[Libvir] Re: [PATCH 2/7] Fix issues with QEMU monitor interface.
On Sun, Aug 12, 2007 at 07:11:34PM -0400, Jim Paris wrote:
Due to the TTY layer, sending "\n" to the qemu monitor
translates
into "\r\n" when received. This triggers a bug in older versions of
QEMU (KVM <= 33) because the same command is executed twice, and
still has problems with fixed QEMU because the "(qemu)" prompt is
printed twice. Switch all monitor commands to end with "\r" which
avoids both issues.
The QEMU monitor sends frequent terminal escape sequences, typically
\033[D and \033[K. At times, these interfere with the prompt
detection when they get sent between "\n" and "(qemu) ". Fix the
issue by filtering out these sequences when they are received.
I think DanP can better comment on the QEmu interaction than me,
but the patch looks simple and clean except:
@@ -1333,14 +1335,23 @@ static int qemudMonitorCommand(struct
qemud_driver *driver ATTRIBUTE_UNUSED,
return -1;
}
buf = b;
- memmove(buf+size, data, got);
- buf[size+got] = '\0';
- size += got;
+
+ /* Copy data, skipping 3-byte escape sequences */
+ for (i = 0; i < got; i++) {
+ if (data[i] == '\033')
+ skip = 3;
+ if (skip)
+ skip--;
+ else
+ buf[size++] = data[i];
+ }
+ buf[size] = '\0';
}
It seems that if for some reason you do a partial read on the QEmu
console descriptor ending in the middle of the escape command you may
have a problem. But it's possible that the way reads are done, and input
is chunked garantees that this won't happen, DanP can probably confirm
it's just fine :-)
Daniel
--
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard | virtualization library http://libvirt.org/
veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/