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Copy resolve_ref() return value for longer use

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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>
This commit is contained in:
Nguyễn Thái Ngọc Duy
2011-11-13 17:22:15 +07:00
committed by Junio C Hamano
parent c689332391
commit d5a35c114a
8 changed files with 66 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
builtin/commit.c
View File

@@ -1259,7 +1259,7 @@ static void print_summary(const char *prefix, const unsigned char *sha1,
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 @@ static void print_summary(const char *prefix, const unsigned char *sha1,
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 :