUS_UNMERGED;
  		else if (!DIFF_FILE_VALID(p->one))
  			p->status = DIFF_STATUS_ADDED;
  		else if (!DIFF_FILE_VALID(p->two))
  			p->status = DIFF_STATUS_DELETED;
  		else if (DIFF_PAIR_TYPE_CHANGED(p))
  			p->status = DIFF_STATUS_TYPE_CHANGED;
  
  		/* from this point on, we are dealing with a pair
  		 * whose both sides are valid and of the same type, i.e.
  		 * either in-place edit or rename/copy edit.
  		 */
  		else if (DIFF_PAIR_RENAME(p)) {
  			/*
  			 * A rename might have re-connected a broken
  			 * pair up, causing the pathnames to be the
  			 * same again. If so, that's not a rename at
  			 * all, just a modification..
  			 *
  			 * Otherwise, see if this source was used for
  			 * multiple renames, in which case we decrement
  			 * the count, and call it a copy.
  			 */
  			if (!strcmp(p->one->path, p->two->path))
  				p->status = DIFF_STATUS_MODIFIED;
  			else if (--p->one->rename_used > 0)
  				p->status = DIFF_STATUS_COPIED;
  			else
  				p->status = DIFF_STATUS_RENAMED;
  		}
  		else if (hashcmp(p->one->sha1, p->two->sha1) ||
  			 p->one->mode != p->two->mode ||
  			 p->one->dirty_submodule ||
  			 p->two->dirty_submodule ||
  			 is_null_sha1(p->one->sha1))
  			p->status = DIFF_STATUS_MODIFIED;
  		else {
  			/* This is a "no-change" entry and should not
  			 * happen anymore, but prepare for broken callers.
  			 */
  			error("feeding unmodified %s to diffcore",
  			      p->one->path);
  			p->status = DIFF_STATUS_UNKNOWN;
  		}
  	}
  	diff_debug_queue("resolve-rename-copy done", q);
  }
  
  static int check_pair_status(struct diff_filepair *p)
  {
  	switch (p->status) {
  	case DIFF_STATUS_UNKNOWN:
  		return 0;
  	case 0:
  		die("internal error in diff-resolve-rename-copy");
  	default:
  		return 1;
  	}
  }
  
  static void flush_one_pair(struct diff_filepair *p, struct diff_options *opt)
  {
  	int fmt = opt->output_format;
  
  	if (fmt & DIFF_FORMAT_CHECKDIFF)
  		diff_flush_checkdiff(p, opt);
  	else if (fmt & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS))
  		diff_flush_raw(p, opt);
  	else if (fmt & DIFF_FORMAT_NAME) {
  		const char *name_a, *name_b;
  		name_a = p->two->path;
  		name_b = NULL;
  		strip_prefix(opt->prefix_length, &name_a, &name_b);
  		write_name_quoted(name_a, opt->file, opt->line_termination);
  	}
  }
  
  static void show_file_mode_name(FILE *file, const char *newdelete, struct diff_filespec *fs)
  {
  	if (fs->mode)
  		fprintf(file, " %s mode %06o ", newdelete, fs->mode);
  	else
  		fprintf(file, " %s ", newdelete);
  	write_name_quoted(fs->path, file, '\n');
  }
  
  
  static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name,
  		const char *line_prefix)
  {
  	if (p->one->mode && p->two->mode && p->one->mode != p->two->mode) {
  		fprintf(file, "%s mode change %06o => %06o%c", line_prefix, p->one->mode,
  			p->two->mode, show_name ? ' ' : '\n');
  		if (show_name) {
  			write_name_quoted(p->two->path, file, '\n');
  		}
  	}
  }
  
  static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p,
  			const char *line_prefix)
  {
  	char *names = pprint_rename(p->one->path, p->two->path);
  
  	fprintf(file, " %s %s (%d%%)\n", renamecopy, names, similarity_index(p));
  	free(names);
  	show_mode_change(file, p, 0, line_prefix);
  }
  
  static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
  {
  	FILE *file = opt->file;
  	const char *line_prefix = diff_line_prefix(opt);
  
  	switch(p->status) {
  	case DIFF_STATUS_DELETED:
  		fputs(line_prefix, file);
  		show_file_mode_name(file, "delete", p->one);
  		break;
  	case DIFF_STATUS_ADDED:
  		fputs(line_prefix, file);
  		show_file_mode_name(file, "create", p->two);
  		break;
  	case DIFF_STATUS_COPIED:
  		fputs(line_prefix, file);
  		show_rename_copy(file, "copy", p, line_prefix);
  		break;
  	case DIFF_STATUS_RENAMED:
  		fputs(line_prefix, file);
  		show_rename_copy(file, "rename", p, line_prefix);
  		break;
  	default:
  		if (p->score) {
  			fprintf(file, "%s rewrite ", line_prefix);
  			write_name_quoted(p->two->path, file, ' ');
  			fprintf(file, "(%d%%)\n", similarity_index(p));
  		}
  		show_mode_change(file, p, !p->score, line_prefix);
  		break;
  	}
  }
  
  struct patch_id_t {
  	git_SHA_CTX *ctx;
  	int patchlen;
  };
  
  static int remove_space(char *line, int len)
  {
  	int i;
  	char *dst = line;
  	unsigned char c;
  
  	for (i = 0; i < len; i++)
  		if (!isspace((c = line[i])))
  			*dst++ = c;
  
  	return dst - line;
  }
  
  static void patch_id_consume(void *priv, char *line, unsigned long len)
  {
  	struct patch_id_t *data = priv;
  	int new_len;
  
  	/* Ignore line numbers when computing the SHA1 of the patch */
  	if (starts_with(line, "@@ -"))
  		return;
  
  	new_len = remove_space(line, len);
  
  	git_SHA1_Update(data->ctx, line, new_len);
  	data->patchlen += new_len;
  }
  
  /* returns 0 upon success, and writes result into sha1 */
  static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
  {
  	struct diff_queue_struct *q = &diff_queued_diff;
  	int i;
  	git_SHA_CTX ctx;
  	struct patch_id_t data;
  	char buffer[PATH_MAX * 4 + 20];
  
  	git_SHA1_Init(&ctx);
  	memset(&data, 0, sizeof(struct patch_id_t));
  	data.ctx = &ctx;
  
  	for (i = 0; i < q->nr; i++) {
  		xpparam_t xpp;
  		xdemitconf_t xecfg;
  		mmfile_t mf1, mf2;
  		struct diff_filepair *p = q->queue[i];
  		int len1, len2;
  
  		memset(&xpp, 0, sizeof(xpp));
  		memset(&xecfg, 0, sizeof(xecfg));
  		if (p->status == 0)
  			return error("internal diff status error");
  		if (p->status == DIFF_STATUS_UNKNOWN)
  			continue;
  		if (diff_unmodified_pair(p))
  			continue;
  		if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
  		    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
  			continue;
  		if (DIFF_PAIR_UNMERGED(p))
  			continue;
  
  		diff_fill_sha1_info(p->one);
  		diff_fill_sha1_info(p->two);
  		if (fill_mmfile(&mf1, p->one) < 0 ||
  				fill_mmfile(&mf2, p->two) < 0)
  			return error("unable to read files to diff");
  
  		len1 = remove_space(p->one->path, strlen(p->one->path));
  		len2 = remove_space(p->two->path, strlen(p->two->path));
  		if (p->one->mode == 0)
  			len1 = snprintf(buffer, sizeof(buffer),
  					"diff--gita/%.*sb/%.*s"
  					"newfilemode%06o"
  					"---/dev/null"
  					"+++b/%.*s",
  					len1, p->one->path,
  					len2, p->two->path,
  					p->two->mode,
  					len2, p->two->path);
  		else if (p->two->mode == 0)
  			len1 = snprintf(buffer, sizeof(buffer),
  					"diff--gita/%.*sb/%.*s"
  					"deletedfilemode%06o"
  					"---a/%.*s"
  					"+++/dev/null",
  					len1, p->one->path,
  					len2, p->two->path,
  					p->one->mode,
  					len1, p->one->path);
  		else
  			len1 = snprintf(buffer, sizeof(buffer),
  					"diff--gita/%.*sb/%.*s"
  					"---a/%.*s"
  					"+++b/%.*s",
  					len1, p->one->path,
  					len2, p->two->path,
  					len1, p->one->path,
  					len2, p->two->path);
  		git_SHA1_Update(&ctx, buffer, len1);
  
  		if (diff_filespec_is_binary(p->one) ||
  		    diff_filespec_is_binary(p->two)) {
  			git_SHA1_Update(&ctx, sha1_to_hex(p->one->sha1), 40);
  			git_SHA1_Update(&ctx, sha1_to_hex(p->two->sha1), 40);
  			continue;
  		}
  
  		xpp.flags = 0;
  		xecfg.ctxlen = 3;
  		xecfg.flags = 0;
  		xdi_diff_outf(&mf1, &mf2, patch_id_consume, &data,
  			      &xpp, &xecfg);
  	}
  
  	git_SHA1_Final(sha1, &ctx);
  	return 0;
  }
  
  int diff_flush_patch_id(struct diff_options *options, unsigned char *sha1)
  {
  	struct diff_queue_struct *q = &diff_queued_diff;
  	int i;
  	int result = diff_get_patch_id(options, sha1);
  
  	for (i = 0; i < q->nr; i++)
  		diff_free_filepair(q->queue[i]);
  
  	free(q->queue);
  	DIFF_QUEUE_CLEAR(q);
  
  	return result;
  }
  
  static int is_summary_empty(const struct diff_queue_struct *q)
  {
  	int i;
  
  	for (i = 0; i < q->nr; i++) {
  		const struct diff_filepair *p = q->queue[i];
  
  		switch (p->status) {
  		case DIFF_STATUS_DELETED:
  		case DIFF_STATUS_ADDED:
  		case DIFF_STATUS_COPIED:
  		case DIFF_STATUS_RENAMED:
  			return 0;
  		default:
  			if (p->score)
  				return 0;
  			if (p->one->mode && p->two->mode &&
  			    p->one->mode != p->two->mode)
  				return 0;
  			break;
  		}
  	}
  	return 1;
  }
  
  static const char rename_limit_warning[] =
  "inexact rename detection was skipped due to too many files.";
  
  static const char degrade_cc_to_c_warning[] =
  "only found copies from modified paths due to too many files.";
  
  static const char rename_limit_advice[] =
  "you may want to set your %s variable to at least "
  "%d and retry the command.";
  
  void diff_warn_rename_limit(const char *varname, int needed, int degraded_cc)
  {
  	if (degraded_cc)
  		warning(degrade_cc_to_c_warning);
  	else if (needed)
  		warning(rename_limit_warning);
  	else
  		return;
  	if (0 < needed && needed < 32767)
  		warning(rename_limit_advice, varname, needed);
  }
  
  void diff_flush(struct diff_options *options)
  {
  	struct diff_queue_struct *q = &diff_queued_diff;
  	int i, output_format = options->output_format;
  	int separator = 0;
  	int dirstat_by_line = 0;
  
  	/*
  	 * Order: raw, stat, summary, patch
  	 * or:    name/name-status/checkdiff (other bits clear)
  	 */
  	if (!q->nr)
  		goto free_queue;
  
  	if (output_format & (DIFF_FORMAT_RAW |
  			     DIFF_FORMAT_NAME |
  			     DIFF_FORMAT_NAME_STATUS |
  			     DIFF_FORMAT_CHECKDIFF)) {
  		for (i = 0; i < q->nr; i++) {
  			struct diff_filepair *p = q->queue[i];
  			if (check_pair_status(p))
  				flush_one_pair(p, options);
  		}
  		separator++;
  	}
  
  	if (output_format & DIFF_FORMAT_DIRSTAT && DIFF_OPT_TST(options, DIRSTAT_BY_LINE))
  		dirstat_by_line = 1;
  
  	if (output_format & (DIFF_FORMAT_DIFFSTAT|DIFF_FORMAT_SHORTSTAT|DIFF_FORMAT_NUMSTAT) ||
  	    dirstat_by_line) {
  		struct diffstat_t diffstat;
  
  		memset(&diffstat, 0, sizeof(struct diffstat_t));
  		for (i = 0; i < q->nr; i++) {
  			struct diff_filepair *p = q->queue[i];
  			if (check_pair_status(p))
  				diff_flush_stat(p, options, &diffstat);
  		}
  		if (output_format & DIFF_FORMAT_NUMSTAT)
  			show_numstat(&diffstat, options);
  		if (output_format & DIFF_FORMAT_DIFFSTAT)
  			show_stats(&diffstat, options);
  		if (output_format & DIFF_FORMAT_SHORTSTAT)
  			show_shortstats(&diffstat, options);
  		if (output_format & DIFF_FORMAT_DIRSTAT && dirstat_by_line)
  			show_dirstat_by_line(&diffstat, options);
  		free_diffstat_info(&diffstat);
  		separator++;
  	}
  	if ((output_format & DIFF_FORMAT_DIRSTAT) && !dirstat_by_line)
  		show_dirstat(options);
  
  	if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
  		for (i = 0; i < q->nr; i++) {
  			diff_summary(options, q->queue[i]);
  		}
  		separator++;
  	}
  
  	if (output_format & DIFF_FORMAT_NO_OUTPUT &&
  	    DIFF_OPT_TST(options, EXIT_WITH_STATUS) &&
  	    DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
  		/*
  		 * run diff_flush_patch for the exit status. setting
  		 * options->file to /dev/null should be safe, because we
  		 * aren't supposed to produce any output anyway.
  		 */
  		if (options->close_file)
  			fclose(options->file);
  		options->file = fopen("/dev/null", "w");
  		if (!options->file)
  			die_errno("Could not open /dev/null");
  		options->close_file = 1;
  		for (i = 0; i < q->nr; i++) {
  			struct diff_filepair *p = q->queue[i];
  			if (check_pair_status(p))
  				diff_flush_patch(p, options);
  			if (options->found_changes)
  				break;
  		}
  	}
  
  	if (output_format & DIFF_FORMAT_PATCH) {
  		if (separator) {
  			fprintf(options->file, "%s%c",
  				diff_line_prefix(options),
  				options->line_termination);
  			if (options->stat_sep) {
  				/* attach patch instead of inline */
  				fputs(options->stat_sep, options->file);
  			}
  		}
  
  		for (i = 0; i < q->nr; i++) {
  			struct diff_filepair *p = q->queue[i];
  			if (check_pair_status(p))
  				diff_flush_patch(p, options);
  		}
  	}
  
  	if (output_format & DIFF_FORMAT_CALLBACK)
  		options->format_callback(q, options, options->format_callback_data);
  
  	for (i = 0; i < q->nr; i++)
  		diff_free_filepair(q->queue[i]);
  free_queue:
  	free(q->queue);
  	DIFF_QUEUE_CLEAR(q);
  	if (options->close_file)
  		fclose(options->file);
  
  	/*
  	 * Report the content-level differences with HAS_CHANGES;
  	 * diff_addremove/diff_change does not set the bit when
  	 * DIFF_FROM_CONTENTS is in effect (e.g. with -w).
  	 */
  	if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
  		if (options->found_changes)
  			DIFF_OPT_SET(options, HAS_CHANGES);
  		else
  			DIFF_OPT_CLR(options, HAS_CHANGES);
  	}
  }
  
  static int match_filter(const struct diff_options *options, const struct diff_filepair *p)
  {
  	return (((p->status == DIFF_STATUS_MODIFIED) &&
  		 ((p->score &&
  		   filter_bit_tst(DIFF_STATUS_FILTER_BROKEN, options)) ||
  		  (!p->score &&
  		   filter_bit_tst(DIFF_STATUS_MODIFIED, options)))) ||
  		((p->status != DIFF_STATUS_MODIFIED) &&
  		 filter_bit_tst(p->status, options)));
  }
  
  static void diffcore_apply_filter(struct diff_options *options)
  {
  	int i;
  	struct diff_queue_struct *q = &diff_queued_diff;
  	struct diff_queue_struct outq;
  
  	DIFF_QUEUE_CLEAR(&outq);
  
  	if (!options->filter)
  		return;
  
  	if (filter_bit_tst(DIFF_STATUS_FILTER_AON, options)) {
  		int found;
  		for (i = found = 0; !found && i < q->nr; i++) {
  			if (match_filter(options, q->queue[i]))
  				found++;
  		}
  		if (found)
  			return;
  
  		/* otherwise we will clear the whole queue
  		 * by copying the empty outq at the end of this
  		 * function, but first clear the current entries
  		 * in the queue.
  		 */
  		for (i = 0; i < q->nr; i++)
  			diff_free_filepair(q->queue[i]);
  	}
  	else {
  		/* Only the matching ones */
  		for (i = 0; i < q->nr; i++) {
  			struct diff_filepair *p = q->queue[i];
  			if (match_filter(options, p))
  				diff_q(&outq, p);
  			else
  				diff_free_filepair(p);
  		}
  	}
  	free(q->queue);
  	*q = outq;
  }
  
  /* Check whether two filespecs with the same mode and size are identical */
  static int diff_filespec_is_identical(struct diff_filespec *one,
  				      struct diff_filespec *two)
  {
  	if (S_ISGITLINK(one->mode))
  		return 0;
  	if (diff_populate_filespec(one, 0))
  		return 0;
  	if (diff_populate_filespec(two, 0))
  		return 0;
  	return !memcmp(one->data, two->data, one->size);
  }
  
  static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
  {
  	if (p->done_skip_stat_unmatch)
  		return p->skip_stat_unmatch_result;
  
  	p->done_skip_stat_unmatch = 1;
  	p->skip_stat_unmatch_result = 0;
  	/*
  	 * 1. Entries that come from stat info dirtiness
  	 *    always have both sides (iow, not create/delete),
  	 *    one side of the object name is unknown, with
  	 *    the same mode and size.  Keep the ones that
  	 *    do not match these criteria.  They have real
  	 *    differences.
  	 *
  	 * 2. At this point, the file is known to be modified,
  	 *    with the same mode and size, and the object
  	 *    name of one side is unknown.  Need to inspect
  	 *    the identical contents.
  	 */
  	if (!DIFF_FILE_VALID(p->one) || /* (1) */
  	    !DIFF_FILE_VALID(p->two) ||
  	    (p->one->sha1_valid && p->two->sha1_valid) ||
  	    (p->one->mode != p->two->mode) ||
  	    diff_populate_filespec(p->one, CHECK_SIZE_ONLY) ||
  	    diff_populate_filespec(p->two, CHECK_SIZE_ONLY) ||
  	    (p->one->size != p->two->size) ||
  	    !diff_filespec_is_identical(p->one, p->two)) /* (2) */
  		p->skip_stat_unmatch_result = 1;
  	return p->skip_stat_unmatch_result;
  }
  
  static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
  {
  	int i;
  	struct diff_queue_struct *q = &diff_queued_diff;
  	struct diff_queue_struct outq;
  	DIFF_QUEUE_CLEAR(&outq);
  
  	for (i = 0; i < q->nr; i++) {
  		struct diff_filepair *p = q->queue[i];
  
  		if (diff_filespec_check_stat_unmatch(p))
  			diff_q(&outq, p);
  		else {
  			/*
  			 * The caller can subtract 1 from skip_stat_unmatch
  			 * to determine how many paths were dirty only
  			 * due to stat info mismatch.
  			 */
  			if (!DIFF_OPT_TST(diffopt, NO_INDEX))
  				diffopt->skip_stat_unmatch++;
  			diff_free_filepair(p);
  		}
  	}
  	free(q->queue);
  	*q = outq;
  }
  
  static int diffnamecmp(const void *a_, const void *b_)
  {
  	const struct diff_filepair *a = *((const struct diff_filepair **)a_);
  	const struct diff_filepair *b = *((const struct diff_filepair **)b_);
  	const char *name_a, *name_b;
  
  	name_a = a->one ? a->one->path : a->two->path;
  	name_b = b->one ? b->one->path : b->two->path;
  	return strcmp(name_a, name_b);
  }
  
  void diffcore_fix_diff_index(struct diff_options *options)
  {
  	struct diff_queue_struct *q = &diff_queued_diff;
  	qsort(q->queue, q->nr, sizeof(q->queue[0]), diffnamecmp);
  }
  
  void diffcore_std(struct diff_options *options)
  {
  	/* NOTE please keep the following in sync with diff_tree_combined() */
  	if (options->skip_stat_unmatch)
  		diffcore_skip_stat_unmatch(options);
  	if (!options->found_follow) {
  		/* See try_to_follow_renames() in tree-diff.c */
  		if (options->break_opt != -1)
  			diffcore_break(options->break_opt);
  		if (options->detect_rename)
  			diffcore_rename(options);
  		if (options->break_opt != -1)
  			diffcore_merge_broken();
  	}
  	if (options->pickaxe)
  		diffcore_pickaxe(options);
  	if (options->orderfile)
  		diffcore_order(options->orderfile);
  	if (!options->found_follow)
  		/* See try_to_follow_renames() in tree-diff.c */
  		diff_resolve_rename_copy();
  	diffcore_apply_filter(options);
  
  	if (diff_queued_diff.nr && !DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
  		DIFF_OPT_SET(options, HAS_CHANGES);
  	else
  		DIFF_OPT_CLR(options, HAS_CHANGES);
  
  	options->found_follow = 0;
  }
  
  int diff_result_code(struct diff_options *opt, int status)
  {
  	int result = 0;
  
  	diff_warn_rename_limit("diff.renameLimit",
  			       opt->needed_rename_limit,
  			       opt->degraded_cc_to_c);
  	if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
  	    !(opt->output_format & DIFF_FORMAT_CHECKDIFF))
  		return status;
  	if (DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
  	    DIFF_OPT_TST(opt, HAS_CHANGES))
  		result |= 01;
  	if ((opt->output_format & DIFF_FORMAT_CHECKDIFF) &&
  	    DIFF_OPT_TST(opt, CHECK_FAILED))
  		result |= 02;
  	return result;
  }
  
  int diff_can_quit_early(struct diff_options *opt)
  {
  	return (DIFF_OPT_TST(opt, QUICK) &&
  		!opt->filter &&
  		DIFF_OPT_TST(opt, HAS_CHANGES));
  }
  
  /*
   * Shall changes to this submodule be ignored?
   *
   * Submodule changes can be configured to be ignored separately for each path,
   * but that configuration can be overridden from the command line.
   */
  static int is_submodule_ignored(const char *path, struct diff_options *options)
  {
  	int ignored = 0;
  	unsigned orig_flags = options->flags;
  	if (!DIFF_OPT_TST(options, OVERRIDE_SUBMODULE_CONFIG))
  		set_diffopt_flags_from_submodule_config(options, path);
  	if (DIFF_OPT_TST(options, IGNORE_SUBMODULES))
  		ignored = 1;
  	options->flags = orig_flags;
  	return ignored;
  }
  
  void diff_addremove(struct diff_options *options,
  		    int addremove, unsigned mode,
  		    const unsigned char *sha1,
  		    int sha1_valid,
  		    const char *concatpath, unsigned dirty_submodule)
  {
  	struct diff_filespec *one, *two;
  
  	if (S_ISGITLINK(mode) && is_submodule_ignored(concatpath, options))
  		return;
  
  	/* This may look odd, but it is a preparation for
  	 * feeding "there are unchanged files which should
  	 * not produce diffs, but when you are doing copy
  	 * detection you would need them, so here they are"
  	 * entries to the diff-core.  They will be prefixed
  	 * with something like '=' or '*' (I haven't decided
  	 * which but should not make any difference).
  	 * Feeding the same new and old to diff_change()
  	 * also has the same effect.
  	 * Before the final output happens, they are pruned after
  	 * merged into rename/copy pairs as appropriate.
  	 */
  	if (DIFF_OPT_TST(options, REVERSE_DIFF))
  		addremove = (addremove == '+' ? '-' :
  			     addremove == '-' ? '+' : addremove);
  
  	if (options->prefix &&
  	    strncmp(concatpath, options->prefix, options->prefix_length))
  		return;
  
  	one = alloc_filespec(concatpath);
  	two = alloc_filespec(concatpath);
  
  	if (addremove != '+')
  		fill_filespec(one, sha1, sha1_valid, mode);
  	if (addremove != '-') {
  		fill_filespec(two, sha1, sha1_valid, mode);
  		two->dirty_submodule = dirty_submodule;
  	}
  
  	diff_queue(&diff_queued_diff, one, two);
  	if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
  		DIFF_OPT_SET(options, HAS_CHANGES);
  }
  
  void diff_change(struct diff_options *options,
  		 unsigned old_mode, unsigned new_mode,
  		 const unsigned char *old_sha1,
  		 const unsigned char *new_sha1,
  		 int old_sha1_valid, int new_sha1_valid,
  		 const char *concatpath,
  		 unsigned old_dirty_submodule, unsigned new_dirty_submodule)
  {
  	struct diff_filespec *one, *two;
  	struct diff_filepair *p;
  
  	if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
  	    is_submodule_ignored(concatpath, options))
  		return;
  
  	if (DIFF_OPT_TST(options, REVERSE_DIFF)) {
  		unsigned tmp;
  		const unsigned char *tmp_c;
  		tmp = old_mode; old_mode = new_mode; new_mode = tmp;
  		tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
  		tmp = old_sha1_valid; old_sha1_valid = new_sha1_valid;
  			new_sha1_valid = tmp;
  		tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
  			new_dirty_submodule = tmp;
  	}
  
  	if (options->prefix &&
  	    strncmp(concatpath, options->prefix, options->prefix_length))
  		return;
  
  	one = alloc_filespec(concatpath);
  	two = alloc_filespec(concatpath);
  	fill_filespec(one, old_sha1, old_sha1_valid, old_mode);
  	fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
  	one->dirty_submodule = old_dirty_submodule;
  	two->dirty_submodule = new_dirty_submodule;
  	p = diff_queue(&diff_queued_diff, one, two);
  
  	if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
  		return;
  
  	if (DIFF_OPT_TST(options, QUICK) && options->skip_stat_unmatch &&
  	    !diff_filespec_check_stat_unmatch(p))
  		return;
  
  	DIFF_OPT_SET(options, HAS_CHANGES);
  }
  
  struct diff_filepair *diff_unmerge(struct diff_options *options, const char *path)
  {
  	struct diff_filepair *pair;
  	struct diff_filespec *one, *two;
  
  	if (options->prefix &&
  	    strncmp(path, options->prefix, options->prefix_length))
  		return NULL;
  
  	one = alloc_filespec(path);
  	two = alloc_filespec(path);
  	pair = diff_queue(&diff_queued_diff, one, two);
  	pair->is_unmerged = 1;
  	return pair;
  }
  
  static char *run_textconv(const char *pgm, struct diff_filespec *spec,
  		size_t *outsize)
  {
  	struct diff_tempfile *temp;
  	const char *argv[3];
  	const char **arg = argv;
  	struct child_process child = CHILD_PROCESS_INIT;
  	struct strbuf buf = STRBUF_INIT;
  	int err = 0;
  
  	temp = prepare_temp_file(spec->path, spec);
  	*arg++ = pgm;
  	*arg++ = temp->name;
  	*arg = NULL;
  
  	child.use_shell = 1;
  	child.argv = argv;
  	child.out = -1;
  	if (start_command(&child)) {
  		remove_tempfile();
  		return NULL;
  	}
  
  	if (strbuf_read(&buf, child.out, 0) < 0)
  		err = error("error reading from textconv command '%s'", pgm);
  	close(child.out);
  
  	if (finish_command(&child) || err) {
  		strbuf_release(&buf);
  		remove_tempfile();
  		return NULL;
  	}
  	remove_tempfile();
  
  	return strbuf_detach(&buf, outsize);
  }
  
  size_t fill_textconv(struct userdiff_driver *driver,
  		     struct diff_filespec *df,
  		     char **outbuf)
  {
  	size_t size;
  
  	if (!driver || !driver->textconv) {
  		if (!DIFF_FILE_VALID(df)) {
  			*outbuf = "";
  			return 0;
  		}
  		if (diff_populate_filespec(df, 0))
  			die("unable to read files to diff");
  		*outbuf = df->data;
  		return df->size;
  	}
  
  	if (driver->textconv_cache && df->sha1_valid) {
  		*outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
  					  &size);
  		if (*outbuf)
  			return size;
  	}
  
  	*outbuf = run_textconv(driver->textconv, df, &size);
  	if (!*outbuf)
  		die("unable to read files to diff");
  
  	if (driver->textconv_cache && df->sha1_valid) {
  		/* ignore errors, as we might be in a readonly repository */
  		notes_cache_put(driver->textconv_cache, df->sha1, *outbuf,
  				size);
  		/*
  		 * we could save up changes and flush them all at the end,
  		 * but we would need an extra call after all diffing is done.
  		 * Since generating a cache entry is the slow path anyway,
  		 * this extra overhead probably isn't a big deal.
  		 */
  		notes_cache_write(driver->textconv_cache);
  	}
  
  	return size;
  }
  
  void setup_diff_pager(struct diff_options *opt)
  {
  	/*
  	 * If the user asked for our exit code, then either they want --quiet
  	 * or --exit-code. We should definitely not bother with a pager in the
  	 * former case, as we will generate no output. Since we still properly
  	 * report our exit code even when a pager is run, we _could_ run a
  	 * pager with --exit-code. But since we have not done so historically,
  	 * and because it is easy to find people oneline advising "git diff
  	 * --exit-code" in hooks and other scripts, we do not do so.
  	 */
  	if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
  	    check_pager_config("diff") != 0)
  		setup_pager();
  }
  