show-branch: fix segfault when showbranch.default exists

When running "git show-branch" without any parameter in a repository that has showbranch.default defined, we used to rely on the fact that our handcrafted option parsing loop never looked at av[0]. The array of default strings had the first real command line argument in default_arg[0], but the option parser wanted to look at the array starting at av[1], so we assigned the address of -1th element to av to force the loop start working from default_arg[0]. This no longer worked since 5734365 (show-branch: migrate to parse-options API, 2009-05-21), as parse_options_start() saved the incoming &av[0] in its ctx->out and later in parse_options_end() it did memmove to ctx->out (with ctx->cpidx == 0), overwriting the memory before default_arg[] array. I am not sure if this is a bug in parse_options(), or a bug in the caller, and tonight I do not have enough concentration to figure out which. In any case, this patch works the issue around. Signed-off-by: Junio C Hamano <gitster@pobox.com>

Junio C Hamano committed Jun 8, 2009 at 23:26 UTC 3af1cae469555485cd3ef003aa2a55bd2a4f544f

2 files changed +19 -3

builtin-show-branch.c

+11 -3

@@ -565,7 +565,15 @@ static int git_show_branch_config(const char *var, const char *value, void *cb)

565 if (!strcmp(var, "showbranch.default")) {

566 if (!value)

567 return config_error_nonbool(var);

568 - if (default_alloc <= default_num + 1) {

568 + /*

569 + * default_arg is now passed to parse_options(), so we need to

570 + * mimick the real argv a bit better.

571 + */

572 + if (!default_num) {

573 + default_alloc = 20;

574 + default_arg = xcalloc(default_alloc, sizeof(*default_arg));

575 + default_arg[default_num++] = "show-branch";

576 + } else if (default_alloc <= default_num + 1) {

577 default_alloc = default_alloc * 3 / 2 + 20;

578 default_arg = xrealloc(default_arg, sizeof *default_arg * default_alloc);

579 }

@@ -693,8 +701,8 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)

701

702 /* If nothing is specified, try the default first */

703 if (ac == 1 && default_num) {

696 - ac = default_num + 1;

697 - av = default_arg - 1; /* ick; we would not address av[0] */

704 + ac = default_num;

705 + av = default_arg;

706 }

707

708 ac = parse_options(ac, av, builtin_show_branch_options,

t/t3202-show-branch-octopus.sh

@@ -56,4 +56,12 @@ test_expect_success 'show-branch with more than 8 branches' '

57 '

59 +test_expect_success 'show-branch with showbranch.default' '

60 + for i in $numbers; do

61 + git config --add showbranch.default branch$i

62 + done &&

63 + git show-branch >out &&

64 + test_cmp expect out

65 +'

66 +

67 test_done