Re: [PATCH 03/10] chardev/char-socket: tcp_chr_sync_read: don't clobber errno

[Marc-André Lureau]

On Thu, Nov 11, 2021 at 7:36 PM Roman Kagan  wrote:

> After the return from tcp_chr_recv, tcp_chr_sync_read calls into a
> function which eventually makes a system call and may clobber errno.
>
> Make a copy of errno right after tcp_chr_recv and restore the errno on
> return from tcp_chr_sync_read.
>
> Signed-off-by: Roman Kagan 
>

Reviewed-by: Marc-André Lureau 

---
>  chardev/char-socket.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index 90054ce58c..cf7f2ba65a 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -581,6 +581,7 @@ static int tcp_chr_sync_read(Chardev *chr, const
> uint8_t *buf, int len)
>  {
>  SocketChardev *s = SOCKET_CHARDEV(chr);
>  int size;
> +int saved_errno;
>
>  if (s->state != TCP_CHARDEV_STATE_CONNECTED) {
>  return 0;
> @@ -588,6 +589,7 @@ static int tcp_chr_sync_read(Chardev *chr, const
> uint8_t *buf, int len)
>
>  qio_channel_set_blocking(s->ioc, true, NULL);
>  size = tcp_chr_recv(chr, (void *) buf, len);
> +saved_errno = errno;
>  if (s->state != TCP_CHARDEV_STATE_DISCONNECTED) {
>  qio_channel_set_blocking(s->ioc, false, NULL);
>  }
> @@ -596,6 +598,7 @@ static int tcp_chr_sync_read(Chardev *chr, const
> uint8_t *buf, int len)
>  tcp_chr_disconnect(chr);
>  }
>
> +errno = saved_errno;
>  return size;
>  }
>
> --
> 2.33.1
>
>
>

-- 
Marc-André Lureau

[PATCH 03/10] chardev/char-socket: tcp_chr_sync_read: don't clobber errno

[Roman Kagan]

After the return from tcp_chr_recv, tcp_chr_sync_read calls into a
function which eventually makes a system call and may clobber errno.

Make a copy of errno right after tcp_chr_recv and restore the errno on
return from tcp_chr_sync_read.

Signed-off-by: Roman Kagan 
---
 chardev/char-socket.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 90054ce58c..cf7f2ba65a 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -581,6 +581,7 @@ static int tcp_chr_sync_read(Chardev *chr, const uint8_t 
*buf, int len)
 {
 SocketChardev *s = SOCKET_CHARDEV(chr);
 int size;
+int saved_errno;
 
 if (s->state != TCP_CHARDEV_STATE_CONNECTED) {
 return 0;
@@ -588,6 +589,7 @@ static int tcp_chr_sync_read(Chardev *chr, const uint8_t 
*buf, int len)
 
 qio_channel_set_blocking(s->ioc, true, NULL);
 size = tcp_chr_recv(chr, (void *) buf, len);
+saved_errno = errno;
 if (s->state != TCP_CHARDEV_STATE_DISCONNECTED) {
 qio_channel_set_blocking(s->ioc, false, NULL);
 }
@@ -596,6 +598,7 @@ static int tcp_chr_sync_read(Chardev *chr, const uint8_t 
*buf, int len)
 tcp_chr_disconnect(chr);
 }
 
+errno = saved_errno;
 return size;
 }
 
-- 
2.33.1