Re: [PATCH 24/31] archive-tar: make hash size independent

From: René Scharfe <l.s.r@web.de>
Date: Feb 12, 2019, 17:33 UTC
Message-ID: <2e0ab97b-2a9f-6820-46fa-ba664c42cd87@web.de>
In-Reply-To: <2a6cf99a-c297-225c-b3c9-c30e1ac83948@web.de>

Am 12.02.2019 um 08:20 schrieb René Scharfe:

Show 8 quoted lines

> That command currently prints the pax comment in tar archives if it
> looks like a SHA1 hash based on its length.  It should continue to do
> so, and _also_ show longer hashes.  Your change makes it _only_ show
> those longer hashes.
>
> So it could check for all known valid hash lengths in turn, or accept
> any payload length between 40 and the_hash_algo->hexsz, or loosen up
> totally and show comments of any length.

How about the following patch, as a preparation?

-- >8 --
From: Rene Scharfe <l.s.r@web.de>
Subject: [PATCH] get-tar-commit-id: parse comment record

Parse pax comment records properly and get rid of magic numbers for acceptable comment length. This simplifies a later change to handle longer hashes.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
 builtin/get-tar-commit-id.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
index 2706fcfaf2..312e44ed05 100644
--- a/builtin/get-tar-commit-id.c
+++ b/builtin/get-tar-commit-id.c
@@ -21,6 +21,8 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
 	char *content = buffer + RECORDSIZE;
 	const char *comment;
 	ssize_t n;
+	long len;
+	char *end;

 	if (argc != 1)
 		usage(builtin_get_tar_commit_id_usage);
@@ -32,10 +34,17 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
 		die_errno("git get-tar-commit-id: EOF before reading tar header");
 	if (header->typeflag[0] != 'g')
 		return 1;
-	if (!skip_prefix(content, "52 comment=", &comment))
+
+	len = strtol(content, &end, 10);
+	if (errno == ERANGE || end == content || len < 0)
+		return 1;
+	if (!skip_prefix(end, " comment=", &comment))
+		return 1;
+	len -= comment - content;
+	if (len != GIT_SHA1_HEXSZ + 1)
 		return 1;

-	if (write_in_full(1, comment, 41) < 0)
+	if (write_in_full(1, comment, len) < 0)
 		die_errno("git get-tar-commit-id: write error");

 	return 0;
--
2.20.1