1:28 p.m.
On Fri, Feb 16, 2007 at 02:44:57PM +0000, Mark McLoughlin wrote:
Add a qemudLog() function which uses syslog() if we're in
daemon mode, doesn't output INFO/DEBUG messages unless
the verbose flag is set and doesn't output DEBUG messages
unless compiled with --enable-debug.
The QEMU daemon can run both as root, or non-root. Using syslog
in the non-root case is not particularly helpful because the user
will have no way to retrieve the log messages. We should have
the daemon log to a file under $HOME/.libvirt somewhere, and only
use syslog if explicitly turned on via a command line arg to the
daemon.
I think there's scope for making this more generally useful too,
rather than making it just part of the QEMU daemon. The general
libvirtd will definitely need it, and I think once we have remote
managemnet it'll be important to have a way to do logging in the
client library which integrates into apps using libvirt. eg let
the app register a callback to receive debug messages. The same
core functions
The patch itself looks reasonable, but next time there's a patch
of this scale please post this stuff for review before committing
if (sys) {
- if (snprintf(sockname, sizeof(sockname), "%s/run/libvirt/qemud-sock",
LOCAL_STATE_DIR) >= (int)sizeof(sockname)) {
- return -1;
- }
+ if (snprintf(sockname, sizeof(sockname), "%s/run/libvirt/qemud-sock",
LOCAL_STATE_DIR) >= (int)sizeof(sockname))
+ goto snprintf_error;
+
I've just realized the return value checks I did here are incomplete.
As well as checking for overflow with >=, we also need to check for
general errors which are indicated by a -ve return value.
+ if (snprintf(sockname, sizeof(sockname),
"%s/run/libvirt/qemud-sock-ro", LOCAL_STATE_DIR) >= (int)sizeof(sockname))
+ goto snprintf_error;
- if (snprintf(sockname, sizeof(sockname),
"%s/run/libvirt/qemud-sock-ro", LOCAL_STATE_DIR) >= (int)sizeof(sockname)) {
- return -1;
- }
Likewise.
Dan
unlink(sockname);
if (qemudListenUnix(server, sockname, 1) < 0)
return -1;
@@ -289,29 +375,38 @@ static int qemudListen(struct qemud_serv
int uid;
if ((uid = geteuid()) < 0) {
+ qemudLog(QEMUD_ERR, "You must run the daemon as root to use system
mode");
return -1;
}
This error message looks bogus. This codepath is the per-user unprivileged
session mode, and the error. And actually checking return value at all is
completely unneccesssary because geteuid() is guarenteed not to fail.
We do, however, need a check
if (geteuid() != 0) {
....
}
In the first half of the if() block in the qemudListen function to check for
root privs in system mode.
if ((uid = geteuid()) < 0) {
+ qemudLog(QEMUD_ERR, "You must run the daemon as root to use system
mode");
goto cleanup;
}
Again, same as above.
@@ -1226,6 +1332,7 @@ static int qemudDispatchPoll(struct qemu
while (sock) {
struct qemud_socket *next = sock->next;
+ /* FIXME: the daemon shouldn't exit on error here */
if (fds[fd].revents)
if (qemudDispatchServer(server, sock) < 0)
return -1;
Yes & no. There are two reasons why qemuDispatchServer can fail. Either
it can fail to set CLOSEXEC/NONBLOCK mode on the client socket, in
which case we could simply drop the client & continue without exiting.
If the accept() call fails for anything other than EAGAIN/EINTR then
we arguably should exit, because something serious has gone wrong.
if (fds[fd].revents) {
- QEMUD_DEBUG("Poll data normal\n");
+ qemudDebug("Poll data normal");
if (fds[fd].revents == POLLOUT)
qemudDispatchClientWrite(server, client);
else if (fds[fd].revents == POLLIN)
@@ -1281,7 +1388,7 @@ static int qemudDispatchPoll(struct qemu
}
vm = next;
if (failed)
- ret = -1;
+ ret = -1; /* FIXME: the daemon shouldn't exit on failure here */
}
The failed flag should only get set if something serious went wrong when
trying to cleanup after a dead VM. If cleanup succeeds we stick around,
but if it fails I'm not entirely convinced we shouldn't exit.
Dan.
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