static int daemonForkIntoBackground(const char *argv0)
{
int statuspipe[2];
if (pipe(statuspipe) < 0)
return -1;
pid_t pid = fork();
switch (pid) {
case 0:
{
/* intermediate child */
int stdinfd = -1;
int stdoutfd = -1;
int nextpid;
VIR_FORCE_CLOSE(statuspipe[0]);
if ((stdinfd = open("/dev/null", O_RDONLY)) < 0)
goto cleanup;
if ((stdoutfd = open("/dev/null", O_WRONLY)) < 0)
goto cleanup;
if (dup2(stdinfd, STDIN_FILENO) != STDIN_FILENO)
goto cleanup;
if (dup2(stdoutfd, STDOUT_FILENO) != STDOUT_FILENO)
goto cleanup;
if (dup2(stdoutfd, STDERR_FILENO) != STDERR_FILENO)
goto cleanup;
if (stdinfd > STDERR_FILENO && VIR_CLOSE(stdinfd) < 0)
goto cleanup;
if (stdoutfd > STDERR_FILENO && VIR_CLOSE(stdoutfd) < 0)
goto cleanup;
if (setsid() < 0)
goto cleanup;
nextpid = fork();
switch (nextpid) {
case 0: /* grandchild */
return statuspipe[1];
case -1: /* error */
goto cleanup;
default: /* intermediate child succeeded */
_exit(EXIT_SUCCESS);
}
cleanup:
VIR_FORCE_CLOSE(stdoutfd);
VIR_FORCE_CLOSE(stdinfd);
VIR_FORCE_CLOSE(statuspipe[1]);
_exit(EXIT_FAILURE);
}
case -1: /* error in parent */
goto error;
default:
{
/* parent */
int ret;
char status;
VIR_FORCE_CLOSE(statuspipe[1]);
/* We wait to make sure the first child forked successfully */
if (virPidWait(pid, NULL) < 0)
goto error;
/* If we get here, then the grandchild was spawned, so we
* must exit. Block until the second child initializes
* successfully */
again:
ret = read(statuspipe[0], &status, 1);
if (ret == -1 && errno == EINTR)
goto again;
VIR_FORCE_CLOSE(statuspipe[0]);
if (ret != 1) {
char ebuf[1024];
fprintf(stderr,
_("%s: error: unable to determine if daemon is "
"running: %s\n"), argv0,
virStrerror(errno, ebuf, sizeof(ebuf)));
exit(EXIT_FAILURE);
} else if (status != 0) {
fprintf(stderr,
_("%s: error: %s. Check /var/log/messages or run "
"without --daemon for more info.\n"), argv0,
virDaemonErrTypeToString(status));
exit(EXIT_FAILURE);
}
_exit(EXIT_SUCCESS);
}
}
error:
VIR_FORCE_CLOSE(statuspipe[0]);
VIR_FORCE_CLOSE(statuspipe[1]);
return -1;
}
static int
virLogDaemonForkIntoBackground(const char *argv0)
{
int statuspipe[2];
if (pipe(statuspipe) < 0)
return -1;
pid_t pid = fork();
switch (pid) {
case 0:
{
int stdinfd = -1;
int stdoutfd = -1;
int nextpid;
VIR_FORCE_CLOSE(statuspipe[0]);
if ((stdinfd = open("/dev/null", O_RDONLY)) < 0)
goto cleanup;
if ((stdoutfd = open("/dev/null", O_WRONLY)) < 0)
goto cleanup;
if (dup2(stdinfd, STDIN_FILENO) != STDIN_FILENO)
goto cleanup;
if (dup2(stdoutfd, STDOUT_FILENO) != STDOUT_FILENO)
goto cleanup;
if (dup2(stdoutfd, STDERR_FILENO) != STDERR_FILENO)
goto cleanup;
if (VIR_CLOSE(stdinfd) < 0)
goto cleanup;
if (VIR_CLOSE(stdoutfd) < 0)
goto cleanup;
if (setsid() < 0)
goto cleanup;
nextpid = fork();
switch (nextpid) {
case 0:
return statuspipe[1];
case -1:
return -1;
default:
_exit(0);
}
cleanup:
VIR_FORCE_CLOSE(stdoutfd);
VIR_FORCE_CLOSE(stdinfd);
return -1;
}
case -1:
return -1;
default:
{
int got, exitstatus = 0;
int ret;
char status;
VIR_FORCE_CLOSE(statuspipe[1]);
/* We wait to make sure the first child forked successfully */
if ((got = waitpid(pid, &exitstatus, 0)) < 0 ||
got != pid ||
exitstatus != 0) {
return -1;
}
/* Now block until the second child initializes successfully */
again:
ret = read(statuspipe[0], &status, 1);
if (ret == -1 && errno == EINTR)
goto again;
if (ret == 1 && status != 0) {
fprintf(stderr,
_("%s: error: %s. Check /var/log/messages or run without "
"--daemon for more info.\n"), argv0,
virDaemonErrTypeToString(status));
}
_exit(ret == 1 && status == 0 ? 0 : 1);
}
}
}