Re: [libvirt] [PATCH v5 1/6] qemu-char: Add MSG_CMSG_CLOEXEC flag to recvmsg
On 07/23/2012 07:08 AM, Corey Bryant wrote:
Set the close-on-exec flag for the file descriptor received
via SCM_RIGHTS.
+++ b/qemu-char.c
@@ -2263,9 +2263,17 @@ static ssize_t tcp_chr_recv(CharDriverState *chr, char *buf,
size_t len)
msg.msg_control = &msg_control;
msg.msg_controllen = sizeof(msg_control);
+#ifdef MSG_CMSG_CLOEXEC
+ ret = recvmsg(s->fd, &msg, MSG_CMSG_CLOEXEC);
+#else
ret = recvmsg(s->fd, &msg, 0);
- if (ret > 0 && s->is_unix)
+ if (ret > 0) {
+ qemu_set_cloexec(s->fd);
Wrong fd. You aren't changing cloexec on the socket (s->fd), but on the
fd that was received via msg (which you don't know at this point in time).
+ }
+#endif
+ if (ret > 0 && s->is_unix) {
unix_process_msgfd(chr, &msg);
Only here do you know what fd you received.
I would write it more like:
int flags = 0;
#ifdef MSG_CMSG_CLOEXEC
flags |= MSG_CMSG_CLOEXEC
#endif
ret = recvmsg(s->fd, &msg, flags);
if (ret > 0 && s->is_unix) {
unix_process_msgfd(chr, &msg);
#ifndef MSG_CMSG_CLOEXEC
qemu_set_cloexec(/* fd determined from msg */)
#endif
}
which almost implies that unix_process_msgfd() should be the function
that sets cloexec, but without wasting the time doing so if recvmsg
already did the job.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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