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-rw-r--r--fsck.c1090
1 files changed, 1090 insertions, 0 deletions
diff --git a/fsck.c b/fsck.c
new file mode 100644
index 000000000000..cdb7d8db0301
--- /dev/null
+++ b/fsck.c
@@ -0,0 +1,1090 @@
+#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;
+}