fsck.c:fsck_commit(): use skip_prefix() to verify and skip constant

fsck_commit() uses memcmp() to check if the buffer starts with a
certain prefix, and skips the prefix if it does.

This is exactly what skip_prefix() was designed for.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/fsck.c b/fsck.c
index 7776660d53b334d19b853f10cd006e8c75aa196d..6aab23b84502095fef98f9c1b4fa39d586a74085 100644 (file)
--- a/fsck.c
+++ b/fsck.c
@@ -281,7 +281,7 @@ static int fsck_ident(const char **ident, struct object *obj, fsck_error error_f
 
 static int fsck_commit(struct commit *commit, fsck_error error_func)
 {
-       const char *buffer = commit->buffer;
+       const char *buffer = commit->buffer, *tmp;
        unsigned char tree_sha1[20], sha1[20];
        struct commit_graft *graft;
        int parents = 0;
@@ -290,15 +290,17 @@ static int fsck_commit(struct commit *commit, fsck_error error_func)
        if (commit->date == ULONG_MAX)
                return error_func(&commit->object, FSCK_ERROR, "invalid author/committer line");
 
-       if (memcmp(buffer, "tree ", 5))
+       buffer = skip_prefix(buffer, "tree ");
+       if (!buffer)
                return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'tree' line");
-       if (get_sha1_hex(buffer+5, tree_sha1) || buffer[45] != '\n')
+       if (get_sha1_hex(buffer, tree_sha1) || buffer[40] != '\n')
                return error_func(&commit->object, FSCK_ERROR, "invalid 'tree' line format - bad sha1");
-       buffer += 46;
-       while (!memcmp(buffer, "parent ", 7)) {
-               if (get_sha1_hex(buffer+7, sha1) || buffer[47] != '\n')
+       buffer += 41;
+       while ((tmp = skip_prefix(buffer, "parent "))) {
+               buffer = tmp;
+               if (get_sha1_hex(buffer, sha1) || buffer[40] != '\n')
                        return error_func(&commit->object, FSCK_ERROR, "invalid 'parent' line format - bad sha1");
-               buffer += 48;
+               buffer += 41;
                parents++;
        }
        graft = lookup_commit_graft(commit->object.sha1);
@@ -322,15 +324,15 @@ static int fsck_commit(struct commit *commit, fsck_error error_func)
                if (p || parents)
                        return error_func(&commit->object, FSCK_ERROR, "parent objects missing");
        }
-       if (memcmp(buffer, "author ", 7))
+       buffer = skip_prefix(buffer, "author ");
+       if (!buffer)
                return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'author' line");
-       buffer += 7;
        err = fsck_ident(&buffer, &commit->object, error_func);
        if (err)
                return err;
-       if (memcmp(buffer, "committer ", strlen("committer ")))
+       buffer = skip_prefix(buffer, "committer ");
+       if (!buffer)
                return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'committer' line");
-       buffer += strlen("committer ");
        err = fsck_ident(&buffer, &commit->object, error_func);
        if (err)
                return err;