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Convert libvirtd to use crash-safe pidfile APIs

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Remove the current libvirtd pidfile handling code, in favour of
calling out to the new APIs. This ensures libvirtd's pidfile
handling is crashsafe

This also means that the non-root libvirtd instances (for handling
qemu:///session URIs) can now safely use pidfiles without racing

* daemon/libvirtd.c: Switch to use virPidFileAcquire and
  virPidFileRelease
This commit is contained in:
Daniel P. Berrange 2011-08-05 15:11:11 +01:00
parent e1da464d88
commit c8a3a26513
1 changed files with 11 additions and 49 deletions
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60
daemon/libvirtd.c
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@ -35,6 +35,7 @@
#include "libvirt_internal.h"
#include "virterror_internal.h"
#include "virfile.h"
#include "virpidfile.h"
#define VIR_FROM_THIS VIR_FROM_QEMU
@ -259,44 +260,6 @@ static int daemonForkIntoBackground(const char *argv0)
}
}
static int daemonWritePidFile(const char *pidFile, const char *argv0)
{
int fd;
FILE *fh;
char ebuf[1024];
if (pidFile[0] == '\0')
return 0;
if ((fd = open(pidFile, O_WRONLY|O_CREAT|O_EXCL, 0644)) < 0) {
VIR_ERROR(_("Failed to open pid file '%s' : %s"),
pidFile, virStrerror(errno, ebuf, sizeof ebuf));
return -1;
}
if (!(fh = VIR_FDOPEN(fd, "w"))) {
VIR_ERROR(_("Failed to fdopen pid file '%s' : %s"),
pidFile, virStrerror(errno, ebuf, sizeof ebuf));
VIR_FORCE_CLOSE(fd);
return -1;
}
if (fprintf(fh, "%lu\n", (unsigned long)getpid()) < 0) {
VIR_ERROR(_("%s: Failed to write to pid file '%s' : %s"),
argv0, pidFile, virStrerror(errno, ebuf, sizeof ebuf));
VIR_FORCE_FCLOSE(fh);
return -1;
}
if (VIR_FCLOSE(fh) == EOF) {
VIR_ERROR(_("%s: Failed to close pid file '%s' : %s"),
argv0, pidFile, virStrerror(errno, ebuf, sizeof ebuf));
return -1;
}
return 0;
}
static int
daemonPidFilePath(bool privileged,
@ -1261,6 +1224,7 @@ int main(int argc, char **argv) {
char *remote_config_file = NULL;
int statuswrite = -1;
int ret = 1;
int pid_file_fd = -1;
char *pid_file = NULL;
char *sock_file = NULL;
char *sock_file_ro = NULL;
@ -1378,7 +1342,7 @@ int main(int argc, char **argv) {
if (daemonSetupLogging(config, privileged, verbose, godaemon) < 0)
exit(EXIT_FAILURE);
if (!pid_file && privileged &&
if (!pid_file &&
daemonPidFilePath(privileged,
&pid_file) < 0)
exit(EXIT_FAILURE);
@ -1405,14 +1369,6 @@ int main(int argc, char **argv) {
}
}
/* If we have a pidfile set, claim it now, exiting if already taken */
if (pid_file != NULL &&
daemonWritePidFile(pid_file, argv[0]) < 0) {
VIR_FREE(pid_file); /* Prevent unlinking of someone else's pid ! */
ret = VIR_DAEMON_ERR_PIDFILE;
goto cleanup;
}
/* Ensure the rundir exists (on tmpfs on some systems) */
if (privileged) {
const char *rundir = LOCALSTATEDIR "/run/libvirt";
@ -1432,6 +1388,12 @@ int main(int argc, char **argv) {
umask(old_umask);
}
/* Try to claim the pidfile, exiting if we can't */
if ((pid_file_fd = virPidFileAcquirePath(pid_file, getpid())) < 0) {
ret = VIR_DAEMON_ERR_PIDFILE;
goto cleanup;
}
use_polkit_dbus = config->auth_unix_rw == REMOTE_AUTH_POLKIT ||
config->auth_unix_ro == REMOTE_AUTH_POLKIT;
if (!(srv = virNetServerNew(config->min_workers,
@ -1570,8 +1532,8 @@ cleanup:
}
VIR_FORCE_CLOSE(statuswrite);
}
if (pid_file)
unlink (pid_file);
if (pid_file_fd != -1)
virPidFileReleasePath(pid_file, pid_file_fd);
VIR_FREE(sock_file);
VIR_FREE(sock_file_ro);