Thread (33 messages) flat view 33 messages, 6 authors, 2016-06-15
STALE3720d

[PATCH 6/6] Add fsck_verify_ref_to_tag_object() to verify that refname matches name stored in tag object

From: Johan Herland <hidden>
Date: 2016-06-15 22:43:14
Subsystem: the rest · Maintainer: Linus Torvalds

On Monday 28 May 2007, Junio C Hamano wrote:
However it would be a good
idea to add logic to fsck to warn upon inconsistencis (perhaps
by mistake) between refname and tag's true name.

The check would say something like:

  If an annotated (signed or unsigned) tag has a "tag"
  line to give it the official $name, and if it is pointed
  at by a ref, the refname must end with "/$name".
  Otherwise we warn.

Trivially, the above rule says that having v2.6.22 tag under
refs/tags/v2.6.20 is a mistake we would want to be warned upon.
This patch adds the check described by Junio.

Signed-off-by: Johan Herland <redacted>
---
 builtin-fsck.c |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
diff --git a/builtin-fsck.c b/builtin-fsck.c
index a8914ae..379317e 100644
--- a/builtin-fsck.c
+++ b/builtin-fsck.c
@@ -515,6 +515,25 @@ static int fsck_handle_reflog(const char *logname, const unsigned char *sha1, in
 	return 0;
 }
 
+static void fsck_verify_ref_to_tag_object(const char *refname, struct object *obj)
+{
+	/* Verify that refname matches the name stored in obj's "tag" header */
+	struct tag *tagobj = (struct tag *) parse_object(obj->sha1);
+	size_t tagname_len = strlen(tagobj->tag);
+	size_t refname_len = strlen(refname);
+
+	if (!tagname_len) return; /* No tag name stored in tagobj. Nothing to do. */
+
+	if (tagname_len < refname_len &&
+	    !memcmp(tagobj->tag, refname + (refname_len - tagname_len), tagname_len) &&
+	    refname[(refname_len - tagname_len) - 1] == '/') {
+		/* OK: tag name is "$name", and refname ends with "/$name" */
+		return;
+	}
+	else
+		error("%s: Mismatch between tag ref and tag object's name %s", refname, tagobj->tag);
+}
+
 static int fsck_handle_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
 {
 	struct object *obj;
@@ -529,6 +548,8 @@ static int fsck_handle_ref(const char *refname, const unsigned char *sha1, int f
 		/* We'll continue with the rest despite the error.. */
 		return 0;
 	}
+	if (obj->type == OBJ_TAG) /* ref to tag object */
+		fsck_verify_ref_to_tag_object(refname, obj);
 	default_refs++;
 	obj->used = 1;
 	mark_reachable(obj, REACHABLE);
-- 
1.5.2
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