Re: [Qemu-devel] [PATCH 01/14] Introduce qemu_write_full()

[Kirill A. Shutemov]

2009/12/31 malc <address@hidden>:
> On Thu, 31 Dec 2009, Kirill A. Shutemov wrote:
>
>> On Thu, Dec 31, 2009 at 4:00 AM, malc <address@hidden> wrote:
>> > On Thu, 31 Dec 2009, Kirill A. Shutemov wrote:
>> >
>> >> A variant of write(2) which handles partial write.
>> >>
>> >> Signed-off-by: Kirill A. Shutemov <address@hidden>
>> >> ---
>> >>  osdep.c       |   27 +++++++++++++++++++++++++++
>> >>  qemu-common.h |    1 +
>> >>  2 files changed, 28 insertions(+), 0 deletions(-)
>> >>
>> >> diff --git a/osdep.c b/osdep.c
>> >> index e4836e7..d2406f2 100644
>> >> --- a/osdep.c
>> >> +++ b/osdep.c
>> >> @@ -243,6 +243,33 @@ int qemu_open(const char *name, int flags, ...)
>> >>      return ret;
>> >>  }
>> >>
>> >> +/*
>> >> + * A variant of write(2) which handles partial write.
>> >> + *
>> >> + * Return the number of bytes transferred.
>> >> + * Set errno if fewer than `count' bytes are written.
>> >> + */
>> >> +ssize_t qemu_write_full(int fd, const void *buf, size_t count)
>> >> +{
>> >> +    ssize_t ret = 0;
>> >> +    ssize_t total = 0;
>> >> +
>> >> +    while (count) {
>> >> +        ret = write(fd, buf, count);
>> >> +        if (ret < 0) {
>> >> +            if (errno == EINTR)
>> >> +                continue;
>> >> +            break;
>> >> +        }
>> >> +
>> >> +        count -= ret;
>> >> +        buf += ret;
>> >> +     total += ret;
>> >> +    }
>> >> +
>> >> +    return total;
>> >> +}
>> >
>> > This hides write errors.
>>
>> Why do you think so? Return value < count indicates error.
>
> It does not indicate _which_ error it was.

???

You can check errno.