[Libvir] PATCH: Process QEMU monitor at startup
Mark McLoughlin
markmc at redhat.com
Fri Mar 2 15:06:56 UTC 2007
Hi Dan,
On Fri, 2007-03-02 at 14:35 +0000, Daniel P. Berrange wrote:
>
> +static int qemudOpenMonitor(struct qemud_vm *vm, const char *monitor)
> {
#define MONITOR_POLL_TIMEOUT 5
> + int monfd;
> + char buffer[1024];
> + int got = 0;
> +
> + if (!(monfd = open(monitor, O_RDWR))) {
> + return -1;
> + }
> + if (qemudSetCloseExec(monfd) < 0)
> + goto error;
> + if (qemudSetNonBlock(monfd) < 0)
> + goto error;
> +
> + /* Consume & discard the initial greeting */
> + for(;;) {
> + int ret;
> +
> + ret = read(monfd, buffer+got, sizeof(buffer)-got-1);
What happens if the buffer fills up ?
> + if (ret == 0)
> + goto error;
> + if (ret < 0) {
> + struct pollfd fd = { .fd = monfd, .events = POLLIN };
> + if (errno != EAGAIN &&
> + errno != EINTR)
> + goto error;
> +
> + ret = poll(&fd, 1, 5);
ret = poll(&fd, 1, MONITOR_POLL_TIMEOUT);
Giving up after 5 milliseconds? Are we that afraid of commitment?
> +static int qemudWaitForMonitor(struct qemud_vm *vm) {
We don't set an error in here, so how about returning the appropriate
errno from the function?
> + char buffer[1024]; /* Plenty of space to get startup greeting */
> + int got = 0;
> +
> + for (;;) {
> + int ret;
> +
> + ret = read(vm->stderr, buffer+got, sizeof(buffer)-got-1);
> + if (ret == 0) {
> + return -1;
> + }
> + if (ret < 0) {
> + struct pollfd fd = { .fd = vm->stderr, .events =
> POLLIN };
> + if (errno != EAGAIN &&
> + errno != EINTR) {
> + return -1;
> + }
> +
> + ret = poll(&fd, 1, 5000);
Again, a #define for the timeout would be nice
> + if (ret == 0) {
> + return -1;
> + } else if (ret < 0) {
> + if (errno != EINTR)
> + return -1;
> + } else if (fd.revents != POLLIN) {
> + return -1;
> + }
> + } else {
> + char monitor[100];
> + char *tmp = buffer;
> + got += ret;
> + buffer[got] = '\0';
> + while (tmp && *tmp) {
> + if (sscanf(tmp, "char device redirected to %19s", monitor) == 1) {
Path length of 100, maximum field with of 19? That's all rather
voodooish ... hope about strstr() to find it, buffer length of PATH_MAX
and then just strncpy()? Also, it'd be nice to split that out into e.g.
qemudMonitorPathFromStr(buffer, monitorPath, PATH_MAX)
> + if (qemudOpenMonitor(vm, monitor) < 0)
> + return -1;
> + return 0;
> + }
> + tmp = index(tmp, '\n');
index() is a bit odd, why not strstr() ?
> +static int qemudNextFreeVNCPort(struct qemud_server *server
> ATTRIBUTE_UNUSED) {
I don't really know the context, but it'd be much nicer if we could
just QEMU find a free port itself and then we query the port - e.g. the
obvious race condition.
> + int i;
> +
> + for (i = 5900 ; i < 6000 ; i++) {
> + int fd;
> + struct sockaddr_in addr;
> + addr.sin_family = AF_INET;
> + addr.sin_port = htons(i);
> + addr.sin_addr.s_addr = htonl(INADDR_ANY);
> + fd = socket(PF_INET, SOCK_STREAM, 0);
> + if (fd < 0)
> + return -1;
> +
> + if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) == 0)
Um, why not bind() (with SO_REUSEADDR)?
> ret = 0;
> +
> + if (qemudWaitForMonitor(vm) < 0) {
Set an error based on the returned errno ...
> struct qemud_vm *next = vm->next;
> @@ -1356,6 +1426,7 @@ static int qemudDispatchPoll(struct qemu
> if (stderrfd != -1) {
> if (!failed) {
> if (fds[fd].revents) {
> + printf("%d\n", fds[fd].revents);
Kill this
Cheers,
Mark.
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