On Mon, Dec 01, 2008 at 05:36:34PM -0500, Cole Robinson wrote:
The attached patch cleans up output we read from the qemu monitor. This is a simplified form of a patch I posted awhile ago. From the patch:
/* The monitor doesn't dump clean output after we have written to * it. Every character we write dumps a bunch of useless stuff, * so the result looks like "cXcoXcomXcommXcommaXcommanXcommand" * Try to throw away everything before the first full command * occurence, and inbetween the command and the newline starting * the response */
This extra output makes our qemu log files _huge_ if doing things like polling disk/net stats, and prevents us from returning any useful error message printed from the monitor (say for media/disk eject, disk/net stats, etc).
Yes, this is quite horrific output thanks to QEMU's readline emulation which we can't turn off.
I've been running with this patch for a while and haven't hit any issues. if (buf && ((tmp = strstr(buf, "\n(qemu) ")) != NULL)) { - tmp[0] = '\0'; + /* Preserve the newline */ + tmp[1] = '\0'; + + /* The monitor doesn't dump clean output after we have written to + * it. Every character we write dumps a bunch of useless stuff, + * so the result looks like "cXcoXcomXcommXcommaXcommanXcommand" + * Try to throw away everything before the first full command + * occurence, and inbetween the command and the newline starting + * the response + */ + if ((commptr = strstr(buf, cmd))) { + char *dupptr = strchr(commptr, '\n'); + if (dupptr) { + char *tmpbuf = strdup(dupptr); + VIR_FREE(buf); + buf = strdup(tmpbuf); + } + }
This loooks a little overly complex to me, doesn't handle alloction failures in strdup correctly & leaks tmpbuf. Can't we just simplify it to if ((commptr = strstr(buf, cmd))) memmove(buf, commptr, strlen(commptr)+1); avoiding re-allocation entirely ? Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|