[PATCH 5/6] merge-recursive: copy $GITHEAD strings
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git@vger.kernel.org
From
Jeff King
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Date
2019-01-11 22:16:55 UTC
If $GITHEAD_1234abcd is set in the environment, we use its value as a
"better branch name" in generating conflict markers. However, we pick
these better names early in the process, and the return value from
getenv() is not guaranteed to stay valid.

Let's make a copy of the returned string. And to make memory management
easier, let's just always return an allocated string from
better_branch_name(), so we know that it must always be freed.

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/merge-recursive.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/builtin/merge-recursive.c b/builtin/merge-recursive.c
index 9b2f707c29..7545136c2a 100644
--- a/builtin/merge-recursive.c
+++ b/builtin/merge-recursive.c
@@ -7,16 +7,16 @@
 static const char builtin_merge_recursive_usage[] =
 	"git %s <base>... -- <head> <remote> ...";
 
-static const char *better_branch_name(const char *branch)
+static char *better_branch_name(const char *branch)
 {
 	static char githead_env[8 + GIT_MAX_HEXSZ + 1];
 	char *name;
 
 	if (strlen(branch) != the_hash_algo->hexsz)
-		return branch;
+		return xstrdup(branch);
 	xsnprintf(githead_env, sizeof(githead_env), "GITHEAD_%s", branch);
 	name = getenv(githead_env);
-	return name ? name : branch;
+	return xstrdup(name ? name : branch);
 }
 
 int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
@@ -26,6 +26,7 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 	int i, failed;
 	struct object_id h1, h2;
 	struct merge_options o;
+	char *better1, *better2;
 	struct commit *result;
 
 	init_merge_options(&o);
@@ -70,13 +71,17 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 	if (get_oid(o.branch2, &h2))
 		die(_("could not resolve ref '%s'"), o.branch2);
 
-	o.branch1 = better_branch_name(o.branch1);
-	o.branch2 = better_branch_name(o.branch2);
+	o.branch1 = better1 = better_branch_name(o.branch1);
+	o.branch2 = better2 = better_branch_name(o.branch2);
 
 	if (o.verbosity >= 3)
 		printf(_("Merging %s with %s\n"), o.branch1, o.branch2);
 
 	failed = merge_recursive_generic(&o, &h1, &h2, bases_count, bases, &result);
+
+	free(better1);
+	free(better2);
+
 	if (failed < 0)
 		return 128; /* die() error code */
 	return failed;
-- 
2.20.1.651.g2d41a78c67