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)
213 char filename[UTIL_PATH_SIZE];
216 util_strscpyl(filename, sizeof(filename), "/run/udev/queue.bin", NULL);
217 queue_file = fopen(filename, "re");
218 if (queue_file == NULL)
221 if (udev_queue_read_seqnum(queue_file, seqnum_start) < 0) {
222 udev_err(udev_queue->udev, "corrupt queue file\n");
231 * udev_queue_get_udev_seqnum:
232 * @udev_queue: udev queue context
234 * Get the last known udev event sequence number.
236 * Returns: the sequence number.
238 _public_ unsigned long long int udev_queue_get_udev_seqnum(struct udev_queue *udev_queue)
240 unsigned long long int seqnum_udev;
243 queue_file = open_queue_file(udev_queue, &seqnum_udev);
244 if (queue_file == NULL)
248 unsigned long long int seqnum;
251 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
253 devpath_len = udev_queue_skip_devpath(queue_file);
257 seqnum_udev = seqnum;
265 * udev_queue_get_udev_is_active:
266 * @udev_queue: udev queue context
268 * Check if udev is active on the system.
270 * Returns: a flag indicating if udev is active.
272 _public_ int udev_queue_get_udev_is_active(struct udev_queue *udev_queue)
274 unsigned long long int seqnum_start;
277 queue_file = open_queue_file(udev_queue, &seqnum_start);
278 if (queue_file == NULL)
286 * udev_queue_get_queue_is_empty:
287 * @udev_queue: udev queue context
289 * Check if udev is currently processing any events.
291 * Returns: a flag indicating if udev is currently handling events.
293 _public_ int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue)
295 unsigned long long int seqnum_kernel;
296 unsigned long long int seqnum_udev = 0;
301 if (udev_queue == NULL)
303 queue_file = open_queue_file(udev_queue, &seqnum_udev);
304 if (queue_file == NULL)
308 unsigned long long int seqnum;
311 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
313 devpath_len = udev_queue_skip_devpath(queue_file);
317 if (devpath_len > 0) {
319 seqnum_udev = seqnum;
328 seqnum_kernel = udev_queue_get_kernel_seqnum(udev_queue);
329 if (seqnum_udev < seqnum_kernel)
340 * udev_queue_get_seqnum_sequence_is_finished:
341 * @udev_queue: udev queue context
342 * @start: first event sequence number
343 * @end: last event sequence number
345 * Check if udev is currently processing any events in a given sequence number range.
347 * Returns: a flag indicating if any of the sequence numbers in the given range is currently active.
349 _public_ int udev_queue_get_seqnum_sequence_is_finished(struct udev_queue *udev_queue,
350 unsigned long long int start, unsigned long long int end)
352 unsigned long long int seqnum;
357 if (udev_queue == NULL)
359 queue_file = open_queue_file(udev_queue, &seqnum);
360 if (queue_file == NULL)
368 if (end - start > INT_MAX - 1) {
374 * we might start with 0, and handle the initial seqnum
375 * only when we find an entry in the queue file
377 unfinished = end - start;
380 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
382 devpath_len = udev_queue_skip_devpath(queue_file);
387 * we might start with an empty or re-build queue file, where
388 * the initial seqnum is not recorded as finished
390 if (start == seqnum && devpath_len > 0)
393 if (devpath_len == 0) {
394 if (seqnum >= start && seqnum <= end)
397 } while (unfinished > 0);
401 return (unfinished == 0);
405 * udev_queue_get_seqnum_is_finished:
406 * @udev_queue: udev queue context
407 * @seqnum: sequence number
409 * Check if udev is currently processing a given sequence number.
411 * Returns: a flag indicating if the given sequence number is currently active.
413 _public_ int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum)
415 if (!udev_queue_get_seqnum_sequence_is_finished(udev_queue, seqnum, seqnum))
422 * udev_queue_get_queued_list_entry:
423 * @udev_queue: udev queue context
425 * Get the first entry of the list of queued events.
427 * Returns: a udev_list_entry.
429 _public_ struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue)
431 unsigned long long int seqnum;
434 if (udev_queue == NULL)
436 udev_list_cleanup(&udev_queue->queue_list);
438 queue_file = open_queue_file(udev_queue, &seqnum);
439 if (queue_file == NULL)
443 char syspath[UTIL_PATH_SIZE];
448 struct udev_list_entry *list_entry;
450 if (udev_queue_read_seqnum(queue_file, &seqnum) < 0)
452 snprintf(seqnum_str, sizeof(seqnum_str), "%llu", seqnum);
455 l = util_strpcpy(&s, sizeof(syspath), "/sys");
456 len = udev_queue_read_devpath(queue_file, s, l);
461 udev_list_entry_add(&udev_queue->queue_list, syspath, seqnum_str);
463 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_queue->queue_list)) {
464 if (strcmp(seqnum_str, udev_list_entry_get_value(list_entry)) == 0) {
465 udev_list_entry_delete(list_entry);
473 return udev_list_get_entry(&udev_queue->queue_list);