src/libudev/libudev-queue.c

   1 /*
   2  * libudev - interface to udev device information
   3  *
   4  * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
   5  * Copyright (C) 2009 Alan Jenkins <alan-jenkins@tuffmail.co.uk>
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <stddef.h>
  16 #include <unistd.h>
  17 #include <errno.h>
  18 #include <string.h>
  19 #include <dirent.h>
  20 #include <fcntl.h>
  21 #include <limits.h>
  22 #include <sys/stat.h>
  23
  24 #include "libudev.h"
  25 #include "libudev-private.h"
  26
  27 /**
  28  * SECTION:libudev-queue
  29  * @short_description: access to currently active events
  30  *
  31  * The udev daemon processes events asynchronously. All events which do not have
  32  * interdependencies run in parallel. This exports the current state of the
  33  * event processing queue, and the current event sequence numbers from the kernel
  34  * and the udev daemon.
  35  */
  36
  37 /**
  38  * udev_queue:
  39  *
  40  * Opaque object representing the current event queue in the udev daemon.
  41  */
  42 struct udev_queue {
  43         struct udev *udev;
  44         int refcount;
  45         struct udev_list queue_list;
  46 };
  47
  48 /**
  49  * udev_queue_new:
  50  * @udev: udev library context
  51  *
  52  * The initial refcount is 1, and needs to be decremented to
  53  * release the resources of the udev queue context.
  54  *
  55  * Returns: the udev queue context, or #NULL on error.
  56  **/
  57 _public_ struct udev_queue *udev_queue_new(struct udev *udev)
  58 {
  59         struct udev_queue *udev_queue;
  60
  61         if (udev == NULL)
  62                 return NULL;
  63
  64         udev_queue = calloc(1, sizeof(struct udev_queue));
  65         if (udev_queue == NULL)
  66                 return NULL;
  67         udev_queue->refcount = 1;
  68         udev_queue->udev = udev;
  69         udev_list_init(udev, &udev_queue->queue_list, false);
  70         return udev_queue;
  71 }
  72
  73 /**
  74  * udev_queue_ref:
  75  * @udev_queue: udev queue context
  76  *
  77  * Take a reference of a udev queue context.
  78  *
  79  * Returns: the same udev queue context.
  80  **/
  81 _public_ struct udev_queue *udev_queue_ref(struct udev_queue *udev_queue)
  82 {
  83         if (udev_queue == NULL)
  84                 return NULL;
  85         udev_queue->refcount++;
  86         return udev_queue;
  87 }
  88
  89 /**
  90  * udev_queue_unref:
  91  * @udev_queue: udev queue context
  92  *
  93  * Drop a reference of a udev queue context. If the refcount reaches zero,
  94  * the resources of the queue context will be released.
  95  **/
  96 _public_ struct udev_queue *udev_queue_unref(struct udev_queue *udev_queue)
  97 {
  98         if (udev_queue == NULL)
  99                 return NULL;
 100         udev_queue->refcount--;
 101         if (udev_queue->refcount > 0)
 102                 return udev_queue;
 103         udev_list_cleanup(&udev_queue->queue_list);
 104         free(udev_queue);
 105         return NULL;
 106 }
 107
 108 /**
 109  * udev_queue_get_udev:
 110  * @udev_queue: udev queue context
 111  *
 112  * Retrieve the udev library context the queue context was created with.
 113  *
 114  * Returns: the udev library context.
 115  **/
 116 _public_ struct udev *udev_queue_get_udev(struct udev_queue *udev_queue)
 117 {
 118         if (udev_queue == NULL)
 119                 return NULL;
 120         return udev_queue->udev;
 121 }
 122
 123 unsigned long long int udev_get_kernel_seqnum(struct udev *udev)
 124 {
 125         unsigned long long int seqnum;
 126         int fd;
 127         char buf[32];
 128         ssize_t len;
 129
 130         fd = open("/sys/kernel/uevent_seqnum", O_RDONLY|O_CLOEXEC);
 131         if (fd < 0)
 132                 return 0;
 133         len = read(fd, buf, sizeof(buf));
 134         close(fd);
 135         if (len <= 2)
 136                 return 0;
 137         buf[len-1] = '\0';
 138         seqnum = strtoull(buf, NULL, 10);
 139         return seqnum;
 140 }
 141
 142 /**
 143  * udev_queue_get_kernel_seqnum:
 144  * @udev_queue: udev queue context
 145  *
 146  * Get the current kernel event sequence number.
 147  *
 148  * Returns: the sequence number.
 149  **/
 150 _public_ unsigned long long int udev_queue_get_kernel_seqnum(struct udev_queue *udev_queue)
 151 {
 152         unsigned long long int seqnum;
 153
 154         if (udev_queue == NULL)
 155                 return -EINVAL;
 156
 157         seqnum = udev_get_kernel_seqnum(udev_queue->udev);
 158         return seqnum;
 159 }
 160
 161 int udev_queue_read_seqnum(FILE *queue_file, unsigned long long int *seqnum)
 162 {
 163         if (fread(seqnum, sizeof(unsigned long long int), 1, queue_file) != 1)
 164                 return -1;
 165
 166         return 0;
 167 }
 168
 169 ssize_t udev_queue_skip_devpath(FILE *queue_file)
 170 {
 171         unsigned short int len;
 172
 173         if (fread(&len, sizeof(unsigned short int), 1, queue_file) == 1) {
 174                 char *devpath = alloca(len);
 175
 176                 /* use fread to skip, fseek might drop buffered data */
 177                 if (fread(devpath, 1, len, queue_file) == len)
 178                         return len;
 179         }
 180
 181         return -1;
 182 }
 183
 184 ssize_t udev_queue_read_devpath(FILE *queue_file, char *devpath, size_t size)
 185 {
 186         unsigned short int read_bytes = 0;
 187         unsigned short int len;
 188
 189         if (fread(&len, sizeof(unsigned short int), 1, queue_file) != 1)
 190                 return -1;
 191
 192         read_bytes = (len < size - 1) ? len : size - 1;
 193         if (fread(devpath, 1, read_bytes, queue_file) != read_bytes)
 194                 return -1;
 195         devpath[read_bytes] = '\0';
 196
 197         /* if devpath was too long, skip unread characters */
 198         if (read_bytes != len) {
 199                 unsigned short int skip_bytes = len - read_bytes;
 200                 char *buf = alloca(skip_bytes);
 201
 202                 if (fread(buf, 1, skip_bytes, queue_file) != skip_bytes)
 203                         return -1;
 204         }
 205
 206         return read_bytes;
 207 }
 208
 209 static FILE *open_queue_file(struct udev_queue *udev_queue, unsigned long long int *seqnum_start)
 210 {
 211         char filename[UTIL_PATH_SIZE];
 212         FILE *queue_file;
 213
 214         util_strscpyl(filename, sizeof(filename), "/run/udev/queue.bin", NULL);
 215         queue_file = fopen(filename, "re");
 216         if (queue_file == NULL)
 217                 return NULL;
 218
 219         if (udev_queue_read_seqnum(queue_file, seqnum_start) < 0) {
 220                 udev_err(udev_queue->udev, "corrupt queue file\n");
 221                 fclose(queue_file);
 222                 return NULL;
 223         }
 224
 225         return queue_file;
 226 }
 227
 228 /**
 229  * udev_queue_get_udev_seqnum:
 230  * @udev_queue: udev queue context
 231  *
 232  * Get the last known udev event sequence number.
 233  *
 234  * Returns: the sequence number.
 235  **/
 236 _public_ unsigned long long int udev_queue_get_udev_seqnum(struct udev_queue *udev_queue)
 237 {
 238         unsigned long long int seqnum_udev;
 239         FILE *queue_file;
 240
 241         queue_file = open_queue_file(udev_queue, &seqnum_udev);
 242         if (queue_file == NULL)
 243                 return 0;
 244
 245         for (;;) {
 246                 unsigned long long int seqnum;
 247                 ssize_t devpath_len;
 248
 249                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 250                         break;
 251                 devpath_len = udev_queue_skip_devpath(queue_file);
 252                 if (devpath_len < 0)
 253                         break;
 254                 if (devpath_len > 0)
 255                         seqnum_udev = seqnum;
 256         }
 257
 258         fclose(queue_file);
 259         return seqnum_udev;
 260 }
 261
 262 /**
 263  * udev_queue_get_udev_is_active:
 264  * @udev_queue: udev queue context
 265  *
 266  * Check if udev is active on the system.
 267  *
 268  * Returns: a flag indicating if udev is active.
 269  **/
 270 _public_ int udev_queue_get_udev_is_active(struct udev_queue *udev_queue)
 271 {
 272         unsigned long long int seqnum_start;
 273         FILE *queue_file;
 274
 275         queue_file = open_queue_file(udev_queue, &seqnum_start);
 276         if (queue_file == NULL)
 277                 return 0;
 278
 279         fclose(queue_file);
 280         return 1;
 281 }
 282
 283 /**
 284  * udev_queue_get_queue_is_empty:
 285  * @udev_queue: udev queue context
 286  *
 287  * Check if udev is currently processing any events.
 288  *
 289  * Returns: a flag indicating if udev is currently handling events.
 290  **/
 291 _public_ int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue)
 292 {
 293         unsigned long long int seqnum_kernel;
 294         unsigned long long int seqnum_udev = 0;
 295         int queued = 0;
 296         int is_empty = 0;
 297         FILE *queue_file;
 298
 299         if (udev_queue == NULL)
 300                 return -EINVAL;
 301         queue_file = open_queue_file(udev_queue, &seqnum_udev);
 302         if (queue_file == NULL)
 303                 return 1;
 304
 305         for (;;) {
 306                 unsigned long long int seqnum;
 307                 ssize_t devpath_len;
 308
 309                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 310                         break;
 311                 devpath_len = udev_queue_skip_devpath(queue_file);
 312                 if (devpath_len < 0)
 313                         break;
 314
 315                 if (devpath_len > 0) {
 316                         queued++;
 317                         seqnum_udev = seqnum;
 318                 } else {
 319                         queued--;
 320                 }
 321         }
 322
 323         if (queued > 0)
 324                 goto out;
 325
 326         seqnum_kernel = udev_queue_get_kernel_seqnum(udev_queue);
 327         if (seqnum_udev < seqnum_kernel)
 328                 goto out;
 329
 330         is_empty = 1;
 331
 332 out:
 333         fclose(queue_file);
 334         return is_empty;
 335 }
 336
 337 /**
 338  * udev_queue_get_seqnum_sequence_is_finished:
 339  * @udev_queue: udev queue context
 340  * @start: first event sequence number
 341  * @end: last event sequence number
 342  *
 343  * Check if udev is currently processing any events in a given sequence number range.
 344  *
 345  * Returns: a flag indicating if any of the sequence numbers in the given range is currently active.
 346  **/
 347 _public_ int udev_queue_get_seqnum_sequence_is_finished(struct udev_queue *udev_queue,
 348                                                unsigned long long int start, unsigned long long int end)
 349 {
 350         unsigned long long int seqnum;
 351         ssize_t devpath_len;
 352         int unfinished;
 353         FILE *queue_file;
 354
 355         if (udev_queue == NULL)
 356                 return -EINVAL;
 357         queue_file = open_queue_file(udev_queue, &seqnum);
 358         if (queue_file == NULL)
 359                 return 1;
 360         if (start < seqnum)
 361                 start = seqnum;
 362         if (start > end) {
 363                 fclose(queue_file);
 364                 return 1;
 365         }
 366         if (end - start > INT_MAX - 1) {
 367                 fclose(queue_file);
 368                 return -EOVERFLOW;
 369         }
 370
 371         /*
 372          * we might start with 0, and handle the initial seqnum
 373          * only when we find an entry in the queue file
 374          **/
 375         unfinished = end - start;
 376
 377         do {
 378                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 379                         break;
 380                 devpath_len = udev_queue_skip_devpath(queue_file);
 381                 if (devpath_len < 0)
 382                         break;
 383
 384                 /*
 385                  * we might start with an empty or re-build queue file, where
 386                  * the initial seqnum is not recorded as finished
 387                  */
 388                 if (start == seqnum && devpath_len > 0)
 389                         unfinished++;
 390
 391                 if (devpath_len == 0) {
 392                         if (seqnum >= start && seqnum <= end)
 393                                 unfinished--;
 394                 }
 395         } while (unfinished > 0);
 396
 397         fclose(queue_file);
 398
 399         return (unfinished == 0);
 400 }
 401
 402 /**
 403  * udev_queue_get_seqnum_is_finished:
 404  * @udev_queue: udev queue context
 405  * @seqnum: sequence number
 406  *
 407  * Check if udev is currently processing a given sequence number.
 408  *
 409  * Returns: a flag indicating if the given sequence number is currently active.
 410  **/
 411 _public_ int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum)
 412 {
 413         if (!udev_queue_get_seqnum_sequence_is_finished(udev_queue, seqnum, seqnum))
 414                 return 0;
 415
 416         return 1;
 417 }
 418
 419 /**
 420  * udev_queue_get_queued_list_entry:
 421  * @udev_queue: udev queue context
 422  *
 423  * Get the first entry of the list of queued events.
 424  *
 425  * Returns: a udev_list_entry.
 426  **/
 427 _public_ struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue)
 428 {
 429         unsigned long long int seqnum;
 430         FILE *queue_file;
 431
 432         if (udev_queue == NULL)
 433                 return NULL;
 434         udev_list_cleanup(&udev_queue->queue_list);
 435
 436         queue_file = open_queue_file(udev_queue, &seqnum);
 437         if (queue_file == NULL)
 438                 return NULL;
 439
 440         for (;;) {
 441                 char syspath[UTIL_PATH_SIZE];
 442                 char *s;
 443                 size_t l;
 444                 ssize_t len;
 445                 char seqnum_str[32];
 446                 struct udev_list_entry *list_entry;
 447
 448                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 449                         break;
 450                 snprintf(seqnum_str, sizeof(seqnum_str), "%llu", seqnum);
 451
 452                 s = syspath;
 453                 l = util_strpcpy(&s, sizeof(syspath), "/sys");
 454                 len = udev_queue_read_devpath(queue_file, s, l);
 455                 if (len < 0)
 456                         break;
 457
 458                 if (len > 0) {
 459                         udev_list_entry_add(&udev_queue->queue_list, syspath, seqnum_str);
 460                 } else {
 461                         udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_queue->queue_list)) {
 462                                 if (strcmp(seqnum_str, udev_list_entry_get_value(list_entry)) == 0) {
 463                                         udev_list_entry_delete(list_entry);
 464                                         break;
 465                                 }
 466                         }
 467                 }
 468         }
 469         fclose(queue_file);
 470
 471         return udev_list_get_entry(&udev_queue->queue_list);
 472 }