chiark / gitweb /
[PATCH] klibc: use klcc wrapper instead of our own Makefile
[elogind.git] / udevd.c
diff --git a/udevd.c b/udevd.c
index 331b7e4..2cd3622 100644 (file)
--- a/udevd.c
+++ b/udevd.c
@@ -1,7 +1,8 @@
 /*
  * udevd.c - hotplug event serializer
  *
- * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2004-2005 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2004 Chris Friesen <chris_friesen@sympatico.ca>
  *
  *
  *     This program is free software; you can redistribute it and/or modify it
  *
  */
 
-#include <pthread.h>
 #include <stddef.h>
-#include <sys/types.h>
-#include <sys/wait.h>
 #include <signal.h>
 #include <unistd.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <time.h>
+#include <ctype.h>
+#include <dirent.h>
 #include <fcntl.h>
+#include <sys/select.h>
+#include <sys/wait.h>
+#include <sys/time.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <sys/sysinfo.h>
+#include <sys/stat.h>
 
 #include "list.h"
+#include "udev_libc_wrapper.h"
 #include "udev.h"
 #include "udev_version.h"
+#include "udev_utils.h"
 #include "udevd.h"
 #include "logging.h"
 
-
-unsigned char logname[42];
-static pthread_mutex_t  msg_lock;
-static pthread_mutex_t  msg_active_lock;
-static pthread_cond_t msg_active;
-static pthread_mutex_t  exec_lock;
-static pthread_mutex_t  exec_active_lock;
-static pthread_cond_t exec_active;
-static pthread_mutex_t  running_lock;
-static pthread_attr_t thr_attr;
-static int expected_seqnum = 0;
-
-LIST_HEAD(msg_list);
-LIST_HEAD(exec_list);
-LIST_HEAD(running_list);
-
-
-static void msg_dump_queue(void)
+/* global variables*/
+static int udevsendsock;
+static pid_t sid;
+
+static int pipefds[2];
+static long startup_time;
+static unsigned long long expected_seqnum = 0;
+static volatile int sigchilds_waiting;
+static volatile int run_msg_q;
+static volatile int sig_flag;
+static int run_exec_q;
+
+static LIST_HEAD(msg_list);
+static LIST_HEAD(exec_list);
+static LIST_HEAD(running_list);
+
+static void exec_queue_manager(void);
+static void msg_queue_manager(void);
+static void user_sighandler(void);
+static void reap_sigchilds(void);
+char *udev_bin;
+
+#ifdef USE_LOG
+void log_message (int level, const char *format, ...)
 {
-       struct hotplug_msg *msg;
+       va_list args;
 
-       list_for_each_entry(msg, &msg_list, list)
-               dbg("sequence %d in queue", msg->seqnum);
+       va_start(args, format);
+       vsyslog(level, format, args);
+       va_end(args);
 }
+#endif
 
-static void msg_dump(struct hotplug_msg *msg)
-{
-       dbg("sequence %d, '%s', '%s', '%s'",
-           msg->seqnum, msg->action, msg->devpath, msg->subsystem);
-}
+#define msg_dump(msg) \
+       dbg("msg_dump: sequence %llu, '%s', '%s', '%s'", \
+       msg->seqnum, msg->action, msg->devpath, msg->subsystem);
 
-static struct hotplug_msg *msg_create(void)
+static void msg_dump_queue(void)
 {
-       struct hotplug_msg *new_msg;
+#ifdef DEBUG
+       struct hotplug_msg *msg;
 
-       new_msg = malloc(sizeof(struct hotplug_msg));
-       if (new_msg == NULL) {
-               dbg("error malloc");
-               return NULL;
-       }
-       return new_msg;
+       list_for_each_entry(msg, &msg_list, node)
+               dbg("sequence %llu in queue", msg->seqnum);
+#endif
 }
 
-static void msg_delete(struct hotplug_msg *msg)
+static void run_queue_delete(struct hotplug_msg *msg)
 {
-       if (msg != NULL)
-               free(msg);
+       list_del(&msg->node);
+       free(msg);
 }
 
 /* orders the message in the queue by sequence number */
 static void msg_queue_insert(struct hotplug_msg *msg)
 {
        struct hotplug_msg *loop_msg;
+       struct sysinfo info;
+
+       if (msg->seqnum == 0) {
+               dbg("no SEQNUM, move straight to the exec queue");
+               list_add(&msg->node, &exec_list);
+               run_exec_q = 1;
+               return;
+       }
 
-       /* sort message by sequence number into list*/
-       list_for_each_entry(loop_msg, &msg_list, list)
-               if (loop_msg->seqnum > msg->seqnum)
+       /* sort message by sequence number into list */
+       list_for_each_entry_reverse(loop_msg, &msg_list, node) {
+               if (loop_msg->seqnum < msg->seqnum)
                        break;
-       list_add_tail(&msg->list, &loop_msg->list);
-       dbg("queued message seq %d", msg->seqnum);
+
+               if (loop_msg->seqnum == msg->seqnum) {
+                       dbg("ignoring duplicate message seq %llu", msg->seqnum);
+                       return;
+               }
+       }
 
        /* store timestamp of queuing */
-       msg->queue_time = time(NULL);
+       sysinfo(&info);
+       msg->queue_time = info.uptime;
 
-       /* signal queue activity to manager */
-       pthread_mutex_lock(&msg_active_lock);
-       pthread_cond_signal(&msg_active);
-       pthread_mutex_unlock(&msg_active_lock);
+       list_add(&msg->node, &loop_msg->node);
+       dbg("queued message seq %llu", msg->seqnum);
 
-       return ;
+       /* run msg queue manager */
+       run_msg_q = 1;
+
+       return;
 }
 
 /* forks event and removes event from run queue when finished */
-static void *run_threads(void * parm)
+static void udev_run(struct hotplug_msg *msg)
 {
+       char *const argv[] = { "udev", msg->subsystem, NULL };
        pid_t pid;
-       struct hotplug_msg *msg;
-
-       msg = parm;
-       setenv("ACTION", msg->action, 1);
-       setenv("DEVPATH", msg->devpath, 1);
 
        pid = fork();
        switch (pid) {
        case 0:
                /* child */
-               execl(UDEV_BIN, "udev", msg->subsystem, NULL);
+               close(udevsendsock);
+               logging_close();
+
+               setpriority(PRIO_PROCESS, 0, UDEV_PRIORITY);
+               execve(udev_bin, argv, msg->envp);
                dbg("exec of child failed");
-               exit(1);
+               _exit(1);
                break;
        case -1:
                dbg("fork of child failed");
-               goto exit;
+               run_queue_delete(msg);
+               break;
        default:
-               /* wait for exit of child */
-               dbg("==> exec seq %d [%d] working at '%s'",
-                   msg->seqnum, pid, msg->devpath);
-               wait(NULL);
-               dbg("<== exec seq %d came back", msg->seqnum);
+               /* get SIGCHLD in main loop */
+               dbg("==> exec seq %llu [%d] working at '%s'", msg->seqnum, pid, msg->devpath);
+               msg->pid = pid;
        }
+}
 
-exit:
-       /* remove event from run list */
-       pthread_mutex_lock(&running_lock);
-       list_del_init(&msg->list);
-       pthread_mutex_unlock(&running_lock);
+static int running_processes(void)
+{
+       int f;
+       static char buf[4096];
+       int len;
+       int running;
+       const char *pos;
+
+       f = open("/proc/stat", O_RDONLY);
+       if (f == -1)
+               return -1;
+
+       len = read(f, buf, sizeof(buf));
+       close(f);
+
+       if (len <= 0)
+               return -1;
+       else
+               buf[len] = '\0';
+
+       pos = strstr(buf, "procs_running ");
+       if (pos == NULL)
+               return -1;
+
+       if (sscanf(pos, "procs_running %u", &running) != 1)
+               return -1;
+
+       return running;
+}
+
+/* return the number of process es in our session, count only until limit */
+static int running_processes_in_session(pid_t session, int limit)
+{
+       DIR *dir;
+       struct dirent *dent;
+       int running = 0;
+
+       dir = opendir("/proc");
+       if (!dir)
+               return -1;
+
+       /* read process info from /proc */
+       for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
+               int f;
+               char procdir[64];
+               char line[256];
+               const char *pos;
+               char state;
+               pid_t ppid, pgrp, sess;
+               int len;
+
+               if (!isdigit(dent->d_name[0]))
+                       continue;
+
+               snprintf(procdir, sizeof(procdir), "/proc/%s/stat", dent->d_name);
+               procdir[sizeof(procdir)-1] = '\0';
+
+               f = open(procdir, O_RDONLY);
+               if (f == -1)
+                       continue;
+
+               len = read(f, line, sizeof(line));
+               close(f);
+
+               if (len <= 0)
+                       continue;
+               else
+                       line[len] = '\0';
+
+               /* skip ugly program name */
+               pos = strrchr(line, ')') + 2;
+               if (pos == NULL)
+                       continue;
+
+               if (sscanf(pos, "%c %d %d %d ", &state, &ppid, &pgrp, &sess) != 4)
+                       continue;
+
+               /* count only processes in our session */
+               if (sess != session)
+                       continue;
+
+               /* count only running, no sleeping processes */
+               if (state != 'R')
+                       continue;
+
+               running++;
+               if (limit > 0 && running >= limit)
+                       break;
+       }
+       closedir(dir);
+
+       return running;
+}
+
+static int compare_devpath(const char *running, const char *waiting)
+{
+       int i;
 
-       msg_delete(msg);
+       for (i = 0; i < PATH_SIZE; i++) {
+               /* identical device event found */
+               if (running[i] == '\0' && waiting[i] == '\0')
+                       return 1;
 
-       /* signal queue activity to exec manager */
-       pthread_mutex_lock(&exec_active_lock);
-       pthread_cond_signal(&exec_active);
-       pthread_mutex_unlock(&exec_active_lock);
+               /* parent device event found */
+               if (running[i] == '\0' && waiting[i] == '/')
+                       return 2;
 
-       pthread_exit(0);
+               /* child device event found */
+               if (running[i] == '/' && waiting[i] == '\0')
+                       return 3;
+
+               /* no matching event */
+               if (running[i] != waiting[i])
+                       break;
+       }
+
+       return 0;
 }
 
-/* returns already running task with devpath */
+/* returns still running task for the same device, its parent or its physical device */
 static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
 {
        struct hotplug_msg *loop_msg;
-       struct hotplug_msg *tmp_msg;
 
-       list_for_each_entry_safe(loop_msg, tmp_msg, &running_list, list)
-               if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
+       if (msg->devpath == NULL)
+               return NULL;
+
+       list_for_each_entry(loop_msg, &running_list, node) {
+               if (loop_msg->devpath == NULL)
+                       continue;
+
+               /* return running parent/child device event */
+               if (compare_devpath(loop_msg->devpath, msg->devpath) != 0)
                        return loop_msg;
+
+               /* return running physical device event */
+               if (msg->physdevpath && msg->action && strcmp(msg->action, "add") == 0)
+                       if (compare_devpath(loop_msg->devpath, msg->physdevpath) != 0)
+                               return loop_msg;
+       }
+
        return NULL;
 }
 
-/* queue management executes the events and delays events for the same devpath */
-static void *exec_queue_manager(void * parm)
+/* exec queue management routine executes the events and serializes events in the same sequence */
+static void exec_queue_manager(void)
 {
        struct hotplug_msg *loop_msg;
        struct hotplug_msg *tmp_msg;
        struct hotplug_msg *msg;
-       pthread_t run_tid;
-
-       while (1) {
-               pthread_mutex_lock(&exec_lock);
-               list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
-                       msg = running_with_devpath(loop_msg);
-                       if (msg == NULL) {
-                               /* move event to run list */
-                               pthread_mutex_lock(&running_lock);
-                               list_move_tail(&loop_msg->list, &running_list);
-                               pthread_mutex_unlock(&running_lock);
-
-                               pthread_create(&run_tid, &thr_attr, run_threads, (void *) loop_msg);
-
-                               dbg("moved seq %d to running list", loop_msg->seqnum);
-                       } else {
-                               dbg("delay seq %d, cause seq %d already working on '%s'",
-                                   loop_msg->seqnum, msg->seqnum, msg->devpath);
+       int running;
+
+       running = running_processes();
+       dbg("%d processes runnning on system", running);
+       if (running < 0)
+               running = THROTTLE_MAX_RUNNING_CHILDS;
+
+       list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, node) {
+               /* check running processes in our session and possibly throttle */
+               if (running >= THROTTLE_MAX_RUNNING_CHILDS) {
+                       running = running_processes_in_session(sid, THROTTLE_MAX_RUNNING_CHILDS+10);
+                       dbg("%d processes running in session", running);
+                       if (running >= THROTTLE_MAX_RUNNING_CHILDS) {
+                               dbg("delay seq %llu, cause too many processes already running", loop_msg->seqnum);
+                               return;
                        }
                }
-               pthread_mutex_unlock(&exec_lock);
 
-               /* wait for activation, new events or childs coming back */
-               pthread_mutex_lock(&exec_active_lock);
-               pthread_cond_wait(&exec_active, &exec_active_lock);
-               pthread_mutex_unlock(&exec_active_lock);
+               msg = running_with_devpath(loop_msg);
+               if (!msg) {
+                       /* move event to run list */
+                       list_move_tail(&loop_msg->node, &running_list);
+                       udev_run(loop_msg);
+                       running++;
+                       dbg("moved seq %llu to running list", loop_msg->seqnum);
+               } else {
+                       dbg("delay seq %llu (%s), cause seq %llu (%s) is still running",
+                           loop_msg->seqnum, loop_msg->devpath, msg->seqnum, msg->devpath);
+               }
        }
 }
 
-/* move message from incoming to exec queue */
-static void msg_move_exec(struct list_head *head)
+static void msg_move_exec(struct hotplug_msg *msg)
 {
-       list_move_tail(head, &exec_list);
-       /* signal queue activity to manager */
-       pthread_mutex_lock(&exec_active_lock);
-       pthread_cond_signal(&exec_active);
-       pthread_mutex_unlock(&exec_active_lock);
+       list_move_tail(&msg->node, &exec_list);
+       run_exec_q = 1;
+       expected_seqnum = msg->seqnum+1;
+       dbg("moved seq %llu to exec, next expected is %llu",
+               msg->seqnum, expected_seqnum);
 }
 
-/* queue management thread handles the timeouts and dispatches the events */
-static void *msg_queue_manager(void * parm)
+/* msg queue management routine handles the timeouts and dispatches the events */
+static void msg_queue_manager(void)
 {
        struct hotplug_msg *loop_msg;
        struct hotplug_msg *tmp_msg;
-       time_t msg_age = 0;
-       struct timespec tv;
+       struct sysinfo info;
+       long msg_age = 0;
+       static int timeout = EVENT_INIT_TIMEOUT_SEC;
+       static int init = 1;
 
-       while (1) {
-               dbg("msg queue manager, next expected is %d", expected_seqnum);
-               pthread_mutex_lock(&msg_lock);
-               pthread_mutex_lock(&exec_lock);
+       dbg("msg queue manager, next expected is %llu", expected_seqnum);
 recheck:
-               list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
-                       /* move event with expected sequence to the exec list */
-                       if (loop_msg->seqnum == expected_seqnum) {
-                               msg_move_exec(&loop_msg->list);
-                               expected_seqnum++;
-                               dbg("moved seq %d to exec, next expected is %d",
-                                   loop_msg->seqnum, expected_seqnum);
-                               continue;
-                       }
-
-                       /* move event with expired timeout to the exec list */
-                       msg_age = time(NULL) - loop_msg->queue_time;
-                       if (msg_age > EVENT_TIMEOUT_SEC-1) {
-                               msg_move_exec(&loop_msg->list);
-                               expected_seqnum = loop_msg->seqnum+1;
-                               dbg("moved seq %d to exec, reset next expected to %d",
-                                   loop_msg->seqnum, expected_seqnum);
-                               goto recheck;
-                       } else {
-                               break;
-                       }
+       list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, node) {
+               /* move event with expected sequence to the exec list */
+               if (loop_msg->seqnum == expected_seqnum) {
+                       msg_move_exec(loop_msg);
+                       continue;
                }
 
-               msg_dump_queue();
-               pthread_mutex_unlock(&exec_lock);
-               pthread_mutex_unlock(&msg_lock);
-
-               /* wait until queue gets active or next message timeout expires */
-               pthread_mutex_lock(&msg_active_lock);
+               /* see if we are in the initialization phase and wait for the very first events */
+               if (init && (info.uptime - startup_time >= INIT_TIME_SEC)) {
+                       init = 0;
+                       timeout = EVENT_TIMEOUT_SEC;
+                       dbg("initialization phase passed, set timeout to %i seconds", EVENT_TIMEOUT_SEC);
+               }
 
-               if (list_empty(&msg_list) == 0) {
-                       tv.tv_sec = time(NULL) + EVENT_TIMEOUT_SEC - msg_age;
-                       tv.tv_nsec = 0;
-                       dbg("next event expires in %li seconds",
-                           EVENT_TIMEOUT_SEC - msg_age);
-                       pthread_cond_timedwait(&msg_active, &msg_active_lock, &tv);
+               /* move event with expired timeout to the exec list */
+               sysinfo(&info);
+               msg_age = info.uptime - loop_msg->queue_time;
+               dbg("seq %llu is %li seconds old", loop_msg->seqnum, msg_age);
+               if (msg_age >= timeout) {
+                       msg_move_exec(loop_msg);
+                       goto recheck;
                } else {
-                       pthread_cond_wait(&msg_active, &msg_active_lock);
+                       break;
                }
-               pthread_mutex_unlock(&msg_active_lock);
+       }
+
+       msg_dump_queue();
+
+       /* set timeout for remaining queued events */
+       if (list_empty(&msg_list) == 0) {
+               struct itimerval itv = {{0, 0}, {timeout - msg_age, 0}};
+               dbg("next event expires in %li seconds", timeout - msg_age);
+               setitimer(ITIMER_REAL, &itv, NULL);
        }
 }
 
-/* every connect creates a thread which gets the msg, queues it and exits */
-static void *client_threads(void * parm)
+/* receive the udevsend message and do some sanity checks */
+static struct hotplug_msg *get_udevsend_msg(void)
 {
-       int sock;
+       static struct udevsend_msg usend_msg;
        struct hotplug_msg *msg;
-       int retval;
-
-       sock = (int) parm;
+       int bufpos;
+       int i;
+       ssize_t size;
+       struct msghdr smsg;
+       struct cmsghdr *cmsg;
+       struct iovec iov;
+       struct ucred *cred;
+       char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
+       int envbuf_size;
+
+       memset(&usend_msg, 0x00, sizeof(struct udevsend_msg));
+       iov.iov_base = &usend_msg;
+       iov.iov_len = sizeof(struct udevsend_msg);
+
+       memset(&smsg, 0x00, sizeof(struct msghdr));
+       smsg.msg_iov = &iov;
+       smsg.msg_iovlen = 1;
+       smsg.msg_control = cred_msg;
+       smsg.msg_controllen = sizeof(cred_msg);
+
+       size = recvmsg(udevsendsock, &smsg, 0);
+       if (size <  0) {
+               if (errno != EINTR)
+                       dbg("unable to receive udevsend message");
+               return NULL;
+       }
+       cmsg = CMSG_FIRSTHDR(&smsg);
+       cred = (struct ucred *) CMSG_DATA(cmsg);
 
-       msg = msg_create();
-       if (msg == NULL) {
-               dbg("unable to store message");
-               goto exit;
+       if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
+               dbg("no sender credentials received, message ignored");
+               return NULL;
        }
 
-       retval = recv(sock, msg, sizeof(struct hotplug_msg), 0);
-       if (retval <  0) {
-               dbg("unable to receive message");
-               goto exit;
+       if (cred->uid != 0) {
+               dbg("sender uid=%i, message ignored", cred->uid);
+               return NULL;
        }
 
-       if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
-               dbg("message magic '%s' doesn't match, ignore it", msg->magic);
-               msg_delete(msg);
-               goto exit;
+       if (strncmp(usend_msg.magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
+               dbg("message magic '%s' doesn't match, ignore it", usend_msg.magic);
+               return NULL;
        }
 
-       pthread_mutex_lock(&msg_lock);
-       msg_queue_insert(msg);
-       pthread_mutex_unlock(&msg_lock);
+       envbuf_size = size - offsetof(struct udevsend_msg, envbuf);
+       dbg("envbuf_size=%i", envbuf_size);
+       msg = malloc(sizeof(struct hotplug_msg) + envbuf_size);
+       if (msg == NULL)
+               return NULL;
 
-exit:
-       close(sock);
-       pthread_exit(0);
+       memset(msg, 0x00, sizeof(struct hotplug_msg) + envbuf_size);
+
+       /* copy environment buffer and reconstruct envp */
+       memcpy(msg->envbuf, usend_msg.envbuf, envbuf_size);
+       bufpos = 0;
+       for (i = 0; (bufpos < envbuf_size) && (i < HOTPLUG_NUM_ENVP-2); i++) {
+               int keylen;
+               char *key;
+
+               key = &msg->envbuf[bufpos];
+               keylen = strlen(key);
+               msg->envp[i] = key;
+               bufpos += keylen + 1;
+               dbg("add '%s' to msg.envp[%i]", msg->envp[i], i);
+
+               /* remember some keys for further processing */
+               if (strncmp(key, "ACTION=", 7) == 0)
+                       msg->action = &key[7];
+
+               if (strncmp(key, "DEVPATH=", 8) == 0)
+                       msg->devpath = &key[8];
+
+               if (strncmp(key, "SUBSYSTEM=", 10) == 0)
+                       msg->subsystem = &key[10];
+
+               if (strncmp(key, "SEQNUM=", 7) == 0)
+                       msg->seqnum = strtoull(&key[7], NULL, 10);
+
+               if (strncmp(key, "PHYSDEVPATH=", 12) == 0)
+                       msg->physdevpath = &key[12];
+       }
+       msg->envp[i++] = "UDEVD_EVENT=1";
+       msg->envp[i] = NULL;
+
+       return msg;
 }
 
-static void sig_handler(int signum)
+static void asmlinkage sig_handler(int signum)
 {
+       int rc;
+
        switch (signum) {
                case SIGINT:
                case SIGTERM:
-                       unlink(UDEVD_LOCK);
-                       unlink(UDEVD_SOCK);
                        exit(20 + signum);
                        break;
-               default:
-                       dbg("unhandled signal");
+               case SIGALRM:
+                       /* set flag, then write to pipe if needed */
+                       run_msg_q = 1;
+                       goto do_write;
+                       break;
+               case SIGCHLD:
+                       /* set flag, then write to pipe if needed */
+                       sigchilds_waiting = 1;
+                       goto do_write;
+                       break;
+       }
+
+do_write:
+       /* if pipe is empty, write to pipe to force select to return
+        * immediately when it gets called
+        */
+       if (!sig_flag) {
+               rc = write(pipefds[1],&signum,sizeof(signum));
+               if (rc >= 0)
+                       sig_flag = 1;
+       }
+}
+
+static void udev_done(int pid)
+{
+       /* find msg associated with pid and delete it */
+       struct hotplug_msg *msg;
+
+       list_for_each_entry(msg, &running_list, node) {
+               if (msg->pid == pid) {
+                       dbg("<== exec seq %llu came back", msg->seqnum);
+                       run_queue_delete(msg);
+
+                       /* we want to run the exec queue manager since there may
+                        * be events waiting with the devpath of the one that
+                        * just finished
+                        */
+                       run_exec_q = 1;
+                       return;
+               }
+       }
+}
+
+static void reap_sigchilds(void)
+{
+       while(1) {
+               int pid = waitpid(-1, NULL, WNOHANG);
+               if ((pid == -1) || (pid == 0))
+                       break;
+               udev_done(pid);
        }
 }
 
-static int one_and_only(void)
+/* just read everything from the pipe and clear the flag,
+ * the flags was set in the signal handler
+ */
+static void user_sighandler(void)
 {
-       char string[50];
-       int lock_file;
+       int sig;
+
+       while(1) {
+               int rc = read(pipefds[0], &sig, sizeof(sig));
+               if (rc < 0)
+                       break;
+
+               sig_flag = 0;
+       }
+}
+
+static int init_udevsend_socket(void)
+{
+       struct sockaddr_un saddr;
+       socklen_t addrlen;
+       const int feature_on = 1;
+       int retval;
 
-       lock_file = open(UDEVD_LOCK, O_RDWR | O_CREAT, 0x640);
-       if (lock_file < 0)
+       memset(&saddr, 0x00, sizeof(saddr));
+       saddr.sun_family = AF_LOCAL;
+       /* use abstract namespace for socket path */
+       strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
+       addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
+
+       udevsendsock = socket(AF_LOCAL, SOCK_DGRAM, 0);
+       if (udevsendsock == -1) {
+               dbg("error getting socket, %s", strerror(errno));
                return -1;
+       }
 
-       /* see if we can lock */
-       if (lockf(lock_file, F_TLOCK, 0) < 0) {
-               dbg("file is already locked, exit");
-               close(lock_file);
+       /* the bind takes care of ensuring only one copy running */
+       retval = bind(udevsendsock, (struct sockaddr *) &saddr, addrlen);
+       if (retval < 0) {
+               dbg("bind failed, %s", strerror(errno));
+               close(udevsendsock);
                return -1;
        }
 
-       snprintf(string, sizeof(string), "%d\n", getpid());
-       write(lock_file, string, strlen(string));
+       /* enable receiving of the sender credentials */
+       setsockopt(udevsendsock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));
 
        return 0;
 }
 
-int main(int argc, char *argv[])
+int main(int argc, char *argv[], char *envp[])
 {
-       int ssock;
-       int csock;
-       struct sockaddr_un saddr;
-       struct sockaddr_un caddr;
-       socklen_t clen;
-       pthread_t cli_tid;
-       pthread_t mgr_msg_tid;
-       pthread_t mgr_exec_tid;
+       struct sysinfo info;
+       int maxsockplus;
        int retval;
+       int fd;
+       struct sigaction act;
+       fd_set readfds;
+       const char *udevd_expected_seqnum;
 
-       init_logging("udevd");
+       logging_init("udevd");
+       dbg("version %s", UDEV_VERSION);
 
-       /* only let one version of the daemon run at any one time */
-       if (one_and_only() != 0)
-               exit(0);
+       if (getuid() != 0) {
+               dbg("need to be root, exit");
+               goto exit;
+       }
 
-       signal(SIGINT, sig_handler);
-       signal(SIGTERM, sig_handler);
+       /* daemonize on request */
+       if (argc == 2 && strcmp(argv[1], "-d") == 0) {
+               pid_t pid;
 
-       memset(&saddr, 0x00, sizeof(saddr));
-       saddr.sun_family = AF_LOCAL;
-       strcpy(saddr.sun_path, UDEVD_SOCK);
+               pid = fork();
+               switch (pid) {
+               case 0:
+                       dbg("damonized fork running");
+                       break;
+               case -1:
+                       dbg("fork of daemon failed");
+                       goto exit;
+               default:
+                       logging_close();
+                       exit(0);
+               }
+       }
 
-       unlink(UDEVD_SOCK);
-       ssock = socket(AF_LOCAL, SOCK_STREAM, 0);
-       if (ssock == -1) {
-               dbg("error getting socket");
-               exit(1);
+       /* become session leader */
+       sid = setsid();
+       dbg("our session is %d", sid);
+
+       /* make sure we don't lock any path */
+       chdir("/");
+       umask(umask(077) | 022);
+
+       /*set a reasonable scheduling priority for the daemon */
+       setpriority(PRIO_PROCESS, 0, UDEVD_PRIORITY);
+
+       /* Set fds to dev/null */
+       fd = open( "/dev/null", O_RDWR );
+       if (fd >= 0)  {
+               dup2(fd, 0);
+               dup2(fd, 1);
+               dup2(fd, 2);
+               if (fd > 2)
+                       close(fd);
+       } else
+               dbg("error opening /dev/null %s", strerror(errno));
+
+       /* setup signal handler pipe */
+       retval = pipe(pipefds);
+       if (retval < 0) {
+               dbg("error getting pipes: %s", strerror(errno));
+               goto exit;
        }
 
-       retval = bind(ssock, &saddr, sizeof(saddr));
+       retval = fcntl(pipefds[0], F_SETFL, O_NONBLOCK);
        if (retval < 0) {
-               dbg("bind failed\n");
+               dbg("error fcntl on read pipe: %s", strerror(errno));
                goto exit;
        }
+       retval = fcntl(pipefds[0], F_SETFD, FD_CLOEXEC);
+       if (retval < 0)
+               dbg("error fcntl on read pipe: %s", strerror(errno));
 
-       retval = listen(ssock, SOMAXCONN);
+       retval = fcntl(pipefds[1], F_SETFL, O_NONBLOCK);
        if (retval < 0) {
-               dbg("listen failed\n");
+               dbg("error fcntl on write pipe: %s", strerror(errno));
                goto exit;
        }
+       retval = fcntl(pipefds[1], F_SETFD, FD_CLOEXEC);
+       if (retval < 0)
+               dbg("error fcntl on write pipe: %s", strerror(errno));
+
+       /* set signal handlers */
+       memset(&act, 0x00, sizeof(struct sigaction));
+       act.sa_handler = (void (*) (int))sig_handler;
+       sigemptyset(&act.sa_mask);
+       act.sa_flags = SA_RESTART;
+       sigaction(SIGINT, &act, NULL);
+       sigaction(SIGTERM, &act, NULL);
+       sigaction(SIGALRM, &act, NULL);
+       sigaction(SIGCHLD, &act, NULL);
+
+       if (init_udevsend_socket() < 0) {
+               if (errno == EADDRINUSE)
+                       dbg("another udevd running, exit");
+               else
+                       dbg("error initialising udevsend socket: %s", strerror(errno));
 
-       pthread_mutex_init(&msg_lock, NULL);
-       pthread_mutex_init(&msg_active_lock, NULL);
-       pthread_mutex_init(&exec_lock, NULL);
-       pthread_mutex_init(&exec_active_lock, NULL);
-       pthread_mutex_init(&running_lock, NULL);
+               goto exit;
+       }
 
-       /* set default attributes for created threads */
-       pthread_attr_init(&thr_attr);
-       pthread_attr_setdetachstate(&thr_attr, PTHREAD_CREATE_DETACHED);
-       pthread_attr_setstacksize(&thr_attr, 16 * 1024);
+       /* possible override of udev binary, used for testing */
+       udev_bin = getenv("UDEV_BIN");
+       if (udev_bin != NULL)
+               dbg("udev binary is set to '%s'", udev_bin);
+       else
+               udev_bin = UDEV_BIN;
+
+       /* possible init of expected_seqnum value */
+       udevd_expected_seqnum = getenv("UDEVD_EXPECTED_SEQNUM");
+       if (udevd_expected_seqnum != NULL) {
+               expected_seqnum = strtoull(udevd_expected_seqnum, NULL, 10);
+               dbg("initialize expected_seqnum to %llu", expected_seqnum);
+       }
 
-       /* init queue management */
-       pthread_create(&mgr_msg_tid, &thr_attr, msg_queue_manager, NULL);
-       pthread_create(&mgr_exec_tid, &thr_attr, exec_queue_manager, NULL);
+       /* get current time to provide shorter timeout on startup */
+       sysinfo(&info);
+       startup_time = info.uptime;
 
-       clen = sizeof(caddr);
-       /* main loop */
+       FD_ZERO(&readfds);
+       FD_SET(udevsendsock, &readfds);
+       FD_SET(pipefds[0], &readfds);
+       maxsockplus = udevsendsock+1;
        while (1) {
-               csock = accept(ssock, &caddr, &clen);
-               if (csock < 0) {
-                       dbg("client accept failed\n");
+               struct hotplug_msg *msg;
+
+               fd_set workreadfds = readfds;
+               retval = select(maxsockplus, &workreadfds, NULL, NULL, NULL);
+
+               if (retval < 0) {
+                       if (errno != EINTR)
+                               dbg("error in select: %s", strerror(errno));
                        continue;
                }
-               pthread_create(&cli_tid, &thr_attr, client_threads, (void *) csock);
+
+               if (FD_ISSET(udevsendsock, &workreadfds)) {
+                       msg = get_udevsend_msg();
+                       if (msg)
+                               msg_queue_insert(msg);
+               }
+
+               if (FD_ISSET(pipefds[0], &workreadfds))
+                       user_sighandler();
+
+               if (sigchilds_waiting) {
+                       sigchilds_waiting = 0;
+                       reap_sigchilds();
+               }
+
+               if (run_msg_q) {
+                       run_msg_q = 0;
+                       msg_queue_manager();
+               }
+
+               if (run_exec_q) {
+                        /* clean up running_list before calling exec_queue_manager() */
+                       if (sigchilds_waiting) {
+                               sigchilds_waiting = 0;
+                               reap_sigchilds();
+                       }
+
+                       run_exec_q = 0;
+                       exec_queue_manager();
+               }
        }
+
 exit:
-       close(ssock);
-       unlink(UDEVD_SOCK);
-       exit(1);
+       logging_close();
+       return 1;
 }