Re: [libvirt] [Qemu-devel] [PATCH v4 3/7] qapi: Add pass-fd QMP command
On 06/22/2012 12:36 PM, Corey Bryant wrote:
This patch adds the pass-fd QMP command using the QAPI framework.
Like the getfd command, it is used to pass a file descriptor via
SCM_RIGHTS and associate it with a name. However, the pass-fd
command also returns the received file descriptor, which is a
difference in behavior from the getfd command, which returns
nothing. pass-fd also supports a boolean "force" argument that
can be used to specify that an existing file descriptor is
associated with the specified name, and that it should become a
copy of the newly passed file descriptor.
+ if (replace) {
+ /* the existing fd is replaced with the new fd */
+ close(monfd->fd);
+ monfd->fd = fd;
+ return fd;
+ }
+
+ if (copy) {
Since 'replace' and 'copy' are never both true, should this instead be a
tri-state enum argument instead of two independent bool arguments?
+ /* the existing fd becomes a copy of the new fd */
+ if (dup2(fd, monfd->fd) == -1) {
Broken - you want to use dup3(fd, monfd->fd, O_CLOEXEC) (and fall back
to dup2()+fcntl(F_GETFD/F_SETFD) on platforms where dup3 is not
available; it has been proposed for the next revision of POSIX but right
now is pretty much limited to Linux and Cygwin). Otherwise, you are
undoing the fact that patch 1/7 just changed the 'getfd' list to always
keep all its fds marked cloexec.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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