On Mon, Aug 13, 2007 at 12:54:05PM +0100, Daniel P. Berrange wrote:
On Mon, Aug 13, 2007 at 05:59:15AM -0400, Daniel Veillard wrote:
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:
It looks sane to me - I had no idea QEMU was sending this escape sequences.
@@ -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 :-)
We're reading from a Psuedo-TTY which is line buffered, so I think the OS should guarentee that we can read a whole lines worth of data without getting EAGAIN.
+1 then Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard@redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/