submodule: avoid auto-discovery in prepare_submodule_repo_env()
The function is used to set up the environment variable used in a
subprocess we spawn in a submodule directory. The callers set up a
child_process structure, find the working tree path of one submodule
and set .dir field to it, and then use start_command() API to spawn
the subprocess like "status", "fetch", etc.
When this happens, we expect that the ".git" (either a directory or
a gitfile that points at the real location) in the current working
directory of the subprocess MUST be the repository for the submodule.
If this ".git" thing is a corrupt repository, however, because
prepare_submodule_repo_env() unsets GIT_DIR and GIT_WORK_TREE, the
subprocess will see ".git", thinks it is not a repository, and
attempt to find one by going up, likely to end up in finding the
repository of the superproject. In some codepaths, this will cause
a command run with the "--recurse-submodules" option to recurse
forever.
By exporting GIT_DIR=.git, disable the auto-discovery logic in the
subprocess, which would instead stop it and report an error.
The test illustrates existing problems in a few callsites of this
function. Without this fix, "git fetch --recurse-submodules", "git
status" and "git diff" keep recursing forever.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/submodule.c b/submodule.c
index 4532b11..2801fbb 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1160,4 +1160,5 @@ void prepare_submodule_repo_env(struct argv_array *out)
if (strcmp(*var, CONFIG_DATA_ENVIRONMENT))
argv_array_push(out, *var);
}
+ argv_array_push(out, "GIT_DIR=.git");
}
