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@xxxxxxxxx> --- I fully admit to not understanding all of this setup code, neither in its current incarnation, nor in terms of an ideal end game. This check seems like a good thing to do though. setup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/setup.c b/setup.c index 27747af7a3..52c3c9d31f 100644 --- a/setup.c +++ b/setup.c @@ -1138,7 +1138,7 @@ 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
