chiark / gitweb /
[PATCH] udevd - switch socket path to abstract namespace
[elogind.git] / udevd.c
diff --git a/udevd.c b/udevd.c
index da887ec..24cf9c9 100644 (file)
--- a/udevd.c
+++ b/udevd.c
@@ -1,9 +1,6 @@
 /*
- * udevd.c
+ * udevd.c - hotplug event serializer
  *
- * Userspace devfs
- *
- * Copyright (C) 2004 Ling, Xiaofeng <xiaofeng.ling@intel.com>
  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
  *
  *
  *
  */
 
+#include <pthread.h>
+#include <stddef.h>
 #include <sys/types.h>
-#include <sys/ipc.h>
 #include <sys/wait.h>
-#include <sys/msg.h>
 #include <signal.h>
 #include <unistd.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
 
+#include "list.h"
 #include "udev.h"
+#include "udev_version.h"
 #include "udevd.h"
 #include "logging.h"
 
-#define BUFFER_SIZE                    1024
-#define EVENT_TIMEOUT_SECONDS          10
-#define DAEMON_TIMEOUT_SECONDS         30
 
+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;
 
-static int expect_seqnum = 0;
-static struct hotplug_msg *head = NULL;
+LIST_HEAD(msg_list);
+LIST_HEAD(exec_list);
+LIST_HEAD(running_list);
 
 
-static void sig_alarmhandler(int signum)
+static void msg_dump_queue(void)
 {
-       dbg("caught signal %d", signum);
-       switch (signum) {
-       case SIGALRM:
-               dbg("event timeout reached");
-               break;
+       struct hotplug_msg *msg;
 
-       default:
-               dbg("unhandled signal");
-       }
+       list_for_each_entry(msg, &msg_list, list)
+               dbg("sequence %d in queue", msg->seqnum);
 }
 
-static void dump_queue(void)
+static void msg_dump(struct hotplug_msg *msg)
 {
-       struct hotplug_msg *p;
-       p = head;
+       dbg("sequence %d, '%s', '%s', '%s'",
+           msg->seqnum, msg->action, msg->devpath, msg->subsystem);
+}
+
+static struct hotplug_msg *msg_create(void)
+{
+       struct hotplug_msg *new_msg;
 
-       dbg("next expected sequence is %d", expect_seqnum);
-       while(p != NULL) {
-               dbg("sequence %d in queue", p->seqnum);
-               p = p->next;
+       new_msg = malloc(sizeof(struct hotplug_msg));
+       if (new_msg == NULL) {
+               dbg("error malloc");
+               return NULL;
        }
+       return new_msg;
 }
 
-static void dump_msg(struct hotplug_msg *pmsg)
+static void msg_delete(struct hotplug_msg *msg)
 {
-       dbg("sequence %d, '%s', '%s', '%s'",
-           pmsg->seqnum, pmsg->action, pmsg->devpath, pmsg->subsystem);
+       if (msg != NULL)
+               free(msg);
 }
 
-static int dispatch_msg(struct hotplug_msg *pmsg)
+/* orders the message in the queue by sequence number */
+static void msg_queue_insert(struct hotplug_msg *msg)
 {
-       pid_t pid;
-       char *argv[3];
-       extern char **environ;
+       struct hotplug_msg *loop_msg;
 
-       dump_msg(pmsg);
+       /* sort message by sequence number into list*/
+       list_for_each_entry(loop_msg, &msg_list, list)
+               if (loop_msg->seqnum > msg->seqnum)
+                       break;
+       list_add_tail(&msg->list, &loop_msg->list);
+       dbg("queued message seq %d", msg->seqnum);
+
+       /* store timestamp of queuing */
+       msg->queue_time = time(NULL);
+
+       /* signal queue activity to manager */
+       pthread_mutex_lock(&msg_active_lock);
+       pthread_cond_signal(&msg_active);
+       pthread_mutex_unlock(&msg_active_lock);
+
+       return ;
+}
+
+/* forks event and removes event from run queue when finished */
+static void *run_threads(void * parm)
+{
+       pid_t pid;
+       struct hotplug_msg *msg;
 
-       setenv("ACTION", pmsg->action, 1);
-       setenv("DEVPATH", pmsg->devpath, 1);
-       argv[0] = DEFAULT_UDEV_EXEC;
-       argv[1] = pmsg->subsystem;
-       argv[2] = NULL;
+       msg = parm;
+       setenv("ACTION", msg->action, 1);
+       setenv("DEVPATH", msg->devpath, 1);
 
        pid = fork();
        switch (pid) {
        case 0:
                /* child */
-               execve(argv[0], argv, environ);
+               execl(UDEV_BIN, "udev", msg->subsystem, NULL);
                dbg("exec of child failed");
                exit(1);
                break;
        case -1:
                dbg("fork of child failed");
-               return -1;
+               goto exit;
        default:
-               wait(0);
+               /* 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);
        }
-       return 0;
+
+exit:
+       /* remove event from run list */
+       pthread_mutex_lock(&running_lock);
+       list_del_init(&msg->list);
+       pthread_mutex_unlock(&running_lock);
+
+       msg_delete(msg);
+
+       /* signal queue activity to exec manager */
+       pthread_mutex_lock(&exec_active_lock);
+       pthread_cond_signal(&exec_active);
+       pthread_mutex_unlock(&exec_active_lock);
+
+       pthread_exit(0);
 }
 
-static void set_timer(int seconds)
+/* returns already running task with devpath */
+static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
 {
-       signal(SIGALRM, sig_alarmhandler);
-       alarm(seconds);
+       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)
+                       return loop_msg;
+       return NULL;
 }
 
-static void check_queue(void)
+/* queue management executes the events and delays events for the same devpath */
+static void *exec_queue_manager(void * parm)
 {
-       struct hotplug_msg *p;
-       p = head;
-
-       dump_queue();
-       while(head != NULL && head->seqnum == expect_seqnum) {
-               dispatch_msg(head);
-               expect_seqnum++;
-               p = head;
-               head = head->next;
-               free(p);
+       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);
+                       }
+               }
+               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);
        }
-       if (head != NULL)
-               set_timer(EVENT_TIMEOUT_SECONDS);
-       else
-               set_timer(DAEMON_TIMEOUT_SECONDS);
 }
 
-static void add_queue(struct hotplug_msg *pmsg)
+static void exec_queue_activate(void)
 {
-       struct hotplug_msg *pnewmsg;
-       struct hotplug_msg *p;
-       struct hotplug_msg *p1;
-
-       p = head;
-       p1 = NULL;
-       pnewmsg = malloc(sizeof(struct hotplug_msg));
-       *pnewmsg = *pmsg;
-       pnewmsg->next = NULL;
-       while(p != NULL && pmsg->seqnum > p->seqnum) {
-               p1 = p;
-               p = p->next;
-       }
-       pnewmsg->next = p;
-       if (p1 == NULL) {
-               head = pnewmsg;
-       } else {
-               p1->next = pnewmsg;
-       }
-       dump_queue();
+       pthread_mutex_lock(&exec_active_lock);
+       pthread_cond_signal(&exec_active);
+       pthread_mutex_unlock(&exec_active_lock);
 }
 
-static int process_queue(void)
+/* move message from incoming to exec queue */
+static void msg_move_exec(struct list_head *head)
 {
-       int msgid;
-       key_t key;
-       struct hotplug_msg *pmsg;
-       char buf[BUFFER_SIZE];
-       int ret;
-
-       key = ftok(DEFAULT_UDEVD_EXEC, IPC_KEY_ID);
-       pmsg = (struct hotplug_msg *) buf;
-       msgid = msgget(key, IPC_CREAT);
-       if (msgid == -1) {
-               dbg("open message queue error");
-               return -1;
-       }
+       list_move_tail(head, &exec_list);
+       exec_queue_activate();
+}
+
+/* queue management thread handles the timeouts and dispatches the events */
+static void *msg_queue_manager(void * parm)
+{
+       struct hotplug_msg *loop_msg;
+       struct hotplug_msg *tmp_msg;
+       time_t msg_age = 0;
+       struct timespec tv;
+
        while (1) {
-               ret = msgrcv(msgid, (struct msgbuf *) buf, BUFFER_SIZE-4, HOTPLUGMSGTYPE, 0);
-               if (ret != -1) {
-                       dbg("current sequence %d, expected sequence %d", pmsg->seqnum, expect_seqnum);
-
-                       /* init expected sequence with value from first call */
-                       if (expect_seqnum == 0) {
-                               expect_seqnum = pmsg->seqnum;
-                               dbg("init next expected sequence number to %d", expect_seqnum);
+               dbg("msg queue manager, next expected is %d", expected_seqnum);
+               pthread_mutex_lock(&msg_lock);
+               pthread_mutex_lock(&exec_lock);
+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;
                        }
 
-                       if (pmsg->seqnum > expect_seqnum) {
-                               add_queue(pmsg);
-                               set_timer(EVENT_TIMEOUT_SECONDS);
+                       /* 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 {
-                               if (pmsg->seqnum == expect_seqnum) {
-                                       dispatch_msg(pmsg);
-                                       expect_seqnum++;
-                                       check_queue();
-                               } else {
-                                       dbg("timeout event for unexpected sequence number %d", pmsg->seqnum);
-                               }
+                               break;
                        }
+               }
+
+               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);
+
+               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);
                } else {
-                       if (errno == EINTR) {
-                               if (head != NULL) {
-                                       /* event timeout, skip all missing, proceed with next queued event */
-                                       info("timeout reached, skip events %d - %d", expect_seqnum, head->seqnum-1);
-                                       expect_seqnum = head->seqnum;
-                               } else {
-                                       info("we have nothing to do, so daemon exits...");
-                                       exit(0);
-                               }
-                               check_queue();
-                       } else {
-                               dbg("ipc message receive error '%s'", strerror(errno));
-                       }
+                       pthread_cond_wait(&msg_active, &msg_active_lock);
                }
+               pthread_mutex_unlock(&msg_active_lock);
        }
-       return 0;
+}
+
+/* every connect creates a thread which gets the msg, queues it and exits */
+static void *client_threads(void * parm)
+{
+       int sock;
+       struct hotplug_msg *msg;
+       int retval;
+
+       sock = (int) parm;
+
+       msg = msg_create();
+       if (msg == NULL) {
+               dbg("unable to store message");
+               goto exit;
+       }
+
+       retval = recv(sock, msg, sizeof(struct hotplug_msg), 0);
+       if (retval <  0) {
+               dbg("unable to receive message");
+               goto exit;
+       }
+
+       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 no seqnum is given, we move straight to exec queue */
+       if (msg->seqnum == 0) {
+               pthread_mutex_lock(&exec_lock);
+               list_add(&msg->list, &exec_list);
+               exec_queue_activate();
+               pthread_mutex_unlock(&exec_lock);
+       } else {
+               pthread_mutex_lock(&msg_lock);
+               msg_queue_insert(msg);
+               pthread_mutex_unlock(&msg_lock);
+       }
+
+exit:
+       close(sock);
+       pthread_exit(0);
 }
 
 static void sig_handler(int signum)
 {
-       dbg("caught signal %d", signum);
        switch (signum) {
                case SIGINT:
                case SIGTERM:
-               case SIGKILL:
+                       unlink(UDEVD_LOCK);
                        exit(20 + signum);
                        break;
-
                default:
                        dbg("unhandled signal");
        }
 }
 
+static int one_and_only(void)
+{
+       char string[50];
+       int lock_file;
+
+       lock_file = open(UDEVD_LOCK, O_RDWR | O_CREAT, 0x640);
+       if (lock_file < 0)
+               return -1;
+
+       /* see if we can lock */
+       if (lockf(lock_file, F_TLOCK, 0) < 0) {
+               dbg("file is already locked, exit");
+               close(lock_file);
+               return -1;
+       }
+
+       snprintf(string, sizeof(string), "%d\n", getpid());
+       write(lock_file, string, strlen(string));
+
+       return 0;
+}
+
 int main(int argc, char *argv[])
 {
-       /* set up signal handler */
+       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;
+       int retval;
+
+       init_logging("udevd");
+
+       /* only let one version of the daemon run at any one time */
+       if (one_and_only() != 0)
+               exit(0);
+
        signal(SIGINT, sig_handler);
        signal(SIGTERM, sig_handler);
-       signal(SIGKILL, sig_handler);
 
-       /* we exit if we have nothing to do, next event will start us again */
-       set_timer(DAEMON_TIMEOUT_SECONDS);
+       memset(&saddr, 0x00, sizeof(saddr));
+       saddr.sun_family = AF_LOCAL;
+       /* use abstract namespace for socket path */
+       strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
+
+       ssock = socket(AF_LOCAL, SOCK_STREAM, 0);
+       if (ssock == -1) {
+               dbg("error getting socket");
+               exit(1);
+       }
 
+       retval = bind(ssock, &saddr, sizeof(saddr));
+       if (retval < 0) {
+               dbg("bind failed\n");
+               goto exit;
+       }
+
+       retval = listen(ssock, SOMAXCONN);
+       if (retval < 0) {
+               dbg("listen failed\n");
+               goto exit;
+       }
+
+       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);
+
+       /* 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);
+
+       /* 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);
+
+       clen = sizeof(caddr);
        /* main loop */
-       process_queue();
-       return 0;
+       while (1) {
+               csock = accept(ssock, &caddr, &clen);
+               if (csock < 0) {
+                       dbg("client accept failed\n");
+                       continue;
+               }
+               pthread_create(&cli_tid, &thr_attr, client_threads, (void *) csock);
+       }
+exit:
+       close(ssock);
+       exit(1);
 }