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.
14 * DISCLAIMER - The file format mentioned here is private to udev/libudev,
15 * and may be changed without notice.
17 * The udev event queue is exported as a binary log file.
18 * Each log record consists of a sequence number followed by the device path.
20 * When a new event is queued, its details are appended to the log.
21 * When the event finishes, a second record is appended to the log
22 * with the same sequence number but a devpath len of 0.
25 * { 0x0000000000000001 }
26 * { 0x0000000000000001, 0x0019, "/devices/virtual/mem/null" },
27 * { 0x0000000000000002, 0x001b, "/devices/virtual/mem/random" },
28 * { 0x0000000000000001, 0x0000 },
29 * { 0x0000000000000003, 0x0019, "/devices/virtual/mem/zero" },
31 * Events 2 and 3 are still queued, but event 1 has finished.
33 * The queue does not grow indefinitely. It is periodically re-created
34 * to remove finished events. Atomic rename() makes this transparent to readers.
36 * The queue file starts with a single sequence number which specifies the
37 * minimum sequence number in the log that follows. Any events prior to this
38 * sequence number have already finished.
50 #include <sys/types.h>
53 #include "libudev-private.h"
55 static int rebuild_queue_file(struct udev_queue_export *udev_queue_export);
57 struct udev_queue_export {
59 int failed_count; /* number of failed events exported */
60 int queued_count; /* number of unfinished events exported in queue file */
62 unsigned long long int seqnum_max; /* earliest sequence number in queue file */
63 unsigned long long int seqnum_min; /* latest sequence number in queue file */
64 int waste_bytes; /* queue file bytes wasted on finished events */
67 struct udev_queue_export *udev_queue_export_new(struct udev *udev)
69 struct udev_queue_export *udev_queue_export;
70 unsigned long long int initial_seqnum;
75 udev_queue_export = calloc(1, sizeof(struct udev_queue_export));
76 if (udev_queue_export == NULL)
78 udev_queue_export->udev = udev;
80 initial_seqnum = udev_get_kernel_seqnum(udev);
81 udev_queue_export->seqnum_min = initial_seqnum;
82 udev_queue_export->seqnum_max = initial_seqnum;
84 udev_queue_export_cleanup(udev_queue_export);
85 if (rebuild_queue_file(udev_queue_export) != 0) {
86 free(udev_queue_export);
90 return udev_queue_export;
93 struct udev_queue_export *udev_queue_export_unref(struct udev_queue_export *udev_queue_export)
95 if (udev_queue_export == NULL)
97 if (udev_queue_export->queue_file != NULL)
98 fclose(udev_queue_export->queue_file);
99 free(udev_queue_export);
103 void udev_queue_export_cleanup(struct udev_queue_export *udev_queue_export)
105 char filename[UTIL_PATH_SIZE];
107 if (udev_queue_export == NULL)
109 util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev_queue_export->udev), "/queue.tmp", NULL);
111 util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev_queue_export->udev), "/queue.bin", NULL);
115 static int skip_to(FILE *file, long offset)
119 /* fseek may drop buffered data, avoid it for small seeks */
120 old_offset = ftell(file);
121 if (offset > old_offset && offset - old_offset <= BUFSIZ) {
122 size_t skip_bytes = offset - old_offset;
123 char buf[skip_bytes];
125 if (fread(buf, skip_bytes, 1, file) != skip_bytes)
129 return fseek(file, offset, SEEK_SET);
132 struct queue_devpaths {
133 unsigned int devpaths_first; /* index of first queued event */
134 unsigned int devpaths_size;
135 long devpaths[]; /* seqnum -> offset of devpath in queue file (or 0) */
139 * Returns a table mapping seqnum to devpath file offset for currently queued events.
140 * devpaths[i] represents the event with seqnum = i + udev_queue_export->seqnum_min.
142 static struct queue_devpaths *build_index(struct udev_queue_export *udev_queue_export)
144 struct queue_devpaths *devpaths;
145 unsigned long long int range;
148 unsigned long long int seqnum;
149 unsigned long long int n;
152 /* seek to the first event in the file */
153 rewind(udev_queue_export->queue_file);
154 udev_queue_read_seqnum(udev_queue_export->queue_file, &seqnum);
156 /* allocate the table */
157 range = udev_queue_export->seqnum_min - udev_queue_export->seqnum_max;
158 if (range - 1 > INT_MAX) {
159 err(udev_queue_export->udev, "queue file overflow\n");
162 devpaths = calloc(1, sizeof(struct queue_devpaths) + (range + 1) * sizeof(long));
163 if (devpaths == NULL)
165 devpaths->devpaths_size = range + 1;
167 /* read all records and populate the table */
169 if (udev_queue_read_seqnum(udev_queue_export->queue_file, &seqnum) < 0)
171 n = seqnum - udev_queue_export->seqnum_max;
172 if (n >= devpaths->devpaths_size)
175 devpath_offset = ftell(udev_queue_export->queue_file);
176 devpath_len = udev_queue_skip_devpath(udev_queue_export->queue_file);
181 devpaths->devpaths[n] = devpath_offset;
183 devpaths->devpaths[n] = 0;
186 /* find first queued event */
187 for (i = 0; i < devpaths->devpaths_size; i++) {
188 if (devpaths->devpaths[i] != 0)
191 devpaths->devpaths_first = i;
196 err(udev_queue_export->udev, "queue file corrupted\n");
201 static int rebuild_queue_file(struct udev_queue_export *udev_queue_export)
203 unsigned long long int seqnum;
204 struct queue_devpaths *devpaths = NULL;
205 char filename[UTIL_PATH_SIZE];
206 char filename_tmp[UTIL_PATH_SIZE];
207 FILE *new_queue_file = NULL;
210 /* read old queue file */
211 if (udev_queue_export->queue_file != NULL) {
212 dbg(udev_queue_export->udev, "compacting queue file, freeing %d bytes\n",
213 udev_queue_export->waste_bytes);
215 devpaths = build_index(udev_queue_export);
216 if (devpaths != NULL)
217 udev_queue_export->seqnum_max += devpaths->devpaths_first;
219 if (devpaths == NULL) {
220 dbg(udev_queue_export->udev, "creating empty queue file\n");
221 udev_queue_export->queued_count = 0;
222 udev_queue_export->seqnum_max = udev_queue_export->seqnum_min;
225 /* create new queue file */
226 util_strscpyl(filename_tmp, sizeof(filename_tmp), udev_get_run_path(udev_queue_export->udev), "/queue.tmp", NULL);
227 new_queue_file = fopen(filename_tmp, "w+");
228 if (new_queue_file == NULL)
230 seqnum = udev_queue_export->seqnum_max;
231 fwrite(&seqnum, 1, sizeof(unsigned long long int), new_queue_file);
233 /* copy unfinished events only to the new file */
234 if (devpaths != NULL) {
235 for (i = devpaths->devpaths_first; i < devpaths->devpaths_size; i++) {
236 char devpath[UTIL_PATH_SIZE];
238 unsigned short devpath_len;
240 if (devpaths->devpaths[i] != 0)
242 skip_to(udev_queue_export->queue_file, devpaths->devpaths[i]);
243 err = udev_queue_read_devpath(udev_queue_export->queue_file, devpath, sizeof(devpath));
246 fwrite(&seqnum, sizeof(unsigned long long int), 1, new_queue_file);
247 fwrite(&devpath_len, sizeof(unsigned short), 1, new_queue_file);
248 fwrite(devpath, 1, devpath_len, new_queue_file);
255 fflush(new_queue_file);
256 if (ferror(new_queue_file))
259 /* rename the new file on top of the old one */
260 util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev_queue_export->udev), "/queue.bin", NULL);
261 if (rename(filename_tmp, filename) != 0)
264 if (udev_queue_export->queue_file != NULL)
265 fclose(udev_queue_export->queue_file);
266 udev_queue_export->queue_file = new_queue_file;
267 udev_queue_export->waste_bytes = 0;
272 err(udev_queue_export->udev, "failed to create queue file: %m\n");
273 udev_queue_export_cleanup(udev_queue_export);
275 if (udev_queue_export->queue_file != NULL) {
276 fclose(udev_queue_export->queue_file);
277 udev_queue_export->queue_file = NULL;
279 if (new_queue_file != NULL)
280 fclose(new_queue_file);
282 if (devpaths != NULL)
284 udev_queue_export->queued_count = 0;
285 udev_queue_export->waste_bytes = 0;
286 udev_queue_export->seqnum_max = udev_queue_export->seqnum_min;
291 static int write_queue_record(struct udev_queue_export *udev_queue_export,
292 unsigned long long int seqnum, const char *devpath, size_t devpath_len)
296 if (udev_queue_export->queue_file == NULL) {
297 dbg(udev_queue_export->udev, "can't record event: queue file not available\n");
301 if (fwrite(&seqnum, sizeof(unsigned long long int), 1, udev_queue_export->queue_file) != 1)
304 len = (devpath_len < USHRT_MAX) ? devpath_len : USHRT_MAX;
305 if (fwrite(&len, sizeof(unsigned short), 1, udev_queue_export->queue_file) != 1)
308 if (fwrite(devpath, 1, len, udev_queue_export->queue_file) != len)
312 /* *must* flush output; caller may fork */
313 if (fflush(udev_queue_export->queue_file) != 0)
319 /* if we failed half way through writing a record to a file,
320 we should not try to write any further records to it. */
321 err(udev_queue_export->udev, "error writing to queue file: %m\n");
322 fclose(udev_queue_export->queue_file);
323 udev_queue_export->queue_file = NULL;
334 static inline size_t queue_record_size(size_t devpath_len)
336 return sizeof(unsigned long long int) + sizeof(unsigned short int) + devpath_len;
339 static int update_queue(struct udev_queue_export *udev_queue_export,
340 struct udev_device *udev_device, enum device_state state)
342 unsigned long long int seqnum = udev_device_get_seqnum(udev_device);
343 const char *devpath = NULL;
344 size_t devpath_len = 0;
348 /* FINISHED records have a zero length devpath */
349 if (state == DEVICE_QUEUED) {
350 devpath = udev_device_get_devpath(udev_device);
351 devpath_len = strlen(devpath);
354 /* recover from an earlier failed rebuild */
355 if (udev_queue_export->queue_file == NULL) {
356 if (rebuild_queue_file(udev_queue_export) != 0)
360 /* if we're removing the last event from the queue, that's the best time to rebuild it */
361 if (state != DEVICE_QUEUED && udev_queue_export->queued_count == 1) {
362 /* we don't need to read the old queue file */
363 fclose(udev_queue_export->queue_file);
364 udev_queue_export->queue_file = NULL;
365 rebuild_queue_file(udev_queue_export);
369 /* try to rebuild the queue files before they grow larger than one page. */
370 bytes = ftell(udev_queue_export->queue_file) + queue_record_size(devpath_len);
371 if ((udev_queue_export->waste_bytes > bytes / 2) && bytes > 4096)
372 rebuild_queue_file(udev_queue_export);
374 /* don't record a finished event, if we already dropped the event in a failed rebuild */
375 if (seqnum < udev_queue_export->seqnum_max)
378 /* now write to the queue */
379 if (state == DEVICE_QUEUED) {
380 udev_queue_export->queued_count++;
381 udev_queue_export->seqnum_min = seqnum;
383 udev_queue_export->waste_bytes += queue_record_size(devpath_len) + queue_record_size(0);
384 udev_queue_export->queued_count--;
386 err = write_queue_record(udev_queue_export, seqnum, devpath, devpath_len);
388 /* try to handle ENOSPC */
389 if (err != 0 && udev_queue_export->queued_count == 0) {
390 udev_queue_export_cleanup(udev_queue_export);
391 err = rebuild_queue_file(udev_queue_export);
397 static void update_failed(struct udev_queue_export *udev_queue_export,
398 struct udev_device *udev_device, enum device_state state)
400 struct udev *udev = udev_device_get_udev(udev_device);
401 char filename[UTIL_PATH_SIZE];
403 if (state != DEVICE_FAILED && udev_queue_export->failed_count == 0)
406 /* location of failed file */
407 util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev), "/failed/",
408 udev_device_get_subsystem(udev_device), ":", udev_device_get_sysname(udev_device), NULL);
412 /* record event in the failed directory */
413 udev_queue_export->failed_count++;
414 util_create_path(udev, filename);
415 symlink(udev_device_get_devpath(udev_device), filename);
419 /* delete failed file */
420 if (unlink(filename) == 0) {
421 util_delete_path(udev, filename);
422 udev_queue_export->failed_count--;
426 case DEVICE_FINISHED:
433 static int update(struct udev_queue_export *udev_queue_export,
434 struct udev_device *udev_device, enum device_state state)
436 update_failed(udev_queue_export, udev_device, state);
438 if (update_queue(udev_queue_export, udev_device, state) != 0)
444 int udev_queue_export_device_queued(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
446 return update(udev_queue_export, udev_device, DEVICE_QUEUED);
449 int udev_queue_export_device_finished(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
451 return update(udev_queue_export, udev_device, DEVICE_FINISHED);
454 int udev_queue_export_device_failed(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
456 return update(udev_queue_export, udev_device, DEVICE_FAILED);