Re: [libvirt] [PATCH v4 4/4] qemu-config: Add new -add-fd command line option
On 10/18/2012 01:19 PM, Corey Bryant wrote:
This option can be used for passing file descriptors on the
command line. It mirrors the existing add-fd QMP command which
allows an fd to be passed to QEMU via SCM_RIGHTS and added to an
fd set.
+
+static int cleanup_add_fd(QemuOpts *opts, void *opaque)
+{
+ int fd;
+
+ fd = qemu_opt_get_number(opts, "fd", -1);
+ close(fd);
One other subtle point: Given 'qemu-kvm -add-fd fd=3,set=1 -add-fd
fd=3,set=2', this code will call close(3) twice. In a single-threaded
scenario, we happen to be safe (because we merely ignore that the second
one fails with EBADF), but in a multi-threaded scenario, it is a recipe
for disaster with a chance for closing an fd opened by another thread.
@@ -3320,6 +3390,14 @@ int main(int argc, char **argv, char **envp)
exit(1);
}
+ if (qemu_opts_foreach(qemu_find_opts("add-fd"), parse_add_fd, NULL, 1)) {
+ exit(1);
+ }
+
+ if (qemu_opts_foreach(qemu_find_opts("add-fd"), cleanup_add_fd, NULL, 1))
{
+ exit(1);
+ }
Thankfully, we only ever call that code in main(), prior to spawning
threads. So my positive review still stands.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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