Copy resolve_ref() return value for longer use
resolve_ref() may return a pointer to a static buffer. Callers that
use this value longer than a couple of statements should copy the
value to avoid some hidden resolve_ref() call that may change the
static buffer's value.
The bug found by Tony Wang <wwwjfy@gmail.com> in builtin/merge.c
demonstrates this. The first call is in cmd_merge()
branch = resolve_ref("HEAD", head_sha1, 0, &flag);
Then deep in lookup_commit_or_die() a few lines after, resolve_ref()
may be called again and destroy "branch".
lookup_commit_or_die
lookup_commit_reference
lookup_commit_reference_gently
parse_object
lookup_replace_object
do_lookup_replace_object
prepare_replace_object
for_each_replace_ref
do_for_each_ref
get_loose_refs
get_ref_dir
get_ref_dir
resolve_ref
All call sites are checked and made sure that xstrdup() is called if
the value should be saved.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/commit.c b/builtin/commit.c
index c46f2d1..f3a6ed2 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1259,7 +1259,7 @@
struct commit *commit;
struct strbuf format = STRBUF_INIT;
unsigned char junk_sha1[20];
- const char *head = resolve_ref("HEAD", junk_sha1, 0, NULL);
+ const char *head;
struct pretty_print_context pctx = {0};
struct strbuf author_ident = STRBUF_INIT;
struct strbuf committer_ident = STRBUF_INIT;
@@ -1304,6 +1304,7 @@
rev.diffopt.break_opt = 0;
diff_setup_done(&rev.diffopt);
+ head = resolve_ref("HEAD", junk_sha1, 0, NULL);
printf("[%s%s ",
!prefixcmp(head, "refs/heads/") ?
head + 11 :
