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

[malc]

On Thu, 31 Dec 2009, Kirill A. Shutemov wrote:

> 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.

Uh, yes, sorry, been writing too much driver code lately.

Nitpick then, no reason to set ret to zero at the beginning of the
function.

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