2 * libudev - interface to udev device information
4 * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
5 * Copyright (C) 2009 Alan Jenkins <alan-jenkins@tuffmail.co.uk>
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.
25 #include "libudev-private.h"
28 * SECTION:libudev-queue
29 * @short_description: access to currently active events
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.
40 * Opaque object representing the current event queue in the udev daemon.
45 struct udev_list queue_list;
50 * @udev: udev library context
52 * The initial refcount is 1, and needs to be decremented to
53 * release the resources of the udev queue context.
55 * Returns: the udev queue context, or #NULL on error.
57 _public_ struct udev_queue *udev_queue_new(struct udev *udev)
59 struct udev_queue *udev_queue;
64 udev_queue = calloc(1, sizeof(struct udev_queue));
65 if (udev_queue == NULL)
67 udev_queue->refcount = 1;
68 udev_queue->udev = udev;
69 udev_list_init(udev, &udev_queue->queue_list, false);
75 * @udev_queue: udev queue context
77 * Take a reference of a udev queue context.
79 * Returns: the same udev queue context.
81 _public_ struct udev_queue *udev_queue_ref(struct udev_queue *udev_queue)
83 if (udev_queue == NULL)
85 udev_queue->refcount++;
91 * @udev_queue: udev queue context
93 * Drop a reference of a udev queue context. If the refcount reaches zero,
94 * the resources of the queue context will be released.
96 * Returns: the passed queue context if it has still an active reference, or #NULL otherwise.
98 _public_ struct udev_queue *udev_queue_unref(struct udev_queue *udev_queue)
100 if (udev_queue == NULL)
102 udev_queue->refcount--;
103 if (udev_queue->refcount > 0)
105 udev_list_cleanup(&udev_queue->queue_list);
111 * udev_queue_get_udev:
112 * @udev_queue: udev queue context
114 * Retrieve the udev library context the queue context was created with.
116 * Returns: the udev library context.
118 _public_ struct udev *udev_queue_get_udev(struct udev_queue *udev_queue)
120 if (udev_queue == NULL)
122 return udev_queue->udev;
125 unsigned long long int udev_get_kernel_seqnum(struct udev *udev)
127 unsigned long long int seqnum;
132 fd = open("/sys/kernel/uevent_seqnum", O_RDONLY|O_CLOEXEC);
135 len = read(fd, buf, sizeof(buf));
140 seqnum = strtoull(buf, NULL, 10);
145 * udev_queue_get_kernel_seqnum:
146 * @udev_queue: udev queue context
148 * Get the current kernel event sequence number.
150 * Returns: the sequence number.
152 _public_ unsigned long long int udev_queue_get_kernel_seqnum(struct udev_queue *udev_queue)
154 unsigned long long int seqnum;
156 if (udev_queue == NULL)
159 seqnum = udev_get_kernel_seqnum(udev_queue->udev);
163 int udev_queue_read_seqnum(FILE *queue_file, unsigned long long int *seqnum)
165 if (fread(seqnum, sizeof(unsigned long long int), 1, queue_file) != 1)
171 ssize_t udev_queue_skip_devpath(FILE *queue_file)
173 unsigned short int len;
175 if (fread(&len, sizeof(unsigned short int), 1, queue_file) == 1) {
176 char *devpath = alloca(len);
178 /* use fread to skip, fseek might drop buffered data */
179 if (fread(devpath, 1, len, queue_file) == len)
186 ssize_t udev_queue_read_devpath(FILE *queue_file, char *devpath, size_t size)
188 unsigned short int read_bytes = 0;
189 unsigned short int len;
191 if (fread(&len, sizeof(unsigned short int), 1, queue_file) != 1)
194 read_bytes = (len < size - 1) ? len : size - 1;
195 if (fread(devpath, 1, read_bytes, queue_file) != read_bytes)
197 devpath[read_bytes] = '\0';
199 /* if devpath was too long, skip unread characters */
200 if (read_bytes != len) {
201 unsigned short int skip_bytes = len - read_bytes;
202 char *buf = alloca(skip_bytes);
204 if (fread(buf, 1, skip_bytes, queue_file) != skip_bytes)
211 static FILE *open_queue_file(struct udev_queue *udev_queue, unsigned long long int *seqnum_start)
215 queue_file = fopen("/run/udev/queue.bin", "re");
216 if (queue_file == NULL)
219 if (udev_queue_read_seqnum(queue_file, seqnum_start) < 0) {
220 udev_err(udev_queue->udev, "corrupt queue file\n");
229 * udev_queue_get_udev_seqnum:
230 * @udev_queue: udev queue context
232 * Get the last known udev event sequence number.
234 * Returns: the sequence number.
236 _public_ unsigned long long int udev_queue_get_udev_seqnum(struct udev_queue *udev_queue)
238 unsigned long long int seqnum_udev;
241 queue_file = open_queue_file(udev_queue, &seqnum_udev);
242 if (queue_file == NULL)
246 unsigned long long int seqnum;
249 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
251 devpath_len = udev_queue_skip_devpath(queue_file);
255 seqnum_udev = seqnum;
263 * udev_queue_get_udev_is_active:
264 * @udev_queue: udev queue context
266 * Check if udev is active on the system.
268 * Returns: a flag indicating if udev is active.
270 _public_ int udev_queue_get_udev_is_active(struct udev_queue *udev_queue)
272 unsigned long long int seqnum_start;
275 queue_file = open_queue_file(udev_queue, &seqnum_start);
276 if (queue_file == NULL)
284 * udev_queue_get_queue_is_empty:
285 * @udev_queue: udev queue context
287 * Check if udev is currently processing any events.
289 * Returns: a flag indicating if udev is currently handling events.
291 _public_ int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue)
293 unsigned long long int seqnum_kernel;
294 unsigned long long int seqnum_udev = 0;
299 if (udev_queue == NULL)
301 queue_file = open_queue_file(udev_queue, &seqnum_udev);
302 if (queue_file == NULL)
306 unsigned long long int seqnum;
309 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
311 devpath_len = udev_queue_skip_devpath(queue_file);
315 if (devpath_len > 0) {
317 seqnum_udev = seqnum;
326 seqnum_kernel = udev_queue_get_kernel_seqnum(udev_queue);
327 if (seqnum_udev < seqnum_kernel)
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
343 * Check if udev is currently processing any events in a given sequence number range.
345 * Returns: a flag indicating if any of the sequence numbers in the given range is currently active.
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)
350 unsigned long long int seqnum;
355 if (udev_queue == NULL)
357 queue_file = open_queue_file(udev_queue, &seqnum);
358 if (queue_file == NULL)
366 if (end - start > INT_MAX - 1) {
372 * we might start with 0, and handle the initial seqnum
373 * only when we find an entry in the queue file
375 unfinished = end - start;
378 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
380 devpath_len = udev_queue_skip_devpath(queue_file);
385 * we might start with an empty or re-build queue file, where
386 * the initial seqnum is not recorded as finished
388 if (start == seqnum && devpath_len > 0)
391 if (devpath_len == 0) {
392 if (seqnum >= start && seqnum <= end)
395 } while (unfinished > 0);
399 return (unfinished == 0);
403 * udev_queue_get_seqnum_is_finished:
404 * @udev_queue: udev queue context
405 * @seqnum: sequence number
407 * Check if udev is currently processing a given sequence number.
409 * Returns: a flag indicating if the given sequence number is currently active.
411 _public_ int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum)
413 if (!udev_queue_get_seqnum_sequence_is_finished(udev_queue, seqnum, seqnum))
420 * udev_queue_get_queued_list_entry:
421 * @udev_queue: udev queue context
423 * Get the first entry of the list of queued events.
425 * Returns: a udev_list_entry.
427 _public_ struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue)
429 unsigned long long int seqnum;
432 if (udev_queue == NULL)
434 udev_list_cleanup(&udev_queue->queue_list);
436 queue_file = open_queue_file(udev_queue, &seqnum);
437 if (queue_file == NULL)
441 char syspath[UTIL_PATH_SIZE];
446 struct udev_list_entry *list_entry;
448 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
450 snprintf(seqnum_str, sizeof(seqnum_str), "%llu", seqnum);
453 l = util_strpcpy(&s, sizeof(syspath), "/sys");
454 len = udev_queue_read_devpath(queue_file, s, l);
459 udev_list_entry_add(&udev_queue->queue_list, syspath, seqnum_str);
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);
471 return udev_list_get_entry(&udev_queue->queue_list);