Re: [PATCH v2 1/3] am: add --show-current-patch

> On Fri, Feb 2, 2018 at 4:25 AM, Duy Nguyen <pclouds@gmail.com> wrote:
>> On Wed, Jan 31, 2018 at 02:59:32PM -0800, Junio C Hamano wrote:
>>> Eric Sunshine <sunshine@sunshineco.com> writes:
>>> > On Wed, Jan 31, 2018 at 4:30 AM, Nguyễn Thái Ngọc Duy <pclouds@gmail.com> wrote:
>>> >> +       len = strbuf_read_file(&sb, am_path(state, msgnum(state)), 0);
>>> >> +       if (len < 0)
>>> >> +               die_errno(_("failed to read '%s'"),
>>> >> +                         am_path(state, msgnum(state)));
>>> >
>>> > Isn't this am_path() invocation inside die_errno() likely to clobber
>>> > the 'errno' from strbuf_read_file() which you want to be reporting?
>>> True.
>>
>> Thanks both. Good catch. Of course I will fix this in the re-roll, but
>> should we also do something for the current code base with the
>> following patch?
>>
>> -       die_errno(_("could not read '%s'"), am_path(state, file));
>> +       saved_errno = errno;
>> +       path = am_path(state, file);
>> +       errno = saved_errno;
>> +       die_errno(_("could not read '%s'"), path);
>
> Rather than worrying about catching these at review time, I had been
> thinking about a solution which automates it using variadic macros.
> Something like:
>
>     #define die_errno(...) do { \
>         int saved_errno_ = errno; \
>         die_errno_(saved_errno_, __VA_ARGS__); \
>         } while (0);