src/udev/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         char filename[UTIL_PATH_SIZE];
 125         unsigned long long int seqnum;
 126         int fd;
 127         char buf[32];
 128         ssize_t len;
 129
 130         util_strscpyl(filename, sizeof(filename), udev_get_sys_path(udev), "/kernel/uevent_seqnum", NULL);
 131         fd = open(filename, O_RDONLY|O_CLOEXEC);
 132         if (fd < 0)
 133                 return 0;
 134         len = read(fd, buf, sizeof(buf));
 135         close(fd);
 136         if (len <= 2)
 137                 return 0;
 138         buf[len-1] = '\0';
 139         seqnum = strtoull(buf, NULL, 10);
 140         return seqnum;
 141 }
 142
 143 /**
 144  * udev_queue_get_kernel_seqnum:
 145  * @udev_queue: udev queue context
 146  *
 147  * Returns: the current kernel event sequence number.
 148  **/
 149 _public_ unsigned long long int udev_queue_get_kernel_seqnum(struct udev_queue *udev_queue)
 150 {
 151         unsigned long long int seqnum;
 152
 153         if (udev_queue == NULL)
 154                 return -EINVAL;
 155
 156         seqnum = udev_get_kernel_seqnum(udev_queue->udev);
 157         return seqnum;
 158 }
 159
 160 int udev_queue_read_seqnum(FILE *queue_file, unsigned long long int *seqnum)
 161 {
 162         if (fread(seqnum, sizeof(unsigned long long int), 1, queue_file) != 1)
 163                 return -1;
 164
 165         return 0;
 166 }
 167
 168 ssize_t udev_queue_skip_devpath(FILE *queue_file)
 169 {
 170         unsigned short int len;
 171
 172         if (fread(&len, sizeof(unsigned short int), 1, queue_file) == 1) {
 173                 char *devpath = alloca(len);
 174
 175                 /* use fread to skip, fseek might drop buffered data */
 176                 if (fread(devpath, 1, len, queue_file) == len)
 177                         return len;
 178         }
 179
 180         return -1;
 181 }
 182
 183 ssize_t udev_queue_read_devpath(FILE *queue_file, char *devpath, size_t size)
 184 {
 185         unsigned short int read_bytes = 0;
 186         unsigned short int len;
 187
 188         if (fread(&len, sizeof(unsigned short int), 1, queue_file) != 1)
 189                 return -1;
 190
 191         read_bytes = (len < size - 1) ? len : size - 1;
 192         if (fread(devpath, 1, read_bytes, queue_file) != read_bytes)
 193                 return -1;
 194         devpath[read_bytes] = '\0';
 195
 196         /* if devpath was too long, skip unread characters */
 197         if (read_bytes != len) {
 198                 unsigned short int skip_bytes = len - read_bytes;
 199                 char *buf = alloca(skip_bytes);
 200
 201                 if (fread(buf, 1, skip_bytes, queue_file) != skip_bytes)
 202                         return -1;
 203         }
 204
 205         return read_bytes;
 206 }
 207
 208 static FILE *open_queue_file(struct udev_queue *udev_queue, unsigned long long int *seqnum_start)
 209 {
 210         char filename[UTIL_PATH_SIZE];
 211         FILE *queue_file;
 212
 213         util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev_queue->udev), "/queue.bin", NULL);
 214         queue_file = fopen(filename, "re");
 215         if (queue_file == NULL)
 216                 return NULL;
 217
 218         if (udev_queue_read_seqnum(queue_file, seqnum_start) < 0) {
 219                 err(udev_queue->udev, "corrupt queue file\n");
 220                 fclose(queue_file);
 221                 return NULL;
 222         }
 223
 224         return queue_file;
 225 }
 226
 227 /**
 228  * udev_queue_get_udev_seqnum:
 229  * @udev_queue: udev queue context
 230  *
 231  * Returns: the last known udev event sequence number.
 232  **/
 233 _public_ unsigned long long int udev_queue_get_udev_seqnum(struct udev_queue *udev_queue)
 234 {
 235         unsigned long long int seqnum_udev;
 236         FILE *queue_file;
 237
 238         queue_file = open_queue_file(udev_queue, &seqnum_udev);
 239         if (queue_file == NULL)
 240                 return 0;
 241
 242         for (;;) {
 243                 unsigned long long int seqnum;
 244                 ssize_t devpath_len;
 245
 246                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 247                         break;
 248                 devpath_len = udev_queue_skip_devpath(queue_file);
 249                 if (devpath_len < 0)
 250                         break;
 251                 if (devpath_len > 0)
 252                         seqnum_udev = seqnum;
 253         }
 254
 255         fclose(queue_file);
 256         return seqnum_udev;
 257 }
 258
 259 /**
 260  * udev_queue_get_udev_is_active:
 261  * @udev_queue: udev queue context
 262  *
 263  * Returns: a flag indicating if udev is active.
 264  **/
 265 _public_ int udev_queue_get_udev_is_active(struct udev_queue *udev_queue)
 266 {
 267         unsigned long long int seqnum_start;
 268         FILE *queue_file;
 269
 270         queue_file = open_queue_file(udev_queue, &seqnum_start);
 271         if (queue_file == NULL)
 272                 return 0;
 273
 274         fclose(queue_file);
 275         return 1;
 276 }
 277
 278 /**
 279  * udev_queue_get_queue_is_empty:
 280  * @udev_queue: udev queue context
 281  *
 282  * Returns: a flag indicating if udev is currently handling events.
 283  **/
 284 _public_ int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue)
 285 {
 286         unsigned long long int seqnum_kernel;
 287         unsigned long long int seqnum_udev = 0;
 288         int queued = 0;
 289         int is_empty = 0;
 290         FILE *queue_file;
 291
 292         if (udev_queue == NULL)
 293                 return -EINVAL;
 294         queue_file = open_queue_file(udev_queue, &seqnum_udev);
 295         if (queue_file == NULL)
 296                 return 1;
 297
 298         for (;;) {
 299                 unsigned long long int seqnum;
 300                 ssize_t devpath_len;
 301
 302                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 303                         break;
 304                 devpath_len = udev_queue_skip_devpath(queue_file);
 305                 if (devpath_len < 0)
 306                         break;
 307
 308                 if (devpath_len > 0) {
 309                         queued++;
 310                         seqnum_udev = seqnum;
 311                 } else {
 312                         queued--;
 313                 }
 314         }
 315
 316         if (queued > 0)
 317                 goto out;
 318
 319         seqnum_kernel = udev_queue_get_kernel_seqnum(udev_queue);
 320         if (seqnum_udev < seqnum_kernel)
 321                 goto out;
 322
 323         is_empty = 1;
 324
 325 out:
 326         fclose(queue_file);
 327         return is_empty;
 328 }
 329
 330 /**
 331  * udev_queue_get_seqnum_sequence_is_finished:
 332  * @udev_queue: udev queue context
 333  * @start: first event sequence number
 334  * @end: last event sequence number
 335  *
 336  * Returns: a flag indicating if any of the sequence numbers in the given range is currently active.
 337  **/
 338 _public_ int udev_queue_get_seqnum_sequence_is_finished(struct udev_queue *udev_queue,
 339                                                unsigned long long int start, unsigned long long int end)
 340 {
 341         unsigned long long int seqnum;
 342         ssize_t devpath_len;
 343         int unfinished;
 344         FILE *queue_file;
 345
 346         if (udev_queue == NULL)
 347                 return -EINVAL;
 348         queue_file = open_queue_file(udev_queue, &seqnum);
 349         if (queue_file == NULL)
 350                 return 1;
 351         if (start < seqnum)
 352                 start = seqnum;
 353         if (start > end) {
 354                 fclose(queue_file);
 355                 return 1;
 356         }
 357         if (end - start > INT_MAX - 1) {
 358                 fclose(queue_file);
 359                 return -EOVERFLOW;
 360         }
 361
 362         /*
 363          * we might start with 0, and handle the initial seqnum
 364          * only when we find an entry in the queue file
 365          **/
 366         unfinished = end - start;
 367
 368         do {
 369                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 370                         break;
 371                 devpath_len = udev_queue_skip_devpath(queue_file);
 372                 if (devpath_len < 0)
 373                         break;
 374
 375                 /*
 376                  * we might start with an empty or re-build queue file, where
 377                  * the initial seqnum is not recorded as finished
 378                  */
 379                 if (start == seqnum && devpath_len > 0)
 380                         unfinished++;
 381
 382                 if (devpath_len == 0) {
 383                         if (seqnum >= start && seqnum <= end)
 384                                 unfinished--;
 385                 }
 386         } while (unfinished > 0);
 387
 388         fclose(queue_file);
 389
 390         return (unfinished == 0);
 391 }
 392
 393 /**
 394  * udev_queue_get_seqnum_is_finished:
 395  * @udev_queue: udev queue context
 396  * @seqnum: sequence number
 397  *
 398  * Returns: a flag indicating if the given sequence number is currently active.
 399  **/
 400 _public_ int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum)
 401 {
 402         if (!udev_queue_get_seqnum_sequence_is_finished(udev_queue, seqnum, seqnum))
 403                 return 0;
 404
 405         return 1;
 406 }
 407
 408 /**
 409  * udev_queue_get_queued_list_entry:
 410  * @udev_queue: udev queue context
 411  *
 412  * Returns: the first entry of the list of queued events.
 413  **/
 414 _public_ struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue)
 415 {
 416         unsigned long long int seqnum;
 417         FILE *queue_file;
 418
 419         if (udev_queue == NULL)
 420                 return NULL;
 421         udev_list_cleanup(&udev_queue->queue_list);
 422
 423         queue_file = open_queue_file(udev_queue, &seqnum);
 424         if (queue_file == NULL)
 425                 return NULL;
 426
 427         for (;;) {
 428                 char syspath[UTIL_PATH_SIZE];
 429                 char *s;
 430                 size_t l;
 431                 ssize_t len;
 432                 char seqnum_str[32];
 433                 struct udev_list_entry *list_entry;
 434
 435                 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
 436                         break;
 437                 snprintf(seqnum_str, sizeof(seqnum_str), "%llu", seqnum);
 438
 439                 s = syspath;
 440                 l = util_strpcpyl(&s, sizeof(syspath), udev_get_sys_path(udev_queue->udev), NULL);
 441                 len = udev_queue_read_devpath(queue_file, s, l);
 442                 if (len < 0)
 443                         break;
 444
 445                 if (len > 0) {
 446                         udev_list_entry_add(&udev_queue->queue_list, syspath, seqnum_str);
 447                 } else {
 448                         udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_queue->queue_list)) {
 449                                 if (strcmp(seqnum_str, udev_list_entry_get_value(list_entry)) == 0) {
 450                                         udev_list_entry_delete(list_entry);
 451                                         break;
 452                                 }
 453                         }
 454                 }
 455         }
 456         fclose(queue_file);
 457
 458         return udev_list_get_entry(&udev_queue->queue_list);
 459 }
 460
 461 struct udev_list_entry *udev_queue_get_failed_list_entry(struct udev_queue *udev_queue);
 462 _public_ struct udev_list_entry *udev_queue_get_failed_list_entry(struct udev_queue *udev_queue)
 463 {
 464         errno = ENOSYS;
 465         return NULL;
 466 }