Re: [GSoC][PATCH 08/13] submodule: port submodule subcommand 'summary' from shell to C

[Prathamesh Chavan <pc44800@gmail.com>]

On Tue, Aug 1, 2017 at 4:57 AM, Christian Couder
<christian.couder@gmail.com> wrote:
> On Mon, Jul 31, 2017 at 10:56 PM, Prathamesh Chavan <pc44800@gmail.com> wrote:
>
>> * variable head was no longer used in module_summary() and instead the strbuf
>>   was utilized.
>
> Good but there might be a few problems in the way it is used. See below.
>
>> +static int compute_summary_module_list(char *head, struct summary_cb *info)
>> +{
>> +       struct argv_array diff_args = ARGV_ARRAY_INIT;
>> +       struct rev_info rev;
>> +       struct module_cb_list list = MODULE_CB_LIST_INIT;
>> +
>> +       argv_array_push(&diff_args, info->diff_cmd);
>> +       if (info->cached)
>> +               argv_array_push(&diff_args, "--cached");
>> +       argv_array_pushl(&diff_args, "--ignore-submodules=dirty", "--raw",
>> +                        NULL);
>> +       if (head)
>> +               argv_array_push(&diff_args, head);
>> +       argv_array_push(&diff_args, "--");
>> +       if (info->argc)
>> +               argv_array_pushv(&diff_args, info->argv);
>> +
>> +       git_config(git_diff_basic_config, NULL);
>> +       init_revisions(&rev, info->prefix);
>> +       gitmodules_config();
>> +       rev.abbrev = 0;
>> +       precompose_argv(diff_args.argc, diff_args.argv);
>> +
>> +       diff_args.argc = setup_revisions(diff_args.argc, diff_args.argv,
>> +                                        &rev, NULL);
>> +       rev.diffopt.output_format = DIFF_FORMAT_NO_OUTPUT | DIFF_FORMAT_CALLBACK;
>> +       rev.diffopt.format_callback = submodule_summary_callback;
>> +       rev.diffopt.format_callback_data = &list;
>> +
>> +       if (!info->cached) {
>> +               if (!strcmp(info->diff_cmd, "diff-index"))
>> +                       setup_work_tree();
>> +               if (read_cache_preload(&rev.diffopt.pathspec) < 0) {
>> +                       perror("read_cache_preload");
>> +                       return -1;
>> +               }
>> +       } else if (read_cache() < 0) {
>> +               perror("read_cache");
>> +               return -1;
>> +       }
>> +
>> +       if (!strcmp(info->diff_cmd, "diff-index"))
>> +               run_diff_index(&rev, info->cached);
>> +       else
>> +               run_diff_files(&rev, 0);
>> +       prepare_submodule_summary(info, &list);
>> +
>> +       free(head);
>
> It is a bit strange to have this function free() an argument it is passed.
>
>> +       return 0;
>> +
>
> Spurious new line.
>
>> +}
>> +
>> +static int module_summary(int argc, const char **argv, const char *prefix)
>> +{
>> +       struct summary_cb info = SUMMARY_CB_INIT;
>> +       int cached = 0;
>> +       char *diff_cmd = "diff-index";
>> +       int for_status = 0;
>> +       int quiet = 0;
>> +       int files = 0;
>> +       int summary_limits = -1;
>> +       struct child_process cp_rev = CHILD_PROCESS_INIT;
>> +       struct strbuf sb = STRBUF_INIT;
>
> [...]
>
>> +       if (!capture_command(&cp_rev, &sb, 0)) {
>> +               strbuf_strip_suffix(&sb, "\n");
>> +               if (argc) {
>> +                       argv++;
>> +                       argc--;
>> +               }
>> +       } else if (!argc || !strcmp(argv[0], "HEAD")) {
>> +               /* before the first commit: compare with an empty tree */
>> +               struct stat st;
>> +               struct object_id oid;
>> +               if (fstat(0, &st) < 0 || index_fd(oid.hash, 0, &st, 2, prefix, 3))
>> +                       die("Unable to add %s to database", oid.hash);
>> +               strbuf_addstr(&sb, oid_to_hex(&oid));
>> +               if (argc) {
>> +                       argv++;
>> +                       argc--;
>> +               }
>> +       } else {
>> +               strbuf_addstr(&sb, "HEAD");
>> +       }
>> +
>> +       if (files) {
>> +               if (cached)
>> +                       die(_("The --cached option cannot be used with the --files option"));
>> +               diff_cmd = "diff-files";
>> +
>> +               strbuf_reset(&sb);
>
> strbuf_reset() does not free the memory allocated to sb.buf...
>
>> +               sb.buf = NULL;
>
> ...then this makes sure that the memory previously allocated to sb.buf
> will not be free()d.
>
> Maybe instead of the above 2 lines just: strbuf_release(&sb)
> Or maybe just don't set sb.buf to NULL.
>
>> +       }
>> +
>> +       info.argc = argc;
>> +       info.argv = argv;
>> +       info.prefix = prefix;
>> +       info.cached = !!cached;
>> +       info.for_status = !!for_status;
>> +       info.quiet = quiet;
>> +       info.files = files;
>> +       info.summary_limits = summary_limits;
>> +       info.diff_cmd = diff_cmd;
>> +
>> +       return compute_summary_module_list(strbuf_detach(&sb, NULL), &info);
>
> Maybe you could pass: "sb.len > 0 ? strbuf_detach(&sb, NULL) : NULL"
> This way if sb has previously been released or reset, NULL will be passed.
>
> I would suggest though to just pass sb.buf and to strbuf_release(&sb)
> after calling compute_summary_module_list() and before returning from
> module_summary() instead of having compute_summary_module_list() free
> its first argument.
> If you do that then compute_summary_module_list() should be changed so
> that when it is passed "" it will behave in the same way as when it is
> passed NULL.
>
We can avoid it to behave same for "" and NULL, by checking if diff_cmd
is "cmd_diff_files", since its value is set NULL by this case.

ret = compute_summary_module_list(strcmp(diff_cmd, "diff-files") ?
NULL: sb.buf, &info);
strbuf_release(&sb);

instead of:
ret = compute_summary_module_list(sb.len ? sb.buf : NULL, &info);
if (sb.len)
strbuf_release(&sb);

>> +}