Re: [PATCH 06/15] copy.c: make copy_fd preserve meaningful errno

From: Ronnie Sahlberg <sahlberg@google.com>
Date: Oct 23, 2014, 17:54 UTC
Message-ID: <CAL=YDWkatPumEM7p5Pvh6dxFgO59T-YBbjqS5nWnNpH-azzxBg@mail.gmail.com>
In-Reply-To: <xmqqlho6smi8.fsf@gitster.dls.corp.google.com>

On Thu, Oct 23, 2014 at 10:51 AM, Junio C Hamano <gitster@pobox.com> wrote:

Show 14 quoted lines

> Ronnie Sahlberg <sahlberg@google.com> writes:
>
>> commit 306805ccd147bfdf160b288a8d51fdf9b77ae0fa upstream.
>>
>> Update copy_fd to return a meaningful errno on failure.
>
> These two are good changes, but makes me wonder if more places
> benefit from having error_errno() that does the "save away errno,
> use strerror(errno) to give an error message and restore errno"
> for us.
>
> Not meant as a suggestion for further changes in this series, but as
> a future discussion item.
>

That sounds like a good idea.

As a separate series once these are done, I can volunteer to go through all the errno handling in git and look into that.

Show 35 quoted lines

>>
>> Change-Id: I771f9703acc816902affcf35ff2a56d9426315ac
>> Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
>> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
>> ---
>>  copy.c | 15 ++++++++++-----
>>  1 file changed, 10 insertions(+), 5 deletions(-)
>>
>> diff --git a/copy.c b/copy.c
>> index f2970ec..a8d366e 100644
>> --- a/copy.c
>> +++ b/copy.c
>> @@ -8,12 +8,17 @@ int copy_fd(int ifd, int ofd)
>>               if (!len)
>>                       break;
>>               if (len < 0) {
>> -                     return error("copy-fd: read returned %s",
>> -                                  strerror(errno));
>> +                     int save_errno = errno;
>> +                     error("copy-fd: read returned %s", strerror(errno));
>> +                     errno = save_errno;
>> +                     return -1;
>> +             }
>> +             if (write_in_full(ofd, buffer, len) < 0) {
>> +                     int save_errno = errno;
>> +                     error("copy-fd: write returned %s", strerror(errno));
>> +                     errno = save_errno;
>> +                     return -1;
>>               }
>> -             if (write_in_full(ofd, buffer, len) < 0)
>> -                     return error("copy-fd: write returned %s",
>> -                                  strerror(errno));
>>       }
>>       return 0;
>>  }