[libvirt] Segfault in virCommandRun when trying to start a QEMU guest
In qemudStartVMDaemon in/out/err for the virCommand are set based on
FDs this results in a segfault in virCommandRun here
VIR_DEBUG("Result stdout: '%s' stderr: '%s'",
NULLSTR(*cmd->outbuf),
NULLSTR(*cmd->errbuf));
as cmd->outbuf and cmd->errbuf are NULL.
The two if blocks before that setup cmd->outbuf and cmd->errbuf in
case the caller didn't request output capturing aren't executed
because the caller requested to capture the output to FDs.
/* If caller hasn't requested capture of stdout/err, then capture
* it ourselves so we can log it.
*/
if (!cmd->outfdptr) {
cmd->outfdptr = &cmd->outfd;
cmd->outbuf = &outbuf;
}
if (!cmd->errfdptr) {
cmd->errfdptr = &cmd->errfd;
cmd->errbuf = &errbuf;
}
In the case the caller requested to capture the output to FDs there is
no capturing to cmd->outbuf and cmd->errbuf and they stay NULL.
When I remove that offending VIR_DEBUG line everything works fine.
Also this case of FD only usage is not yet covered in the command API
test cases.
Matthias