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mirror of https://github.com/systemd/systemd-stable.git synced 2024-10-31 07:51:08 +03:00
systemd-stable/udevd.c

395 lines
9.0 KiB
C

/*
* udevd.c - hotplug event serializer
*
* Copyright (C) 2004 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.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <stddef.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 <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/time.h>
#include "list.h"
#include "udev.h"
#include "udev_version.h"
#include "udevd.h"
#include "logging.h"
static int expected_seqnum = 0;
volatile static int children_waiting;
volatile static int msg_q_timeout;
LIST_HEAD(msg_list);
LIST_HEAD(exec_list);
LIST_HEAD(running_list);
static void exec_queue_manager(void);
static void msg_queue_manager(void);
#ifdef LOG
unsigned char logname[42];
void log_message (int level, const char *format, ...)
{
va_list args;
va_start(args, format);
vsyslog(level, format, args);
va_end(args);
}
#endif
static void msg_dump_queue(void)
{
struct hotplug_msg *msg;
list_for_each_entry(msg, &msg_list, list)
dbg("sequence %d in queue", msg->seqnum);
}
static void msg_dump(struct hotplug_msg *msg)
{
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;
new_msg = malloc(sizeof(struct hotplug_msg));
if (new_msg == NULL)
dbg("error malloc");
return new_msg;
}
static void run_queue_delete(struct hotplug_msg *msg)
{
list_del(&msg->list);
free(msg);
exec_queue_manager();
}
/* orders the message in the queue by sequence number */
static void msg_queue_insert(struct hotplug_msg *msg)
{
struct hotplug_msg *loop_msg;
/* 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);
/* run msg queue manager */
msg_queue_manager();
return ;
}
/* forks event and removes event from run queue when finished */
static void udev_run(struct hotplug_msg *msg)
{
pid_t pid;
char action[32];
char devpath[256];
char *env[] = { action, devpath, NULL };
snprintf(action, sizeof(action), "ACTION=%s", msg->action);
snprintf(devpath, sizeof(devpath), "DEVPATH=%s", msg->devpath);
pid = fork();
switch (pid) {
case 0:
/* child */
execle(UDEV_BIN, "udev", msg->subsystem, NULL, env);
dbg("exec of child failed");
exit(1);
break;
case -1:
dbg("fork of child failed");
run_queue_delete(msg);
break;
default:
/* get SIGCHLD in main loop */
dbg("==> exec seq %d [%d] working at '%s'", msg->seqnum, pid, msg->devpath);
msg->pid = pid;
}
}
/* returns already running task with devpath */
static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
{
struct hotplug_msg *loop_msg;
list_for_each_entry(loop_msg, &running_list, list)
if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
return loop_msg;
return NULL;
}
/* exec queue management routine executes the events and delays events for the same devpath */
static void exec_queue_manager()
{
struct hotplug_msg *loop_msg;
struct hotplug_msg *tmp_msg;
struct hotplug_msg *msg;
list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
msg = running_with_devpath(loop_msg);
if (!msg) {
/* move event to run list */
list_move_tail(&loop_msg->list, &running_list);
udev_run(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);
}
}
}
static void msg_move_exec(struct hotplug_msg *msg)
{
list_move_tail(&msg->list, &exec_list);
exec_queue_manager();
expected_seqnum = msg->seqnum+1;
dbg("moved seq %d to exec, next expected is %d",
msg->seqnum, expected_seqnum);
}
/* msg queue management routine handles the timeouts and dispatches the events */
static void msg_queue_manager()
{
struct hotplug_msg *loop_msg;
struct hotplug_msg *tmp_msg;
time_t msg_age = 0;
dbg("msg queue manager, next expected is %d", 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);
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);
goto recheck;
} else {
break;
}
}
msg_dump_queue();
if (list_empty(&msg_list) == 0) {
/* set timeout for remaining queued events */
struct itimerval itv = {{0, 0}, {EVENT_TIMEOUT_SEC - msg_age, 0}};
dbg("next event expires in %li seconds",
EVENT_TIMEOUT_SEC - msg_age);
setitimer(ITIMER_REAL, &itv, 0);
}
}
/* receive the msg, do some basic sanity checks, and queue it */
static void handle_msg(int sock)
{
struct hotplug_msg *msg;
int retval;
struct msghdr smsg;
struct cmsghdr *cmsg;
struct iovec iov;
struct ucred *cred;
char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
msg = msg_create();
if (msg == NULL) {
dbg("unable to store message");
return;
}
iov.iov_base = msg;
iov.iov_len = sizeof(struct hotplug_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);
retval = recvmsg(sock, &smsg, 0);
if (retval < 0) {
if (errno != EINTR)
dbg("unable to receive message");
return;
}
cmsg = CMSG_FIRSTHDR(&smsg);
cred = (struct ucred *) CMSG_DATA(cmsg);
if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
dbg("no sender credentials received, message ignored");
goto skip;
}
if (cred->uid != 0) {
dbg("sender uid=%i, message ignored", cred->uid);
goto skip;
}
if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
dbg("message magic '%s' doesn't match, ignore it", msg->magic);
goto skip;
}
/* if no seqnum is given, we move straight to exec queue */
if (msg->seqnum == -1) {
list_add(&msg->list, &exec_list);
exec_queue_manager();
} else {
msg_queue_insert(msg);
}
return;
skip:
free(msg);
return;
}
static void sig_handler(int signum)
{
switch (signum) {
case SIGINT:
case SIGTERM:
exit(20 + signum);
break;
case SIGALRM:
msg_q_timeout = 1;
break;
case SIGCHLD:
children_waiting = 1;
break;
default:
dbg("unhandled signal");
}
}
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, list) {
if (msg->pid == pid) {
dbg("<== exec seq %d came back", msg->seqnum);
run_queue_delete(msg);
return;
}
}
}
int main(int argc, char *argv[])
{
int ssock;
struct sockaddr_un saddr;
socklen_t addrlen;
int retval;
const int on = 1;
struct sigaction act;
init_logging("udevd");
dbg("version %s", UDEV_VERSION);
if (getuid() != 0) {
dbg("need to be root, exit");
exit(1);
}
/* set signal handler */
act.sa_handler = sig_handler;
sigemptyset (&act.sa_mask);
act.sa_flags = SA_RESTART;
sigaction(SIGINT, &act, NULL);
sigaction(SIGTERM, &act, NULL);
/* we want these two to interrupt system calls */
act.sa_flags = 0;
sigaction(SIGALRM, &act, NULL);
sigaction(SIGCHLD, &act, NULL);
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;
ssock = socket(AF_LOCAL, SOCK_DGRAM, 0);
if (ssock == -1) {
dbg("error getting socket, exit");
exit(1);
}
/* the bind takes care of ensuring only one copy running */
retval = bind(ssock, (struct sockaddr *) &saddr, addrlen);
if (retval < 0) {
dbg("bind failed, exit");
goto exit;
}
/* enable receiving of the sender credentials */
setsockopt(ssock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
while (1) {
handle_msg(ssock);
while(msg_q_timeout) {
msg_q_timeout = 0;
msg_queue_manager();
}
while(children_waiting) {
children_waiting = 0;
/* reap all dead children */
while(1) {
int pid = waitpid(-1, 0, WNOHANG);
if ((pid == -1) || (pid == 0))
break;
udev_done(pid);
}
}
}
exit:
close(ssock);
exit(1);
}