From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 29 Jan 2019 20:47:51 +0000 (-0800)
Subject: Merge branch 'kg/external-diff-save-env'
X-Git-Tag: v2.21.0-rc0~75
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/6a015cecbe662b00c8ac697b95d966def569f4e7?hp=16a465bc018d09e9d7bbbdc5f40a7fb99c21f8ef

Merge branch 'kg/external-diff-save-env'

The code to drive GIT_EXTERNAL_DIFF command relied on the string
returned from getenv() to be non-volatile, which is not true, that
has been corrected.

* kg/external-diff-save-env:
diff: ensure correct lifetime of external_diff_cmd
---

diff --git a/diff.c b/diff.c
index 1b5f276360..b96b7a4fc6 100644
--- a/diff.c
+++ b/diff.c
@@ -493,7 +493,7 @@ static const char *external_diff(void)
 
 	if (done_preparing)
 		return external_diff_cmd;
-	external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
+	external_diff_cmd = xstrdup_or_null(getenv("GIT_EXTERNAL_DIFF"));
 	if (!external_diff_cmd)
 		external_diff_cmd = external_diff_cmd_cfg;
 	done_preparing = 1;