root/fsck.c

DEFINITIONS

1. FOREACH_MSG_ID
2. MSG_ID
3. parse_msg_id
4. fsck_msg_type
5. init_skiplist
6. parse_msg_type
7. is_valid_msg_type
8. fsck_set_msg_type
9. fsck_set_msg_types
10. append_msg_id
11. report
12. fsck_walk_tree
13. fsck_walk_commit
14. fsck_walk_tag
15. fsck_walk
16. verify_ordered
17. fsck_tree
18. verify_headers
19. fsck_ident
20. fsck_commit_buffer
21. fsck_commit
22. fsck_tag_buffer
23. fsck_tag
24. fsck_object
25. fsck_error_function

#include "cache.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 "sha1-array.h"

#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_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) \
        /* 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) \
        /* infos (reported as warnings, but ignored by default) */ \
        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, FSCK_##msg_type },
static struct {
        const char *id_string;
        const char *downcased;
        int msg_type;
} msg_id_info[FSCK_MSG_MAX + 1] = {
        FOREACH_MSG_ID(MSG_ID)
        { NULL, NULL, -1 }
};
#undef MSG_ID

static int parse_msg_id(const char *text)
{
        int i;

        if (!msg_id_info[0].downcased) {
                /* 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';
                }
        }

        for (i = 0; i < FSCK_MSG_MAX; i++)
                if (!strcmp(text, msg_id_info[i].downcased))
                        return i;

        return -1;
}

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 void init_skiplist(struct fsck_options *options, const char *path)
{
        static struct sha1_array skiplist = SHA1_ARRAY_INIT;
        int sorted, fd;
        char buffer[41];
        unsigned char sha1[20];

        if (options->skiplist)
                sorted = options->skiplist->sorted;
        else {
                sorted = 1;
                options->skiplist = &skiplist;
        }

        fd = open(path, O_RDONLY);
        if (fd < 0)
                die("Could not open skip list: %s", path);
        for (;;) {
                int result = read_in_full(fd, buffer, sizeof(buffer));
                if (result < 0)
                        die_errno("Could not read '%s'", path);
                if (!result)
                        break;
                if (get_sha1_hex(buffer, sha1) || buffer[40] != '\n')
                        die("Invalid SHA-1: %s", buffer);
                sha1_array_append(&skiplist, sha1);
                if (sorted && skiplist.nr > 1 &&
                                hashcmp(skiplist.sha1[skiplist.nr - 2],
                                        sha1) > 0)
                        sorted = 0;
        }
        close(fd);

        if (sorted)
                skiplist.sorted = 1;
}

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 = xmalloc(sizeof(int) * 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");
                        init_skiplist(options, 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, ": ");
}

__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 (options->skiplist && object &&
                        sha1_array_lookup(options->skiplist, object->sha1) >= 0)
                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(object, msg_type, sb.buf);
        strbuf_release(&sb);
        va_end(ap);

        return result;
}

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;

        if (parse_tree(tree))
                return -1;

        init_tree_desc(&desc, tree->buffer, tree->size);
        while (tree_entry(&desc, &entry)) {
                int result;

                if (S_ISGITLINK(entry.mode))
                        continue;
                if (S_ISDIR(entry.mode))
                        result = options->walk(&lookup_tree(entry.sha1)->object, OBJ_TREE, data, options);
                else if (S_ISREG(entry.mode) || S_ISLNK(entry.mode))
                        result = options->walk(&lookup_blob(entry.sha1)->object, OBJ_BLOB, data, options);
                else {
                        result = error("in tree %s: entry %s has bad mode %.6o",
                                        sha1_to_hex(tree->object.sha1), 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)
{
        struct commit_list *parents;
        int res;
        int result;

        if (parse_commit(commit))
                return -1;

        result = options->walk((struct object *)commit->tree, OBJ_TREE, data, options);
        if (result < 0)
                return result;
        res = result;

        parents = commit->parents;
        while (parents) {
                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)
{
        if (parse_tag(tag))
                return -1;
        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;
        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", sha1_to_hex(obj->sha1));
                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;
        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;

        init_tree_desc(&desc, item->buffer, item->size);

        o_mode = 0;
        o_name = NULL;

        while (desc.size) {
                unsigned mode;
                const char *name;
                const unsigned char *sha1;

                sha1 = tree_entry_extract(&desc, &name, &mode);

                has_null_sha1 |= is_null_sha1(sha1);
                has_full_path |= !!strchr(name, '/');
                has_empty_name |= !*name;
                has_dot |= !strcmp(name, ".");
                has_dotdot |= !strcmp(name, "..");
                has_dotgit |= (!strcmp(name, ".git") ||
                               is_hfs_dotgit(name) ||
                               is_ntfs_dotgit(name));
                has_zero_pad |= *(char *)desc.buffer == '0';
                update_tree_entry(&desc);

                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;
                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;
        }

        retval = 0;
        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(strtoul(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)
{
        unsigned char tree_sha1[20], sha1[20];
        struct commit_graft *graft;
        unsigned parent_count, parent_line_count = 0, author_count;
        int err;

        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 (get_sha1_hex(buffer, tree_sha1) || buffer[40] != '\n') {
                err = report(options, &commit->object, FSCK_MSG_BAD_TREE_SHA1, "invalid 'tree' line format - bad sha1");
                if (err)
                        return err;
        }
        buffer += 41;
        while (skip_prefix(buffer, "parent ", &buffer)) {
                if (get_sha1_hex(buffer, sha1) || buffer[40] != '\n') {
                        err = report(options, &commit->object, FSCK_MSG_BAD_PARENT_SHA1, "invalid 'parent' line format - bad sha1");
                        if (err)
                                return err;
                }
                buffer += 41;
                parent_line_count++;
        }
        graft = lookup_commit_graft(commit->object.sha1);
        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 (!commit->tree)
                return report(options, &commit->object, FSCK_MSG_BAD_TREE, "could not load commit's tree %s", sha1_to_hex(tree_sha1));

        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)
{
        unsigned char sha1[20];
        int ret = 0;
        const char *buffer;
        char *to_free = NULL, *eol;
        struct strbuf sb = STRBUF_INIT;

        if (data)
                buffer = data;
        else {
                enum object_type type;

                buffer = to_free =
                        read_sha1_file(tag->object.sha1, &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",
                            typename(type));
                        goto done;
                }
        }

        if (verify_headers(buffer, size, &tag->object, options))
                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 (get_sha1_hex(buffer, sha1) || buffer[40] != '\n') {
                ret = report(options, &tag->object, FSCK_MSG_BAD_OBJECT_SHA1, "invalid 'object' line format - bad sha1");
                if (ret)
                        goto done;
        }
        buffer += 41;

        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);
}

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 0;
        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 object *obj, int msg_type, const char *message)
{
        if (msg_type == FSCK_WARN) {
                warning("object %s: %s", sha1_to_hex(obj->sha1), message);
                return 0;
        }
        error("object %s: %s", sha1_to_hex(obj->sha1), message);
        return 1;
}