text: /* vi: set sw=4 ts=4: */
  /*
   * sed.c - very minimalist version of sed
   *
   * Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
   * Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
   * Copyright (C) 2002  Matt Kraai
   * Copyright (C) 2003 by Glenn McGrath
   * Copyright (C) 2003,2004 by Rob Landley <rob@landley.net>
   *
   * MAINTAINER: Rob Landley <rob@landley.net>
   *
   * Licensed under GPLv2, see file LICENSE in this source tree.
   */
  /* Code overview.
   *
   * Files are laid out to avoid unnecessary function declarations.  So for
   * example, every function add_cmd calls occurs before add_cmd in this file.
   *
   * add_cmd() is called on each line of sed command text (from a file or from
   * the command line).  It calls get_address() and parse_cmd_args().  The
   * resulting sed_cmd_t structures are appended to a linked list
   * (G.sed_cmd_head/G.sed_cmd_tail).
   *
   * process_files() does actual sedding, reading data lines from each input FILE*
   * (which could be stdin) and applying the sed command list (sed_cmd_head) to
   * each of the resulting lines.
   *
   * sed_main() is where external code calls into this, with a command line.
   */
  /* Supported features and commands in this version of sed:
   *
   * - comments ('#')
   * - address matching: num|/matchstr/[,num|/matchstr/|$]command
   * - commands: (p)rint, (d)elete, (s)ubstitue (with g & I flags)
   * - edit commands: (a)ppend, (i)nsert, (c)hange
   * - file commands: (r)ead
   * - backreferences in substitution expressions (\0, \1, \2...\9)
   * - grouped commands: {cmd1;cmd2}
   * - transliteration (y/source-chars/dest-chars/)
   * - pattern space hold space storing / swapping (g, h, x)
   * - labels / branching (: label, b, t, T)
   *
   * (Note: Specifying an address (range) to match is *optional*; commands
   * default to the whole pattern space if no specific address match was
   * requested.)
   *
   * Todo:
   * - Create a wrapper around regex to make libc's regex conform with sed
   *
   * Reference
   * http://www.opengroup.org/onlinepubs/007904975/utilities/sed.html
   * http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html
   * http://sed.sourceforge.net/sedfaq3.html
   */
  //config:config SED
  //config:	bool "sed (12 kb)"
  //config:	default y
  //config:	help
  //config:	sed is used to perform text transformations on a file
  //config:	or input from a pipeline.
  
  //applet:IF_SED(APPLET(sed, BB_DIR_BIN, BB_SUID_DROP))
  
  //kbuild:lib-$(CONFIG_SED) += sed.o
  
  //usage:#define sed_trivial_usage
  //usage:       "[-i[SFX]] [-nrE] [-f FILE]... [-e CMD]... [FILE]...\n"
  //usage:       "or: sed [-i[SFX]] [-nrE] CMD [FILE]..."
  //usage:#define sed_full_usage "\n\n"
  //usage:       "	-e CMD	Add CMD to sed commands to be executed"
  //usage:     "\n	-f FILE	Add FILE contents to sed commands to be executed"
  //usage:     "\n	-i[SFX]	Edit files in-place (otherwise sends to stdout)"
  //usage:     "\n		Optionally back files up, appending SFX"
  //usage:     "\n	-n	Suppress automatic printing of pattern space"
  //usage:     "\n	-r,-E	Use extended regex syntax"
  //usage:     "\n"
  //usage:     "\nIf no -e or -f, the first non-option argument is the sed command string."
  //usage:     "\nRemaining arguments are input files (stdin if none)."
  //usage:
  //usage:#define sed_example_usage
  //usage:       "$ echo \"foo\" | sed -e 's/f[a-zA-Z]o/bar/g'\n"
  //usage:       "bar\n"
  
  #include "libbb.h"
  #include "common_bufsiz.h"
  #include "xregex.h"
  
  #if 0
  # define dbg(...) bb_error_msg(__VA_ARGS__)
  #else
  # define dbg(...) ((void)0)
  #endif
  
  
  enum {
  	OPT_in_place = 1 << 0,
  };
  
  /* Each sed command turns into one of these structures. */
  typedef struct sed_cmd_s {
  	/* Ordered by alignment requirements: currently 36 bytes on x86 */
  	struct sed_cmd_s *next; /* Next command (linked list, NULL terminated) */
  
  	/* address storage */
  	regex_t *beg_match;     /* sed -e '/match/cmd' */
  	regex_t *end_match;     /* sed -e '/match/,/end_match/cmd' */
  	regex_t *sub_match;     /* For 's/sub_match/string/' */
  	int beg_line;           /* 'sed 1p'   0 == apply commands to all lines */
  	int beg_line_orig;      /* copy of the above, needed for -i */
  	int end_line;           /* 'sed 1,3p' 0 == one line only. -1 = last line ($). -2-N = +N */
  	int end_line_orig;
  
  	FILE *sw_file;          /* File (sw) command writes to, NULL for none. */
  	char *string;           /* Data string for (saicytb) commands. */
  
  	unsigned which_match;   /* (s) Which match to replace (0 for all) */
  
  	/* Bitfields (gcc won't group them if we don't) */
  	unsigned invert:1;      /* the '!' after the address */
  	unsigned in_match:1;    /* Next line also included in match? */
  	unsigned sub_p:1;       /* (s) print option */
  
  	char sw_last_char;      /* Last line written by (sw) had no '\n' */
  
  	/* GENERAL FIELDS */
  	char cmd;               /* The command char: abcdDgGhHilnNpPqrstwxy:={} */
  } sed_cmd_t;
  
  static const char semicolon_whitespace[] ALIGN1 = "; \n\r\t\v";
  
  struct globals {
  	/* options */
  	int be_quiet, regex_type;
  
  	FILE *nonstdout;
  	char *outname, *hold_space;
  	smallint exitcode;
  
  	/* list of input files */
  	int current_input_file, last_input_file;
  	char **input_file_list;
  	FILE *current_fp;
  
  	regmatch_t regmatch[10];
  	regex_t *previous_regex_ptr;
  
  	/* linked list of sed commands */
  	sed_cmd_t *sed_cmd_head, **sed_cmd_tail;
  
  	/* linked list of append lines */
  	llist_t *append_head;
  
  	char *add_cmd_line;
  
  	struct pipeline {
  		char *buf;  /* Space to hold string */
  		int idx;    /* Space used */
  		int len;    /* Space allocated */
  	} pipeline;
  } FIX_ALIASING;
  #define G (*(struct globals*)bb_common_bufsiz1)
  #define INIT_G() do { \
  	setup_common_bufsiz(); \
  	BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
  	G.sed_cmd_tail = &G.sed_cmd_head; \
  } while (0)
  
  
  #if ENABLE_FEATURE_CLEAN_UP
  static void sed_free_and_close_stuff(void)
  {
  	sed_cmd_t *sed_cmd = G.sed_cmd_head;
  
  	llist_free(G.append_head, free);
  
  	while (sed_cmd) {
  		sed_cmd_t *sed_cmd_next = sed_cmd->next;
  
  		if (sed_cmd->sw_file)
  			fclose(sed_cmd->sw_file);
  
  		/* Used to free regexps, but now there is code
  		 * in get_address() which can reuse a regexp
  		 * for constructs as /regexp/cmd1;//cmd2
  		 * leading to double-frees here:
  		 */
  		//if (sed_cmd->beg_match) {
  		//	regfree(sed_cmd->beg_match);
  		//	free(sed_cmd->beg_match);
  		//}
  		//if (sed_cmd->end_match) {
  		//	regfree(sed_cmd->end_match);
  		//	free(sed_cmd->end_match);
  		//}
  		//if (sed_cmd->sub_match) {
  		//	regfree(sed_cmd->sub_match);
  		//	free(sed_cmd->sub_match);
  		//}
  		free(sed_cmd->string);
  		free(sed_cmd);
  		sed_cmd = sed_cmd_next;
  	}
  
  	free(G.hold_space);
  
  	if (G.current_fp)
  		fclose(G.current_fp);
  }
  #else
  void sed_free_and_close_stuff(void);
  #endif
  
  /* If something bad happens during -i operation, delete temp file */
  
  static void cleanup_outname(void)
  {
  	if (G.outname) unlink(G.outname);
  }
  
  /* strcpy, replacing "\from" with 'to'. If to is NUL, replacing "\any" with 'any' */
  
  static unsigned parse_escapes(char *dest, const char *string, int len, char from, char to)
  {
  	char *d = dest;
  	int i = 0;
  
  	if (len == -1)
  		len = strlen(string);
  
  	while (i < len) {
  		if (string[i] == '\\') {
  			if (!to || string[i+1] == from) {
  				if ((*d = to ? to : string[i+1]) == '\0')
  					return d - dest;
  				i += 2;
  				d++;
  				continue;
  			}
  			i++; /* skip backslash in string[] */
  			*d++ = '\\';
  			/* fall through: copy next char verbatim */
  		}
  		if ((*d = string[i++]) == '\0')
  			return d - dest;
  		d++;
  	}
  	*d = '\0';
  	return d - dest;
  }
  
  static char *copy_parsing_escapes(const char *string, int len)
  {
  	const char *s;
  	char *dest = xmalloc(len + 1);
  
  	/* sed recognizes \n */
  	/* GNU sed also recognizes \t and \r */
  	for (s = "\nn\tt\rr"; *s; s += 2) {
  		len = parse_escapes(dest, string, len, s[1], s[0]);
  		string = dest;
  	}
  	return dest;
  }
  
  
  /*
   * index_of_next_unescaped_regexp_delim - walks left to right through a string
   * beginning at a specified index and returns the index of the next regular
   * expression delimiter (typically a forward slash ('/')) not preceded by
   * a backslash ('\').  A negative delimiter disables square bracket checking.
   */
  static int index_of_next_unescaped_regexp_delim(int delimiter, const char *str)
  {
  	int bracket = -1;
  	int escaped = 0;
  	int idx = 0;
  	char ch;
  
  	if (delimiter < 0) {
  		bracket--;
  		delimiter = -delimiter;
  	}
  
  	for (; (ch = str[idx]) != '\0'; idx++) {
  		if (bracket >= 0) {
  			if (ch == ']'
  			 && !(bracket == idx - 1 || (bracket == idx - 2 && str[idx - 1] == '^'))
  			) {
  				bracket = -1;
  			}
  		} else if (escaped)
  			escaped = 0;
  		else if (ch == '\\')
  			escaped = 1;
  		else if (bracket == -1 && ch == '[')
  			bracket = idx;
  		else if (ch == delimiter)
  			return idx;
  	}
  
  	/* if we make it to here, we've hit the end of the string */
  	bb_error_msg_and_die("unmatched '%c'", delimiter);
  }
  
  /*
   *  Returns the index of the third delimiter
   */
  static int parse_regex_delim(const char *cmdstr, char **match, char **replace)
  {
  	const char *cmdstr_ptr = cmdstr;
  	unsigned char delimiter;
  	int idx = 0;
  
  	/* verify that the 's' or 'y' is followed by something.  That something
  	 * (typically a 'slash') is now our regexp delimiter... */
  	if (*cmdstr == '\0')
  		bb_error_msg_and_die("bad format in substitution expression");
  	delimiter = *cmdstr_ptr++;
  
  	/* save the match string */
  	idx = index_of_next_unescaped_regexp_delim(delimiter, cmdstr_ptr);
  	*match = copy_parsing_escapes(cmdstr_ptr, idx);
  
  	/* save the replacement string */
  	cmdstr_ptr += idx + 1;
  	idx = index_of_next_unescaped_regexp_delim(- (int)delimiter, cmdstr_ptr);
  	*replace = copy_parsing_escapes(cmdstr_ptr, idx);
  
  	return ((cmdstr_ptr - cmdstr) + idx);
  }
  
  /*
   * returns the index in the string just past where the address ends.
   */
  static int get_address(const char *my_str, int *linenum, regex_t ** regex)
  {
  	const char *pos = my_str;
  
  	if (isdigit(*my_str)) {
  		*linenum = strtol(my_str, (char**)&pos, 10);
  		/* endstr shouldn't ever equal NULL */
  	} else if (*my_str == '$') {
  		*linenum = -1;
  		pos++;
  	} else if (*my_str == '/' || *my_str == '\\') {
  		int next;
  		char delimiter;
  		char *temp;
  
  		delimiter = '/';
  		if (*my_str == '\\')
  			delimiter = *++pos;
  		next = index_of_next_unescaped_regexp_delim(delimiter, ++pos);
  		if (next != 0) {
  			temp = copy_parsing_escapes(pos, next);
  			G.previous_regex_ptr = *regex = xzalloc(sizeof(regex_t));
  			xregcomp(*regex, temp, G.regex_type);
  			free(temp);
  		} else {
  			*regex = G.previous_regex_ptr;
  			if (!G.previous_regex_ptr)
  				bb_error_msg_and_die("no previous regexp");
  		}
  		/* Move position to next character after last delimiter */
  		pos += (next+1);
  	}
  	return pos - my_str;
  }
  
  /* Grab a filename.  Whitespace at start is skipped, then goes to EOL. */
  static int parse_file_cmd(/*sed_cmd_t *sed_cmd,*/ const char *filecmdstr, char **retval)
  {
  	int start = 0, idx, hack = 0;
  
  	/* Skip whitespace, then grab filename to end of line */
  	while (isspace(filecmdstr[start]))
  		start++;
  	idx = start;
  	while (filecmdstr[idx] && filecmdstr[idx] != '\n')
  		idx++;
  
  	/* If lines glued together, put backslash back. */
  	if (filecmdstr[idx] == '\n')
  		hack = 1;
  	if (idx == start)
  		bb_error_msg_and_die("empty filename");
  	*retval = xstrndup(filecmdstr+start, idx-start+hack+1);
  	if (hack)
  		(*retval)[idx-start] = '\\';
  
  	return idx;
  }
  
  static int parse_subst_cmd(sed_cmd_t *sed_cmd, const char *substr)
  {
  	int cflags = G.regex_type;
  	char *match;
  	int idx;
  
  	/*
  	 * A substitution command should look something like this:
  	 *    s/match/replace/ #giIpw
  	 *    ||     |        |||
  	 *    mandatory       optional
  	 */
  	idx = parse_regex_delim(substr, &match, &sed_cmd->string);
  
  	/* determine the number of back references in the match string */
  	/* Note: we compute this here rather than in the do_subst_command()
  	 * function to save processor time, at the expense of a little more memory
  	 * (4 bits) per sed_cmd */
  
  	/* process the flags */
  
  	sed_cmd->which_match = 1;
  	dbg("s flags:'%s'", substr + idx + 1);
  	while (substr[++idx]) {
  		dbg("s flag:'%c'", substr[idx]);
  		/* Parse match number */
  		if (isdigit(substr[idx])) {
  			if (match[0] != '^') {
  				/* Match 0 treated as all, multiple matches we take the last one. */
  				const char *pos = substr + idx;
  /* FIXME: error check? */
  				sed_cmd->which_match = (unsigned)strtol(substr+idx, (char**) &pos, 10);
  				idx = pos - substr - 1;
  			}
  			continue;
  		}
  		/* Skip spaces */
  		if (isspace(substr[idx]))
  			continue;
  
  		switch (substr[idx]) {
  		/* Replace all occurrences */
  		case 'g':
  			if (match[0] != '^')
  				sed_cmd->which_match = 0;
  			break;
  		/* Print pattern space */
  		case 'p':
  			sed_cmd->sub_p = 1;
  			break;
  		/* Write to file */
  		case 'w':
  		{
  			char *fname;
  			idx += parse_file_cmd(/*sed_cmd,*/ substr+idx+1, &fname);
  			sed_cmd->sw_file = xfopen_for_write(fname);
  			sed_cmd->sw_last_char = '\n';
  			free(fname);
  			break;
  		}
  		/* Ignore case (gnu extension) */
  		case 'i':
  		case 'I':
  			cflags |= REG_ICASE;
  			break;
  		/* Comment */
  		case '#':
  			// while (substr[++idx]) continue;
  			idx += strlen(substr + idx); // same
  			/* Fall through */
  		/* End of command */
  		case ';':
  		case '}':
  			goto out;
  		default:
  			dbg("s bad flags:'%s'", substr + idx);
  			bb_error_msg_and_die("bad option in substitution expression");
  		}
  	}
   out:
  	/* compile the match string into a regex */
  	if (*match != '\0') {
  		/* If match is empty, we use last regex used at runtime */
  		sed_cmd->sub_match = xzalloc(sizeof(regex_t));
  		dbg("xregcomp('%s',%x)", match, cflags);
  		xregcomp(sed_cmd->sub_match, match, cflags);
  		dbg("regcomp ok");
  	}
  	free(match);
  
  	return idx;
  }
  
  /*
   *  Process the commands arguments
   */
  static const char *parse_cmd_args(sed_cmd_t *sed_cmd, const char *cmdstr)
  {
  	static const char cmd_letters[] ALIGN1 = "saicrw:btTydDgGhHlnNpPqx={}";
  	enum {
  		IDX_s = 0,
  		IDX_a,
  		IDX_i,
  		IDX_c,
  		IDX_r,
  		IDX_w,
  		IDX_colon,
  		IDX_b,
  		IDX_t,
  		IDX_T,
  		IDX_y,
  		IDX_d,
  		IDX_D,
  		IDX_g,
  		IDX_G,
  		IDX_h,
  		IDX_H,
  		IDX_l,
  		IDX_n,
  		IDX_N,
  		IDX_p,
  		IDX_P,
  		IDX_q,
  		IDX_x,
  		IDX_equal,
  		IDX_lbrace,
  		IDX_rbrace,
  		IDX_nul
  	};
  	unsigned idx;
  
  	BUILD_BUG_ON(sizeof(cmd_letters)-1 != IDX_nul);
  
  	idx = strchrnul(cmd_letters, sed_cmd->cmd) - cmd_letters;
  
  	/* handle (s)ubstitution command */
  	if (idx == IDX_s) {
  		cmdstr += parse_subst_cmd(sed_cmd, cmdstr);
  	}
  	/* handle edit cmds: (a)ppend, (i)nsert, and (c)hange */
  	else if (idx <= IDX_c) { /* a,i,c */
  		unsigned len;
  
  		if (idx < IDX_c) { /* a,i */
  			if (sed_cmd->end_line || sed_cmd->end_match)
  				bb_error_msg_and_die("command '%c' uses only one address", sed_cmd->cmd);
  		}
  		for (;;) {
  			if (*cmdstr == '\n' || *cmdstr == '\\') {
  				cmdstr++;
  				break;
  			}
  			if (!isspace(*cmdstr))
  				break;
  			cmdstr++;
  		}
  		len = strlen(cmdstr);
  		sed_cmd->string = copy_parsing_escapes(cmdstr, len);
  		cmdstr += len;
  		/* "\anychar" -> "anychar" */
  		parse_escapes(sed_cmd->string, sed_cmd->string, -1, '\0', '\0');
  	}
  	/* handle file cmds: (r)ead */
  	else if (idx <= IDX_w) { /* r,w */
  		if (idx < IDX_w) { /* r */
  			if (sed_cmd->end_line || sed_cmd->end_match)
  				bb_error_msg_and_die("command '%c' uses only one address", sed_cmd->cmd);
  		}
  		cmdstr += parse_file_cmd(/*sed_cmd,*/ cmdstr, &sed_cmd->string);
  		if (sed_cmd->cmd == 'w') {
  			sed_cmd->sw_file = xfopen_for_write(sed_cmd->string);
  			sed_cmd->sw_last_char = '\n';
  		}
  	}
  	/* handle branch commands */
  	else if (idx <= IDX_T) { /* :,b,t,T */
  		int length;
  
  		cmdstr = skip_whitespace(cmdstr);
  		length = strcspn(cmdstr, semicolon_whitespace);
  		if (length) {
  			sed_cmd->string = xstrndup(cmdstr, length);
  			cmdstr += length;
  		}
  	}
  	/* translation command */
  	else if (idx == IDX_y) {
  		char *match, *replace;
  		int i = cmdstr[0];
  
  		cmdstr += parse_regex_delim(cmdstr, &match, &replace)+1;
  		/* \n already parsed, but \delimiter needs unescaping. */
  		parse_escapes(match,   match,   -1, i, i);
  		parse_escapes(replace, replace, -1, i, i);
  
  		sed_cmd->string = xzalloc((strlen(match) + 1) * 2);
  		for (i = 0; match[i] && replace[i]; i++) {
  			sed_cmd->string[i*2] = match[i];
  			sed_cmd->string[i*2+1] = replace[i];
  		}
  		free(match);
  		free(replace);
  	}
  	/* if it wasn't a single-letter command that takes no arguments
  	 * then it must be an invalid command.
  	 */
  	else if (idx >= IDX_nul) { /* not d,D,g,G,h,H,l,n,N,p,P,q,x,=,{,} */
  		bb_error_msg_and_die("unsupported command %c", sed_cmd->cmd);
  	}
  
  	/* give back whatever's left over */
  	return cmdstr;
  }
  
  
  /* Parse address+command sets, skipping comment lines. */
  
  static void add_cmd(const char *cmdstr)
  {
  	sed_cmd_t *sed_cmd;
  	unsigned len, n;
  
  	/* Append this line to any unfinished line from last time. */
  	if (G.add_cmd_line) {
  		char *tp = xasprintf("%s\n%s", G.add_cmd_line, cmdstr);
  		free(G.add_cmd_line);
  		cmdstr = G.add_cmd_line = tp;
  	}
  
  	/* If this line ends with unescaped backslash, request next line. */
  	n = len = strlen(cmdstr);
  	while (n && cmdstr[n-1] == '\\')
  		n--;
  	if ((len - n) & 1) { /* if odd number of trailing backslashes */
  		if (!G.add_cmd_line)
  			G.add_cmd_line = xstrdup(cmdstr);
  		G.add_cmd_line[len-1] = '\0';
  		return;
  	}
  
  	/* Loop parsing all commands in this line. */
  	while (*cmdstr) {
  		/* Skip leading whitespace and semicolons */
  		cmdstr += strspn(cmdstr, semicolon_whitespace);
  
  		/* If no more commands, exit. */
  		if (!*cmdstr) break;
  
  		/* if this is a comment, jump past it and keep going */
  		if (*cmdstr == '#') {
  			/* "#n" is the same as using -n on the command line */
  			if (cmdstr[1] == 'n')
  				G.be_quiet++;
  			cmdstr = strpbrk(cmdstr, "\n\r");
  			if (!cmdstr) break;
  			continue;
  		}
  
  		/* parse the command
  		 * format is: [addr][,addr][!]cmd
  		 *            |----||-----||-|
  		 *            part1 part2  part3
  		 */
  
  		sed_cmd = xzalloc(sizeof(sed_cmd_t));
  
  		/* first part (if present) is an address: either a '$', a number or a /regex/ */
  		cmdstr += get_address(cmdstr, &sed_cmd->beg_line, &sed_cmd->beg_match);
  		sed_cmd->beg_line_orig = sed_cmd->beg_line;
  
  		/* second part (if present) will begin with a comma */
  		if (*cmdstr == ',') {
  			int idx;
  
  			cmdstr++;
  			if (*cmdstr == '+' && isdigit(cmdstr[1])) {
  				/* http://sed.sourceforge.net/sedfaq3.html#s3.3
  				 * Under GNU sed 3.02+, ssed, and sed15+, <address2>
  				 * may also be a notation of the form +num,
  				 * indicating the next num lines after <address1> is
  				 * matched.
  				 * GNU sed 4.2.1 accepts even "+" (meaning "+0").
  				 * We don't (we check for isdigit, see above), think
  				 * about the "+-3" case.
  				 */
  				char *end;
  				/* code is smaller compared to using &cmdstr here: */
  				idx = strtol(cmdstr+1, &end, 10);
  				sed_cmd->end_line = -2 - idx;
  				cmdstr = end;
  			} else {
  				idx = get_address(cmdstr, &sed_cmd->end_line, &sed_cmd->end_match);
  				cmdstr += idx;
  				idx--; /* if 0, trigger error check below */
  			}
  			if (idx < 0)
  				bb_error_msg_and_die("no address after comma");
  			sed_cmd->end_line_orig = sed_cmd->end_line;
  		}
  
  		/* skip whitespace before the command */
  		cmdstr = skip_whitespace(cmdstr);
  
  		/* Check for inversion flag */
  		if (*cmdstr == '!') {
  			sed_cmd->invert = 1;
  			cmdstr++;
  
  			/* skip whitespace before the command */
  			cmdstr = skip_whitespace(cmdstr);
  		}
  
  		/* last part (mandatory) will be a command */
  		if (!*cmdstr)
  			bb_error_msg_and_die("missing command");
  		sed_cmd->cmd = *cmdstr++;
  		cmdstr = parse_cmd_args(sed_cmd, cmdstr);
  
  		/* cmdstr now points past args.
  		 * GNU sed requires a separator, if there are more commands,
  		 * else it complains "char N: extra characters after command".
  		 * Example: "sed 'p;d'". We also allow "sed 'pd'".
  		 */
  
  		/* Add the command to the command array */
  		*G.sed_cmd_tail = sed_cmd;
  		G.sed_cmd_tail = &sed_cmd->next;
  	}
  
  	/* If we glued multiple lines together, free the memory. */
  	free(G.add_cmd_line);
  	G.add_cmd_line = NULL;
  }
  
  /* Append to a string, reallocating memory as necessary. */
  
  #define PIPE_GROW 64
  
  static void pipe_putc(char c)
  {
  	if (G.pipeline.idx == G.pipeline.len) {
  		G.pipeline.buf = xrealloc(G.pipeline.buf,
  				G.pipeline.len + PIPE_GROW);
  		G.pipeline.len += PIPE_GROW;
  	}
  	G.pipeline.buf[G.pipeline.idx++] = c;
  }
  
  static void do_subst_w_backrefs(char *line, char *replace)
  {
  	int i, j;
  
  	/* go through the replacement string */
  	for (i = 0; replace[i]; i++) {
  		/* if we find a backreference (\1, \2, etc.) print the backref'ed text */
  		if (replace[i] == '\\') {
  			unsigned backref = replace[++i] - '0';
  			if (backref <= 9) {
  				/* print out the text held in G.regmatch[backref] */
  				if (G.regmatch[backref].rm_so != -1) {
  					j = G.regmatch[backref].rm_so;
  					while (j < G.regmatch[backref].rm_eo)
  						pipe_putc(line[j++]);
  				}
  				continue;
  			}
  			/* I _think_ it is impossible to get '\' to be
  			 * the last char in replace string. Thus we don't check
  			 * for replace[i] == NUL. (counterexample anyone?) */
  			/* if we find a backslash escaped character, print the character */
  			pipe_putc(replace[i]);
  			continue;
  		}
  		/* if we find an unescaped '&' print out the whole matched text. */
  		if (replace[i] == '&') {
  			j = G.regmatch[0].rm_so;
  			while (j < G.regmatch[0].rm_eo)
  				pipe_putc(line[j++]);
  			continue;
  		}
  		/* Otherwise just output the character. */
  		pipe_putc(replace[i]);
  	}
  }
  
  static int do_subst_command(sed_cmd_t *sed_cmd, char **line_p)
  {
  	char *line = *line_p;
  	unsigned match_count = 0;
  	bool altered = 0;
  	bool prev_match_empty = 1;
  	bool tried_at_eol = 0;
  	regex_t *current_regex;
  
  	current_regex = sed_cmd->sub_match;
  	/* Handle empty regex. */
  	if (!current_regex) {
  		current_regex = G.previous_regex_ptr;
  		if (!current_regex)
  			bb_error_msg_and_die("no previous regexp");
  	}
  	G.previous_regex_ptr = current_regex;
  
  	/* Find the first match */
  	dbg("matching '%s'", line);
  	if (REG_NOMATCH == regexec(current_regex, line, 10, G.regmatch, 0)) {
  		dbg("no match");
  		return 0;
  	}
  	dbg("match");
  
  	/* Initialize temporary output buffer. */
  	G.pipeline.buf = xmalloc(PIPE_GROW);
  	G.pipeline.len = PIPE_GROW;
  	G.pipeline.idx = 0;
  
  	/* Now loop through, substituting for matches */
  	do {
  		int start = G.regmatch[0].rm_so;
  		int end = G.regmatch[0].rm_eo;
  		int i;
  
  		match_count++;
  
  		/* If we aren't interested in this match, output old line to
  		 * end of match and continue */
  		if (sed_cmd->which_match
  		 && (sed_cmd->which_match != match_count)
  		) {
  			for (i = 0; i < end; i++)
  				pipe_putc(*line++);
  			/* Null match? Print one more char */
  			if (start == end && *line)
  				pipe_putc(*line++);
  			goto next;
  		}
  
  		/* Print everything before the match */
  		for (i = 0; i < start; i++)
  			pipe_putc(line[i]);
  
  		/* Then print the substitution string,
  		 * unless we just matched empty string after non-empty one.
  		 * Example: string "cccd", pattern "c*", repl "R":
  		 * result is "RdR", not "RRdR": first match "ccc",
  		 * second is "" before "d", third is "" after "d".
  		 * Second match is NOT replaced!
  		 */
  		if (prev_match_empty || start != 0 || start != end) {
  			//dbg("%d %d %d", prev_match_empty, start, end);
  			dbg("inserting replacement at %d in '%s'", start, line);
  			do_subst_w_backrefs(line, sed_cmd->string);
  			/* Flag that something has changed */
  			altered = 1;
  		} else {
  			dbg("NOT inserting replacement at %d in '%s'", start, line);
  		}
  
  		/* If matched string is empty (f.e. "c*" pattern),
  		 * copy verbatim one char after it before attempting more matches
  		 */
  		prev_match_empty = (start == end);
  		if (prev_match_empty) {
  			if (!line[end]) {
  				tried_at_eol = 1;
  			} else {
  				pipe_putc(line[end]);
  				end++;
  			}
  		}
  
  		/* Advance past the match */
  		dbg("line += %d", end);
  		line += end;
  
  		/* if we're not doing this globally, get out now */
  		if (sed_cmd->which_match != 0)
  			break;
   next:
  		/* Exit if we are at EOL and already tried matching at it */
  		if (*line == '\0') {
  			if (tried_at_eol)
  				break;
  			tried_at_eol = 1;
  		}
  
  //maybe (end ? REG_NOTBOL : 0) instead of unconditional REG_NOTBOL?
  	} while (regexec(current_regex, line, 10, G.regmatch, REG_NOTBOL) != REG_NOMATCH);
  
  	/* Copy rest of string into output pipeline */
  	while (1) {
  		char c = *line++;
  		pipe_putc(c);
  		if (c == '\0')
  			break;
  	}
  
  	free(*line_p);
  	*line_p = G.pipeline.buf;
  	return altered;
  }
  
  /* Set command pointer to point to this label.  (Does not handle null label.) */
  static sed_cmd_t *branch_to(char *label)
  {
  	sed_cmd_t *sed_cmd;
  
  	for (sed_cmd = G.sed_cmd_head; sed_cmd; sed_cmd = sed_cmd->next) {
  		if (sed_cmd->cmd == ':'
  		 && sed_cmd->string
  		 && strcmp(sed_cmd->string, label) == 0
  		) {
  			return sed_cmd;
  		}
  	}
  	bb_error_msg_and_die("can't find label for jump to '%s'", label);
  }
  
  static void append(char *s)
  {
  	llist_add_to_end(&G.append_head, s);
  }
  
  /* Output line of text. */
  /* Note:
   * The tricks with NO_EOL_CHAR and last_puts_char are there to emulate gnu sed.
   * Without them, we had this:
   * echo -n thingy >z1
   * echo -n again >z2
   * >znull
   * sed "s/i/z/" z1 z2 znull | hexdump -vC
   * output:
   * gnu sed 4.1.5:
   * 00000000  74 68 7a 6e 67 79 0a 61  67 61 7a 6e              |thzngy.agazn|
   * bbox:
   * 00000000  74 68 7a 6e 67 79 61 67  61 7a 6e                 |thzngyagazn|
   */
  enum {
  	NO_EOL_CHAR = 1,
  	LAST_IS_NUL = 2,
  };
  static void puts_maybe_newline(char *s, FILE *file, char *last_puts_char, char last_gets_char)
  {
  	char lpc = *last_puts_char;
  
  	/* Need to insert a '\n' between two files because first file's
  	 * last line wasn't terminated? */
  	if (lpc != '\n' && lpc != '\0') {
  		fputc('\n', file);
  		lpc = '\n';
  	}
  	fputs(s, file);
  
  	/* 'x' - just something which is not '\n', '\0' or NO_EOL_CHAR */
  	if (s[0])
  		lpc = 'x';
  
  	/* had trailing '\0' and it was last char of file? */
  	if (last_gets_char == LAST_IS_NUL) {
  		fputc('\0', file);
  		lpc = 'x'; /* */
  	} else
  	/* had trailing '\n' or '\0'? */
  	if (last_gets_char != NO_EOL_CHAR) {
  		fputc(last_gets_char, file);
  		lpc = last_gets_char;
  	}
  
  	if (ferror(file)) {
  		xfunc_error_retval = 4;  /* It's what gnu sed exits with... */
  		bb_error_msg_and_die(bb_msg_write_error);
  	}
  	*last_puts_char = lpc;
  }
  
  static void flush_append(char *last_puts_char)
  {
  	char *data;
  
  	/* Output appended lines. */
  	while ((data = (char *)llist_pop(&G.append_head)) != NULL) {
  		/* Append command does not respect "nonterminated-ness"
  		 * of last line. Try this:
  		 * $ echo -n "woot" | sed -e '/woot/a woo' -
  		 * woot
  		 * woo
  		 * (both lines are terminated with \n)
  		 * Therefore we do not propagate "last_gets_char" here,
  		 * pass '\n' instead:
  		 */
  		puts_maybe_newline(data, G.nonstdout, last_puts_char, '\n');
  		free(data);
  	}
  }
  
  /* Get next line of input from G.input_file_list, flushing append buffer and
   * noting if we ran out of files without a newline on the last line we read.
   */
  static char *get_next_line(char *gets_char, char *last_puts_char)
  {
  	char *temp = NULL;
  	size_t len;
  	char gc;
  
  	flush_append(last_puts_char);
  
  	/* will be returned if last line in the file
  	 * doesn't end with either '\n' or '\0' */
  	gc = NO_EOL_CHAR;
  	for (; G.current_input_file <= G.last_input_file; G.current_input_file++) {
  		FILE *fp = G.current_fp;
  		if (!fp) {
  			const char *path = G.input_file_list[G.current_input_file];
  			fp = stdin;
  			if (path != bb_msg_standard_input) {
  				fp = fopen_or_warn(path, "r");
  				if (!fp) {
  					G.exitcode = EXIT_FAILURE;
  					continue;
  				}
  			}
  			G.current_fp = fp;
  		}
  		/* Read line up to a newline or NUL byte, inclusive,
  		 * return malloc'ed char[]. length of the chunk read
  		 * is stored in len. NULL if EOF/error */
  		temp = bb_get_chunk_from_file(fp, &len);
  		if (temp) {
  			/* len > 0 here, it's ok to do temp[len-1] */
  			char c = temp[len-1];
  			if (c == '\n' || c == '\0') {
  				temp[len-1] = '\0';
  				gc = c;
  				if (c == '\0') {
  					int ch = fgetc(fp);
  					if (ch != EOF)
  						ungetc(ch, fp);
  					else
  						gc = LAST_IS_NUL;
  				}
  			}
  			/* else we put NO_EOL_CHAR into *gets_char */
  			break;
  
  		/* NB: I had the idea of peeking next file(s) and returning
  		 * NO_EOL_CHAR only if it is the *last* non-empty
  		 * input file. But there is a case where this won't work:
  		 * file1: "a woo\nb woo"
  		 * file2: "c no\nd no"
  		 * sed -ne 's/woo/bang/p' input1 input2 => "a bang\nb bang"
  		 * (note: *no* newline after "b bang"!) */
  		}
  		/* Close this file and advance to next one */
  		fclose_if_not_stdin(fp);
  		G.current_fp = NULL;
  	}
  	*gets_char = gc;
  	return temp;
  }
  
  #define sed_puts(s, n) (puts_maybe_newline(s, G.nonstdout, &last_puts_char, n))
  
  static int beg_match(sed_cmd_t *sed_cmd, const char *pattern_space)
  {
  	int retval = sed_cmd->beg_match && !regexec(sed_cmd->beg_match, pattern_space, 0, NULL, 0);
  	if (retval)
  		G.previous_regex_ptr = sed_cmd->beg_match;
  	return retval;
  }
  
  /* Process all the lines in all the files */
  
  static void process_files(void)
  {
  	char *pattern_space, *next_line;
  	int linenum = 0;
  	char last_puts_char = '\n';
  	char last_gets_char, next_gets_char;
  	sed_cmd_t *sed_cmd;
  	int substituted;
  
  	/* Prime the pump */
  	next_line = get_next_line(&next_gets_char, &last_puts_char);
  
  	/* Go through every line in each file */
   again:
  	substituted = 0;
  
  	/* Advance to next line.  Stop if out of lines. */
  	pattern_space = next_line;
  	if (!pattern_space)
  		return;
  	last_gets_char = next_gets_char;
  
  	/* Read one line in advance so we can act on the last line,
  	 * the '$' address */
  	next_line = get_next_line(&next_gets_char, &last_puts_char);
  	linenum++;
  
  	/* For every line, go through all the commands */
   restart:
  	for (sed_cmd = G.sed_cmd_head; sed_cmd; sed_cmd = sed_cmd->next) {
  		int old_matched, matched;
  
  		old_matched = sed_cmd->in_match;
  
  		/* Determine if this command matches this line: */
  
  		dbg("match1:%d", sed_cmd->in_match);
  		dbg("match2:%d", (!sed_cmd->beg_line && !sed_cmd->end_line
  				&& !sed_cmd->beg_match && !sed_cmd->end_match));
  		dbg("match3:%d", (sed_cmd->beg_line > 0
  			&& (sed_cmd->end_line || sed_cmd->end_match
  			    ? (sed_cmd->beg_line <= linenum)
  			    : (sed_cmd->beg_line == linenum)
  			    )
  			));
  		dbg("match4:%d", (beg_match(sed_cmd, pattern_space)));
  		dbg("match5:%d", (sed_cmd->beg_line == -1 && next_line == NULL));
  
  		/* Are we continuing a previous multi-line match? */
  		sed_cmd->in_match = sed_cmd->in_match
  			/* Or is no range necessary? */
  			|| (!sed_cmd->beg_line && !sed_cmd->end_line
  				&& !sed_cmd->beg_match && !sed_cmd->end_match)
  			/* Or did we match the start of a numerical range? */
  			|| (sed_cmd->beg_line > 0
  			    && (sed_cmd->end_line || sed_cmd->end_match
  				  /* note: even if end is numeric and is < linenum too,
  				   * GNU sed matches! We match too, therefore we don't
  				   * check here that linenum <= end.
  				   * Example:
  				   * printf '1\n2\n3\n4\n' | sed -n '1{N;N;d};1p;2,3p;3p;4p'
  				   * first three input lines are deleted;
  				   * 4th line is matched and printed
  				   * by "2,3" (!) and by "4" ranges
  				   */
  				? (sed_cmd->beg_line <= linenum)    /* N,end */
  				: (sed_cmd->beg_line == linenum)    /* N */
  				)
  			    )
  			/* Or does this line match our begin address regex? */
  			|| (beg_match(sed_cmd, pattern_space))
  			/* Or did we match last line of input? */
  			|| (sed_cmd->beg_line == -1 && next_line == NULL);
  
  		/* Snapshot the value */
  		matched = sed_cmd->in_match;
  
  		dbg("cmd:'%c' matched:%d beg_line:%d end_line:%d linenum:%d",
  			sed_cmd->cmd, matched, sed_cmd->beg_line, sed_cmd->end_line, linenum);
  
  		/* Is this line the end of the current match? */
  
  		if (matched) {
  			if (sed_cmd->end_line <= -2) {
  				/* address2 is +N, i.e. N lines from beg_line */
  				sed_cmd->end_line = linenum + (-sed_cmd->end_line - 2);
  			}
  			/* once matched, "n,xxx" range is dead, disabling it */
  			if (sed_cmd->beg_line > 0) {
  				sed_cmd->beg_line = -2;
  			}
  			dbg("end1:%d", sed_cmd->end_line ? sed_cmd->end_line == -1
  						? !next_line : (sed_cmd->end_line <= linenum)
  					: !sed_cmd->end_match);
  			dbg("end2:%d", sed_cmd->end_match && old_matched
  					&& !regexec(sed_cmd->end_match,pattern_space, 0, NULL, 0));
  			sed_cmd->in_match = !(
  				/* has the ending line come, or is this a single address command? */
  				(sed_cmd->end_line
  					? sed_cmd->end_line == -1
  						? !next_line
  						: (sed_cmd->end_line <= linenum)
  					: !sed_cmd->end_match
  				)
  				/* or does this line matches our last address regex */
  				|| (sed_cmd->end_match && old_matched
  				     && (regexec(sed_cmd->end_match,
  						pattern_space, 0, NULL, 0) == 0)
  				)
  			);
  		}
  
  		/* Skip blocks of commands we didn't match */
  		if (sed_cmd->cmd == '{') {
  			if (sed_cmd->invert ? matched : !matched) {
  				unsigned nest_cnt = 0;
  				while (1) {
  					if (sed_cmd->cmd == '{')
  						nest_cnt++;
  					if (sed_cmd->cmd == '}') {
  						nest_cnt--;
  						if (nest_cnt == 0)
  							break;
  					}
  					sed_cmd = sed_cmd->next;
  					if (!sed_cmd)
  						bb_error_msg_and_die("unterminated {");
  				}
  			}
  			continue;
  		}
  
  		/* Okay, so did this line match? */
  		if (sed_cmd->invert ? matched : !matched)
  			continue; /* no */
  
  		/* Update last used regex in case a blank substitute BRE is found */
  		if (sed_cmd->beg_match) {
  			G.previous_regex_ptr = sed_cmd->beg_match;
  		}
  
  		/* actual sedding */
  		dbg("pattern_space:'%s' next_line:'%s' cmd:%c",
  				pattern_space, next_line, sed_cmd->cmd);
  		switch (sed_cmd->cmd) {
  
  		/* Print line number */
  		case '=':
  			fprintf(G.nonstdout, "%d\n", linenum);
  			break;
  
  		/* Write the current pattern space up to the first newline */
  		case 'P':
  		{
  			char *tmp = strchr(pattern_space, '\n');
  			if (tmp) {
  				*tmp = '\0';
  				/* TODO: explain why '\n' below */
  				sed_puts(pattern_space, '\n');
  				*tmp = '\n';
  				break;
  			}
  			/* Fall Through */
  		}
  
  		/* Write the current pattern space to output */
  		case 'p':
  			/* NB: we print this _before_ the last line
  			 * (of current file) is printed. Even if
  			 * that line is nonterminated, we print
  			 * '\n' here (gnu sed does the same) */
  			sed_puts(pattern_space, '\n');
  			break;
  		/* Delete up through first newline */
  		case 'D':
  		{
  			char *tmp = strchr(pattern_space, '\n');
  			if (tmp) {
  				overlapping_strcpy(pattern_space, tmp + 1);
  				goto restart;
  			}
  		}
  		/* discard this line. */
  		case 'd':
  			goto discard_line;
  
  		/* Substitute with regex */
  		case 's':
  			if (!do_subst_command(sed_cmd, &pattern_space))
  				break;
  			dbg("do_subst_command succeeded:'%s'", pattern_space);
  			substituted |= 1;
  
  			/* handle p option */
  			if (sed_cmd->sub_p)
  				sed_puts(pattern_space, last_gets_char);
  			/* handle w option */
  			if (sed_cmd->sw_file)
  				puts_maybe_newline(
  					pattern_space, sed_cmd->sw_file,
  					&sed_cmd->sw_last_char, last_gets_char);
  			break;
  
  		/* Append line to linked list to be printed later */
  		case 'a':
  			append(xstrdup(sed_cmd->string));
  			break;
  
  		/* Insert text before this line */
  		case 'i':
  			sed_puts(sed_cmd->string, '\n');
  			break;
  
  		/* Cut and paste text (replace) */
  		case 'c':
  			/* Only triggers on last line of a matching range. */
  			if (!sed_cmd->in_match)
  				sed_puts(sed_cmd->string, '\n');
  			goto discard_line;
  
  		/* Read file, append contents to output */
  		case 'r':
  		{
  			FILE *rfile;
  			rfile = fopen_for_read(sed_cmd->string);
  			if (rfile) {
  				char *line;
  				while ((line = xmalloc_fgetline(rfile))
  						!= NULL)
  					append(line);
  				fclose(rfile);
  			}
  
  			break;
  		}
  
  		/* Write pattern space to file. */
  		case 'w':
  			puts_maybe_newline(
  				pattern_space, sed_cmd->sw_file,
  				&sed_cmd->sw_last_char, last_gets_char);
  			break;
  
  		/* Read next line from input */
  		case 'n':
  			if (!G.be_quiet)
  				sed_puts(pattern_space, last_gets_char);
  			if (next_line == NULL) {
  				/* If no next line, jump to end of script and exit. */
  				goto discard_line;
  			}
  			free(pattern_space);
  			pattern_space = next_line;
  			last_gets_char = next_gets_char;
  			next_line = get_next_line(&next_gets_char, &last_puts_char);
  			substituted = 0;
  			linenum++;
  			break;
  
  		/* Quit.  End of script, end of input. */
  		case 'q':
  			/* Exit the outer while loop */
  			free(next_line);
  			next_line = NULL;
  			goto discard_commands;
  
  		/* Append the next line to the current line */
  		case 'N':
  		{
  			int len;
  			/* If no next line, jump to end of script and exit. */
  			/* http://www.gnu.org/software/sed/manual/sed.html:
  			 * "Most versions of sed exit without printing anything
  			 * when the N command is issued on the last line of
  			 * a file. GNU sed prints pattern space before exiting
  			 * unless of course the -n command switch has been
  			 * specified. This choice is by design."
  			 */
  			if (next_line == NULL) {
  				//goto discard_line;
  				goto discard_commands; /* GNU behavior */
  			}
  			/* Append next_line, read new next_line. */
  			len = strlen(pattern_space);
  			pattern_space = xrealloc(pattern_space, len + strlen(next_line) + 2);
  			pattern_space[len] = '\n';
  			strcpy(pattern_space + len+1, next_line);
  			last_gets_char = next_gets_char;
  			next_line = get_next_line(&next_gets_char, &last_puts_char);
  			linenum++;
  			break;
  		}
  
  		/* Test/branch if substitution occurred */
  		case 't':
  			if (!substituted) break;
  			substituted = 0;
  			/* Fall through */
  		/* Test/branch if substitution didn't occur */
  		case 'T':
  			if (substituted) break;
  			/* Fall through */
  		/* Branch to label */
  		case 'b':
  			if (!sed_cmd->string) goto discard_commands;
  			else sed_cmd = branch_to(sed_cmd->string);
  			break;
  		/* Transliterate characters */
  		case 'y':
  		{
  			int i, j;
  			for (i = 0; pattern_space[i]; i++) {
  				for (j = 0; sed_cmd->string[j]; j += 2) {
  					if (pattern_space[i] == sed_cmd->string[j]) {
  						pattern_space[i] = sed_cmd->string[j + 1];
  						break;
  					}
  				}
  			}
  
  			break;
  		}
  		case 'g':	/* Replace pattern space with hold space */
  			free(pattern_space);
  			pattern_space = xstrdup(G.hold_space ? G.hold_space : "");
  			break;
  		case 'G':	/* Append newline and hold space to pattern space */
  		{
  			int pattern_space_size = 2;
  			int hold_space_size = 0;
  
  			if (pattern_space)
  				pattern_space_size += strlen(pattern_space);
  			if (G.hold_space)
  				hold_space_size = strlen(G.hold_space);
  			pattern_space = xrealloc(pattern_space,
  					pattern_space_size + hold_space_size);
  			if (pattern_space_size == 2)
  				pattern_space[0] = 0;
  			strcat(pattern_space, "\n");
  			if (G.hold_space)
  				strcat(pattern_space, G.hold_space);
  			last_gets_char = '\n';
  
  			break;
  		}
  		case 'h':	/* Replace hold space with pattern space */
  			free(G.hold_space);
  			G.hold_space = xstrdup(pattern_space);
  			break;
  		case 'H':	/* Append newline and pattern space to hold space */
  		{
  			int hold_space_size = 2;
  			int pattern_space_size = 0;
  
  			if (G.hold_space)
  				hold_space_size += strlen(G.hold_space);
  			if (pattern_space)
  				pattern_space_size = strlen(pattern_space);
  			G.hold_space = xrealloc(G.hold_space,
  					hold_space_size + pattern_space_size);
  
  			if (hold_space_size == 2)
  				*G.hold_space = 0;
  			strcat(G.hold_space, "\n");
  			if (pattern_space)
  				strcat(G.hold_space, pattern_space);
  
  			break;
  		}
  		case 'x': /* Exchange hold and pattern space */
  		{
  			char *tmp = pattern_space;
  			pattern_space = G.hold_space ? G.hold_space : xzalloc(1);
  			last_gets_char = '\n';
  			G.hold_space = tmp;
  			break;
  		}
  		} /* switch */
  	} /* for each cmd */
  
  	/*
  	 * Exit point from sedding...
  	 */
   discard_commands:
  	/* we will print the line unless we were told to be quiet ('-n')
  	   or if the line was suppressed (ala 'd'elete) */
  	if (!G.be_quiet)
  		sed_puts(pattern_space, last_gets_char);
  
  	/* Delete and such jump here. */
   discard_line:
  	flush_append(&last_puts_char /*,last_gets_char*/);
  	free(pattern_space);
  
  	goto again;
  }
  
  /* It is possible to have a command line argument with embedded
   * newlines.  This counts as multiple command lines.
   * However, newline can be escaped: 's/e/z\<newline>z/'
   * add_cmd() handles this.
   */
  
  static void add_cmd_block(char *cmdstr)
  {
  	char *sv, *eol;
  
  	cmdstr = sv = xstrdup(cmdstr);
  	do {
  		eol = strchr(cmdstr, '\n');
  		if (eol)
  			*eol = '\0';
  		add_cmd(cmdstr);
  		cmdstr = eol + 1;
  	} while (eol);
  	free(sv);
  }
  
  int sed_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  int sed_main(int argc UNUSED_PARAM, char **argv)
  {
  	unsigned opt;
  	llist_t *opt_e, *opt_f;
  	char *opt_i;
  
  #if ENABLE_LONG_OPTS
  	static const char sed_longopts[] ALIGN1 =
  		/* name             has_arg             short */
  		"in-place\0"        Optional_argument   "i"
  		"regexp-extended\0" No_argument         "r"
  		"quiet\0"           No_argument         "n"
  		"silent\0"          No_argument         "n"
  		"expression\0"      Required_argument   "e"
  		"file\0"            Required_argument   "f";
  #endif
  
  	INIT_G();
  
  	/* destroy command strings on exit */
  	if (ENABLE_FEATURE_CLEAN_UP) atexit(sed_free_and_close_stuff);
  
  	/* Lie to autoconf when it starts asking stupid questions. */
  	if (argv[1] && strcmp(argv[1], "--version") == 0) {
  		puts("This is not GNU sed version 4.0");
  		return 0;
  	}
  
  	/* do normal option parsing */
  	opt_e = opt_f = NULL;
  	opt_i = NULL;
  	/* -i must be first, to match OPT_in_place definition */
  	/* -E is a synonym of -r:
  	 * GNU sed 4.2.1 mentions it in neither --help
  	 * nor manpage, but does recognize it.
  	 */
  	opt = getopt32long(argv, "^"
  			"i::rEne:*f:*"
  			"\0" "nn"/*count -n*/,
  			sed_longopts,
  			&opt_i, &opt_e, &opt_f,
  			&G.be_quiet); /* counter for -n */
  	//argc -= optind;
  	argv += optind;
  	if (opt & OPT_in_place) { // -i
  		die_func = cleanup_outname;
  	}
  	if (opt & (2|4))
  		G.regex_type |= REG_EXTENDED; // -r or -E
  	//if (opt & 8)
  	//	G.be_quiet++; // -n (implemented with a counter instead)
  	while (opt_e) { // -e
  		add_cmd_block(llist_pop(&opt_e));
  	}
  	while (opt_f) { // -f
  		char *line;
  		FILE *cmdfile;
  		cmdfile = xfopen_stdin(llist_pop(&opt_f));
  		while ((line = xmalloc_fgetline(cmdfile)) != NULL) {
  			add_cmd(line);
  			free(line);
  		}
  		fclose_if_not_stdin(cmdfile);
  	}
  	/* if we didn't get a pattern from -e or -f, use argv[0] */
  	if (!(opt & 0x30)) {
  		if (!*argv)
  			bb_show_usage();
  		add_cmd_block(*argv++);
  	}
  	/* Flush any unfinished commands. */
  	add_cmd("");
  
  	/* By default, we write to stdout */
  	G.nonstdout = stdout;
  
  	/* argv[0..(argc-1)] should be names of file to process. If no
  	 * files were specified or '-' was specified, take input from stdin.
  	 * Otherwise, we process all the files specified. */
  	G.input_file_list = argv;
  	if (!argv[0]) {
  		if (opt & OPT_in_place)
  			bb_error_msg_and_die(bb_msg_requires_arg, "-i");
  		argv[0] = (char*)bb_msg_standard_input;
  		/* G.last_input_file = 0; - already is */
  	} else {
  		goto start;
  
  		for (; *argv; argv++) {
  			struct stat statbuf;
  			int nonstdoutfd;
  			sed_cmd_t *sed_cmd;
  
  			G.last_input_file++;
   start:
  			if (!(opt & OPT_in_place)) {
  				if (LONE_DASH(*argv)) {
  					*argv = (char*)bb_msg_standard_input;
  					process_files();
  				}
  				continue;
  			}
  
  			/* -i: process each FILE separately: */
  
  			if (stat(*argv, &statbuf) != 0) {
  				bb_simple_perror_msg(*argv);
  				G.exitcode = EXIT_FAILURE;
  				G.current_input_file++;
  				continue;
  			}
  			G.outname = xasprintf("%sXXXXXX", *argv);
  			nonstdoutfd = xmkstemp(G.outname);
  			G.nonstdout = xfdopen_for_write(nonstdoutfd);
  			/* Set permissions/owner of output file */
  			/* chmod'ing AFTER chown would preserve suid/sgid bits,
  			 * but GNU sed 4.2.1 does not preserve them either */
  			fchmod(nonstdoutfd, statbuf.st_mode);
  			fchown(nonstdoutfd, statbuf.st_uid, statbuf.st_gid);
  
  			process_files();
  			fclose(G.nonstdout);
  			G.nonstdout = stdout;
  
  			if (opt_i) {
  				char *backupname = xasprintf("%s%s", *argv, opt_i);
  				xrename(*argv, backupname);
  				free(backupname);
  			}
  			/* else unlink(*argv); - rename below does this */
  			xrename(G.outname, *argv); //TODO: rollback backup on error?
  			free(G.outname);
  			G.outname = NULL;
  
  			/* Fix disabled range matches and mangled ",+N" ranges */
  			for (sed_cmd = G.sed_cmd_head; sed_cmd; sed_cmd = sed_cmd->next) {
  				sed_cmd->beg_line = sed_cmd->beg_line_orig;
  				sed_cmd->end_line = sed_cmd->end_line_orig;
  			}
  		}
  		/* Here, to handle "sed 'cmds' nonexistent_file" case we did:
  		 * if (G.current_input_file[G.current_input_file] == NULL)
  		 *	return G.exitcode;
  		 * but it's not needed since process_files() works correctly
  		 * in this case too. */
  	}
  
  	process_files();
  
  	return G.exitcode;
  }
  