Subject: Re: git error in tag ...: unterminated header

From: Junio C Hamano <[email-masked]>
Date: Fri, 26 Jun 2015 10:37:19 -0700

Jeff King <[email-masked]> writes:

> On Fri, Jun 26, 2015 at 10:06:20AM +0200, Johannes Schindelin wrote:
>
>> I understood what you were saying, but it still appears too fragile to
>> me to mix functions that assume NUL-terminated strings with an ad-hoc
>> counted string check.
>
> Yeah, I agree. It is not that you cannot make it safe, but that it is
> simply a fragile maintenance burden in the future. I thought we dealt
> with this already with a1e920a (index-pack: terminate object buffers
> with NUL, 2014-12-08), though.

Hmph, that is an interesting point.

It would mean that the require_eoh() can be reduced a bit further.

 * It is still a good idea to make sure we do not have NUL in the
   header part,

 * It can still stop scanning when it finds a blank line (i.e. we do
   not care what is in the message part of commit and tag),

 * It does not have to insist that a commit or a tag has a blank
   line to reject a header-only object.

That would mean the name of the helper needs to change, though.

Perhaps like this?

 fsck.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fsck.c b/fsck.c
index 10bcb65..c23e84e 100644
--- a/fsck.c
+++ b/fsck.c
@@ -241,8 +241,8 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func)
 	return retval;
 }
 
-static int require_end_of_header(const void *data, unsigned long size,
-	struct object *obj, fsck_error error_func)
+static int verify_headers(const void *data, unsigned long size,
+			  struct object *obj, fsck_error error_func)
 {
 	const char *buffer = (const char *)data;
 	unsigned long i;
@@ -257,8 +257,13 @@ static int require_end_of_header(const void *data, unsigned long size,
 				return 0;
 		}
 	}
-
-	return error_func(obj, FSCK_ERROR, "unterminated header");
+	/*
+	 * did not find a blank line -- is the last header line
+	 * correctly terminated with LF?
+	 */
+	if (size && buffer[size - 1] != '\n')
+		return error_func(obj, FSCK_ERROR, "unterminated header");
+	return 0;
 }
 
 static int fsck_ident(const char **ident, struct object *obj, fsck_error error_func)