Re: [libvirt] [PATCH 05/15] Make use of private data structure for monitor state

On Tue, Nov 03, 2009 at 02:49:59PM -0500, Daniel P. Berrange wrote: > Introduce a new qemuDomainObjPrivate object which is used to store > the private QEMU specific data associated with each virDomainObjPtr > instance. This contains a single member, an instance of the new > qemuMonitorPtr object which encapsulates the QEMU monitor state. > The internals of the latter are private to the qemu_monitor* files, > not to be shown to qemu_driver.c > > * src/qemu/qemu_conf.h: Definition of qemuDomainObjPrivate. > * src/qemu/qemu_driver.c: Register a functions for creating > and freeing qemuDomainObjPrivate instances with the domain > capabilities. Remove the qemudDispatchVMEvent() watch since > I/O watches are now handled by the monitor code itself. Pass > a new qemuHandleMonitorEOF() callback into qemuMonitorOpen > to allow notification when the monitor quits. > * src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h: Introduce > the 'qemuMonitor' object. Temporarily add new APIs > qemuMonitorWrite, qemuMonitorRead, qemuMonitorWaitForInput > to allow text based monitor impl to perform I/O. > * src/qemu/qemu_monitor_text.c: Call APIs for reading/writing > to monitor instead of accessing the file handle directly. [...] > +int qemuMonitorWriteWithFD(qemuMonitorPtr mon, > + const char *data, > + size_t len, > + int fd) > +{ > + struct msghdr msg; > + struct iovec iov[1]; > + ssize_t ret; > + char control[CMSG_SPACE(sizeof(int))]; > + struct cmsghdr *cmsg; > + > + if (!mon->hasSendFD) { > + errno = EINVAL; > return -1; > } > + > + memset(&msg, 0, sizeof(msg)); > + > + iov[0].iov_base = (void *)data; > + iov[0].iov_len = len; > + > + msg.msg_iov = iov; > + msg.msg_iovlen = 1; > + > + msg.msg_control = control; > + msg.msg_controllen = sizeof(control); > + > + cmsg = CMSG_FIRSTHDR(&msg); > + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); > + cmsg->cmsg_level = SOL_SOCKET; > + cmsg->cmsg_type = SCM_RIGHTS; > + memcpy(CMSG_DATA(cmsg), &fd, sizeof(int)); > + > + do { > + ret = sendmsg(mon->fd, &msg, 0); > + } while (ret < 0 && errno == EINTR); > + > + return ret == len ? 0 : -1; > +} I must admit I'm a bit puzzled by this function, we are sending both data and a file descriptor ? But it's an in-process exchange, why would that be needed, I'm at loss ...