stash: always have the owner of "stash_info" free it

Change the initialization of the "revision" member of "struct
stash_info" to be initialized vi a macro, and more importantly that
that initializing function be tasked to free it, usually via a "goto
cleanup" pattern.

Despite the "revision" name (and the topic of the series containing
this commit) the "stash info" has nothing to do with the "struct
rev_info". I'm making this change because in the subsequent commit
when we do want to free the "struct rev_info" via a "goto cleanup"
pattern we'd otherwise free() uninitialized memory in some cases, as
we only strbuf_init() the string in get_stash_info().

So while it's not the smallest possible change, let's convert all
users of this pattern in the file while we're at it.

A good follow-up to this change would be to change all the "ret = -1;
goto done;" in this file to instead use a "goto cleanup", and
initialize "int ret = -1" at the start of the relevant functions. That
would allow us to drop a lot of needless brace verbosity on two-line
"if" statements, but let's leave that alone for now.

To ensure that there's a 1=1 mapping between owners of the "struct
stash_info" and free_stash_info() change the assert_stash_ref()
function to be a trivial get_stash_info_assert() wrapper. The caller
will call free_stash_info(), and by returning -1 we'll eventually (via
!!ret) exit with status 1 anyway.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/stash.c b/builtin/stash.c
index 8c90db479ce3578a25056c068a27eb716a39c9b9..a96d84a5a97a93a3484f47a3094b7ca2d0c9830f 100644 (file)
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -116,6 +116,10 @@ struct stash_info {
        int has_u;
 };
 
+#define STASH_INFO_INIT { \
+       .revision = STRBUF_INIT, \
+}
+
 static void free_stash_info(struct stash_info *info)
 {
        strbuf_release(&info->revision);
@@ -157,10 +161,8 @@ static int get_stash_info(struct stash_info *info, int argc, const char **argv)
        if (argc == 1)
                commit = argv[0];
 
-       strbuf_init(&info->revision, 0);
        if (!commit) {
                if (!ref_exists(ref_stash)) {
-                       free_stash_info(info);
                        fprintf_ln(stderr, _("No stash entries found."));
                        return -1;
                }
@@ -174,11 +176,8 @@ static int get_stash_info(struct stash_info *info, int argc, const char **argv)
 
        revision = info->revision.buf;
 
-       if (get_oid(revision, &info->w_commit)) {
-               error(_("%s is not a valid reference"), revision);
-               free_stash_info(info);
-               return -1;
-       }
+       if (get_oid(revision, &info->w_commit))
+               return error(_("%s is not a valid reference"), revision);
 
        assert_stash_like(info, revision);
 
@@ -197,7 +196,7 @@ static int get_stash_info(struct stash_info *info, int argc, const char **argv)
                info->is_stash_ref = !strcmp(expanded_ref, ref_stash);
                break;
        default: /* Invalid or ambiguous */
-               free_stash_info(info);
+               break;
        }
 
        free(expanded_ref);
@@ -598,10 +597,10 @@ restore_untracked:
 
 static int apply_stash(int argc, const char **argv, const char *prefix)
 {
-       int ret;
+       int ret = -1;
        int quiet = 0;
        int index = 0;
-       struct stash_info info;
+       struct stash_info info = STASH_INFO_INIT;
        struct option options[] = {
                OPT__QUIET(&quiet, N_("be quiet, only report errors")),
                OPT_BOOL(0, "index", &index,
@@ -613,9 +612,10 @@ static int apply_stash(int argc, const char **argv, const char *prefix)
                             git_stash_apply_usage, 0);
 
        if (get_stash_info(&info, argc, argv))
-               return -1;
+               goto cleanup;
 
        ret = do_apply_stash(prefix, &info, index, quiet);
+cleanup:
        free_stash_info(&info);
        return ret;
 }
@@ -651,20 +651,25 @@ static int do_drop_stash(struct stash_info *info, int quiet)
        return 0;
 }
 
-static void assert_stash_ref(struct stash_info *info)
+static int get_stash_info_assert(struct stash_info *info, int argc,
+                                const char **argv)
 {
-       if (!info->is_stash_ref) {
-               error(_("'%s' is not a stash reference"), info->revision.buf);
-               free_stash_info(info);
-               exit(1);
-       }
+       int ret = get_stash_info(info, argc, argv);
+
+       if (ret < 0)
+               return ret;
+
+       if (!info->is_stash_ref)
+               return error(_("'%s' is not a stash reference"), info->revision.buf);
+
+       return 0;
 }
 
 static int drop_stash(int argc, const char **argv, const char *prefix)
 {
-       int ret;
+       int ret = -1;
        int quiet = 0;
-       struct stash_info info;
+       struct stash_info info = STASH_INFO_INIT;
        struct option options[] = {
                OPT__QUIET(&quiet, N_("be quiet, only report errors")),
                OPT_END()
@@ -673,22 +678,21 @@ static int drop_stash(int argc, const char **argv, const char *prefix)
        argc = parse_options(argc, argv, prefix, options,
                             git_stash_drop_usage, 0);
 
-       if (get_stash_info(&info, argc, argv))
-               return -1;
-
-       assert_stash_ref(&info);
+       if (get_stash_info_assert(&info, argc, argv))
+               goto cleanup;
 
        ret = do_drop_stash(&info, quiet);
+cleanup:
        free_stash_info(&info);
        return ret;
 }
 
 static int pop_stash(int argc, const char **argv, const char *prefix)
 {
-       int ret;
+       int ret = -1;
        int index = 0;
        int quiet = 0;
-       struct stash_info info;
+       struct stash_info info = STASH_INFO_INIT;
        struct option options[] = {
                OPT__QUIET(&quiet, N_("be quiet, only report errors")),
                OPT_BOOL(0, "index", &index,
@@ -699,25 +703,25 @@ static int pop_stash(int argc, const char **argv, const char *prefix)
        argc = parse_options(argc, argv, prefix, options,
                             git_stash_pop_usage, 0);
 
-       if (get_stash_info(&info, argc, argv))
-               return -1;
+       if (get_stash_info_assert(&info, argc, argv))
+               goto cleanup;
 
-       assert_stash_ref(&info);
        if ((ret = do_apply_stash(prefix, &info, index, quiet)))
                printf_ln(_("The stash entry is kept in case "
                            "you need it again."));
        else
                ret = do_drop_stash(&info, quiet);
 
+cleanup:
        free_stash_info(&info);
        return ret;
 }
 
 static int branch_stash(int argc, const char **argv, const char *prefix)
 {
-       int ret;
+       int ret = -1;
        const char *branch = NULL;
-       struct stash_info info;
+       struct stash_info info = STASH_INFO_INIT;
        struct child_process cp = CHILD_PROCESS_INIT;
        struct option options[] = {
                OPT_END()
@@ -734,7 +738,7 @@ static int branch_stash(int argc, const char **argv, const char *prefix)
        branch = argv[0];
 
        if (get_stash_info(&info, argc - 1, argv + 1))
-               return -1;
+               goto cleanup;
 
        cp.git_cmd = 1;
        strvec_pushl(&cp.args, "checkout", "-b", NULL);
@@ -746,8 +750,8 @@ static int branch_stash(int argc, const char **argv, const char *prefix)
        if (!ret && info.is_stash_ref)
                ret = do_drop_stash(&info, 0);
 
+cleanup:
        free_stash_info(&info);
-
        return ret;
 }
 
@@ -825,8 +829,8 @@ static void diff_include_untracked(const struct stash_info *info, struct diff_op
 static int show_stash(int argc, const char **argv, const char *prefix)
 {
        int i;
-       int ret = 0;
-       struct stash_info info;
+       int ret = -1;
+       struct stash_info info = STASH_INFO_INIT;
        struct rev_info rev;
        struct strvec stash_args = STRVEC_INIT;
        struct strvec revision_args = STRVEC_INIT;
@@ -844,6 +848,7 @@ static int show_stash(int argc, const char **argv, const char *prefix)
                              UNTRACKED_ONLY, PARSE_OPT_NONEG),
                OPT_END()
        };
+       int do_usage = 0;
 
        init_diff_ui_defaults();
        git_config(git_diff_ui_config, NULL);
@@ -861,10 +866,8 @@ static int show_stash(int argc, const char **argv, const char *prefix)
                        strvec_push(&revision_args, argv[i]);
        }
 
-       ret = get_stash_info(&info, stash_args.nr, stash_args.v);
-       strvec_clear(&stash_args);
-       if (ret)
-               return -1;
+       if (get_stash_info(&info, stash_args.nr, stash_args.v))
+               goto cleanup;
 
        /*
         * The config settings are applied only if there are not passed
@@ -878,16 +881,14 @@ static int show_stash(int argc, const char **argv, const char *prefix)
                        rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
 
                if (!show_stat && !show_patch) {
-                       free_stash_info(&info);
-                       return 0;
+                       ret = 0;
+                       goto cleanup;
                }
        }
 
        argc = setup_revisions(revision_args.nr, revision_args.v, &rev, NULL);
-       if (argc > 1) {
-               free_stash_info(&info);
-               usage_with_options(git_stash_show_usage, options);
-       }
+       if (argc > 1)
+               goto usage;
        if (!rev.diffopt.output_format) {
                rev.diffopt.output_format = DIFF_FORMAT_PATCH;
                diff_setup_done(&rev.diffopt);
@@ -912,8 +913,16 @@ static int show_stash(int argc, const char **argv, const char *prefix)
        }
        log_tree_diff_flush(&rev);
 
+       ret = diff_result_code(&rev.diffopt, 0);
+cleanup:
+       strvec_clear(&stash_args);
        free_stash_info(&info);
-       return diff_result_code(&rev.diffopt, 0);
+       if (do_usage)
+               usage_with_options(git_stash_show_usage, options);
+       return ret;
+usage:
+       do_usage = 1;
+       goto cleanup;
 }
 
 static int do_store_stash(const struct object_id *w_commit, const char *stash_msg,
@@ -1409,9 +1418,9 @@ done:
 
 static int create_stash(int argc, const char **argv, const char *prefix)
 {
-       int ret = 0;
+       int ret;
        struct strbuf stash_msg_buf = STRBUF_INIT;
-       struct stash_info info;
+       struct stash_info info = STASH_INFO_INIT;
        struct pathspec ps;
 
        /* Starting with argv[1], since argv[0] is "create" */
@@ -1426,6 +1435,7 @@ static int create_stash(int argc, const char **argv, const char *prefix)
        if (!ret)
                printf_ln("%s", oid_to_hex(&info.w_commit));
 
+       free_stash_info(&info);
        strbuf_release(&stash_msg_buf);
        return ret;
 }
@@ -1434,7 +1444,7 @@ static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int q
                         int keep_index, int patch_mode, int include_untracked, int only_staged)
 {
        int ret = 0;
-       struct stash_info info;
+       struct stash_info info = STASH_INFO_INIT;
        struct strbuf patch = STRBUF_INIT;
        struct strbuf stash_msg_buf = STRBUF_INIT;
        struct strbuf untracked_files = STRBUF_INIT;
@@ -1632,6 +1642,7 @@ static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int q
        }
 
 done:
+       free_stash_info(&info);
        strbuf_release(&stash_msg_buf);
        return ret;
 }