Re: [PATCH] git.c: fix help.autocorrect after 57ea712 breaks it

[Junio C Hamano <gitster@pobox.com>]

Junio C Hamano <gitster@pobox.com> writes:

> I spoke too soon, I am afraid.
> ...
> I wonder if this would be better done as a multi-part series that
> goes like this:
> ...

So here is the first of the three-patch series to replace it.

-- >8 --
From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 26 Jan 2016 11:46:53 -0800
Subject: [PATCH 1/3] git: remove an early return from save_env_before_alias()

When help.autocorrect is in effect, an attempt to auto-execute an
uniquely corrected result of a misspelled alias will result in an
irrelevant error message.  The codepath that causes this issue calls
save_env_before_alias() and restore_env() as a pair in handle_alias(),
and that happens twice.  A global variable orig_cwd is allocated and
holds the return value of getcwd() in save_env_before_alias(), which
is used in restore_env() to go back to that directory and freed.

However, save_env_before_alias() is not prepared to be called twice.
It returns early when it knows it has already been called, leaving
orig_cwd undefined, which is then checked in the second call to
restore_env(), and by that time, the memory that used to hold the
contents of orig_cwd is either freed or reused to hold something else,
and this is fed to chdir(), causing it to fail.

Fix this by making sure save_env() does do the saving when called.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 git.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/git.c b/git.c
index 98d4412..a57a4cb 100644
--- a/git.c
+++ b/git.c
@@ -30,8 +30,6 @@ static int saved_env_before_alias;
 static void save_env_before_alias(void)
 {
 	int i;
-	if (saved_env_before_alias)
-		return;
 	saved_env_before_alias = 1;
 	orig_cwd = xgetcwd();
 	for (i = 0; i < ARRAY_SIZE(env_names); i++) {
-- 
2.7.0-366-g065efda