On Fri, Mar 02, 2007 at 03:06:56PM +0000, Mark McLoughlin wrote:
> 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 ?
Sorry, wrong version of the patch - the for(;;) should have been
while (got < (sizeof(buffer)-1)) {
I'll repost the correct patch when I've done of the other fixes.
>
> > + 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?
Again, wrong patch - it should have been 5 seconds.
> > +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?
I'll add in some error reporting.
> > + 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)
I'll have a go at splitting it out.
>
> > + if (qemudOpenMonitor(vm, monitor) < 0)
> > + return -1;
> > + return 0;
> > + }
> > + tmp = index(tmp, '\n');
>
> index() is a bit odd, why not strstr() ?
Well we're only looking for a single character match - index() is for
single characters, strstr() is for strings.
> > +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.
Currently QEMU can't auto-allocate itself a patch - I'm planning to port
the Xen auto-allocation patch to mainline QEMU. Until then, this code is
better than the the current situation, even though there is an obvious
race.
> > + if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) == 0)
>
> Um, why not bind() (with SO_REUSEADDR)?
No particular reason - either will work just fine.
Regards,
Dan.
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