Re: [libvirt] [Qemu-devel] [PATCH v4 1/7] qemu-char: Add MSG_CMSG_CLOEXEC flag to recvmsg

On Fri, Jun 22, 2012 at 01:31:17PM -0600, Eric Blake wrote: > On 06/22/2012 12:36 PM, Corey Bryant wrote: >> This sets the close-on-exec flag for the file descriptor received >> via SCM_RIGHTS. >> >> Signed-off-by: Corey Bryant <coreyb(a)linux.vnet.ibm.com&gt; >> --- >> v4 >> -This patch is new in v4 (eblake(a)redhat.com) >> >> qemu-char.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/qemu-char.c b/qemu-char.c >> index c2aaaee..f890113 100644 >> --- a/qemu-char.c >> +++ b/qemu-char.c >> @@ -2263,7 +2263,7 @@ static ssize_t tcp_chr_recv(CharDriverState *chr, char *buf, size_t len) >> msg.msg_control = &msg_control; >> msg.msg_controllen = sizeof(msg_control); >> >> - ret = recvmsg(s->fd, &msg, 0); >> + ret = recvmsg(s->fd, &msg, MSG_CMSG_CLOEXEC); > > MSG_CMSG_CLOEXEC is not (yet) in POSIX (although it has been proposed > for addition); therefore, at the moment, it only exists on Linux and > Cygwin. Does this need to have conditional code to allow compilation on > BSD, such as: > > #ifndef MSG_CMSG_CLOEXEC > # define MSG_CMSG_CLOEXEC 0 > #endif > > as well as fallback code that sets FD_CLOEXEC manually via fcntl() when > MSG_CMSG_CLOEXEC is missing? Good point. I think the answer is yes. Just like qemu_open() we can wrap "recvmsg(2) with fd" so that platforms with MSG_CMSG_CLOEXEC use that flag and other platforms use qemu_set_cloexec(). Stefan