On Thu, Oct 06, 2022 at 12:12:18PM +0400, marcandre.lur...@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lur...@redhat.com>
>
> With a pipe or other reasons, read/write may return less than the
> requested bytes. This happens with the test-io-channel-command test on
> Windows. glib spawn code uses a binary pipe of 4096 bytes, and the first
> read returns that much (although more are requested), for some unclear
> reason...
Wow, lucky this function isn't too widely used historically!
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> ---
> util/osdep.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
Reviewed-by: Daniel P. Berrangé <berra...@redhat.com>
>
> diff --git a/util/osdep.c b/util/osdep.c
> index 60fcbbaebe..b85715a743 100644
> --- a/util/osdep.c
> +++ b/util/osdep.c
There's a comment just above here that says
helper function for iov_send_recv
which is not true, as iov_send_recv just calls send/recv instead,
again in a loop with the exact same logic flaw. Care to fix the
comment and also fix iov_send_recv in the same way ?
> @@ -544,12 +544,17 @@ readv_writev(int fd, const struct iovec *iov, int
> iov_cnt, bool do_write)
> {
> unsigned i = 0;
> ssize_t ret = 0;
> + ssize_t off = 0;
> while (i < iov_cnt) {
> ssize_t r = do_write
> - ? write(fd, iov[i].iov_base, iov[i].iov_len)
> - : read(fd, iov[i].iov_base, iov[i].iov_len);
> + ? write(fd, iov[i].iov_base + off, iov[i].iov_len - off)
> + : read(fd, iov[i].iov_base + off, iov[i].iov_len - off);
> if (r > 0) {
> ret += r;
> + off += r;
> + if (off < iov[i].iov_len) {
> + continue;
> + }
> } else if (!r) {
> break;
> } else if (errno == EINTR) {
> @@ -562,6 +567,7 @@ readv_writev(int fd, const struct iovec *iov, int
> iov_cnt, bool do_write)
> }
> break;
> }
> + off = 0;
> i++;
> }
> return ret;
> --
> 2.37.3
>
With regards,
Daniel
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