From dd3258133e54bd2c3355b09f43059f56fab5ee14 Mon Sep 17 00:00:00 2001
From: Hector Martin
Date: Wed, 19 Aug 2009 03:25:34 +0200
Subject: Fix daemonization and lockfile madness
---
usbmuxd/main.c | 201 ++++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 140 insertions(+), 61 deletions(-)
diff --git a/usbmuxd/main.c b/usbmuxd/main.c
index be7451f..6b3c881 100644
--- a/usbmuxd/main.c
+++ b/usbmuxd/main.c
@@ -33,7 +33,8 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/stat.h>
-#include <sys/fcntl.h>
+#include <sys/types.h>
+#include <fcntl.h>
#include <getopt.h>
#include <pwd.h>
#include <grp.h>
@@ -44,7 +45,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#include "client.h"
static const char *socket_path = "/var/run/usbmuxd";
-static const char *lockfile = "/var/run/usbmuxd.lock";
+static const char *lockfile = "/var/run/usbmuxd.pid";
int should_exit;
@@ -55,6 +56,9 @@ static const char *drop_user = "usbmux";
static int opt_udev = 0;
static int opt_exit = 0;
static int exit_signal = 0;
+static int daemon_pipe;
+
+static int report_to_parent = 0;
int create_socket(void) {
struct sockaddr_un bind_addr;
@@ -191,25 +195,47 @@ int main_loop(int listenfd)
/**
* make this program run detached from the current console
*/
-static int daemonize()
+static int daemonize(void)
{
pid_t pid;
pid_t sid;
+ int pfd[2];
+ int res;
// already a daemon
if (getppid() == 1)
return 0;
+ if((res = pipe(pfd)) < 0) {
+ usbmuxd_log(LL_FATAL, "pipe() failed.");
+ return res;
+ }
+
pid = fork();
if (pid < 0) {
- exit(EXIT_FAILURE);
+ usbmuxd_log(LL_FATAL, "fork() failed.");
+ return pid;
}
if (pid > 0) {
// exit parent process
- exit(EXIT_SUCCESS);
+ int status;
+ close(pfd[1]);
+
+ if((res = read(pfd[0],&status,sizeof(int))) != sizeof(int)) {
+ fprintf(stderr, "usbmuxd: ERROR: Failed to get init status from child, check syslog for messages.\n");
+ exit(1);
+ }
+ if(status != 0)
+ fprintf(stderr, "usbmuxd: ERROR: Child process exited with error %d, check syslog for messages.\n", status);
+ exit(status);
}
// At this point we are executing as the child process
+ // but we need to do one more fork
+
+ daemon_pipe = pfd[1];
+ close(pfd[0]);
+ report_to_parent = 1;
// Change the file mode mask
umask(0);
@@ -217,23 +243,57 @@ static int daemonize()
// Create a new SID for the child process
sid = setsid();
if (sid < 0) {
+ usbmuxd_log(LL_FATAL, "setsid() failed.");
return -1;
}
+
+ pid = fork();
+ if (pid < 0) {
+ usbmuxd_log(LL_FATAL, "fork() failed (second).");
+ return pid;
+ }
+
+ if (pid > 0) {
+ // exit parent process
+ close(daemon_pipe);
+ exit(0);
+ }
+
// Change the current working directory.
if ((chdir("/")) < 0) {
+ usbmuxd_log(LL_FATAL, "chdir() failed");
return -2;
}
// Redirect standard files to /dev/null
if (!freopen("/dev/null", "r", stdin)) {
- usbmuxd_log(LL_ERROR, "ERROR: redirection of stdin failed.");
+ usbmuxd_log(LL_FATAL, "Redirection of stdin failed.");
+ return -3;
}
if (!freopen("/dev/null", "w", stdout)) {
- usbmuxd_log(LL_ERROR, "ERROR: redirection of stdout failed.");
+ usbmuxd_log(LL_FATAL, "Redirection of stdout failed.");
+ return -3;
+ }
+
+ return 0;
+}
+
+static int notify_parent(int status)
+{
+ int res;
+
+ report_to_parent = 0;
+ if ((res = write(daemon_pipe, &status, sizeof(int))) != sizeof(int)) {
+ usbmuxd_log(LL_FATAL, "Could not notify parent!");
+ if(res >= 0)
+ return -2;
+ else
+ return res;
}
+ close(daemon_pipe);
if (!freopen("/dev/null", "w", stderr)) {
- usbmuxd_log(LL_ERROR, "ERROR: redirection of stderr failed.");
+ usbmuxd_log(LL_FATAL, "Redirection of stderr failed.");
+ return -1;
}
-
return 0;
}
@@ -310,8 +370,9 @@ int main(int argc, char *argv[])
{
int listenfd;
int res = 0;
- FILE *lfd = NULL;
+ int lfd;
struct flock lock;
+ char pids[10];
parse_opts(argc, argv);
@@ -333,60 +394,77 @@ int main(int argc, char *argv[])
set_signal_handlers();
- lfd = fopen(lockfile, "r");
- if (lfd) {
- lock.l_type = 0;
- lock.l_whence = SEEK_SET;
- lock.l_start = 0;
- lock.l_len = 0;
- fcntl(fileno(lfd), F_GETLK, &lock);
- fclose(lfd);
- if (lock.l_type != F_UNLCK) {
- if (opt_exit) {
- if (lock.l_pid && !kill(lock.l_pid, 0)) {
- usbmuxd_log(LL_NOTICE, "sending signal %d to instance with pid %d", exit_signal, lock.l_pid);
- if (kill(lock.l_pid, exit_signal) < 0) {
- usbmuxd_log(LL_FATAL, "Error: could not deliver signal %d to pid %d", exit_signal, lock.l_pid);
- }
- res = 0;
- goto terminate;
- } else {
- usbmuxd_log(LL_ERROR, "Could not determine pid of the other running instance!");
+ res = lfd = open(lockfile, O_WRONLY|O_CREAT, 0644);
+ if(res == -1) {
+ usbmuxd_log(LL_FATAL, "Could not open lockfile");
+ goto terminate;
+ }
+ lock.l_type = F_WRLCK;
+ lock.l_whence = SEEK_SET;
+ lock.l_start = 0;
+ lock.l_len = 0;
+ fcntl(lfd, F_GETLK, &lock);
+ close(lfd);
+ if (lock.l_type != F_UNLCK) {
+ if (opt_exit) {
+ if (lock.l_pid && !kill(lock.l_pid, 0)) {
+ usbmuxd_log(LL_NOTICE, "Sending signal %d to instance with pid %d", exit_signal, lock.l_pid);
+ res = 0;
+ if (kill(lock.l_pid, exit_signal) < 0) {
+ usbmuxd_log(LL_FATAL, "Could not deliver signal %d to pid %d", exit_signal, lock.l_pid);
res = -1;
- goto terminate;
}
+ goto terminate;
} else {
- if (!opt_udev) {
- usbmuxd_log(LL_ERROR, "Another instance is already running (pid %d). exiting.", lock.l_pid);
- res = -1;
- } else {
- usbmuxd_log(LL_NOTICE, "Another instance is already running (pid %d). exiting.", lock.l_pid);
- res = 0;
- }
+ usbmuxd_log(LL_ERROR, "Could not determine pid of the other running instance!");
+ res = -1;
goto terminate;
}
+ } else {
+ if (!opt_udev) {
+ usbmuxd_log(LL_ERROR, "Another instance is already running (pid %d). exiting.", lock.l_pid);
+ res = -1;
+ } else {
+ usbmuxd_log(LL_NOTICE, "Another instance is already running (pid %d). exiting.", lock.l_pid);
+ res = 0;
+ }
+ goto terminate;
}
}
+ unlink(lockfile);
if (opt_exit) {
usbmuxd_log(LL_NOTICE, "No running instance found, none killed. exiting.");
goto terminate;
}
- // now open the lockfile and place the lock
- lfd = fopen(lockfile, "w");
- if (lfd) {
- lock.l_type = F_WRLCK;
- lock.l_whence = SEEK_SET;
- lock.l_start = 0;
- lock.l_len = 0;
- if ((res = fcntl(fileno(lfd), F_SETLK, &lock)) < 0) {
- usbmuxd_log(LL_FATAL, "Lockfile locking failed!");
+ if (!foreground) {
+ if ((res = daemonize()) < 0) {
+ fprintf(stderr, "usbmuxd: FATAL: Could not daemonize!\n");
+ usbmuxd_log(LL_FATAL, "Could not daemonize!");
goto terminate;
}
- } else {
- usbmuxd_log(LL_FATAL, "Lockfile open failed!");
- res = -1;
+ }
+
+ // now open the lockfile and place the lock
+ res = lfd = open(lockfile, O_WRONLY|O_CREAT|O_TRUNC|O_EXCL, 0644);
+ if(res < 0) {
+ usbmuxd_log(LL_FATAL, "Could not open lockfile");
+ goto terminate;
+ }
+ lock.l_type = F_WRLCK;
+ lock.l_whence = SEEK_SET;
+ lock.l_start = 0;
+ lock.l_len = 0;
+ if ((res = fcntl(lfd, F_SETLK, &lock)) < 0) {
+ usbmuxd_log(LL_FATAL, "Lockfile locking failed!");
+ goto terminate;
+ }
+ sprintf(pids, "%d", getpid());
+ if ((res = write(lfd, pids, strlen(pids))) != strlen(pids)) {
+ usbmuxd_log(LL_FATAL, "Could not write pidfile!");
+ if(res >= 0)
+ res = -2;
goto terminate;
}
@@ -400,7 +478,7 @@ int main(int argc, char *argv[])
struct passwd *pw = getpwnam(drop_user);
if (!pw) {
usbmuxd_log(LL_FATAL, "Dropping privileges failed, check if user '%s' exists!", drop_user);
- res = 1;
+ res = -1;
goto terminate;
}
@@ -420,12 +498,12 @@ int main(int argc, char *argv[])
// security check
if (setuid(0) != -1) {
usbmuxd_log(LL_FATAL, "Failed to drop privileges properly!");
- res = 1;
+ res = -1;
goto terminate;
}
if (getuid() != pw->pw_uid || getgid() != pw->pw_gid) {
usbmuxd_log(LL_FATAL, "Failed to drop privileges properly!");
- res = 1;
+ res = -1;
goto terminate;
}
usbmuxd_log(LL_NOTICE, "Successfully dropped privileges to '%s'", drop_user);
@@ -441,13 +519,9 @@ int main(int argc, char *argv[])
usbmuxd_log(LL_NOTICE, "Initialization complete");
- if (!foreground) {
- if ((res = daemonize()) < 0) {
- fprintf(stderr, "usbmuxd: FATAL: Could not daemonize!\n");
- usbmuxd_log(LL_FATAL, "Could not daemonize!");
+ if (report_to_parent)
+ if((res = notify_parent(0)) < 0)
goto terminate;
- }
- }
res = main_loop(listenfd);
if(res < 0)
@@ -463,7 +537,12 @@ int main(int argc, char *argv[])
terminate:
log_disable_syslog();
- if(res < 0)
- return -res;
- return 0;
+ if (res < 0)
+ res = -res;
+ else
+ res = 0;
+ if (report_to_parent)
+ notify_parent(res);
+
+ return res;
}
--
cgit v1.1-32-gdbae