libudev-monitor.c revision 8753fadf2a6ecead372e71b8bf9336cf29f9c958
/*
* libudev - interface to udev device information
*
* Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
*
* 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, either version 2 of the License, or
* (at your option) any later version.
*
* 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, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <linux/netlink.h>
#include "libudev.h"
#include "libudev-private.h"
struct udev_monitor {
struct udev *udev;
int refcount;
int sock;
struct sockaddr_nl snl;
struct sockaddr_un sun;
socklen_t addrlen;
};
/**
* udev_monitor_new_from_socket:
* @udev: udev library context
* @socket_path: unix socket path
*
* Create new udev monitor, setup and connect to a specified socket. The
* path to a socket can point to an existing socket file, or it will be
* created if needed. If neccessary, the permissions adjustment as well as
* the later cleanup of the socket file, needs to be done by the caller.
* If the socket path starts with a '@' character, an abstract namespace
* socket will be used.
*
* The initial refcount is 1, and needs to be decremented to
* release the ressources of the udev monitor.
*
* Returns: a new udev monitor, or #NULL, in case of an error
**/
struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
{
struct udev_monitor *udev_monitor;
if (udev == NULL)
return NULL;
if (socket_path == NULL)
return NULL;
udev_monitor = malloc(sizeof(struct udev_monitor));
if (udev_monitor == NULL)
return NULL;
memset(udev_monitor, 0x00, sizeof(struct udev_monitor));
udev_monitor->refcount = 1;
udev_monitor->udev = udev;
udev_monitor->sun.sun_family = AF_LOCAL;
strcpy(udev_monitor->sun.sun_path, socket_path);
udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(udev_monitor->sun.sun_path);
/* translate leading '@' to abstract namespace */
if (udev_monitor->sun.sun_path[0] == '@')
udev_monitor->sun.sun_path[0] = '\0';
udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
if (udev_monitor->sock == -1) {
err(udev, "error getting socket: %s\n", strerror(errno));
free(udev_monitor);
return NULL;
}
info(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
return udev_monitor;
}
struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev)
{
struct udev_monitor *udev_monitor;
if (udev == NULL)
return NULL;
udev_monitor = malloc(sizeof(struct udev_monitor));
if (udev_monitor == NULL)
return NULL;
memset(udev_monitor, 0x00, sizeof(struct udev_monitor));
udev_monitor->refcount = 1;
udev_monitor->udev = udev;
udev_monitor->sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
if (udev_monitor->sock == -1) {
err(udev, "error getting socket: %s\n", strerror(errno));
free(udev_monitor);
return NULL;
}
udev_monitor->snl.nl_family = AF_NETLINK;
udev_monitor->snl.nl_pid = getpid();
udev_monitor->snl.nl_groups = 1;
info(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT\n", udev_monitor);
return udev_monitor;
}
int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
{
int err;
const int on = 1;
if (udev_monitor->snl.nl_family != 0) {
err = bind(udev_monitor->sock, (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
if (err < 0) {
err(udev_monitor->udev, "bind failed: %s\n", strerror(errno));
return err;
}
info(udev_monitor->udev, "monitor %p listening on netlink\n", udev_monitor);
} else if (udev_monitor->sun.sun_family != 0) {
err = bind(udev_monitor->sock, (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
if (err < 0) {
err(udev_monitor->udev, "bind failed: %s\n", strerror(errno));
return err;
}
/* enable receiving of the sender credentials */
setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
info(udev_monitor->udev, "monitor %p listening on socket\n", udev_monitor);
}
return 0;
}
/**
* udev_monitor_ref:
* @udev_monitor: udev monitor
*
* Take a reference of a udev monitor.
*
* Returns: the passed udev monitor
**/
struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return NULL;
udev_monitor->refcount++;
return udev_monitor;
}
/**
* udev_monitor_unref:
* @udev_monitor: udev monitor
*
* Drop a reference ofa udev monitor. If the refcount reaches zero,
* the bound socket will be closed, and the ressources of the monitor
* will be released.
*
**/
void udev_monitor_unref(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return;
udev_monitor->refcount--;
if (udev_monitor->refcount > 0)
return;
if (udev_monitor->sock >= 0)
close(udev_monitor->sock);
info(udev_monitor->udev, "monitor %p released\n", udev_monitor);
free(udev_monitor);
}
/**
* udev_monitor_get_udev:
* @udev_monitor: udev monitor
*
* Retrieve the udev library context the monitor was created with.
*
* Returns: the udev library context
**/
struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return NULL;
return udev_monitor->udev;
}
/**
* udev_monitor_get_fd:
* @udev_monitor: udev monitor
*
* Retrieve the socket file descriptor associated with the monitor.
*
* Returns: the socket file descriptor
**/
int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return -1;
return udev_monitor->sock;
}
/**
* udev_monitor_receive_device:
* @udev_monitor: udev monitor
*
* Receive data from the udev monitor socket, allocate a new udev
* device, fill in the received data, and return the device.
*
* Only socket connections with uid=0 are accepted. The caller
* needs to make sure, that there is data to read from the socket,
* the call will block until the socket becomes readable.
*
* The initial refcount is 1, and needs to be decremented to
* release the ressources of the udev device.
*
* Returns: a new udev device, or #NULL, in case of an error
**/
struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
{
struct udev_device *udev_device;
struct msghdr smsg;
struct iovec iov;
char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
char buf[4096];
size_t bufpos;
int maj = 0;
int min = 0;
if (udev_monitor == NULL)
return NULL;
memset(buf, 0x00, sizeof(buf));
iov.iov_base = &buf;
iov.iov_len = sizeof(buf);
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);
if (recvmsg(udev_monitor->sock, &smsg, 0) < 0) {
if (errno != EINTR)
info(udev_monitor->udev, "unable to receive message");
return NULL;
}
if (udev_monitor->sun.sun_family != 0) {
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&smsg);
struct ucred *cred = (struct ucred *)CMSG_DATA (cmsg);
if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
info(udev_monitor->udev, "no sender credentials received, message ignored");
return NULL;
}
if (cred->uid != 0) {
info(udev_monitor->udev, "sender uid=%d, message ignored", cred->uid);
return NULL;
}
}
/* skip header */
bufpos = strlen(buf) + 1;
if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {
info(udev_monitor->udev, "invalid message length");
return NULL;
}
/* check message header */
if (strstr(buf, "@/") == NULL) {
info(udev_monitor->udev, "unrecognized message header");
return NULL;
}
udev_device = device_init(udev_monitor->udev);
if (udev_device == NULL) {
return NULL;
}
while (bufpos < sizeof(buf)) {
char *key;
size_t keylen;
key = &buf[bufpos];
keylen = strlen(key);
if (keylen == 0)
break;
bufpos += keylen + 1;
if (strncmp(key, "DEVPATH=", 8) == 0) {
char path[UTIL_PATH_SIZE];
util_strlcpy(path, udev_get_sys_path(udev_monitor->udev), sizeof(path));
util_strlcat(path, &key[8], sizeof(path));
device_set_syspath(udev_device, path);
} else if (strncmp(key, "SUBSYSTEM=", 10) == 0) {
device_set_subsystem(udev_device, &key[10]);
} else if (strncmp(key, "DEVNAME=", 8) == 0) {
device_set_devname(udev_device, &key[8]);
} else if (strncmp(key, "DEVLINKS=", 9) == 0) {
char *slink = &key[9];
char *next = strchr(slink, ' ');
while (next != NULL) {
next[0] = '\0';
device_add_devlink(udev_device, slink);
slink = &next[1];
next = strchr(slink, ' ');
}
if (slink[0] != '\0')
device_add_devlink(udev_device, slink);
} else if (strncmp(key, "DRIVER=", 7) == 0) {
device_set_driver(udev_device, &key[7]);
} else if (strncmp(key, "ACTION=", 7) == 0) {
device_set_action(udev_device, &key[7]);
} 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, "DEVPATH_OLD=", 12) == 0) {
device_set_devpath_old(udev_device, &key[12]);
} else if (strncmp(key, "PHYSDEVPATH=", 12) == 0) {
device_set_physdevpath(udev_device, &key[12]);
} else if (strncmp(key, "SEQNUM=", 7) == 0) {
device_set_seqnum(udev_device, strtoull(&key[7], NULL, 10));
} else if (strncmp(key, "TIMEOUT=", 8) == 0) {
device_set_timeout(udev_device, strtoull(&key[8], NULL, 10));
}
if (strncmp(key, "PHYSDEV", 7) == 0)
continue;
device_add_property_from_string(udev_device, key);
}
device_set_devnum(udev_device, makedev(maj, min));
return udev_device;
}