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_ void udev_queue_unref(struct udev_queue *udev_queue)
  97 {
  98         if (udev_queue == NULL)
  99                 return;
 100         udev_queue->refcount--;
 101         if (udev_queue->refcount > 0)
 102                 return;
 103         udev_list_cleanup(&udev_queue->queue_list);
 104         free(udev_queue);
 105 }
 106
 107 /**
 108  * udev_queue_get_udev:
 109  * @udev_queue: udev queue context
 110  *
 111  * Retrieve the udev library context the queue context was created with.
 112  *
 113  * Returns: the udev library context.
 114  **/
 115 _public_ struct udev *udev_queue_get_udev(struct udev_queue *udev_queue)
 116 {
 117         if (udev_queue == NULL)
 118                 return NULL;
 119         return udev_queue->udev;
 120 }
 121
 122 unsigned long long int udev_get_kernel_seqnum(struct udev *udev)
 123 {
 124         unsigned long long int seqnum;
 125         int fd;
 126         char buf[32];
 127         ssize_t len;
 128
 129         fd = open("/sys/kernel/uevent_seqnum", O_RDONLY|O_CLOEXEC);
 130         if (fd < 0)
 131                 return 0;
 132         len = read(fd, buf, sizeof(buf));
 133         close(fd);
 134         if (len <= 2)
 135                 return 0;
 136         buf[len-1] = '\0';
 137         seqnum = strtoull(buf, NULL, 10);
 138         return seqnum;
 139 }
 140
 141 /**
 142  * udev_queue_get_kernel_seqnum:
 143  * @udev_queue: udev queue context
 144  *
 145  * Returns: the current kernel event sequence number.
 146  **/
 147 _public_ unsigned long long int udev_queue_get_kernel_seqnum(struct udev_queue *udev_queue)
 148 {
 149         unsigned long long int seqnum;
 150
 151         if (udev_queue == NULL)
 152                 return -EINVAL;
 153
 154         seqnum = udev_get_kernel_seqnum(udev_queue->udev);
 155         return seqnum;
 156 }
 157
 158 int udev_queue_read_seqnum(FILE *queue_file, unsigned long long int *seqnum)
 159 {
 160         if (fread(seqnum, sizeof(unsigned long long int), 1, queue_file) != 1)
 161                 return -1;
 162
 163         return 0;
 164 }
 165
 166 ssize_t udev_queue_skip_devpath(FILE *queue_file)
 167 {
 168         unsigned short int len;
 169
 170         if (fread(&len, sizeof(unsigned short int), 1, queue_file) == 1) {
 171                 char *devpath = alloca(len);
 172
 173                 /* use fread to skip, fseek might drop buffered data */
 174                 if (fread(devpath, 1, len, queue_file) == len)
 175                         return len;
 176         }
 177
 178         return -1;
 179 }
 180
 181 ssize_t udev_queue_read_devpath(FILE *queue_file, char *devpath, size_t size)
 182 {
 183         unsigned short int read_bytes = 0;
 184         unsigned short int len;
 185
 186         if (fread(&len, sizeof(unsigned short int), 1, queue_file) != 1)
 187                 return -1;
 188
 189         read_bytes = (len < size - 1) ? len : size - 1;
 190         if (fread(devpath, 1, read_bytes, queue_file) != read_bytes)
 191                 return -1;
 192         devpath[read_bytes] = '\0';
 193
 194         /* if devpath was too long, skip unread characters */
 195         if (read_bytes != len) {
 196                 unsigned short int skip_bytes = len - read_bytes;
 197                 char *buf = alloca(skip_bytes);
 198
 199                 if (fread(buf, 1, skip_bytes, queue_file) != skip_bytes)
 200                         return -1;
 201         }
 202
 203         return read_bytes;
 204 }
 205
 206 static FILE *open_queue_file(struct udev_queue *udev_queue, unsigned long long int *seqnum_start)
 207 {
 208         char filename[UTIL_PATH_SIZE];
 209         FILE *queue_file;
 210
 211         util_strscpyl(filename, sizeof(filename), "/run/udev/queue.bin", NULL);
 212         queue_file = fopen(filename, "re");
 213         if (queue_file == NULL)
 214                 return NULL;
 215
 216         if (udev_queue_read_seqnum(queue_file, seqnum_start) < 0) {
 217                 err(udev_queue->udev, "corrupt queue file\n");
 218                 fclose(queue_file);
 219                 return NULL;
 220         }
 221
 222         return queue_file;
 223 }
 224
 225 /**
 226  * udev_queue_get_udev_seqnum:
 227  * @udev_queue: udev queue context
 228  *
 229  * Returns: the last known udev event sequence number.
 230  **/
 231 _public_ unsigned long long int udev_queue_get_udev_seqnum(struct udev_queue *udev_queue)
 232 {
 233         unsigned long long int seqnum_udev;
 234         FILE *queue_file;
 235
 236         queue_file = open_queue_file(udev_queue, &seqnum_udev);
 237         if (queue_file == NULL)
 238                 return 0;
 239
 240         for (;;) {
 241                 unsigned long long int seqnum;
 242                 ssize_t devpath_len;
 243
 244                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 245                         break;
 246                 devpath_len = udev_queue_skip_devpath(queue_file);
 247                 if (devpath_len < 0)
 248                         break;
 249                 if (devpath_len > 0)
 250                         seqnum_udev = seqnum;
 251         }
 252
 253         fclose(queue_file);
 254         return seqnum_udev;
 255 }
 256
 257 /**
 258  * udev_queue_get_udev_is_active:
 259  * @udev_queue: udev queue context
 260  *
 261  * Returns: a flag indicating if udev is active.
 262  **/
 263 _public_ int udev_queue_get_udev_is_active(struct udev_queue *udev_queue)
 264 {
 265         unsigned long long int seqnum_start;
 266         FILE *queue_file;
 267
 268         queue_file = open_queue_file(udev_queue, &seqnum_start);
 269         if (queue_file == NULL)
 270                 return 0;
 271
 272         fclose(queue_file);
 273         return 1;
 274 }
 275
 276 /**
 277  * udev_queue_get_queue_is_empty:
 278  * @udev_queue: udev queue context
 279  *
 280  * Returns: a flag indicating if udev is currently handling events.
 281  **/
 282 _public_ int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue)
 283 {
 284         unsigned long long int seqnum_kernel;
 285         unsigned long long int seqnum_udev = 0;
 286         int queued = 0;
 287         int is_empty = 0;
 288         FILE *queue_file;
 289
 290         if (udev_queue == NULL)
 291                 return -EINVAL;
 292         queue_file = open_queue_file(udev_queue, &seqnum_udev);
 293         if (queue_file == NULL)
 294                 return 1;
 295
 296         for (;;) {
 297                 unsigned long long int seqnum;
 298                 ssize_t devpath_len;
 299
 300                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 301                         break;
 302                 devpath_len = udev_queue_skip_devpath(queue_file);
 303                 if (devpath_len < 0)
 304                         break;
 305
 306                 if (devpath_len > 0) {
 307                         queued++;
 308                         seqnum_udev = seqnum;
 309                 } else {
 310                         queued--;
 311                 }
 312         }
 313
 314         if (queued > 0)
 315                 goto out;
 316
 317         seqnum_kernel = udev_queue_get_kernel_seqnum(udev_queue);
 318         if (seqnum_udev < seqnum_kernel)
 319                 goto out;
 320
 321         is_empty = 1;
 322
 323 out:
 324         fclose(queue_file);
 325         return is_empty;
 326 }
 327
 328 /**
 329  * udev_queue_get_seqnum_sequence_is_finished:
 330  * @udev_queue: udev queue context
 331  * @start: first event sequence number
 332  * @end: last event sequence number
 333  *
 334  * Returns: a flag indicating if any of the sequence numbers in the given range is currently active.
 335  **/
 336 _public_ int udev_queue_get_seqnum_sequence_is_finished(struct udev_queue *udev_queue,
 337                                                unsigned long long int start, unsigned long long int end)
 338 {
 339         unsigned long long int seqnum;
 340         ssize_t devpath_len;
 341         int unfinished;
 342         FILE *queue_file;
 343
 344         if (udev_queue == NULL)
 345                 return -EINVAL;
 346         queue_file = open_queue_file(udev_queue, &seqnum);
 347         if (queue_file == NULL)
 348                 return 1;
 349         if (start < seqnum)
 350                 start = seqnum;
 351         if (start > end) {
 352                 fclose(queue_file);
 353                 return 1;
 354         }
 355         if (end - start > INT_MAX - 1) {
 356                 fclose(queue_file);
 357                 return -EOVERFLOW;
 358         }
 359
 360         /*
 361          * we might start with 0, and handle the initial seqnum
 362          * only when we find an entry in the queue file
 363          **/
 364         unfinished = end - start;
 365
 366         do {
 367                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 368                         break;
 369                 devpath_len = udev_queue_skip_devpath(queue_file);
 370                 if (devpath_len < 0)
 371                         break;
 372
 373                 /*
 374                  * we might start with an empty or re-build queue file, where
 375                  * the initial seqnum is not recorded as finished
 376                  */
 377                 if (start == seqnum && devpath_len > 0)
 378                         unfinished++;
 379
 380                 if (devpath_len == 0) {
 381                         if (seqnum >= start && seqnum <= end)
 382                                 unfinished--;
 383                 }
 384         } while (unfinished > 0);
 385
 386         fclose(queue_file);
 387
 388         return (unfinished == 0);
 389 }
 390
 391 /**
 392  * udev_queue_get_seqnum_is_finished:
 393  * @udev_queue: udev queue context
 394  * @seqnum: sequence number
 395  *
 396  * Returns: a flag indicating if the given sequence number is currently active.
 397  **/
 398 _public_ int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum)
 399 {
 400         if (!udev_queue_get_seqnum_sequence_is_finished(udev_queue, seqnum, seqnum))
 401                 return 0;
 402
 403         return 1;
 404 }
 405
 406 /**
 407  * udev_queue_get_queued_list_entry:
 408  * @udev_queue: udev queue context
 409  *
 410  * Returns: the first entry of the list of queued events.
 411  **/
 412 _public_ struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue)
 413 {
 414         unsigned long long int seqnum;
 415         FILE *queue_file;
 416
 417         if (udev_queue == NULL)
 418                 return NULL;
 419         udev_list_cleanup(&udev_queue->queue_list);
 420
 421         queue_file = open_queue_file(udev_queue, &seqnum);
 422         if (queue_file == NULL)
 423                 return NULL;
 424
 425         for (;;) {
 426                 char syspath[UTIL_PATH_SIZE];
 427                 char *s;
 428                 size_t l;
 429                 ssize_t len;
 430                 char seqnum_str[32];
 431                 struct udev_list_entry *list_entry;
 432
 433                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 434                         break;
 435                 snprintf(seqnum_str, sizeof(seqnum_str), "%llu", seqnum);
 436
 437                 s = syspath;
 438                 l = util_strpcpy(&s, sizeof(syspath), "/sys");
 439                 len = udev_queue_read_devpath(queue_file, s, l);
 440                 if (len < 0)
 441                         break;
 442
 443                 if (len > 0) {
 444                         udev_list_entry_add(&udev_queue->queue_list, syspath, seqnum_str);
 445                 } else {
 446                         udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_queue->queue_list)) {
 447                                 if (strcmp(seqnum_str, udev_list_entry_get_value(list_entry)) == 0) {
 448                                         udev_list_entry_delete(list_entry);
 449                                         break;
 450                                 }
 451                         }
 452                 }
 453         }
 454         fclose(queue_file);
 455
 456         return udev_list_get_entry(&udev_queue->queue_list);
 457 }
 458
 459 struct udev_list_entry *udev_queue_get_failed_list_entry(struct udev_queue *udev_queue);
 460 _public_ struct udev_list_entry *udev_queue_get_failed_list_entry(struct udev_queue *udev_queue)
 461 {
 462         err(udev_queue->udev, "udev_queue_get_failed_list_entry() does not return anything; failed events are not recorded\n");
 463         errno = ENOSYS;
 464         return NULL;
 465 }