Re: [libvirt] [PATCH v4 4/4] qemu-config: Add new -add-fd command line option

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. This can be combined with commands such as -drive to link file descriptors in an fd set to a drive: qemu-kvm -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" -drive file=/dev/fdset/2,index=0,media=disk This example adds dups of fds 3 and 4, and the accompanying opaque strings to the fd set with ID=2. qemu_open() already knows how to handle a filename of this format. qemu_open() searches the corresponding fd set for an fd and when it finds a match, QEMU goes on to use a dup of that fd just like it would have used an fd that it opened itself. Signed-off-by: Corey Bryant <coreyb(a)linux.vnet.ibm.com&gt;

+ + if (fcntl(fd, F_GETFD) & FD_CLOEXEC) { + qerror_report(ERROR_CLASS_GENERIC_ERROR, + "fd is not valid or already in use"); + return -1; + }