On 08/04/2011 09:31 AM, Alex Jia wrote:
In fact, 'pos' is always -1, this reason is because qemuProcessStart function
assigns -1 to 'pos' variable then call qemuProcessWaitForMonitor,
Actually, qemuProcessStart always calls qemuProcessWaitForMonitor with
non-negative pos (pos was set by lseek()ing to the end of the log file).
> meanwhile,
qemuProcessAttach function also call qemuProcessWaitForMonitor and directly
pass -1 as an argument, so if (pos != -1) statement can't been run for ever,
Rather, this merely means that the if (pos != -1) statement wasn't run
when called by qemuProcessAttach.
it also means we can't allocate memory to 'buf' variable, that is, 'buf' is
a initial value NULL, however, the function
qemuProcessReadLogFD(logfd, buf, buf_size, strlen(buf)) will be called
on 'cleanup' section, null pointer passed as an argument.
* src/qemu/qemu_process.c: avoid null pointer passed as an argument to a
'nonnull' parameter.
We definitely have a bug here, but this is not the right fix. The bug
is that the cleanup: label is trying to read from logfd if the vm
crashed, without having opened logfd in the qemuProcessAttach case.
I think the more appropriate patch is this:
diff --git i/src/qemu/qemu_process.c w/src/qemu/qemu_process.c
index 8508ff6..1eea45f 100644
--- i/src/qemu/qemu_process.c
+++ w/src/qemu/qemu_process.c
@@ -1214,7 +1214,7 @@ qemuProcessWaitForMonitor(struct qemud_driver* driver,
cleanup:
virHashFree(paths);
- if (kill(vm->pid, 0) == -1 && errno == ESRCH) {
+ if (pos != -1 && kill(vm->pid, 0) == -1 && errno == ESRCH) {
/* VM is dead, any other error raised in the interim is probably
* not as important as the qemu cmdline output */
qemuProcessReadLogFD(logfd, buf, buf_size, strlen(buf));
--
Eric Blake eblake@xxxxxxxxxx +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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