Re: [PATCH v2 5/6] bisect--helper: `is_expected_rev` & `check_expected_revs` shell function in C

[Christian Couder <christian.couder@gmail.com>]

On Thu, Jun 16, 2016 at 9:25 PM, Pranit Bauva <pranit.bauva@gmail.com> wrote:
> Hey Eric,
>
> On Fri, Jun 17, 2016 at 12:46 AM, Eric Sunshine <sunshine@sunshineco.com> wrote:
>> On Thu, Jun 16, 2016 at 3:05 PM, Pranit Bauva <pranit.bauva@gmail.com> wrote:
>>> On Thu, Jun 16, 2016 at 2:44 AM, Eric Sunshine <sunshine@sunshineco.com> wrote:
>>>> On Wed, Jun 15, 2016 at 10:00 AM, Pranit Bauva <pranit.bauva@gmail.com> wrote:
>>>>> Reimplement `is_expected_rev` & `check_expected_revs` shell function in
>>>>> C and add a `--check-expected-revs` subcommand to `git bisect--helper` to
>>>>> call it from git-bisect.sh .
>>>>> [...]
>>>>> Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
>>>>> ---
>>>>> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
>>>>> @@ -162,13 +162,44 @@ static int bisect_reset(const char *commit)
>>>>> +static int is_expected_rev(const char *expected_hex)
>>>>> +{
>>>>> +       struct strbuf actual_hex = STRBUF_INIT;
>>>>> +       int res;
>>>>> +
>>>>> +       if (strbuf_read_file(&actual_hex, git_path_bisect_expected_rev(), 0) < 0) {
>>>>> +               strbuf_release(&actual_hex);
>>>>> +               return 0;
>>>>> +       }
>>>>> +
>>>>> +       strbuf_trim(&actual_hex);
>>>>> +       res = !strcmp(actual_hex.buf, expected_hex);
>>>>> +       strbuf_release(&actual_hex);
>>>>> +       return res;
>>>>> +}
>>>>
>>>> Not worth a re-roll, but this could be re-structured to avoid having
>>>> to remember to release the strbuf at all exits:
>>>>
>>>>     struct strbuf actual_hex = ...;
>>>>     int res = 0;
>>>>
>>>>     if (strbuf_read_file(...) >= 0) {
>>>>         strbuf_trim(...);
>>>>         res = !strcmp(...);
>>>>     }
>>>>     strbuf_release(...);
>>>>     return res;
>>>>
>>>> Alternately:
>>>>
>>>>     if (strbuf_read_file(...) < 0)
>>>>         goto done;
>>>>
>>>>     strbuf_trim(...);
>>>>     res = !strcmp(...);
>>>>
>>>> done:
>>>>     strbuf_release(...);
>>>>     return res;
>>>>
>>>> which is a bit less compact.
>>>
>>> I will avoid this for the reason that I will have to create a label
>>> for a lot of functions. If I choose to do this for one function, I
>>> think it would be more appropriate to do the same for other functions.
>>> There would be a lot of functions in future which would be in the same
>>> scenario and creating a separate label for each of them would be quite
>>> tedious. What do you think?
>>
>> Not sure what you're talking about. Label names are not shared across
>> functions. Anyhow, the first suggestion I presented above is more
>> concise than the 'goto' version.
>
> Yes I am aware of the fact that labels aren't shared across functions.
> What I meant by "separate label" was that I will have to make a label
> "fail" in each function. But I recently noticed that its used quite a
> lot so I think it would be okay to use it. Will re-roll with using
> labels and goto.

My opinion is that if there is a more concise version without labels
and gotos, it's better to use it, so I would suggest Eric's first
suggestion which is:

>     struct strbuf actual_hex = ...;
>     int res = 0;
>
>     if (strbuf_read_file(...) >= 0) {
>         strbuf_trim(...);
>         res = !strcmp(...);
>     }
>     strbuf_release(...);
>     return res;

Thanks,
Christian.