[PATCH 2/6] commit: copy saved getenv() result
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git@vger.kernel.org
From
Jeff King
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Date
2019-01-11 22:15:40 UTC
We save the result of $GIT_INDEX_FILE so that we can restore it after
setting it to a new value and running add--interactive. However, the
pointer returned by getenv() is not guaranteed to be valid after calling
setenv(). This _usually_ works fine, but can fail if libc needs to
reallocate the environment block during the setenv().

Let's just duplicate the string, so we know that it remains valid.

In the long run it may be more robust to teach interactive_add() to take
a set of environment variables to pass along to run-command when it
execs add--interactive. And then we would not have to do this
save/restore dance at all. But this is an easy fix in the meantime.

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/commit.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index 004b816635..7d2e0b61e5 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -351,7 +351,7 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 		if (write_locked_index(&the_index, &index_lock, 0))
 			die(_("unable to create temporary index"));
 
-		old_index_env = getenv(INDEX_ENVIRONMENT);
+		old_index_env = xstrdup_or_null(getenv(INDEX_ENVIRONMENT));
 		setenv(INDEX_ENVIRONMENT, get_lock_file_path(&index_lock), 1);
 
 		if (interactive_add(argc, argv, prefix, patch_interactive) != 0)
@@ -361,6 +361,7 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 			setenv(INDEX_ENVIRONMENT, old_index_env, 1);
 		else
 			unsetenv(INDEX_ENVIRONMENT);
+		FREE_AND_NULL(old_index_env);
 
 		discard_cache();
 		read_cache_from(get_lock_file_path(&index_lock));
-- 
2.20.1.651.g2d41a78c67