On Wed, Sep 03, 2025 at 12:44:02PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> First, qio_channel_readv_full() already guarantees BLOCKING and
> CLOEXEC states for incoming descriptors, no reason call extra
> ioctls.
>
> Second, current implementation calls _set_block() and _set_cloexec()
> again on old descriptors on failure path - we fix this too.
>
> Finally, handling errors exactly after qio_channel_readv_full() call
> looks more readable.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
> ---
> chardev/char-socket.c | 37 +++++++++++++------------------------
> 1 file changed, 13 insertions(+), 24 deletions(-)
>
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index 1e8313915b..5b9b19ba8b 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -293,6 +293,18 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf,
> size_t len)
> 0, &err);
> }
>
> + if (ret == QIO_CHANNEL_ERR_BLOCK) {
> + errno = EAGAIN;
> + return -1;
> + } else if (ret == -1) {
> + trace_chr_socket_recv_err(chr, chr->label, error_get_pretty(err));
> + error_free(err);
> + errno = EIO;
> + return -1;
> + }
> +
> + assert(ret >= 0);
Moving this logic to here means that in the blocking I/O, and/or error
paths, we are not clearing out the previously read s->read_msgfds_num
These should be considered obsolete at the point we start a new read
call, regardless of its success, hence why we had the code ordered in
this way.
> +
> if (msgfds_num) {
> /* close and clean read_msgfds */
> for (i = 0; i < s->read_msgfds_num; i++) {
> @@ -307,30 +319,7 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf,
> size_t len)
> s->read_msgfds_num = msgfds_num;
> }
>
> - for (i = 0; i < s->read_msgfds_num; i++) {
> - int fd = s->read_msgfds[i];
> - if (fd < 0) {
> - continue;
> - }
> -
> - /* O_NONBLOCK is preserved across SCM_RIGHTS so reset it */
> - qemu_socket_set_block(fd);
> -
> -#ifndef MSG_CMSG_CLOEXEC
> - qemu_set_cloexec(fd);
> -#endif
> - }
This for(){} removal is fnie.
> -
> - if (ret == QIO_CHANNEL_ERR_BLOCK) {
> - errno = EAGAIN;
> - ret = -1;
> - } else if (ret == -1) {
> - trace_chr_socket_recv_err(chr, chr->label, error_get_pretty(err));
> - error_free(err);
> - errno = EIO;
> - } else if (ret == 0) {
> - trace_chr_socket_recv_eof(chr, chr->label);
> - }
> + trace_chr_socket_recv_eof(chr, chr->label);
>
> return ret;
> }
> --
> 2.48.1
>
With regards,
Daniel
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