blame: improve diagnosis for "--reverse NEW"
[gitweb.git] / fsck.c
diff --git a/fsck.c b/fsck.c
index 24b2a5f36c0c04c8bd956777eb86b23dfb0ca7fc..3366b3fb620fddaf542d7c23e1f6c1c564f8fbe8 100644 (file)
--- a/fsck.c
+++ b/fsck.c
@@ -8,8 +8,296 @@
 #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) \
+       FUNC(NUL_IN_COMMIT, 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;
+               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");
+                       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 int fsck_walk_tree(struct tree *tree, fsck_walk_func walk, void *data)
+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->oid.hash) >= 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;
@@ -25,12 +313,12 @@ static int fsck_walk_tree(struct tree *tree, fsck_walk_func walk, void *data)
                if (S_ISGITLINK(entry.mode))
                        continue;
                if (S_ISDIR(entry.mode))
-                       result = walk(&lookup_tree(entry.sha1)->object, OBJ_TREE, data);
+                       result = options->walk(&lookup_tree(entry.sha1)->object, OBJ_TREE, data, options);
                else if (S_ISREG(entry.mode) || S_ISLNK(entry.mode))
-                       result = walk(&lookup_blob(entry.sha1)->object, OBJ_BLOB, data);
+                       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);
+                                       oid_to_hex(&tree->object.oid), entry.path, entry.mode);
                }
                if (result < 0)
                        return result;
@@ -40,7 +328,7 @@ static int fsck_walk_tree(struct tree *tree, fsck_walk_func walk, void *data)
        return res;
 }
 
-static int fsck_walk_commit(struct commit *commit, fsck_walk_func walk, void *data)
+static int fsck_walk_commit(struct commit *commit, void *data, struct fsck_options *options)
 {
        struct commit_list *parents;
        int res;
@@ -49,14 +337,14 @@ static int fsck_walk_commit(struct commit *commit, fsck_walk_func walk, void *da
        if (parse_commit(commit))
                return -1;
 
-       result = walk((struct object *)commit->tree, OBJ_TREE, data);
+       result = options->walk((struct object *)commit->tree, OBJ_TREE, data, options);
        if (result < 0)
                return result;
        res = result;
 
        parents = commit->parents;
        while (parents) {
-               result = walk((struct object *)parents->item, OBJ_COMMIT, data);
+               result = options->walk((struct object *)parents->item, OBJ_COMMIT, data, options);
                if (result < 0)
                        return result;
                if (!res)
@@ -66,14 +354,14 @@ static int fsck_walk_commit(struct commit *commit, fsck_walk_func walk, void *da
        return res;
 }
 
-static int fsck_walk_tag(struct tag *tag, fsck_walk_func walk, void *data)
+static int fsck_walk_tag(struct tag *tag, void *data, struct fsck_options *options)
 {
        if (parse_tag(tag))
                return -1;
-       return walk(tag->tagged, OBJ_ANY, data);
+       return options->walk(tag->tagged, OBJ_ANY, data, options);
 }
 
-int fsck_walk(struct object *obj, fsck_walk_func walk, void *data)
+int fsck_walk(struct object *obj, void *data, struct fsck_options *options)
 {
        if (!obj)
                return -1;
@@ -81,13 +369,13 @@ int fsck_walk(struct object *obj, fsck_walk_func walk, void *data)
        case OBJ_BLOB:
                return 0;
        case OBJ_TREE:
-               return fsck_walk_tree((struct tree *)obj, walk, data);
+               return fsck_walk_tree((struct tree *)obj, data, options);
        case OBJ_COMMIT:
-               return fsck_walk_commit((struct commit *)obj, walk, data);
+               return fsck_walk_commit((struct commit *)obj, data, options);
        case OBJ_TAG:
-               return fsck_walk_tag((struct tag *)obj, walk, data);
+               return fsck_walk_tag((struct tag *)obj, data, options);
        default:
-               error("Unknown object type for %s", sha1_to_hex(obj->sha1));
+               error("Unknown object type for %s", oid_to_hex(&obj->oid));
                return -1;
        }
 }
@@ -138,7 +426,7 @@ static int verify_ordered(unsigned mode1, const char *name1, unsigned mode2, con
        return c1 < c2 ? 0 : TREE_UNORDERED;
 }
 
-static int fsck_tree(struct tree *item, int strict, fsck_error error_func)
+static int fsck_tree(struct tree *item, struct fsck_options *options)
 {
        int retval;
        int has_null_sha1 = 0;
@@ -194,7 +482,7 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func)
                 * bits..
                 */
                case S_IFREG | 0664:
-                       if (!strict)
+                       if (!options->strict)
                                break;
                default:
                        has_bad_modes = 1;
@@ -219,30 +507,30 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func)
 
        retval = 0;
        if (has_null_sha1)
-               retval += error_func(&item->object, FSCK_WARN, "contains entries pointing to null sha1");
+               retval += report(options, &item->object, FSCK_MSG_NULL_SHA1, "contains entries pointing to null sha1");
        if (has_full_path)
-               retval += error_func(&item->object, FSCK_WARN, "contains full pathnames");
+               retval += report(options, &item->object, FSCK_MSG_FULL_PATHNAME, "contains full pathnames");
        if (has_empty_name)
-               retval += error_func(&item->object, FSCK_WARN, "contains empty pathname");
+               retval += report(options, &item->object, FSCK_MSG_EMPTY_NAME, "contains empty pathname");
        if (has_dot)
-               retval += error_func(&item->object, FSCK_WARN, "contains '.'");
+               retval += report(options, &item->object, FSCK_MSG_HAS_DOT, "contains '.'");
        if (has_dotdot)
-               retval += error_func(&item->object, FSCK_WARN, "contains '..'");
+               retval += report(options, &item->object, FSCK_MSG_HAS_DOTDOT, "contains '..'");
        if (has_dotgit)
-               retval += error_func(&item->object, FSCK_WARN, "contains '.git'");
+               retval += report(options, &item->object, FSCK_MSG_HAS_DOTGIT, "contains '.git'");
        if (has_zero_pad)
-               retval += error_func(&item->object, FSCK_WARN, "contains zero-padded file modes");
+               retval += report(options, &item->object, FSCK_MSG_ZERO_PADDED_FILEMODE, "contains zero-padded file modes");
        if (has_bad_modes)
-               retval += error_func(&item->object, FSCK_WARN, "contains bad file modes");
+               retval += report(options, &item->object, FSCK_MSG_BAD_FILEMODE, "contains bad file modes");
        if (has_dup_entries)
-               retval += error_func(&item->object, FSCK_ERROR, "contains duplicate file entries");
+               retval += report(options, &item->object, FSCK_MSG_DUPLICATE_ENTRIES, "contains duplicate file entries");
        if (not_properly_sorted)
-               retval += error_func(&item->object, FSCK_ERROR, "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, fsck_error error_func)
+                         struct object *obj, struct fsck_options *options)
 {
        const char *buffer = (const char *)data;
        unsigned long i;
@@ -250,8 +538,9 @@ static int verify_headers(const void *data, unsigned long size,
        for (i = 0; i < size; i++) {
                switch (buffer[i]) {
                case '\0':
-                       return error_func(obj, FSCK_ERROR,
-                               "unterminated header: NUL at offset %d", i);
+                       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;
@@ -267,109 +556,144 @@ static int verify_headers(const void *data, unsigned long size,
        if (size && buffer[size - 1] == '\n')
                return 0;
 
-       return error_func(obj, FSCK_ERROR, "unterminated header");
+       return report(options, obj,
+               FSCK_MSG_UNTERMINATED_HEADER, "unterminated header");
 }
 
-static int fsck_ident(const char **ident, struct object *obj, fsck_error error_func)
+static int fsck_ident(const char **ident, struct object *obj, struct fsck_options *options)
 {
+       const char *p = *ident;
        char *end;
 
-       if (**ident == '<')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - missing space before email");
-       *ident += strcspn(*ident, "<>\n");
-       if (**ident == '>')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - bad name");
-       if (**ident != '<')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - missing email");
-       if ((*ident)[-1] != ' ')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - missing space before email");
-       (*ident)++;
-       *ident += strcspn(*ident, "<>\n");
-       if (**ident != '>')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - bad email");
-       (*ident)++;
-       if (**ident != ' ')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - missing space before date");
-       (*ident)++;
-       if (**ident == '0' && (*ident)[1] != ' ')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - zero-padded date");
-       if (date_overflows(strtoul(*ident, &end, 10)))
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - date causes integer overflow");
-       if (end == *ident || *end != ' ')
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - bad date");
-       *ident = end + 1;
-       if ((**ident != '+' && **ident != '-') ||
-           !isdigit((*ident)[1]) ||
-           !isdigit((*ident)[2]) ||
-           !isdigit((*ident)[3]) ||
-           !isdigit((*ident)[4]) ||
-           ((*ident)[5] != '\n'))
-               return error_func(obj, FSCK_ERROR, "invalid author/committer line - bad time zone");
-       (*ident) += 6;
+       *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, fsck_error error_func)
+       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;
+       unsigned parent_count, parent_line_count = 0, author_count;
        int err;
+       const char *buffer_begin = buffer;
 
-       if (verify_headers(buffer, size, &commit->object, error_func))
+       if (verify_headers(buffer, size, &commit->object, options))
                return -1;
 
        if (!skip_prefix(buffer, "tree ", &buffer))
-               return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'tree' line");
-       if (get_sha1_hex(buffer, tree_sha1) || buffer[40] != '\n')
-               return error_func(&commit->object, FSCK_ERROR, "invalid 'tree' line format - bad sha1");
+               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')
-                       return error_func(&commit->object, FSCK_ERROR, "invalid 'parent' line format - bad sha1");
+               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);
+       graft = lookup_commit_graft(commit->object.oid.hash);
        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)
-                       return error_func(&commit->object, FSCK_ERROR, "graft objects missing");
+               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)
-                       return error_func(&commit->object, FSCK_ERROR, "parent objects missing");
+               if (parent_count != parent_line_count) {
+                       err = report(options, &commit->object, FSCK_MSG_MISSING_PARENT, "parent objects missing");
+                       if (err)
+                               return err;
+               }
        }
-       if (!skip_prefix(buffer, "author ", &buffer))
-               return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'author' line");
-       err = fsck_ident(&buffer, &commit->object, error_func);
+       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 error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'committer' line");
-       err = fsck_ident(&buffer, &commit->object, error_func);
+               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 error_func(&commit->object, FSCK_ERROR, "could not load commit's tree %s", sha1_to_hex(tree_sha1));
-
+       if (!commit->tree) {
+               err = report(options, &commit->object, FSCK_MSG_BAD_TREE, "could not load commit's tree %s", sha1_to_hex(tree_sha1));
+               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, fsck_error error_func)
+       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, error_func);
+       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, fsck_error error_func)
+       unsigned long size, struct fsck_options *options)
 {
        unsigned char sha1[20];
        int ret = 0;
@@ -383,67 +707,78 @@ static int fsck_tag_buffer(struct tag *tag, const char *data,
                enum object_type type;
 
                buffer = to_free =
-                       read_sha1_file(tag->object.sha1, &type, &size);
+                       read_sha1_file(tag->object.oid.hash, &type, &size);
                if (!buffer)
-                       return error_func(&tag->object, FSCK_ERROR,
+                       return report(options, &tag->object,
+                               FSCK_MSG_MISSING_TAG_OBJECT,
                                "cannot read tag object");
 
                if (type != OBJ_TAG) {
-                       ret = error_func(&tag->object, FSCK_ERROR,
+                       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, error_func))
+       ret = verify_headers(buffer, size, &tag->object, options);
+       if (ret)
                goto done;
 
        if (!skip_prefix(buffer, "object ", &buffer)) {
-               ret = error_func(&tag->object, FSCK_ERROR, "invalid format - expected 'object' line");
+               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 = error_func(&tag->object, FSCK_ERROR, "invalid 'object' line format - bad sha1");
-               goto done;
+               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 = error_func(&tag->object, FSCK_ERROR, "invalid format - expected 'type' line");
+               ret = report(options, &tag->object, FSCK_MSG_MISSING_TYPE_ENTRY, "invalid format - expected 'type' line");
                goto done;
        }
        eol = strchr(buffer, '\n');
        if (!eol) {
-               ret = error_func(&tag->object, FSCK_ERROR, "invalid format - unexpected end after 'type' line");
+               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 = error_func(&tag->object, FSCK_ERROR, "invalid 'type' value");
+               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 = error_func(&tag->object, FSCK_ERROR, "invalid format - expected 'tag' line");
+               ret = report(options, &tag->object, FSCK_MSG_MISSING_TAG_ENTRY, "invalid format - expected 'tag' line");
                goto done;
        }
        eol = strchr(buffer, '\n');
        if (!eol) {
-               ret = error_func(&tag->object, FSCK_ERROR, "invalid format - unexpected end after 'type' line");
+               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))
-               error_func(&tag->object, FSCK_WARN, "invalid 'tag' name: %.*s",
+       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))
+       if (!skip_prefix(buffer, "tagger ", &buffer)) {
                /* early tags do not contain 'tagger' lines; warn only */
-               error_func(&tag->object, FSCK_WARN, "invalid format - expected 'tagger' line");
+               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, error_func);
+               ret = fsck_ident(&buffer, &tag->object, options);
 
 done:
        strbuf_release(&sb);
@@ -452,49 +787,43 @@ static int fsck_tag_buffer(struct tag *tag, const char *data,
 }
 
 static int fsck_tag(struct tag *tag, const char *data,
-       unsigned long size, fsck_error error_func)
+       unsigned long size, struct fsck_options *options)
 {
        struct object *tagged = tag->tagged;
 
        if (!tagged)
-               return error_func(&tag->object, FSCK_ERROR, "could not load tagged object");
+               return report(options, &tag->object, FSCK_MSG_BAD_TAG_OBJECT, "could not load tagged object");
 
-       return fsck_tag_buffer(tag, data, size, error_func);
+       return fsck_tag_buffer(tag, data, size, options);
 }
 
 int fsck_object(struct object *obj, void *data, unsigned long size,
-       int strict, fsck_error error_func)
+       struct fsck_options *options)
 {
        if (!obj)
-               return error_func(obj, FSCK_ERROR, "no valid object to fsck");
+               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, strict, error_func);
+               return fsck_tree((struct tree *) obj, options);
        if (obj->type == OBJ_COMMIT)
                return fsck_commit((struct commit *) obj, (const char *) data,
-                       size, error_func);
+                       size, options);
        if (obj->type == OBJ_TAG)
                return fsck_tag((struct tag *) obj, (const char *) data,
-                       size, error_func);
+                       size, options);
 
-       return error_func(obj, FSCK_ERROR, "unknown type '%d' (internal fsck error)",
+       return report(options, obj, FSCK_MSG_UNKNOWN_TYPE, "unknown type '%d' (internal fsck error)",
                          obj->type);
 }
 
-int fsck_error_function(struct object *obj, int type, const char *fmt, ...)
+int fsck_error_function(struct object *obj, int msg_type, const char *message)
 {
-       va_list ap;
-       struct strbuf sb = STRBUF_INIT;
-
-       strbuf_addf(&sb, "object %s:", sha1_to_hex(obj->sha1));
-
-       va_start(ap, fmt);
-       strbuf_vaddf(&sb, fmt, ap);
-       va_end(ap);
-
-       error("%s", sb.buf);
-       strbuf_release(&sb);
+       if (msg_type == FSCK_WARN) {
+               warning("object %s: %s", oid_to_hex(&obj->oid), message);
+               return 0;
+       }
+       error("object %s: %s", oid_to_hex(&obj->oid), message);
        return 1;
 }