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

gitster · gitster · commit 6a015cecbe66 · 2019-01-29T12:47:52.000-08:00
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
@@ -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;
