src/udev/udevadm-monitor.c

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2
   3 #include <errno.h>
   4 #include <getopt.h>
   5 #include <signal.h>
   6 #include <stddef.h>
   7 #include <stdio.h>
   8 #include <string.h>
   9 #include <sys/epoll.h>
  10 #include <sys/time.h>
  11 #include <time.h>
  12
  13 #include "fd-util.h"
  14 #include "format-util.h"
  15 #include "udev.h"
  16 #include "udevadm-util.h"
  17
  18 static bool udev_exit;
  19
  20 static void sig_handler(int signum) {
  21         if (IN_SET(signum, SIGINT, SIGTERM))
  22                 udev_exit = true;
  23 }
  24
  25 static void print_device(struct udev_device *device, const char *source, int prop) {
  26         struct timespec ts;
  27
  28         assert_se(clock_gettime(CLOCK_MONOTONIC, &ts) == 0);
  29         printf("%-6s[%"PRI_TIME".%06"PRI_NSEC"] %-8s %s (%s)\n",
  30                source,
  31                ts.tv_sec, (nsec_t)ts.tv_nsec/1000,
  32                udev_device_get_action(device),
  33                udev_device_get_devpath(device),
  34                udev_device_get_subsystem(device));
  35         if (prop) {
  36                 struct udev_list_entry *list_entry;
  37
  38                 udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(device))
  39                         printf("%s=%s\n",
  40                                udev_list_entry_get_name(list_entry),
  41                                udev_list_entry_get_value(list_entry));
  42                 printf("\n");
  43         }
  44 }
  45
  46 static void help(void) {
  47         printf("%s monitor [OPTIONS]\n\n"
  48                "Listen to kernel and udev events.\n\n"
  49                "  -h --help                                Show this help\n"
  50                "  -V --version                             Show package version\n"
  51                "  -p --property                            Print the event properties\n"
  52                "  -k --kernel                              Print kernel uevents\n"
  53                "  -u --udev                                Print udev events\n"
  54                "  -s --subsystem-match=SUBSYSTEM[/DEVTYPE] Filter events by subsystem\n"
  55                "  -t --tag-match=TAG                       Filter events by tag\n"
  56                , program_invocation_short_name);
  57 }
  58
  59 static int adm_monitor(int argc, char *argv[]) {
  60         struct sigaction act = {};
  61         sigset_t mask;
  62         bool prop = false;
  63         bool print_kernel = false;
  64         bool print_udev = false;
  65         _cleanup_(udev_list_cleanup) struct udev_list subsystem_match_list;
  66         _cleanup_(udev_list_cleanup) struct udev_list tag_match_list;
  67         _cleanup_(udev_monitor_unrefp) struct udev_monitor *udev_monitor = NULL;
  68         _cleanup_(udev_monitor_unrefp) struct udev_monitor *kernel_monitor = NULL;
  69         _cleanup_close_ int fd_ep = -1;
  70         int fd_kernel = -1, fd_udev = -1;
  71         struct epoll_event ep_kernel, ep_udev;
  72         int c;
  73
  74         static const struct option options[] = {
  75                 { "property",        no_argument,       NULL, 'p' },
  76                 { "environment",     no_argument,       NULL, 'e' }, /* alias for -p */
  77                 { "kernel",          no_argument,       NULL, 'k' },
  78                 { "udev",            no_argument,       NULL, 'u' },
  79                 { "subsystem-match", required_argument, NULL, 's' },
  80                 { "tag-match",       required_argument, NULL, 't' },
  81                 { "version",         no_argument,       NULL, 'V' },
  82                 { "help",            no_argument,       NULL, 'h' },
  83                 {}
  84         };
  85
  86         udev_list_init(NULL, &subsystem_match_list, true);
  87         udev_list_init(NULL, &tag_match_list, true);
  88
  89         while ((c = getopt_long(argc, argv, "pekus:t:Vh", options, NULL)) >= 0)
  90                 switch (c) {
  91                 case 'p':
  92                 case 'e':
  93                         prop = true;
  94                         break;
  95                 case 'k':
  96                         print_kernel = true;
  97                         break;
  98                 case 'u':
  99                         print_udev = true;
 100                         break;
 101                 case 's':
 102                         {
 103                                 char subsys[UTIL_NAME_SIZE];
 104                                 char *devtype;
 105
 106                                 strscpy(subsys, sizeof(subsys), optarg);
 107                                 devtype = strchr(subsys, '/');
 108                                 if (devtype != NULL) {
 109                                         devtype[0] = '\0';
 110                                         devtype++;
 111                                 }
 112                                 udev_list_entry_add(&subsystem_match_list, subsys, devtype);
 113                                 break;
 114                         }
 115                 case 't':
 116                         udev_list_entry_add(&tag_match_list, optarg, NULL);
 117                         break;
 118                 case 'V':
 119                         print_version();
 120                         return 0;
 121                 case 'h':
 122                         help();
 123                         return 0;
 124                 default:
 125                         return 1;
 126                 }
 127
 128         if (!print_kernel && !print_udev) {
 129                 print_kernel = true;
 130                 print_udev = true;
 131         }
 132
 133         /* set signal handlers */
 134         act.sa_handler = sig_handler;
 135         act.sa_flags = SA_RESTART;
 136         assert_se(sigaction(SIGINT, &act, NULL) == 0);
 137         assert_se(sigaction(SIGTERM, &act, NULL) == 0);
 138         assert_se(sigemptyset(&mask) == 0);
 139         assert_se(sigaddset(&mask, SIGINT) == 0);
 140         assert_se(sigaddset(&mask, SIGTERM) == 0);
 141         assert_se(sigprocmask(SIG_UNBLOCK, &mask, NULL) == 0);
 142
 143         /* Callers are expecting to see events as they happen: Line buffering */
 144         setlinebuf(stdout);
 145
 146         fd_ep = epoll_create1(EPOLL_CLOEXEC);
 147         if (fd_ep < 0) {
 148                 log_error_errno(errno, "error creating epoll fd: %m");
 149                 return 1;
 150         }
 151
 152         printf("monitor will print the received events for:\n");
 153         if (print_udev) {
 154                 struct udev_list_entry *entry;
 155
 156                 udev_monitor = udev_monitor_new_from_netlink(NULL, "udev");
 157                 if (udev_monitor == NULL) {
 158                         fprintf(stderr, "error: unable to create netlink socket\n");
 159                         return 1;
 160                 }
 161                 udev_monitor_set_receive_buffer_size(udev_monitor, 128*1024*1024);
 162                 fd_udev = udev_monitor_get_fd(udev_monitor);
 163
 164                 udev_list_entry_foreach(entry, udev_list_get_entry(&subsystem_match_list)) {
 165                         const char *subsys = udev_list_entry_get_name(entry);
 166                         const char *devtype = udev_list_entry_get_value(entry);
 167
 168                         if (udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, subsys, devtype) < 0)
 169                                 fprintf(stderr, "error: unable to apply subsystem filter '%s'\n", subsys);
 170                 }
 171
 172                 udev_list_entry_foreach(entry, udev_list_get_entry(&tag_match_list)) {
 173                         const char *tag = udev_list_entry_get_name(entry);
 174
 175                         if (udev_monitor_filter_add_match_tag(udev_monitor, tag) < 0)
 176                                 fprintf(stderr, "error: unable to apply tag filter '%s'\n", tag);
 177                 }
 178
 179                 if (udev_monitor_enable_receiving(udev_monitor) < 0) {
 180                         fprintf(stderr, "error: unable to subscribe to udev events\n");
 181                         return 2;
 182                 }
 183
 184                 memzero(&ep_udev, sizeof(struct epoll_event));
 185                 ep_udev.events = EPOLLIN;
 186                 ep_udev.data.fd = fd_udev;
 187                 if (epoll_ctl(fd_ep, EPOLL_CTL_ADD, fd_udev, &ep_udev) < 0) {
 188                         log_error_errno(errno, "fail to add fd to epoll: %m");
 189                         return 2;
 190                 }
 191
 192                 printf("UDEV - the event which udev sends out after rule processing\n");
 193         }
 194
 195         if (print_kernel) {
 196                 struct udev_list_entry *entry;
 197
 198                 kernel_monitor = udev_monitor_new_from_netlink(NULL, "kernel");
 199                 if (kernel_monitor == NULL) {
 200                         fprintf(stderr, "error: unable to create netlink socket\n");
 201                         return 3;
 202                 }
 203                 udev_monitor_set_receive_buffer_size(kernel_monitor, 128*1024*1024);
 204                 fd_kernel = udev_monitor_get_fd(kernel_monitor);
 205
 206                 udev_list_entry_foreach(entry, udev_list_get_entry(&subsystem_match_list)) {
 207                         const char *subsys = udev_list_entry_get_name(entry);
 208
 209                         if (udev_monitor_filter_add_match_subsystem_devtype(kernel_monitor, subsys, NULL) < 0)
 210                                 fprintf(stderr, "error: unable to apply subsystem filter '%s'\n", subsys);
 211                 }
 212
 213                 if (udev_monitor_enable_receiving(kernel_monitor) < 0) {
 214                         fprintf(stderr, "error: unable to subscribe to kernel events\n");
 215                         return 4;
 216                 }
 217
 218                 memzero(&ep_kernel, sizeof(struct epoll_event));
 219                 ep_kernel.events = EPOLLIN;
 220                 ep_kernel.data.fd = fd_kernel;
 221                 if (epoll_ctl(fd_ep, EPOLL_CTL_ADD, fd_kernel, &ep_kernel) < 0) {
 222                         log_error_errno(errno, "fail to add fd to epoll: %m");
 223                         return 5;
 224                 }
 225
 226                 printf("KERNEL - the kernel uevent\n");
 227         }
 228         printf("\n");
 229
 230         while (!udev_exit) {
 231                 int fdcount;
 232                 struct epoll_event ev[4];
 233                 int i;
 234
 235                 fdcount = epoll_wait(fd_ep, ev, ELEMENTSOF(ev), -1);
 236                 if (fdcount < 0) {
 237                         if (errno != EINTR)
 238                                 fprintf(stderr, "error receiving uevent message: %m\n");
 239                         continue;
 240                 }
 241
 242                 for (i = 0; i < fdcount; i++) {
 243                         if (ev[i].data.fd == fd_kernel && ev[i].events & EPOLLIN) {
 244                                 struct udev_device *device;
 245
 246                                 device = udev_monitor_receive_device(kernel_monitor);
 247                                 if (device == NULL)
 248                                         continue;
 249                                 print_device(device, "KERNEL", prop);
 250                                 udev_device_unref(device);
 251                         } else if (ev[i].data.fd == fd_udev && ev[i].events & EPOLLIN) {
 252                                 struct udev_device *device;
 253
 254                                 device = udev_monitor_receive_device(udev_monitor);
 255                                 if (device == NULL)
 256                                         continue;
 257                                 print_device(device, "UDEV", prop);
 258                                 udev_device_unref(device);
 259                         }
 260                 }
 261         }
 262
 263         return 0;
 264 }
 265
 266 const struct udevadm_cmd udevadm_monitor = {
 267         .name = "monitor",
 268         .cmd = adm_monitor,
 269         .help = "Listen to kernel and udev events",
 270 };