[thirdparty/systemd.git] / udevd.c

/*
 * Copyright (C) 2004-2006 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
 *      under the terms of the GNU General Public License as published by the
 *      Free Software Foundation version 2 of the License.
 *
 *      This program is distributed in the hope that it will be useful, but
 *      WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *      General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License along
 *      with this program; if not, write to the Free Software Foundation, Inc.,
 *      51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#include <stddef.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <dirent.h>
#include <fcntl.h>
#include <syslog.h>
#include <time.h>
#include <getopt.h>
#include <sys/select.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/netlink.h>

#include "udev.h"
#include "udev_rules.h"
#include "udevd.h"
#include "udev_selinux.h"

static int debug_trace;
static int verbose;

static struct udev_rules rules;
static int udevd_sock = -1;
static int uevent_netlink_sock = -1;
static int inotify_fd = -1;
static pid_t sid;

static int signal_pipe[2] = {-1, -1};
static volatile int sigchilds_waiting;
static volatile int udev_exit;
static volatile int reload_config;
static int run_exec_q;
static int stop_exec_q;
static int max_childs;
static int max_childs_running;
static char udev_log[32];

static LIST_HEAD(exec_list);
static LIST_HEAD(running_list);


#ifdef USE_LOG
void log_message(int priority, const char *format, ...)
{
        va_list args;

        if (priority > udev_log_priority)
                return;

        va_start(args, format);
        vsyslog(priority, format, args);
        va_end(args);

        if (verbose) {
                va_start(args, format);
                vprintf(format, args);
                va_end(args);
                printf("\n");
        }
}

#endif

static void asmlinkage udev_event_sig_handler(int signum)
{
        if (signum == SIGALRM)
                exit(1);
}

static int udev_event_process(struct udevd_uevent_msg *msg)
{
        struct sigaction act;
        struct udevice *udev;
        int i;
        int retval;

        /* set signal handlers */
        memset(&act, 0x00, sizeof(act));
        act.sa_handler = (void (*)(int)) udev_event_sig_handler;
        sigemptyset (&act.sa_mask);
        act.sa_flags = 0;
        sigaction(SIGALRM, &act, NULL);

        /* reset to default */
        act.sa_handler = SIG_DFL;
        sigaction(SIGINT, &act, NULL);
        sigaction(SIGTERM, &act, NULL);
        sigaction(SIGCHLD, &act, NULL);
        sigaction(SIGHUP, &act, NULL);

        /* trigger timeout to prevent hanging processes */
        alarm(UDEV_ALARM_TIMEOUT);

        /* reconstruct event environment from message */
        for (i = 0; msg->envp[i]; i++)
                putenv(msg->envp[i]);

        udev = udev_device_init();
        if (udev == NULL)
                return -1;
        strlcpy(udev->action, msg->action, sizeof(udev->action));
        sysfs_device_set_values(udev->dev, msg->devpath, msg->subsystem, msg->driver);
        udev->devt = msg->devt;

        retval = udev_device_event(&rules, udev);

        /* run programs collected by RUN-key*/
        if (retval == 0 && !udev->ignore_device && udev_run) {
                struct name_entry *name_loop;

                dbg("executing run list");
                list_for_each_entry(name_loop, &udev->run_list, node) {
                        if (strncmp(name_loop->name, "socket:", strlen("socket:")) == 0)
                                pass_env_to_socket(&name_loop->name[strlen("socket:")], udev->dev->devpath, udev->action);
                        else {
                                char program[PATH_SIZE];

                                strlcpy(program, name_loop->name, sizeof(program));
                                udev_rules_apply_format(udev, program, sizeof(program));
                                if (run_program(program, udev->dev->subsystem, NULL, 0, NULL,
                                                (udev_log_priority >= LOG_INFO)))
                                        retval = -1;
                        }
                }
        }

        udev_device_cleanup(udev);
        return retval;
}

enum event_state {
        EVENT_QUEUED,
        EVENT_FINISHED,
        EVENT_FAILED,
};

static void export_event_state(struct udevd_uevent_msg *msg, enum event_state state)
{
        char filename[PATH_SIZE];
        char filename_failed[PATH_SIZE];
        size_t start, end, i;
        struct udevd_uevent_msg *loop_msg;
        int fd;

        /* add location of queue files */
        strlcpy(filename, udev_root, sizeof(filename));
        strlcat(filename, "/", sizeof(filename));
        start = strlcat(filename, EVENT_QUEUE_DIR, sizeof(filename));
        end = strlcat(filename, msg->devpath, sizeof(filename));
        if (end > sizeof(filename))
                end = sizeof(filename);

        /* replace '/' to transform path into a filename */
        for (i = start+1; i < end; i++)
                if (filename[i] == '/')
                        filename[i] = PATH_TO_NAME_CHAR;

        /* add location of failed files */
        strlcpy(filename_failed, udev_root, sizeof(filename_failed));
        strlcat(filename_failed, "/", sizeof(filename_failed));
        start = strlcat(filename_failed, EVENT_FAILED_DIR, sizeof(filename_failed));
        end = strlcat(filename_failed, msg->devpath, sizeof(filename_failed));
        if (end > sizeof(filename_failed))
                end = sizeof(filename_failed);

        /* replace '/' to transform path into a filename */
        for (i = start+1; i < end; i++)
                if (filename_failed[i] == '/')
                        filename_failed[i] = PATH_TO_NAME_CHAR;

        switch (state) {
        case EVENT_QUEUED:
                unlink(filename_failed);
                delete_path(filename_failed);
                create_path(filename);
                fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0644);
                if (fd > 0)
                        close(fd);
                return;
        case EVENT_FINISHED:
        case EVENT_FAILED:
                unlink(filename_failed);
                delete_path(filename_failed);

                /* don't remove, if events for the same path are still pending */
                list_for_each_entry(loop_msg, &running_list, node)
                        if (loop_msg->devpath && strcmp(loop_msg->devpath, msg->devpath) == 0)
                                return;

                list_for_each_entry(loop_msg, &exec_list, node)
                        if (loop_msg->devpath && strcmp(loop_msg->devpath, msg->devpath) == 0)
                                return;

                /* move failed events to the failed directory */
                if (state == EVENT_FAILED) {
                        create_path(filename_failed);
                        rename(filename, filename_failed);
                } else {
                        unlink(filename);
                }

                /* clean up the queue directory */
                delete_path(filename);

                return;
        }
}

static void msg_queue_delete(struct udevd_uevent_msg *msg)
{
        list_del(&msg->node);

        /* mark as failed, if add event returns non-zero */
        if (msg->exitstatus && strcmp(msg->action, "add") == 0)
                export_event_state(msg, EVENT_FAILED);
        else
                export_event_state(msg, EVENT_FINISHED);

        free(msg);
}

static void udev_event_run(struct udevd_uevent_msg *msg)
{
        pid_t pid;
        int retval;

        pid = fork();
        switch (pid) {
        case 0:
                /* child */
                close(uevent_netlink_sock);
                close(udevd_sock);
                if (inotify_fd >= 0)
                        close(inotify_fd);
                close(signal_pipe[READ_END]);
                close(signal_pipe[WRITE_END]);
                logging_close();

                logging_init("udevd-event");
                setpriority(PRIO_PROCESS, 0, UDEV_PRIORITY);

                retval = udev_event_process(msg);
                info("seq %llu finished", msg->seqnum);

                logging_close();
                if (retval)
                        exit(1);
                exit(0);
        case -1:
                err("fork of child failed: %s", strerror(errno));
                msg_queue_delete(msg);
                break;
        default:
                /* get SIGCHLD in main loop */
                info("seq %llu forked, pid [%d], '%s' '%s', %ld seconds old",
                     msg->seqnum, pid,  msg->action, msg->subsystem, time(NULL) - msg->queue_time);
                msg->pid = pid;
        }
}

static void msg_queue_insert(struct udevd_uevent_msg *msg)
{
        char filename[PATH_SIZE];
        int fd;

        msg->queue_time = time(NULL);

        strlcpy(filename, udev_root, sizeof(filename));
        strlcat(filename, "/" EVENT_SEQNUM, sizeof(filename));
        fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0644);
        if (fd >= 0) {
                char str[32];
                int len;

                len = sprintf(str, "%llu\n", msg->seqnum);
                write(fd, str, len);
                close(fd);
        }

        export_event_state(msg, EVENT_QUEUED);

        /* run one event after the other in debug mode */
        if (debug_trace) {
                list_add_tail(&msg->node, &running_list);
                udev_event_run(msg);
                waitpid(msg->pid, NULL, 0);
                msg_queue_delete(msg);
                return;
        }

        /* run all events with a timeout set immediately */
        if (msg->timeout != 0) {
                list_add_tail(&msg->node, &running_list);
                udev_event_run(msg);
                return;
        }

        list_add_tail(&msg->node, &exec_list);
        run_exec_q = 1;
}

static int mem_size_mb(void)
{
        int f;
        char buf[8192];
        long int len;
        const char *pos;
        long int memsize;

        f = open("/proc/meminfo", O_RDONLY);
        if (f == -1)
                return -1;

        len = read(f, buf, sizeof(buf)-1);
        close(f);

        if (len <= 0)
                return -1;
        buf[len] = '\0';

        pos = strstr(buf, "MemTotal: ");
        if (pos == NULL)
                return -1;

        if (sscanf(pos, "MemTotal: %ld kB", &memsize) != 1)
                return -1;

        return memsize / 1024;
}

static int cpu_count(void)
{
        int f;
        char buf[32768];
        int len;
        const char *pos;
        int count = 0;

        f = open("/proc/stat", O_RDONLY);
        if (f == -1)
                return -1;

        len = read(f, buf, sizeof(buf)-1);
        close(f);
        if (len <= 0)
                return -1;
        buf[len] = '\0';

        pos = strstr(buf, "cpu");
        if (pos == NULL)
                return -1;

        while (pos != NULL) {
                if (strncmp(pos, "cpu", 3) == 0 &&isdigit(pos[3]))
                        count++;
                pos = strstr(&pos[3], "cpu");
        }

        if (count == 0)
                return -1;
        return count;
}

static int running_processes(void)
{
        int f;
        char buf[32768];
        int len;
        int running;
        const char *pos;

        f = open("/proc/stat", O_RDONLY);
        if (f == -1)
                return -1;

        len = read(f, buf, sizeof(buf)-1);
        close(f);
        if (len <= 0)
                return -1;
        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)-1);
                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;

        for (i = 0; i < PATH_SIZE; i++) {
                /* identical device event found */
                if (running[i] == '\0' && waiting[i] == '\0')
                        return 1;

                /* parent device event found */
                if (running[i] == '\0' && waiting[i] == '/')
                        return 2;

                /* child device event found */
                if (running[i] == '/' && waiting[i] == '\0')
                        return 3;

                /* no matching event */
                if (running[i] != waiting[i])
                        break;
        }

        return 0;
}

/* returns still running task for the same device, its parent or its physical device */
static int running_with_devpath(struct udevd_uevent_msg *msg, int limit)
{
        struct udevd_uevent_msg *loop_msg;
        int childs_count = 0;

        list_for_each_entry(loop_msg, &running_list, node) {
                if (limit && childs_count++ > limit) {
                        dbg("%llu, maximum number (%i) of child reached", msg->seqnum, childs_count);
                        return 1;
                }

                /* return running parent/child device event */
                if (compare_devpath(loop_msg->devpath, msg->devpath) != 0) {
                        dbg("%llu, child device event still running %llu (%s)",
                            msg->seqnum, loop_msg->seqnum, loop_msg->devpath);
                        return 2;
                }

                /* return running physical device event */
                if (msg->physdevpath && msg->action && strcmp(msg->action, "add") == 0)
                        if (compare_devpath(loop_msg->devpath, msg->physdevpath) != 0) {
                                dbg("%llu, physical device event still running %llu (%s)",
                                    msg->seqnum, loop_msg->seqnum, loop_msg->devpath);
                                return 3;
                        }
        }

        return 0;
}

/* exec queue management routine executes the events and serializes events in the same sequence */
static void msg_queue_manager(void)
{
        struct udevd_uevent_msg *loop_msg;
        struct udevd_uevent_msg *tmp_msg;
        int running;

        if (list_empty(&exec_list))
                return;

        running = running_processes();
        dbg("%d processes runnning on system", running);
        if (running < 0)
                running = max_childs_running;

        list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, node) {
                /* check running processes in our session and possibly throttle */
                if (running >= max_childs_running) {
                        running = running_processes_in_session(sid, max_childs_running+10);
                        dbg("at least %d processes running in session", running);
                        if (running >= max_childs_running) {
                                dbg("delay seq %llu, too many processes already running", loop_msg->seqnum);
                                return;
                        }
                }

                /* don't run two processes for the same devpath and wait for the parent*/
                if (running_with_devpath(loop_msg, max_childs)) {
                        dbg("delay seq %llu (%s)", loop_msg->seqnum, loop_msg->devpath);
                        continue;
                }

                /* move event to run list */
                list_move_tail(&loop_msg->node, &running_list);
                udev_event_run(loop_msg);
                running++;
                dbg("moved seq %llu to running list", loop_msg->seqnum);
        }
}

static struct udevd_uevent_msg *get_msg_from_envbuf(const char *buf, int buf_size)
{
        int bufpos;
        int i;
        struct udevd_uevent_msg *msg;
        char *physdevdriver_key = NULL;
        int maj = 0;
        int min = 0;

        msg = malloc(sizeof(struct udevd_uevent_msg) + buf_size);
        if (msg == NULL)
                return NULL;
        memset(msg, 0x00, sizeof(struct udevd_uevent_msg) + buf_size);

        /* copy environment buffer and reconstruct envp */
        memcpy(msg->envbuf, buf, buf_size);
        bufpos = 0;
        for (i = 0; (bufpos < buf_size) && (i < UEVENT_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];
                else if (strncmp(key, "DEVPATH=", 8) == 0)
                        msg->devpath = &key[8];
                else if (strncmp(key, "SUBSYSTEM=", 10) == 0)
                        msg->subsystem = &key[10];
                else if (strncmp(key, "DRIVER=", 7) == 0)
                        msg->driver = &key[7];
                else if (strncmp(key, "SEQNUM=", 7) == 0)
                        msg->seqnum = strtoull(&key[7], NULL, 10);
                else if (strncmp(key, "PHYSDEVPATH=", 12) == 0)
                        msg->physdevpath = &key[12];
                else if (strncmp(key, "PHYSDEVDRIVER=", 14) == 0)
                        physdevdriver_key = key;
                else if (strncmp(key, "MAJOR=", 6) == 0)
                        maj = strtoull(&key[6], NULL, 10);
                else if (strncmp(key, "MINOR=", 6) == 0)
                        min = strtoull(&key[6], NULL, 10);
                else if (strncmp(key, "TIMEOUT=", 8) == 0)
                        msg->timeout = strtoull(&key[8], NULL, 10);
        }
        msg->devt = makedev(maj, min);
        msg->envp[i++] = "UDEVD_EVENT=1";

        if (msg->driver == NULL && msg->physdevpath == NULL && physdevdriver_key != NULL) {
                /* for older kernels DRIVER is empty for a bus device, export PHYSDEVDRIVER as DRIVER */
                msg->envp[i++] = &physdevdriver_key[7];
                msg->driver = &physdevdriver_key[14];
        }

        msg->envp[i] = NULL;

        if (msg->devpath == NULL || msg->action == NULL) {
                info("DEVPATH or ACTION missing, ignore message");
                free(msg);
                return NULL;
        }
        return msg;
}

/* receive the udevd message from userspace */
static void get_ctrl_msg(void)
{
        struct udevd_ctrl_msg ctrl_msg;
        ssize_t size;
        struct msghdr smsg;
        struct cmsghdr *cmsg;
        struct iovec iov;
        struct ucred *cred;
        char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
        int *intval;

        memset(&ctrl_msg, 0x00, sizeof(struct udevd_ctrl_msg));
        iov.iov_base = &ctrl_msg;
        iov.iov_len = sizeof(struct udevd_ctrl_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(udevd_sock, &smsg, 0);
        if (size <  0) {
                if (errno != EINTR)
                        err("unable to receive user udevd message: %s", strerror(errno));
                return;
        }
        cmsg = CMSG_FIRSTHDR(&smsg);
        cred = (struct ucred *) CMSG_DATA(cmsg);

        if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
                err("no sender credentials received, message ignored");
                return;
        }

        if (cred->uid != 0) {
                err("sender uid=%i, message ignored", cred->uid);
                return;
        }

        if (strncmp(ctrl_msg.magic, UDEVD_CTRL_MAGIC, sizeof(UDEVD_CTRL_MAGIC)) != 0 ) {
                err("message magic '%s' doesn't match, ignore it", ctrl_msg.magic);
                return;
        }

        switch (ctrl_msg.type) {
        case UDEVD_CTRL_STOP_EXEC_QUEUE:
                info("udevd message (STOP_EXEC_QUEUE) received");
                stop_exec_q = 1;
                break;
        case UDEVD_CTRL_START_EXEC_QUEUE:
                info("udevd message (START_EXEC_QUEUE) received");
                stop_exec_q = 0;
                msg_queue_manager();
                break;
        case UDEVD_CTRL_SET_LOG_LEVEL:
                intval = (int *) ctrl_msg.buf;
                info("udevd message (SET_LOG_PRIORITY) received, udev_log_priority=%i", *intval);
                udev_log_priority = *intval;
                sprintf(udev_log, "UDEV_LOG=%i", udev_log_priority);
                putenv(udev_log);
                break;
        case UDEVD_CTRL_SET_MAX_CHILDS:
                intval = (int *) ctrl_msg.buf;
                info("udevd message (UDEVD_SET_MAX_CHILDS) received, max_childs=%i", *intval);
                max_childs = *intval;
                break;
        case UDEVD_CTRL_SET_MAX_CHILDS_RUNNING:
                intval = (int *) ctrl_msg.buf;
                info("udevd message (UDEVD_SET_MAX_CHILDS_RUNNING) received, max_childs=%i", *intval);
                max_childs_running = *intval;
                break;
        case UDEVD_CTRL_RELOAD_RULES:
                info("udevd message (RELOAD_RULES) received");
                reload_config = 1;
                break;
        default:
                err("unknown control message type");
        }
}

/* receive the kernel user event message and do some sanity checks */
static struct udevd_uevent_msg *get_netlink_msg(void)
{
        struct udevd_uevent_msg *msg;
        int bufpos;
        ssize_t size;
        static char buffer[UEVENT_BUFFER_SIZE+512];
        char *pos;

        size = recv(uevent_netlink_sock, &buffer, sizeof(buffer), 0);
        if (size <  0) {
                if (errno != EINTR)
                        err("unable to receive kernel netlink message: %s", strerror(errno));
                return NULL;
        }

        if ((size_t)size > sizeof(buffer)-1)
                size = sizeof(buffer)-1;
        buffer[size] = '\0';
        dbg("uevent_size=%zi", size);

        /* start of event payload */
        bufpos = strlen(buffer)+1;
        msg = get_msg_from_envbuf(&buffer[bufpos], size-bufpos);
        if (msg == NULL)
                return NULL;

        /* validate message */
        pos = strchr(buffer, '@');
        if (pos == NULL) {
                err("invalid uevent '%s'", buffer);
                free(msg);
                return NULL;
        }
        pos[0] = '\0';

        if (msg->action == NULL) {
                info("no ACTION in payload found, skip event '%s'", buffer);
                free(msg);
                return NULL;
        }

        if (strcmp(msg->action, buffer) != 0) {
                err("ACTION in payload does not match uevent, skip event '%s'", buffer);
                free(msg);
                return NULL;
        }

        return msg;
}

static void asmlinkage sig_handler(int signum)
{
        switch (signum) {
                case SIGINT:
                case SIGTERM:
                        udev_exit = 1;
                        break;
                case SIGCHLD:
                        /* set flag, then write to pipe if needed */
                        sigchilds_waiting = 1;
                        break;
                case SIGHUP:
                        reload_config = 1;
                        break;
        }

        /* write to pipe, which will wakeup select() in our mainloop */
        write(signal_pipe[WRITE_END], "", 1);
}

static void udev_done(int pid, int exitstatus)
{
        /* find msg associated with pid and delete it */
        struct udevd_uevent_msg *msg;

        list_for_each_entry(msg, &running_list, node) {
                if (msg->pid == pid) {
                        info("seq %llu, pid [%d] exit with %i, %ld seconds old", msg->seqnum, msg->pid,
                             exitstatus, time(NULL) - msg->queue_time);
                        msg->exitstatus = exitstatus;
                        msg_queue_delete(msg);

                        /* there may be events waiting with the same devpath */
                        run_exec_q = 1;
                        return;
                }
        }
}

static void reap_sigchilds(void)
{
        pid_t pid;
        int status;

        while (1) {
                pid = waitpid(-1, &status, WNOHANG);
                if (pid <= 0)
                        break;
                if (WIFEXITED(status))
                        status = WEXITSTATUS(status);
                else if (WIFSIGNALED(status))
                        status = WTERMSIG(status) + 128;
                else
                        status = 0;
                udev_done(pid, status);
        }
}

static int init_udevd_socket(void)
{
        struct sockaddr_un saddr;
        socklen_t addrlen;
        const int feature_on = 1;
        int retval;

        memset(&saddr, 0x00, sizeof(saddr));
        saddr.sun_family = AF_LOCAL;
        /* use abstract namespace for socket path */
        strcpy(&saddr.sun_path[1], UDEVD_CTRL_SOCK_PATH);
        addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;

        udevd_sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
        if (udevd_sock == -1) {
                err("error getting socket: %s", strerror(errno));
                return -1;
        }

        /* the bind takes care of ensuring only one copy running */
        retval = bind(udevd_sock, (struct sockaddr *) &saddr, addrlen);
        if (retval < 0) {
                err("bind failed: %s", strerror(errno));
                close(udevd_sock);
                udevd_sock = -1;
                return -1;
        }

        /* enable receiving of the sender credentials */
        setsockopt(udevd_sock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));

        return 0;
}

static int init_uevent_netlink_sock(void)
{
        struct sockaddr_nl snl;
        const int buffersize = 16 * 1024 * 1024;
        int retval;

        memset(&snl, 0x00, sizeof(struct sockaddr_nl));
        snl.nl_family = AF_NETLINK;
        snl.nl_pid = getpid();
        snl.nl_groups = 1;

        uevent_netlink_sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
        if (uevent_netlink_sock == -1) {
                err("error getting socket: %s", strerror(errno));
                return -1;
        }

        /* set receive buffersize */
        setsockopt(uevent_netlink_sock, SOL_SOCKET, SO_RCVBUFFORCE, &buffersize, sizeof(buffersize));

        retval = bind(uevent_netlink_sock, (struct sockaddr *) &snl, sizeof(struct sockaddr_nl));
        if (retval < 0) {
                err("bind failed: %s", strerror(errno));
                close(uevent_netlink_sock);
                uevent_netlink_sock = -1;
                return -1;
        }
        return 0;
}

static void export_initial_seqnum(void)
{
        char filename[PATH_SIZE];
        int fd;
        char seqnum[32];
        ssize_t len = 0;

        strlcpy(filename, sysfs_path, sizeof(filename));
        strlcat(filename, "/kernel/uevent_seqnum", sizeof(filename));
        fd = open(filename, O_RDONLY);
        if (fd >= 0) {
                len = read(fd, seqnum, sizeof(seqnum)-1);
                close(fd);
        }
        if (len <= 0) {
                strcpy(seqnum, "0\n");
                len = 3;
        }
        strlcpy(filename, udev_root, sizeof(filename));
        strlcat(filename, "/" EVENT_SEQNUM, sizeof(filename));
        create_path(filename);
        fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0644);
        if (fd >= 0) {
                write(fd, seqnum, len);
                close(fd);
        }
}

int main(int argc, char *argv[], char *envp[])
{
        int retval;
        int fd;
        struct sigaction act;
        fd_set readfds;
        const char *value;
        int daemonize = 0;
        int option;
        static const struct option options[] = {
                { "daemon", 0, NULL, 'd' },
                { "debug-trace", 0, NULL, 't' },
                { "verbose", 0, NULL, 'v' },
                { "help", 0, NULL, 'h' },
                {}
        };
        int rc = 1;
        int maxfd;

        logging_init("udevd");
        udev_config_init();
        selinux_init();
        dbg("version %s", UDEV_VERSION);

        /* parse commandline options */
        while (1) {
                option = getopt_long(argc, argv, "dtvh", options, NULL);
                if (option == -1)
                        break;

                switch (option) {
                case 'd':
                        daemonize = 1;
                        break;
                case 't':
                        debug_trace = 1;
                        break;
                case 'v':
                        verbose = 1;
                        if (udev_log_priority < LOG_INFO)
                                udev_log_priority = LOG_INFO;
                        break;
                case 'h':
                        printf("Usage: udevd [--help] [--daemon] [--debug-trace] [--verbose]\n");
                        goto exit;
                default:
                        goto exit;
                }
        }

        if (getuid() != 0) {
                fprintf(stderr, "root privileges required\n");
                err("root privileges required");
                goto exit;
        }

        /* init sockets to receive events */
        if (init_udevd_socket() < 0) {
                if (errno == EADDRINUSE) {
                        fprintf(stderr, "another udev daemon already running\n");
                        err("another udev daemon already running");
                        rc = 1;
                } else {
                        fprintf(stderr, "error initializing udevd socket\n");
                        err("error initializing udevd socket");
                        rc = 2;
                }
                goto exit;
        }

        if (init_uevent_netlink_sock() < 0) {
                fprintf(stderr, "error initializing netlink socket\n");
                err("error initializing netlink socket");
                rc = 3;
                goto exit;
        }

        /* setup signal handler pipe */
        retval = pipe(signal_pipe);
        if (retval < 0) {
                err("error getting pipes: %s", strerror(errno));
                goto exit;
        }

        retval = fcntl(signal_pipe[READ_END], F_GETFL, 0);
        if (retval < 0) {
                err("error fcntl on read pipe: %s", strerror(errno));
                goto exit;
        }
        retval = fcntl(signal_pipe[READ_END], F_SETFL, retval | O_NONBLOCK);
        if (retval < 0) {
                err("error fcntl on read pipe: %s", strerror(errno));
                goto exit;
        }

        retval = fcntl(signal_pipe[WRITE_END], F_GETFL, 0);
        if (retval < 0) {
                err("error fcntl on write pipe: %s", strerror(errno));
                goto exit;
        }
        retval = fcntl(signal_pipe[WRITE_END], F_SETFL, retval | O_NONBLOCK);
        if (retval < 0) {
                err("error fcntl on write pipe: %s", strerror(errno));
                goto exit;
        }

        /* parse the rules and keep them in memory */
        sysfs_init();
        udev_rules_init(&rules, 1);

        export_initial_seqnum();

        if (daemonize) {
                pid_t pid;

                pid = fork();
                switch (pid) {
                case 0:
                        dbg("daemonized fork running");
                        break;
                case -1:
                        err("fork of daemon failed: %s", strerror(errno));
                        rc = 4;
                        goto exit;
                default:
                        dbg("child [%u] running, parent exits", pid);
                        rc = 0;
                        goto exit;
                }
        }

        /* redirect std fd's */
        fd = open("/dev/null", O_RDWR);
        if (fd >= 0) {
                dup2(fd, STDIN_FILENO);
                if (!verbose)
                        dup2(fd, STDOUT_FILENO);
                dup2(fd, STDERR_FILENO);
                if (fd > STDERR_FILENO)
                        close(fd);
        } else
                err("error opening /dev/null: %s", strerror(errno));

        /* set scheduling priority for the daemon */
        setpriority(PRIO_PROCESS, 0, UDEVD_PRIORITY);

        chdir("/");
        umask(022);

        /* become session leader */
        sid = setsid();
        dbg("our session is %d", sid);

        /* OOM_DISABLE == -17 */
        fd = open("/proc/self/oom_adj", O_RDWR);
        if (fd < 0)
                err("error disabling OOM: %s", strerror(errno));
        else {
                write(fd, "-17", 3);
                close(fd);
        }

        /* 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(SIGCHLD, &act, NULL);
        sigaction(SIGHUP, &act, NULL);

        /* watch rules directory */
        inotify_fd = inotify_init();
        if (inotify_fd >= 0)
                inotify_add_watch(inotify_fd, udev_rules_dir, IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
        else if (errno == ENOSYS)
                err("the kernel does not support inotify, udevd can't monitor configuration file changes");
        else
                err("inotify_init failed: %s", strerror(errno));

        /* maximum limit of forked childs */
        value = getenv("UDEVD_MAX_CHILDS");
        if (value)
                max_childs = strtoul(value, NULL, 10);
        else {
                int memsize = mem_size_mb();
                if (memsize > 0)
                        max_childs = 128 + (memsize / 4);
                else
                        max_childs = UDEVD_MAX_CHILDS;
        }
        info("initialize max_childs to %u", max_childs);

        /* start to throttle forking if maximum number of _running_ childs is reached */
        value = getenv("UDEVD_MAX_CHILDS_RUNNING");
        if (value)
                max_childs_running = strtoull(value, NULL, 10);
        else {
                int cpus = cpu_count();
                if (cpus > 0)
                        max_childs_running = 8 + (8 * cpus);
                else
                        max_childs_running = UDEVD_MAX_CHILDS_RUNNING;
        }
        info("initialize max_childs_running to %u", max_childs_running);

        /* clear environment for forked event processes */
        clearenv();

        /* export log_priority , as called programs may want to follow that setting */
        sprintf(udev_log, "UDEV_LOG=%i", udev_log_priority);
        putenv(udev_log);
        if (debug_trace)
                putenv("DEBUG=1");

        maxfd = udevd_sock;
        maxfd = UDEV_MAX(maxfd, uevent_netlink_sock);
        maxfd = UDEV_MAX(maxfd, signal_pipe[READ_END]);
        maxfd = UDEV_MAX(maxfd, inotify_fd);

        while (!udev_exit) {
                struct udevd_uevent_msg *msg;
                int fdcount;

                FD_ZERO(&readfds);
                FD_SET(signal_pipe[READ_END], &readfds);
                FD_SET(udevd_sock, &readfds);
                FD_SET(uevent_netlink_sock, &readfds);
                if (inotify_fd >= 0)
                        FD_SET(inotify_fd, &readfds);

                fdcount = select(maxfd+1, &readfds, NULL, NULL, NULL);
                if (fdcount < 0) {
                        if (errno != EINTR)
                                err("error in select: %s", strerror(errno));
                        continue;
                }

                /* get control message */
                if (FD_ISSET(udevd_sock, &readfds))
                        get_ctrl_msg();

                /* get netlink message */
                if (FD_ISSET(uevent_netlink_sock, &readfds)) {
                        msg = get_netlink_msg();
                        if (msg)
                                msg_queue_insert(msg);
                }

                /* received a signal, clear our notification pipe */
                if (FD_ISSET(signal_pipe[READ_END], &readfds)) {
                        char buf[256];

                        read(signal_pipe[READ_END], &buf, sizeof(buf));
                }

                /* rules directory inotify watch */
                if ((inotify_fd >= 0) && FD_ISSET(inotify_fd, &readfds)) {
                        int nbytes;

                        /* discard all possible events, we can just reload the config */
                        if ((ioctl(inotify_fd, FIONREAD, &nbytes) == 0) && nbytes) {
                                char *buf;

                                reload_config = 1;
                                buf = malloc(nbytes);
                                if (!buf) {
                                        err("error getting buffer for inotify, disable watching");
                                        close(inotify_fd);
                                        inotify_fd = -1;
                                }
                                read(inotify_fd, buf, nbytes);
                                free(buf);
                        }
                }

                /* rules changed, set by inotify or a HUP signal */
                if (reload_config) {
                        reload_config = 0;
                        udev_rules_cleanup(&rules);
                        udev_rules_init(&rules, 1);
                }

                /* forked child has returned */
                if (sigchilds_waiting) {
                        sigchilds_waiting = 0;
                        reap_sigchilds();
                }

                if (run_exec_q) {
                        run_exec_q = 0;
                        if (!stop_exec_q)
                                msg_queue_manager();
                }
        }
        rc = 0;

exit:
        udev_rules_cleanup(&rules);
        sysfs_cleanup();

        if (signal_pipe[READ_END] >= 0)
                close(signal_pipe[READ_END]);
        if (signal_pipe[WRITE_END] >= 0)
                close(signal_pipe[WRITE_END]);

        if (udevd_sock >= 0)
                close(udevd_sock);
        if (inotify_fd >= 0)
                close(inotify_fd);
        if (uevent_netlink_sock >= 0)
                close(uevent_netlink_sock);

        logging_close();

        return rc;
}