From: Kirill Smelkov <kirr@mns.spb.ru>
Date: Thu, 11 Nov 2010 18:08:23 +0000 (+0300)
Subject: setup: make sure git_dir path is in a permanent buffer, getenv(3) case
X-Git-Tag: v1.7.3.4~19^2
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=15431ca651050ba315fa4e2e74527f6d115e706c;p=git.git

setup: make sure git_dir path is in a permanent buffer, getenv(3) case

getenv(3) returns not-permanent buffer which may be changed by e.g.
putenv(3) call (*).

In practice I've noticed this when trying to do `git commit -m abc`
inside msysgit under wine, getting

    $ git commit -m abc
    fatal: could not open 'DIR=.git/COMMIT_EDITMSG': No such file or directory
                           ^^^^
    (notice introduced 'DIR=' artifact.)

The problem was showing itself only with -m option, and actually, as
debugging showed, originally

    git_dir = getenv("GIT_DIR")

returned pointer to

        "GIT_DIR=.git\0"
                 ^
               git_dir

, we stored it in git_dir, than, after processing -m git-commit option,
we did setenv("GIT_EDITOR", ":") which as (*) says changed environment
variables memory layout - something like this

       "...\0GIT_DIR=.git\0"
                 ^
               git_dir

and oops - we got wrong git_dir.

Avoid that by strdupping getenv("GIT_DIR") result like we did in 06f354
(setup: make sure git dir path is in a permanent buffer). Unfortunately
this also shows that other getenv usage inside git needs auditing...

(*) from man 3 getenv:

       The implementation of getenv() is not required to  be  reentrant.   The
       string  pointed  to  by  the return value of getenv() may be statically
       allocated, and can be  modified  by  a  subsequent  call  to  getenv(),
       putenv(3), setenv(3), or unsetenv(3).

Cc: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

diff --git a/environment.c b/environment.c
index de5581fe5..18aded6dc 100644
--- a/environment.c
+++ b/environment.c
@@ -87,6 +87,7 @@ const char * const local_repo_env[LOCAL_REPO_ENV_SIZE + 1] = {
 static void setup_git_env(void)
 {
 	git_dir = getenv(GIT_DIR_ENVIRONMENT);
+	git_dir = git_dir ? xstrdup(git_dir) : NULL;
 	if (!git_dir) {
 		git_dir = read_gitfile_gently(DEFAULT_GIT_DIR_ENVIRONMENT);
 		git_dir = git_dir ? xstrdup(git_dir) : NULL;