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From: Martin Ågren <martin.agren@gmail.com>
To: git@vger.kernel.org
Cc: Jeff King <peff@peff.net>,
	"brian m . carlson" <sandals@crustytoothpaste.net>
Subject: [PATCH v2 2/3] setup: do not use invalid `repository_format`
Date: Mon, 14 Jan 2019 19:34:56 +0100
Message-ID: <a7e58385290e6789105d2d5b794f4bf8607285dd.1547488709.git.martin.agren@gmail.com> (raw)
In-Reply-To: <cover.1547488709.git.martin.agren@gmail.com>

If `read_repository_format()` encounters an error, `format->version`
will be -1 and all other fields of `format` will be undefined. However,
in `setup_git_directory_gently()`, we use `repo_fmt.hash_algo`
regardless of the value of `repo_fmt.version`.

This can be observed by adding this to the end of
`read_repository_format()`:

	if (format->version == -1)
		format->hash_algo = 0; /* no-one should peek at this! */

This causes, e.g., "git branch -m q q2 without config should succeed" in
t3200 to fail with "fatal: Failed to resolve HEAD as a valid ref."
because it has moved .git/config out of the way and is now trying to use
a bad hash algorithm.

Check that `version` is non-negative before using `hash_algo`.

This patch adds no tests, but do note that if we skip this patch, the
next patch would cause existing tests to fail as outlined above.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
 setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup.c b/setup.c
index bb633942bb..4d3d67c50b 100644
--- a/setup.c
+++ b/setup.c
@@ -1140,7 +1140,7 @@ const char *setup_git_directory_gently(int *nongit_ok)
 				gitdir = DEFAULT_GIT_DIR_ENVIRONMENT;
 			setup_git_env(gitdir);
 		}
-		if (startup_info->have_repository)
+		if (startup_info->have_repository && repo_fmt.version > -1)
 			repo_set_hash_algo(the_repository, repo_fmt.hash_algo);
 	}
 
-- 
2.20.1


  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-18  7:25 [PATCH 0/3] setup: add `clear_repository_format()` Martin Ågren
2018-12-18  7:25 ` [PATCH 1/3] setup: drop return value from `read_repository_format()` Martin Ågren
2018-12-19 15:27   ` Jeff King
2018-12-19 21:42     ` Martin Ågren
2018-12-20  0:17     ` brian m. carlson
2018-12-20  2:52       ` Jeff King
2018-12-20  3:45         ` brian m. carlson
2018-12-20 14:53           ` Jeff King
2018-12-18  7:25 ` [PATCH 2/3] setup: do not use invalid `repository_format` Martin Ågren
2018-12-19  0:18   ` brian m. carlson
2018-12-19 21:43     ` Martin Ågren
2018-12-19 15:38   ` Jeff King
2018-12-19 21:46     ` Martin Ågren
2018-12-19 23:17       ` Jeff King
2018-12-20  0:21     ` brian m. carlson
2018-12-18  7:25 ` [PATCH 3/3] setup: add `clear_repository_format()` Martin Ågren
2018-12-19 15:48   ` Jeff King
2018-12-19 21:49     ` Martin Ågren
2019-01-14 18:34 ` [PATCH v2 0/3] " Martin Ågren
2019-01-14 18:34   ` [PATCH v2 1/3] setup: free old value before setting `work_tree` Martin Ågren
2019-01-14 18:34   ` Martin Ågren [this message]
2019-01-15 19:31     ` [PATCH v2 2/3] setup: do not use invalid `repository_format` Jeff King
2019-01-17  6:31       ` Martin Ågren
2019-01-14 18:34   ` [PATCH v2 3/3] setup: add `clear_repository_format()` Martin Ågren

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