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
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