text: #include "cache.h"
  #include "object-store.h"
  #include "repository.h"
  #include "object.h"
  #include "blob.h"
  #include "tree.h"
  #include "tree-walk.h"
  #include "commit.h"
  #include "tag.h"
  #include "fsck.h"
  #include "refs.h"
  #include "utf8.h"
  #include "decorate.h"
  #include "oidset.h"
  #include "packfile.h"
  #include "submodule-config.h"
  #include "config.h"
  #include "help.h"
  
  static struct oidset gitmodules_found = OIDSET_INIT;
  static struct oidset gitmodules_done = OIDSET_INIT;
  
  #define FSCK_FATAL -1
  #define FSCK_INFO -2
  
  #define FOREACH_MSG_ID(FUNC) \
  	/* fatal errors */ \
  	FUNC(NUL_IN_HEADER, FATAL) \
  	FUNC(UNTERMINATED_HEADER, FATAL) \
  	/* errors */ \
  	FUNC(BAD_DATE, ERROR) \
  	FUNC(BAD_DATE_OVERFLOW, ERROR) \
  	FUNC(BAD_EMAIL, ERROR) \
  	FUNC(BAD_NAME, ERROR) \
  	FUNC(BAD_OBJECT_SHA1, ERROR) \
  	FUNC(BAD_PARENT_SHA1, ERROR) \
  	FUNC(BAD_TAG_OBJECT, ERROR) \
  	FUNC(BAD_TIMEZONE, ERROR) \
  	FUNC(BAD_TREE, ERROR) \
  	FUNC(BAD_TREE_SHA1, ERROR) \
  	FUNC(BAD_TYPE, ERROR) \
  	FUNC(DUPLICATE_ENTRIES, ERROR) \
  	FUNC(MISSING_AUTHOR, ERROR) \
  	FUNC(MISSING_COMMITTER, ERROR) \
  	FUNC(MISSING_EMAIL, ERROR) \
  	FUNC(MISSING_GRAFT, ERROR) \
  	FUNC(MISSING_NAME_BEFORE_EMAIL, ERROR) \
  	FUNC(MISSING_OBJECT, ERROR) \
  	FUNC(MISSING_PARENT, ERROR) \
  	FUNC(MISSING_SPACE_BEFORE_DATE, ERROR) \
  	FUNC(MISSING_SPACE_BEFORE_EMAIL, ERROR) \
  	FUNC(MISSING_TAG, ERROR) \
  	FUNC(MISSING_TAG_ENTRY, ERROR) \
  	FUNC(MISSING_TAG_OBJECT, ERROR) \
  	FUNC(MISSING_TREE, ERROR) \
  	FUNC(MISSING_TREE_OBJECT, ERROR) \
  	FUNC(MISSING_TYPE, ERROR) \
  	FUNC(MISSING_TYPE_ENTRY, ERROR) \
  	FUNC(MULTIPLE_AUTHORS, ERROR) \
  	FUNC(TAG_OBJECT_NOT_TAG, ERROR) \
  	FUNC(TREE_NOT_SORTED, ERROR) \
  	FUNC(UNKNOWN_TYPE, ERROR) \
  	FUNC(ZERO_PADDED_DATE, ERROR) \
  	FUNC(GITMODULES_MISSING, ERROR) \
  	FUNC(GITMODULES_BLOB, ERROR) \
  	FUNC(GITMODULES_LARGE, ERROR) \
  	FUNC(GITMODULES_NAME, ERROR) \
  	FUNC(GITMODULES_SYMLINK, ERROR) \
  	FUNC(GITMODULES_URL, ERROR) \
  	FUNC(GITMODULES_PATH, ERROR) \
  	/* warnings */ \
  	FUNC(BAD_FILEMODE, WARN) \
  	FUNC(EMPTY_NAME, WARN) \
  	FUNC(FULL_PATHNAME, WARN) \
  	FUNC(HAS_DOT, WARN) \
  	FUNC(HAS_DOTDOT, WARN) \
  	FUNC(HAS_DOTGIT, WARN) \
  	FUNC(NULL_SHA1, WARN) \
  	FUNC(ZERO_PADDED_FILEMODE, WARN) \
  	FUNC(NUL_IN_COMMIT, WARN) \
  	/* infos (reported as warnings, but ignored by default) */ \
  	FUNC(GITMODULES_PARSE, INFO) \
  	FUNC(BAD_TAG_NAME, INFO) \
  	FUNC(MISSING_TAGGER_ENTRY, INFO)
  
  #define MSG_ID(id, msg_type) FSCK_MSG_##id,
  enum fsck_msg_id {
  	FOREACH_MSG_ID(MSG_ID)
  	FSCK_MSG_MAX
  };
  #undef MSG_ID
  
  #define STR(x) #x
  #define MSG_ID(id, msg_type) { STR(id), NULL, NULL, FSCK_##msg_type },
  static struct {
  	const char *id_string;
  	const char *downcased;
  	const char *camelcased;
  	int msg_type;
  } msg_id_info[FSCK_MSG_MAX + 1] = {
  	FOREACH_MSG_ID(MSG_ID)
  	{ NULL, NULL, NULL, -1 }
  };
  #undef MSG_ID
  
  static void prepare_msg_ids(void)
  {
  	int i;
  
  	if (msg_id_info[0].downcased)
  		return;
  
  	/* convert id_string to lower case, without underscores. */
  	for (i = 0; i < FSCK_MSG_MAX; i++) {
  		const char *p = msg_id_info[i].id_string;
  		int len = strlen(p);
  		char *q = xmalloc(len);
  
  		msg_id_info[i].downcased = q;
  		while (*p)
  			if (*p == '_')
  				p++;
  			else
  				*(q)++ = tolower(*(p)++);
  		*q = '\0';
  
  		p = msg_id_info[i].id_string;
  		q = xmalloc(len);
  		msg_id_info[i].camelcased = q;
  		while (*p) {
  			if (*p == '_') {
  				p++;
  				if (*p)
  					*q++ = *p++;
  			} else {
  				*q++ = tolower(*p++);
  			}
  		}
  		*q = '\0';
  	}
  }
  
  static int parse_msg_id(const char *text)
  {
  	int i;
  
  	prepare_msg_ids();
  
  	for (i = 0; i < FSCK_MSG_MAX; i++)
  		if (!strcmp(text, msg_id_info[i].downcased))
  			return i;
  
  	return -1;
  }
  
  void list_config_fsck_msg_ids(struct string_list *list, const char *prefix)
  {
  	int i;
  
  	prepare_msg_ids();
  
  	for (i = 0; i < FSCK_MSG_MAX; i++)
  		list_config_item(list, prefix, msg_id_info[i].camelcased);
  }
  
  static int fsck_msg_type(enum fsck_msg_id msg_id,
  	struct fsck_options *options)
  {
  	int msg_type;
  
  	assert(msg_id >= 0 && msg_id < FSCK_MSG_MAX);
  
  	if (options->msg_type)
  		msg_type = options->msg_type[msg_id];
  	else {
  		msg_type = msg_id_info[msg_id].msg_type;
  		if (options->strict && msg_type == FSCK_WARN)
  			msg_type = FSCK_ERROR;
  	}
  
  	return msg_type;
  }
  
  static int parse_msg_type(const char *str)
  {
  	if (!strcmp(str, "error"))
  		return FSCK_ERROR;
  	else if (!strcmp(str, "warn"))
  		return FSCK_WARN;
  	else if (!strcmp(str, "ignore"))
  		return FSCK_IGNORE;
  	else
  		die("Unknown fsck message type: '%s'", str);
  }
  
  int is_valid_msg_type(const char *msg_id, const char *msg_type)
  {
  	if (parse_msg_id(msg_id) < 0)
  		return 0;
  	parse_msg_type(msg_type);
  	return 1;
  }
  
  void fsck_set_msg_type(struct fsck_options *options,
  		const char *msg_id, const char *msg_type)
  {
  	int id = parse_msg_id(msg_id), type;
  
  	if (id < 0)
  		die("Unhandled message id: %s", msg_id);
  	type = parse_msg_type(msg_type);
  
  	if (type != FSCK_ERROR && msg_id_info[id].msg_type == FSCK_FATAL)
  		die("Cannot demote %s to %s", msg_id, msg_type);
  
  	if (!options->msg_type) {
  		int i;
  		int *msg_type;
  		ALLOC_ARRAY(msg_type, FSCK_MSG_MAX);
  		for (i = 0; i < FSCK_MSG_MAX; i++)
  			msg_type[i] = fsck_msg_type(i, options);
  		options->msg_type = msg_type;
  	}
  
  	options->msg_type[id] = type;
  }
  
  void fsck_set_msg_types(struct fsck_options *options, const char *values)
  {
  	char *buf = xstrdup(values), *to_free = buf;
  	int done = 0;
  
  	while (!done) {
  		int len = strcspn(buf, " ,|"), equal;
  
  		done = !buf[len];
  		if (!len) {
  			buf++;
  			continue;
  		}
  		buf[len] = '\0';
  
  		for (equal = 0;
  		     equal < len && buf[equal] != '=' && buf[equal] != ':';
  		     equal++)
  			buf[equal] = tolower(buf[equal]);
  		buf[equal] = '\0';
  
  		if (!strcmp(buf, "skiplist")) {
  			if (equal == len)
  				die("skiplist requires a path");
  			oidset_parse_file(&options->skiplist, buf + equal + 1);
  			buf += len + 1;
  			continue;
  		}
  
  		if (equal == len)
  			die("Missing '=': '%s'", buf);
  
  		fsck_set_msg_type(options, buf, buf + equal + 1);
  		buf += len + 1;
  	}
  	free(to_free);
  }
  
  static void append_msg_id(struct strbuf *sb, const char *msg_id)
  {
  	for (;;) {
  		char c = *(msg_id)++;
  
  		if (!c)
  			break;
  		if (c != '_')
  			strbuf_addch(sb, tolower(c));
  		else {
  			assert(*msg_id);
  			strbuf_addch(sb, *(msg_id)++);
  		}
  	}
  
  	strbuf_addstr(sb, ": ");
  }
  
  static int object_on_skiplist(struct fsck_options *opts, struct object *obj)
  {
  	return opts && obj && oidset_contains(&opts->skiplist, &obj->oid);
  }
  
  __attribute__((format (printf, 4, 5)))
  static int report(struct fsck_options *options, struct object *object,
  	enum fsck_msg_id id, const char *fmt, ...)
  {
  	va_list ap;
  	struct strbuf sb = STRBUF_INIT;
  	int msg_type = fsck_msg_type(id, options), result;
  
  	if (msg_type == FSCK_IGNORE)
  		return 0;
  
  	if (object_on_skiplist(options, object))
  		return 0;
  
  	if (msg_type == FSCK_FATAL)
  		msg_type = FSCK_ERROR;
  	else if (msg_type == FSCK_INFO)
  		msg_type = FSCK_WARN;
  
  	append_msg_id(&sb, msg_id_info[id].id_string);
  
  	va_start(ap, fmt);
  	strbuf_vaddf(&sb, fmt, ap);
  	result = options->error_func(options, object, msg_type, sb.buf);
  	strbuf_release(&sb);
  	va_end(ap);
  
  	return result;
  }
  
  static char *get_object_name(struct fsck_options *options, struct object *obj)
  {
  	if (!options->object_names)
  		return NULL;
  	return lookup_decoration(options->object_names, obj);
  }
  
  static void put_object_name(struct fsck_options *options, struct object *obj,
  	const char *fmt, ...)
  {
  	va_list ap;
  	struct strbuf buf = STRBUF_INIT;
  	char *existing;
  
  	if (!options->object_names)
  		return;
  	existing = lookup_decoration(options->object_names, obj);
  	if (existing)
  		return;
  	va_start(ap, fmt);
  	strbuf_vaddf(&buf, fmt, ap);
  	add_decoration(options->object_names, obj, strbuf_detach(&buf, NULL));
  	va_end(ap);
  }
  
  static const char *describe_object(struct fsck_options *o, struct object *obj)
  {
  	static struct strbuf buf = STRBUF_INIT;
  	char *name;
  
  	strbuf_reset(&buf);
  	strbuf_addstr(&buf, oid_to_hex(&obj->oid));
  	if (o->object_names && (name = lookup_decoration(o->object_names, obj)))
  		strbuf_addf(&buf, " (%s)", name);
  
  	return buf.buf;
  }
  
  static int fsck_walk_tree(struct tree *tree, void *data, struct fsck_options *options)
  {
  	struct tree_desc desc;
  	struct name_entry entry;
  	int res = 0;
  	const char *name;
  
  	if (parse_tree(tree))
  		return -1;
  
  	name = get_object_name(options, &tree->object);
  	if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
  		return -1;
  	while (tree_entry_gently(&desc, &entry)) {
  		struct object *obj;
  		int result;
  
  		if (S_ISGITLINK(entry.mode))
  			continue;
  
  		if (S_ISDIR(entry.mode)) {
  			obj = (struct object *)lookup_tree(the_repository, &entry.oid);
  			if (name && obj)
  				put_object_name(options, obj, "%s%s/", name,
  					entry.path);
  			result = options->walk(obj, OBJ_TREE, data, options);
  		}
  		else if (S_ISREG(entry.mode) || S_ISLNK(entry.mode)) {
  			obj = (struct object *)lookup_blob(the_repository, &entry.oid);
  			if (name && obj)
  				put_object_name(options, obj, "%s%s", name,
  					entry.path);
  			result = options->walk(obj, OBJ_BLOB, data, options);
  		}
  		else {
  			result = error("in tree %s: entry %s has bad mode %.6o",
  					describe_object(options, &tree->object), entry.path, entry.mode);
  		}
  		if (result < 0)
  			return result;
  		if (!res)
  			res = result;
  	}
  	return res;
  }
  
  static int fsck_walk_commit(struct commit *commit, void *data, struct fsck_options *options)
  {
  	int counter = 0, generation = 0, name_prefix_len = 0;
  	struct commit_list *parents;
  	int res;
  	int result;
  	const char *name;
  
  	if (parse_commit(commit))
  		return -1;
  
  	name = get_object_name(options, &commit->object);
  	if (name)
  		put_object_name(options, &get_commit_tree(commit)->object,
  				"%s:", name);
  
  	result = options->walk((struct object *)get_commit_tree(commit),
  			       OBJ_TREE, data, options);
  	if (result < 0)
  		return result;
  	res = result;
  
  	parents = commit->parents;
  	if (name && parents) {
  		int len = strlen(name), power;
  
  		if (len && name[len - 1] == '^') {
  			generation = 1;
  			name_prefix_len = len - 1;
  		}
  		else { /* parse ~<generation> suffix */
  			for (generation = 0, power = 1;
  			     len && isdigit(name[len - 1]);
  			     power *= 10)
  				generation += power * (name[--len] - '0');
  			if (power > 1 && len && name[len - 1] == '~')
  				name_prefix_len = len - 1;
  		}
  	}
  
  	while (parents) {
  		if (name) {
  			struct object *obj = &parents->item->object;
  
  			if (counter++)
  				put_object_name(options, obj, "%s^%d",
  					name, counter);
  			else if (generation > 0)
  				put_object_name(options, obj, "%.*s~%d",
  					name_prefix_len, name, generation + 1);
  			else
  				put_object_name(options, obj, "%s^", name);
  		}
  		result = options->walk((struct object *)parents->item, OBJ_COMMIT, data, options);
  		if (result < 0)
  			return result;
  		if (!res)
  			res = result;
  		parents = parents->next;
  	}
  	return res;
  }
  
  static int fsck_walk_tag(struct tag *tag, void *data, struct fsck_options *options)
  {
  	char *name = get_object_name(options, &tag->object);
  
  	if (parse_tag(tag))
  		return -1;
  	if (name)
  		put_object_name(options, tag->tagged, "%s", name);
  	return options->walk(tag->tagged, OBJ_ANY, data, options);
  }
  
  int fsck_walk(struct object *obj, void *data, struct fsck_options *options)
  {
  	if (!obj)
  		return -1;
  
  	if (obj->type == OBJ_NONE)
  		parse_object(the_repository, &obj->oid);
  
  	switch (obj->type) {
  	case OBJ_BLOB:
  		return 0;
  	case OBJ_TREE:
  		return fsck_walk_tree((struct tree *)obj, data, options);
  	case OBJ_COMMIT:
  		return fsck_walk_commit((struct commit *)obj, data, options);
  	case OBJ_TAG:
  		return fsck_walk_tag((struct tag *)obj, data, options);
  	default:
  		error("Unknown object type for %s", describe_object(options, obj));
  		return -1;
  	}
  }
  
  /*
   * The entries in a tree are ordered in the _path_ order,
   * which means that a directory entry is ordered by adding
   * a slash to the end of it.
   *
   * So a directory called "a" is ordered _after_ a file
   * called "a.c", because "a/" sorts after "a.c".
   */
  #define TREE_UNORDERED (-1)
  #define TREE_HAS_DUPS  (-2)
  
  static int verify_ordered(unsigned mode1, const char *name1, unsigned mode2, const char *name2)
  {
  	int len1 = strlen(name1);
  	int len2 = strlen(name2);
  	int len = len1 < len2 ? len1 : len2;
  	unsigned char c1, c2;
  	int cmp;
  
  	cmp = memcmp(name1, name2, len);
  	if (cmp < 0)
  		return 0;
  	if (cmp > 0)
  		return TREE_UNORDERED;
  
  	/*
  	 * Ok, the first <len> characters are the same.
  	 * Now we need to order the next one, but turn
  	 * a '\0' into a '/' for a directory entry.
  	 */
  	c1 = name1[len];
  	c2 = name2[len];
  	if (!c1 && !c2)
  		/*
  		 * git-write-tree used to write out a nonsense tree that has
  		 * entries with the same name, one blob and one tree.  Make
  		 * sure we do not have duplicate entries.
  		 */
  		return TREE_HAS_DUPS;
  	if (!c1 && S_ISDIR(mode1))
  		c1 = '/';
  	if (!c2 && S_ISDIR(mode2))
  		c2 = '/';
  	return c1 < c2 ? 0 : TREE_UNORDERED;
  }
  
  static int fsck_tree(struct tree *item, struct fsck_options *options)
  {
  	int retval = 0;
  	int has_null_sha1 = 0;
  	int has_full_path = 0;
  	int has_empty_name = 0;
  	int has_dot = 0;
  	int has_dotdot = 0;
  	int has_dotgit = 0;
  	int has_zero_pad = 0;
  	int has_bad_modes = 0;
  	int has_dup_entries = 0;
  	int not_properly_sorted = 0;
  	struct tree_desc desc;
  	unsigned o_mode;
  	const char *o_name;
  
  	if (init_tree_desc_gently(&desc, item->buffer, item->size)) {
  		retval += report(options, &item->object, FSCK_MSG_BAD_TREE, "cannot be parsed as a tree");
  		return retval;
  	}
  
  	o_mode = 0;
  	o_name = NULL;
  
  	while (desc.size) {
  		unsigned short mode;
  		const char *name;
  		const struct object_id *oid;
  
  		oid = tree_entry_extract(&desc, &name, &mode);
  
  		has_null_sha1 |= is_null_oid(oid);
  		has_full_path |= !!strchr(name, '/');
  		has_empty_name |= !*name;
  		has_dot |= !strcmp(name, ".");
  		has_dotdot |= !strcmp(name, "..");
  		has_dotgit |= is_hfs_dotgit(name) || is_ntfs_dotgit(name);
  		has_zero_pad |= *(char *)desc.buffer == '0';
  
  		if (is_hfs_dotgitmodules(name) || is_ntfs_dotgitmodules(name)) {
  			if (!S_ISLNK(mode))
  				oidset_insert(&gitmodules_found, oid);
  			else
  				retval += report(options, &item->object,
  						 FSCK_MSG_GITMODULES_SYMLINK,
  						 ".gitmodules is a symbolic link");
  		}
  
  		if (update_tree_entry_gently(&desc)) {
  			retval += report(options, &item->object, FSCK_MSG_BAD_TREE, "cannot be parsed as a tree");
  			break;
  		}
  
  		switch (mode) {
  		/*
  		 * Standard modes..
  		 */
  		case S_IFREG | 0755:
  		case S_IFREG | 0644:
  		case S_IFLNK:
  		case S_IFDIR:
  		case S_IFGITLINK:
  			break;
  		/*
  		 * This is nonstandard, but we had a few of these
  		 * early on when we honored the full set of mode
  		 * bits..
  		 */
  		case S_IFREG | 0664:
  			if (!options->strict)
  				break;
  			/* fallthrough */
  		default:
  			has_bad_modes = 1;
  		}
  
  		if (o_name) {
  			switch (verify_ordered(o_mode, o_name, mode, name)) {
  			case TREE_UNORDERED:
  				not_properly_sorted = 1;
  				break;
  			case TREE_HAS_DUPS:
  				has_dup_entries = 1;
  				break;
  			default:
  				break;
  			}
  		}
  
  		o_mode = mode;
  		o_name = name;
  	}
  
  	if (has_null_sha1)
  		retval += report(options, &item->object, FSCK_MSG_NULL_SHA1, "contains entries pointing to null sha1");
  	if (has_full_path)
  		retval += report(options, &item->object, FSCK_MSG_FULL_PATHNAME, "contains full pathnames");
  	if (has_empty_name)
  		retval += report(options, &item->object, FSCK_MSG_EMPTY_NAME, "contains empty pathname");
  	if (has_dot)
  		retval += report(options, &item->object, FSCK_MSG_HAS_DOT, "contains '.'");
  	if (has_dotdot)
  		retval += report(options, &item->object, FSCK_MSG_HAS_DOTDOT, "contains '..'");
  	if (has_dotgit)
  		retval += report(options, &item->object, FSCK_MSG_HAS_DOTGIT, "contains '.git'");
  	if (has_zero_pad)
  		retval += report(options, &item->object, FSCK_MSG_ZERO_PADDED_FILEMODE, "contains zero-padded file modes");
  	if (has_bad_modes)
  		retval += report(options, &item->object, FSCK_MSG_BAD_FILEMODE, "contains bad file modes");
  	if (has_dup_entries)
  		retval += report(options, &item->object, FSCK_MSG_DUPLICATE_ENTRIES, "contains duplicate file entries");
  	if (not_properly_sorted)
  		retval += report(options, &item->object, FSCK_MSG_TREE_NOT_SORTED, "not properly sorted");
  	return retval;
  }
  
  static int verify_headers(const void *data, unsigned long size,
  			  struct object *obj, struct fsck_options *options)
  {
  	const char *buffer = (const char *)data;
  	unsigned long i;
  
  	for (i = 0; i < size; i++) {
  		switch (buffer[i]) {
  		case '\0':
  			return report(options, obj,
  				FSCK_MSG_NUL_IN_HEADER,
  				"unterminated header: NUL at offset %ld", i);
  		case '\n':
  			if (i + 1 < size && buffer[i + 1] == '\n')
  				return 0;
  		}
  	}
  
  	/*
  	 * We did not find double-LF that separates the header
  	 * and the body.  Not having a body is not a crime but
  	 * we do want to see the terminating LF for the last header
  	 * line.
  	 */
  	if (size && buffer[size - 1] == '\n')
  		return 0;
  
  	return report(options, obj,
  		FSCK_MSG_UNTERMINATED_HEADER, "unterminated header");
  }
  
  static int fsck_ident(const char **ident, struct object *obj, struct fsck_options *options)
  {
  	const char *p = *ident;
  	char *end;
  
  	*ident = strchrnul(*ident, '\n');
  	if (**ident == '\n')
  		(*ident)++;
  
  	if (*p == '<')
  		return report(options, obj, FSCK_MSG_MISSING_NAME_BEFORE_EMAIL, "invalid author/committer line - missing space before email");
  	p += strcspn(p, "<>\n");
  	if (*p == '>')
  		return report(options, obj, FSCK_MSG_BAD_NAME, "invalid author/committer line - bad name");
  	if (*p != '<')
  		return report(options, obj, FSCK_MSG_MISSING_EMAIL, "invalid author/committer line - missing email");
  	if (p[-1] != ' ')
  		return report(options, obj, FSCK_MSG_MISSING_SPACE_BEFORE_EMAIL, "invalid author/committer line - missing space before email");
  	p++;
  	p += strcspn(p, "<>\n");
  	if (*p != '>')
  		return report(options, obj, FSCK_MSG_BAD_EMAIL, "invalid author/committer line - bad email");
  	p++;
  	if (*p != ' ')
  		return report(options, obj, FSCK_MSG_MISSING_SPACE_BEFORE_DATE, "invalid author/committer line - missing space before date");
  	p++;
  	if (*p == '0' && p[1] != ' ')
  		return report(options, obj, FSCK_MSG_ZERO_PADDED_DATE, "invalid author/committer line - zero-padded date");
  	if (date_overflows(parse_timestamp(p, &end, 10)))
  		return report(options, obj, FSCK_MSG_BAD_DATE_OVERFLOW, "invalid author/committer line - date causes integer overflow");
  	if ((end == p || *end != ' '))
  		return report(options, obj, FSCK_MSG_BAD_DATE, "invalid author/committer line - bad date");
  	p = end + 1;
  	if ((*p != '+' && *p != '-') ||
  	    !isdigit(p[1]) ||
  	    !isdigit(p[2]) ||
  	    !isdigit(p[3]) ||
  	    !isdigit(p[4]) ||
  	    (p[5] != '\n'))
  		return report(options, obj, FSCK_MSG_BAD_TIMEZONE, "invalid author/committer line - bad time zone");
  	p += 6;
  	return 0;
  }
  
  static int fsck_commit_buffer(struct commit *commit, const char *buffer,
  	unsigned long size, struct fsck_options *options)
  {
  	struct object_id tree_oid, oid;
  	struct commit_graft *graft;
  	unsigned parent_count, parent_line_count = 0, author_count;
  	int err;
  	const char *buffer_begin = buffer;
  	const char *p;
  
  	if (verify_headers(buffer, size, &commit->object, options))
  		return -1;
  
  	if (!skip_prefix(buffer, "tree ", &buffer))
  		return report(options, &commit->object, FSCK_MSG_MISSING_TREE, "invalid format - expected 'tree' line");
  	if (parse_oid_hex(buffer, &tree_oid, &p) || *p != '\n') {
  		err = report(options, &commit->object, FSCK_MSG_BAD_TREE_SHA1, "invalid 'tree' line format - bad sha1");
  		if (err)
  			return err;
  	}
  	buffer = p + 1;
  	while (skip_prefix(buffer, "parent ", &buffer)) {
  		if (parse_oid_hex(buffer, &oid, &p) || *p != '\n') {
  			err = report(options, &commit->object, FSCK_MSG_BAD_PARENT_SHA1, "invalid 'parent' line format - bad sha1");
  			if (err)
  				return err;
  		}
  		buffer = p + 1;
  		parent_line_count++;
  	}
  	graft = lookup_commit_graft(the_repository, &commit->object.oid);
  	parent_count = commit_list_count(commit->parents);
  	if (graft) {
  		if (graft->nr_parent == -1 && !parent_count)
  			; /* shallow commit */
  		else if (graft->nr_parent != parent_count) {
  			err = report(options, &commit->object, FSCK_MSG_MISSING_GRAFT, "graft objects missing");
  			if (err)
  				return err;
  		}
  	} else {
  		if (parent_count != parent_line_count) {
  			err = report(options, &commit->object, FSCK_MSG_MISSING_PARENT, "parent objects missing");
  			if (err)
  				return err;
  		}
  	}
  	author_count = 0;
  	while (skip_prefix(buffer, "author ", &buffer)) {
  		author_count++;
  		err = fsck_ident(&buffer, &commit->object, options);
  		if (err)
  			return err;
  	}
  	if (author_count < 1)
  		err = report(options, &commit->object, FSCK_MSG_MISSING_AUTHOR, "invalid format - expected 'author' line");
  	else if (author_count > 1)
  		err = report(options, &commit->object, FSCK_MSG_MULTIPLE_AUTHORS, "invalid format - multiple 'author' lines");
  	if (err)
  		return err;
  	if (!skip_prefix(buffer, "committer ", &buffer))
  		return report(options, &commit->object, FSCK_MSG_MISSING_COMMITTER, "invalid format - expected 'committer' line");
  	err = fsck_ident(&buffer, &commit->object, options);
  	if (err)
  		return err;
  	if (!get_commit_tree(commit)) {
  		err = report(options, &commit->object, FSCK_MSG_BAD_TREE, "could not load commit's tree %s", oid_to_hex(&tree_oid));
  		if (err)
  			return err;
  	}
  	if (memchr(buffer_begin, '\0', size)) {
  		err = report(options, &commit->object, FSCK_MSG_NUL_IN_COMMIT,
  			     "NUL byte in the commit object body");
  		if (err)
  			return err;
  	}
  	return 0;
  }
  
  static int fsck_commit(struct commit *commit, const char *data,
  	unsigned long size, struct fsck_options *options)
  {
  	const char *buffer = data ?  data : get_commit_buffer(commit, &size);
  	int ret = fsck_commit_buffer(commit, buffer, size, options);
  	if (!data)
  		unuse_commit_buffer(commit, buffer);
  	return ret;
  }
  
  static int fsck_tag_buffer(struct tag *tag, const char *data,
  	unsigned long size, struct fsck_options *options)
  {
  	struct object_id oid;
  	int ret = 0;
  	const char *buffer;
  	char *to_free = NULL, *eol;
  	struct strbuf sb = STRBUF_INIT;
  	const char *p;
  
  	if (data)
  		buffer = data;
  	else {
  		enum object_type type;
  
  		buffer = to_free =
  			read_object_file(&tag->object.oid, &type, &size);
  		if (!buffer)
  			return report(options, &tag->object,
  				FSCK_MSG_MISSING_TAG_OBJECT,
  				"cannot read tag object");
  
  		if (type != OBJ_TAG) {
  			ret = report(options, &tag->object,
  				FSCK_MSG_TAG_OBJECT_NOT_TAG,
  				"expected tag got %s",
  			    type_name(type));
  			goto done;
  		}
  	}
  
  	ret = verify_headers(buffer, size, &tag->object, options);
  	if (ret)
  		goto done;
  
  	if (!skip_prefix(buffer, "object ", &buffer)) {
  		ret = report(options, &tag->object, FSCK_MSG_MISSING_OBJECT, "invalid format - expected 'object' line");
  		goto done;
  	}
  	if (parse_oid_hex(buffer, &oid, &p) || *p != '\n') {
  		ret = report(options, &tag->object, FSCK_MSG_BAD_OBJECT_SHA1, "invalid 'object' line format - bad sha1");
  		if (ret)
  			goto done;
  	}
  	buffer = p + 1;
  
  	if (!skip_prefix(buffer, "type ", &buffer)) {
  		ret = report(options, &tag->object, FSCK_MSG_MISSING_TYPE_ENTRY, "invalid format - expected 'type' line");
  		goto done;
  	}
  	eol = strchr(buffer, '\n');
  	if (!eol) {
  		ret = report(options, &tag->object, FSCK_MSG_MISSING_TYPE, "invalid format - unexpected end after 'type' line");
  		goto done;
  	}
  	if (type_from_string_gently(buffer, eol - buffer, 1) < 0)
  		ret = report(options, &tag->object, FSCK_MSG_BAD_TYPE, "invalid 'type' value");
  	if (ret)
  		goto done;
  	buffer = eol + 1;
  
  	if (!skip_prefix(buffer, "tag ", &buffer)) {
  		ret = report(options, &tag->object, FSCK_MSG_MISSING_TAG_ENTRY, "invalid format - expected 'tag' line");
  		goto done;
  	}
  	eol = strchr(buffer, '\n');
  	if (!eol) {
  		ret = report(options, &tag->object, FSCK_MSG_MISSING_TAG, "invalid format - unexpected end after 'type' line");
  		goto done;
  	}
  	strbuf_addf(&sb, "refs/tags/%.*s", (int)(eol - buffer), buffer);
  	if (check_refname_format(sb.buf, 0)) {
  		ret = report(options, &tag->object, FSCK_MSG_BAD_TAG_NAME,
  			   "invalid 'tag' name: %.*s",
  			   (int)(eol - buffer), buffer);
  		if (ret)
  			goto done;
  	}
  	buffer = eol + 1;
  
  	if (!skip_prefix(buffer, "tagger ", &buffer)) {
  		/* early tags do not contain 'tagger' lines; warn only */
  		ret = report(options, &tag->object, FSCK_MSG_MISSING_TAGGER_ENTRY, "invalid format - expected 'tagger' line");
  		if (ret)
  			goto done;
  	}
  	else
  		ret = fsck_ident(&buffer, &tag->object, options);
  
  done:
  	strbuf_release(&sb);
  	free(to_free);
  	return ret;
  }
  
  static int fsck_tag(struct tag *tag, const char *data,
  	unsigned long size, struct fsck_options *options)
  {
  	struct object *tagged = tag->tagged;
  
  	if (!tagged)
  		return report(options, &tag->object, FSCK_MSG_BAD_TAG_OBJECT, "could not load tagged object");
  
  	return fsck_tag_buffer(tag, data, size, options);
  }
  
  struct fsck_gitmodules_data {
  	struct object *obj;
  	struct fsck_options *options;
  	int ret;
  };
  
  static int fsck_gitmodules_fn(const char *var, const char *value, void *vdata)
  {
  	struct fsck_gitmodules_data *data = vdata;
  	const char *subsection, *key;
  	int subsection_len;
  	char *name;
  
  	if (parse_config_key(var, "submodule", &subsection, &subsection_len, &key) < 0 ||
  	    !subsection)
  		return 0;
  
  	name = xmemdupz(subsection, subsection_len);
  	if (check_submodule_name(name) < 0)
  		data->ret |= report(data->options, data->obj,
  				    FSCK_MSG_GITMODULES_NAME,
  				    "disallowed submodule name: %s",
  				    name);
  	if (!strcmp(key, "url") && value &&
  	    looks_like_command_line_option(value))
  		data->ret |= report(data->options, data->obj,
  				    FSCK_MSG_GITMODULES_URL,
  				    "disallowed submodule url: %s",
  				    value);
  	if (!strcmp(key, "path") && value &&
  	    looks_like_command_line_option(value))
  		data->ret |= report(data->options, data->obj,
  				    FSCK_MSG_GITMODULES_PATH,
  				    "disallowed submodule path: %s",
  				    value);
  	free(name);
  
  	return 0;
  }
  
  static int fsck_blob(struct blob *blob, const char *buf,
  		     unsigned long size, struct fsck_options *options)
  {
  	struct fsck_gitmodules_data data;
  	struct config_options config_opts = { 0 };
  
  	if (!oidset_contains(&gitmodules_found, &blob->object.oid))
  		return 0;
  	oidset_insert(&gitmodules_done, &blob->object.oid);
  
  	if (object_on_skiplist(options, &blob->object))
  		return 0;
  
  	if (!buf) {
  		/*
  		 * A missing buffer here is a sign that the caller found the
  		 * blob too gigantic to load into memory. Let's just consider
  		 * that an error.
  		 */
  		return report(options, &blob->object,
  			      FSCK_MSG_GITMODULES_LARGE,
  			      ".gitmodules too large to parse");
  	}
  
  	data.obj = &blob->object;
  	data.options = options;
  	data.ret = 0;
  	config_opts.error_action = CONFIG_ERROR_SILENT;
  	if (git_config_from_mem(fsck_gitmodules_fn, CONFIG_ORIGIN_BLOB,
  				".gitmodules", buf, size, &data, &config_opts))
  		data.ret |= report(options, &blob->object,
  				   FSCK_MSG_GITMODULES_PARSE,
  				   "could not parse gitmodules blob");
  
  	return data.ret;
  }
  
  int fsck_object(struct object *obj, void *data, unsigned long size,
  	struct fsck_options *options)
  {
  	if (!obj)
  		return report(options, obj, FSCK_MSG_BAD_OBJECT_SHA1, "no valid object to fsck");
  
  	if (obj->type == OBJ_BLOB)
  		return fsck_blob((struct blob *)obj, data, size, options);
  	if (obj->type == OBJ_TREE)
  		return fsck_tree((struct tree *) obj, options);
  	if (obj->type == OBJ_COMMIT)
  		return fsck_commit((struct commit *) obj, (const char *) data,
  			size, options);
  	if (obj->type == OBJ_TAG)
  		return fsck_tag((struct tag *) obj, (const char *) data,
  			size, options);
  
  	return report(options, obj, FSCK_MSG_UNKNOWN_TYPE, "unknown type '%d' (internal fsck error)",
  			  obj->type);
  }
  
  int fsck_error_function(struct fsck_options *o,
  	struct object *obj, int msg_type, const char *message)
  {
  	if (msg_type == FSCK_WARN) {
  		warning("object %s: %s", describe_object(o, obj), message);
  		return 0;
  	}
  	error("object %s: %s", describe_object(o, obj), message);
  	return 1;
  }
  
  int fsck_finish(struct fsck_options *options)
  {
  	int ret = 0;
  	struct oidset_iter iter;
  	const struct object_id *oid;
  
  	oidset_iter_init(&gitmodules_found, &iter);
  	while ((oid = oidset_iter_next(&iter))) {
  		struct blob *blob;
  		enum object_type type;
  		unsigned long size;
  		char *buf;
  
  		if (oidset_contains(&gitmodules_done, oid))
  			continue;
  
  		blob = lookup_blob(the_repository, oid);
  		if (!blob) {
  			struct object *obj = lookup_unknown_object(oid);
  			ret |= report(options, obj,
  				      FSCK_MSG_GITMODULES_BLOB,
  				      "non-blob found at .gitmodules");
  			continue;
  		}
  
  		buf = read_object_file(oid, &type, &size);
  		if (!buf) {
  			if (is_promisor_object(&blob->object.oid))
  				continue;
  			ret |= report(options, &blob->object,
  				      FSCK_MSG_GITMODULES_MISSING,
  				      "unable to read .gitmodules blob");
  			continue;
  		}
  
  		if (type == OBJ_BLOB)
  			ret |= fsck_blob(blob, buf, size, options);
  		else
  			ret |= report(options, &blob->object,
  				      FSCK_MSG_GITMODULES_BLOB,
  				      "non-blob found at .gitmodules");
  		free(buf);
  	}
  
  
  	oidset_clear(&gitmodules_found);
  	oidset_clear(&gitmodules_done);
  	return ret;
  }
  