Re: [PATCH 2/3] tag: die when listing missing or corrupt objects

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 6, 2012, 18:13 UTC
Message-ID: <7vty337rug.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20120206083832.GA9425@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

> OK, that's easy enough to do. Should we show lightweight tags to commits
> for backwards compatibility (and just drop the parse_signature junk in
> that case)? The showing of blobs or trees is the really bad thing, I
> think.

For now, dropping 3/3 and queuing this instead...

---
Subject: tag: do not show non-tag contents with "-n"

"git tag -n" did not check the type of the object it is reading the top n lines from. At least, avoid showing the beginning of trees and blobs when dealing with lightweight tags that point at them.

As the payload of a tag and a commit look similar in that they both start with a header block, which is skipped for the purpose of "-n" output, followed by human readable text, allow the message of commit objects to be shown just like the contents of tag objects. This avoids regression for people who have been using "tag -n" to show the log messages of commits that are pointed at by lightweight tags.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/tag.c |   22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/builtin/tag.c b/builtin/tag.c
index 1e27f5c..6d6ae88 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -95,19 +95,20 @@ static void show_tag_lines(const unsigned char *sha1, int lines)
 	buf = read_sha1_file(sha1, &type, &size);
 	if (!buf)
 		die_errno("unable to read object %s", sha1_to_hex(sha1));
-	if (!size) {
-		free(buf);
-		return;
-	}
+	if (type != OBJ_COMMIT || type != OBJ_TAG)
+		goto free_return;
+	if (!size)
+		die("an empty %s object %s?",
+		    typename(type), sha1_to_hex(sha1));
 
 	/* skip header */
 	sp = strstr(buf, "\n\n");
-	if (!sp) {
-		free(buf);
-		return;
-	}
-	/* only take up to "lines" lines, and strip the signature */
-	size = parse_signature(buf, size);
+	if (!sp)
+		goto free_return;
+
+	/* only take up to "lines" lines, and strip the signature from a tag */
+	if (type == OBJ_TAG)
+		size = parse_signature(buf, size);
 	for (i = 0, sp += 2; i < lines && sp < buf + size; i++) {
 		if (i)
 			printf("\n    ");
@@ -118,6 +119,7 @@ static void show_tag_lines(const unsigned char *sha1, int lines)
 			break;
 		sp = eol + 1;
 	}
+free_return:
 	free(buf);
 }