summaryrefslogtreecommitdiff
path: root/src/libudev-device.c
blob: 10f28b8cd5bb5a4a4fb40067d2f4cfdd3b1155d3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
/*
 * libudev - interface to udev device information
 *
 * Copyright (C) 2008-2010 Kay Sievers <kay.sievers@vrfy.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <stdbool.h>
#include <errno.h>
#include <string.h>
#include <dirent.h>
#include <fcntl.h>
#include <ctype.h>
#include <net/if.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/sockios.h>

#include "libudev.h"
#include "libudev-private.h"

/**
 * SECTION:libudev-device
 * @short_description: kernel sys devices
 *
 * Representation of kernel sys devices. Devices are uniquely identified
 * by their syspath, every device has exactly one path in the kernel sys
 * filesystem. Devices usually belong to a kernel subsystem, and and have
 * a unique name inside that subsystem.
 */

/**
 * udev_device:
 *
 * Opaque object representing one kernel sys device.
 */
struct udev_device {
        struct udev *udev;
        struct udev_device *parent_device;
        char *syspath;
        const char *devpath;
        char *sysname;
        const char *sysnum;
        char *devnode;
        mode_t devnode_mode;
        char *subsystem;
        char *devtype;
        char *driver;
        char *action;
        char *devpath_old;
        char *id_filename;
        char **envp;
        char *monitor_buf;
        size_t monitor_buf_len;
        struct udev_list devlinks_list;
        struct udev_list properties_list;
        struct udev_list sysattr_value_list;
        struct udev_list sysattr_list;
        struct udev_list tags_list;
        unsigned long long int seqnum;
        unsigned long long int usec_initialized;
        int devlink_priority;
        int refcount;
        dev_t devnum;
        int ifindex;
        int watch_handle;
        int maj, min;
        bool parent_set;
        bool subsystem_set;
        bool devtype_set;
        bool devlinks_uptodate;
        bool envp_uptodate;
        bool tags_uptodate;
        bool driver_set;
        bool info_loaded;
        bool db_loaded;
        bool uevent_loaded;
        bool is_initialized;
        bool sysattr_list_read;
        bool db_persist;
};

/**
 * udev_device_get_seqnum:
 * @udev_device: udev device
 *
 * This is only valid if the device was received through a monitor. Devices read from
 * sys do not have a sequence number.
 *
 * Returns: the kernel event sequence number, or 0 if there is no sequence number available.
 **/
UDEV_EXPORT unsigned long long int udev_device_get_seqnum(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return 0;
        return udev_device->seqnum;
}

static int udev_device_set_seqnum(struct udev_device *udev_device, unsigned long long int seqnum)
{
        char num[32];

        udev_device->seqnum = seqnum;
        snprintf(num, sizeof(num), "%llu", seqnum);
        udev_device_add_property(udev_device, "SEQNUM", num);
        return 0;
}

int udev_device_get_ifindex(struct udev_device *udev_device)
{
        if (!udev_device->info_loaded)
                udev_device_read_uevent_file(udev_device);
        return udev_device->ifindex;
}

static int udev_device_set_ifindex(struct udev_device *udev_device, int ifindex)
{
        char num[32];

        udev_device->ifindex = ifindex;
        snprintf(num, sizeof(num), "%u", ifindex);
        udev_device_add_property(udev_device, "IFINDEX", num);
        return 0;
}

/**
 * udev_device_get_devnum:
 * @udev_device: udev device
 *
 * Returns: the device major/minor number.
 **/
UDEV_EXPORT dev_t udev_device_get_devnum(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return makedev(0, 0);
        if (!udev_device->info_loaded)
                udev_device_read_uevent_file(udev_device);
        return udev_device->devnum;
}

static int udev_device_set_devnum(struct udev_device *udev_device, dev_t devnum)
{
        char num[32];

        udev_device->devnum = devnum;

        snprintf(num, sizeof(num), "%u", major(devnum));
        udev_device_add_property(udev_device, "MAJOR", num);
        snprintf(num, sizeof(num), "%u", minor(devnum));
        udev_device_add_property(udev_device, "MINOR", num);
        return 0;
}

const char *udev_device_get_devpath_old(struct udev_device *udev_device)
{
        return udev_device->devpath_old;
}

static int udev_device_set_devpath_old(struct udev_device *udev_device, const char *devpath_old)
{
        const char *pos;

        free(udev_device->devpath_old);
        udev_device->devpath_old = strdup(devpath_old);
        if (udev_device->devpath_old == NULL)
                return -ENOMEM;
        udev_device_add_property(udev_device, "DEVPATH_OLD", udev_device->devpath_old);

        pos = strrchr(udev_device->devpath_old, '/');
        if (pos == NULL)
                return -EINVAL;
        return 0;
}

/**
 * udev_device_get_driver:
 * @udev_device: udev device
 *
 * Returns: the driver string, or #NULL if there is no driver attached.
 **/
UDEV_EXPORT const char *udev_device_get_driver(struct udev_device *udev_device)
{
        char driver[UTIL_NAME_SIZE];

        if (udev_device == NULL)
                return NULL;
        if (!udev_device->driver_set) {
                udev_device->driver_set = true;
                if (util_get_sys_core_link_value(udev_device->udev, "driver", udev_device->syspath, driver, sizeof(driver)) > 0)
                        udev_device->driver = strdup(driver);
        }
        return udev_device->driver;
}

static int udev_device_set_driver(struct udev_device *udev_device, const char *driver)
{
        free(udev_device->driver);
        udev_device->driver = strdup(driver);
        if (udev_device->driver == NULL)
                return -ENOMEM;
        udev_device->driver_set = true;
        udev_device_add_property(udev_device, "DRIVER", udev_device->driver);
        return 0;
}

/**
 * udev_device_get_devtype:
 * @udev_device: udev device
 *
 * Retrieve the devtype string of the udev device.
 *
 * Returns: the devtype name of the udev device, or #NULL if it can not be determined
 **/
UDEV_EXPORT const char *udev_device_get_devtype(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        if (!udev_device->devtype_set) {
                udev_device->devtype_set = true;
                udev_device_read_uevent_file(udev_device);
        }
        return udev_device->devtype;
}

static int udev_device_set_devtype(struct udev_device *udev_device, const char *devtype)
{
        free(udev_device->devtype);
        udev_device->devtype = strdup(devtype);
        if (udev_device->devtype == NULL)
                return -ENOMEM;
        udev_device->devtype_set = true;
        udev_device_add_property(udev_device, "DEVTYPE", udev_device->devtype);
        return 0;
}

static int udev_device_set_subsystem(struct udev_device *udev_device, const char *subsystem)
{
        free(udev_device->subsystem);
        udev_device->subsystem = strdup(subsystem);
        if (udev_device->subsystem == NULL)
                return -ENOMEM;
        udev_device->subsystem_set = true;
        udev_device_add_property(udev_device, "SUBSYSTEM", udev_device->subsystem);
        return 0;
}

/**
 * udev_device_get_subsystem:
 * @udev_device: udev device
 *
 * Retrieve the subsystem string of the udev device. The string does not
 * contain any "/".
 *
 * Returns: the subsystem name of the udev device, or #NULL if it can not be determined
 **/
UDEV_EXPORT const char *udev_device_get_subsystem(struct udev_device *udev_device)
{
        char subsystem[UTIL_NAME_SIZE];

        if (udev_device == NULL)
                return NULL;
        if (!udev_device->subsystem_set) {
                udev_device->subsystem_set = true;
                /* read "subsystem" link */
                if (util_get_sys_core_link_value(udev_device->udev, "subsystem", udev_device->syspath, subsystem, sizeof(subsystem)) > 0) {
                        udev_device_set_subsystem(udev_device, subsystem);
                        return udev_device->subsystem;
                }
                /* implicit names */
                if (strncmp(udev_device->devpath, "/module/", 8) == 0) {
                        udev_device_set_subsystem(udev_device, "module");
                        return udev_device->subsystem;
                }
                if (strstr(udev_device->devpath, "/drivers/") != NULL) {
                        udev_device_set_subsystem(udev_device, "drivers");
                        return udev_device->subsystem;
                }
                if (strncmp(udev_device->devpath, "/subsystem/", 11) == 0 ||
                    strncmp(udev_device->devpath, "/class/", 7) == 0 ||
                    strncmp(udev_device->devpath, "/bus/", 5) == 0) {
                        udev_device_set_subsystem(udev_device, "subsystem");
                        return udev_device->subsystem;
                }
        }
        return udev_device->subsystem;
}

mode_t udev_device_get_devnode_mode(struct udev_device *udev_device)
{
        if (!udev_device->info_loaded)
                udev_device_read_uevent_file(udev_device);
        return udev_device->devnode_mode;
}

static int udev_device_set_devnode_mode(struct udev_device *udev_device, mode_t mode)
{
        char num[32];

        udev_device->devnode_mode = mode;
        snprintf(num, sizeof(num), "%#o", mode);
        udev_device_add_property(udev_device, "DEVMODE", num);
        return 0;
}

struct udev_list_entry *udev_device_add_property(struct udev_device *udev_device, const char *key, const char *value)
{
        udev_device->envp_uptodate = false;
        if (value == NULL) {
                struct udev_list_entry *list_entry;

                list_entry = udev_device_get_properties_list_entry(udev_device);
                list_entry = udev_list_entry_get_by_name(list_entry, key);
                if (list_entry != NULL)
                        udev_list_entry_delete(list_entry);
                return NULL;
        }
        return udev_list_entry_add(&udev_device->properties_list, key, value);
}

static struct udev_list_entry *udev_device_add_property_from_string(struct udev_device *udev_device, const char *property)
{
        char name[UTIL_LINE_SIZE];
        char *val;

        util_strscpy(name, sizeof(name), property);
        val = strchr(name, '=');
        if (val == NULL)
                return NULL;
        val[0] = '\0';
        val = &val[1];
        if (val[0] == '\0')
                val = NULL;
        return udev_device_add_property(udev_device, name, val);
}

/*
 * parse property string, and if needed, update internal values accordingly
 *
 * udev_device_add_property_from_string_parse_finish() needs to be
 * called after adding properties, and its return value checked
 *
 * udev_device_set_info_loaded() needs to be set, to avoid trying
 * to use a device without a DEVPATH set
 */
void udev_device_add_property_from_string_parse(struct udev_device *udev_device, const char *property)
{
        if (strncmp(property, "DEVPATH=", 8) == 0) {
                char path[UTIL_PATH_SIZE];

                util_strscpyl(path, sizeof(path), udev_get_sys_path(udev_device->udev), &property[8], NULL);
                udev_device_set_syspath(udev_device, path);
        } else if (strncmp(property, "SUBSYSTEM=", 10) == 0) {
                udev_device_set_subsystem(udev_device, &property[10]);
        } else if (strncmp(property, "DEVTYPE=", 8) == 0) {
                udev_device_set_devtype(udev_device, &property[8]);
        } else if (strncmp(property, "DEVNAME=", 8) == 0) {
                udev_device_set_devnode(udev_device, &property[8]);
        } else if (strncmp(property, "DEVLINKS=", 9) == 0) {
                char devlinks[UTIL_PATH_SIZE];
                char *slink;
                char *next;

                util_strscpy(devlinks, sizeof(devlinks), &property[9]);
                slink = devlinks;
                next = strchr(slink, ' ');
                while (next != NULL) {
                        next[0] = '\0';
                        udev_device_add_devlink(udev_device, slink, 0);
                        slink = &next[1];
                        next = strchr(slink, ' ');
                }
                if (slink[0] != '\0')
                        udev_device_add_devlink(udev_device, slink, 0);
        } else if (strncmp(property, "TAGS=", 5) == 0) {
                char tags[UTIL_PATH_SIZE];
                char *next;

                util_strscpy(tags, sizeof(tags), &property[5]);
                next = strchr(tags, ':');
                if (next != NULL) {
                        next++;
                        while (next[0] != '\0') {
                                char *tag;

                                tag = next;
                                next = strchr(tag, ':');
                                if (next == NULL)
                                        break;
                                next[0] = '\0';
                                next++;
                                udev_device_add_tag(udev_device, tag);
                        }
                }
        } else if (strncmp(property, "USEC_INITIALIZED=", 19) == 0) {
                udev_device_set_usec_initialized(udev_device, strtoull(&property[19], NULL, 10));
        } else if (strncmp(property, "DRIVER=", 7) == 0) {
                udev_device_set_driver(udev_device, &property[7]);
        } else if (strncmp(property, "ACTION=", 7) == 0) {
                udev_device_set_action(udev_device, &property[7]);
        } else if (strncmp(property, "MAJOR=", 6) == 0) {
                udev_device->maj = strtoull(&property[6], NULL, 10);
        } else if (strncmp(property, "MINOR=", 6) == 0) {
                udev_device->min = strtoull(&property[6], NULL, 10);
        } else if (strncmp(property, "DEVPATH_OLD=", 12) == 0) {
                udev_device_set_devpath_old(udev_device, &property[12]);
        } else if (strncmp(property, "SEQNUM=", 7) == 0) {
                udev_device_set_seqnum(udev_device, strtoull(&property[7], NULL, 10));
        } else if (strncmp(property, "IFINDEX=", 8) == 0) {
                udev_device_set_ifindex(udev_device, strtoull(&property[8], NULL, 10));
        } else if (strncmp(property, "DEVMODE=", 8) == 0) {
                udev_device_set_devnode_mode(udev_device, strtoul(&property[8], NULL, 8));
        } else {
                udev_device_add_property_from_string(udev_device, property);
        }
}

int udev_device_add_property_from_string_parse_finish(struct udev_device *udev_device)
{
        if (udev_device->maj > 0)
                udev_device_set_devnum(udev_device, makedev(udev_device->maj, udev_device->min));
        udev_device->maj = 0;
        udev_device->min = 0;

        if (udev_device->devpath == NULL || udev_device->subsystem == NULL)
                return -EINVAL;
        return 0;
}

/**
 * udev_device_get_property_value:
 * @udev_device: udev device
 * @key: property name
 *
 * Returns: the value of a device property, or #NULL if there is no such property.
 **/
UDEV_EXPORT const char *udev_device_get_property_value(struct udev_device *udev_device, const char *key)
{
        struct udev_list_entry *list_entry;

        if (udev_device == NULL)
                return NULL;
        if (key == NULL)
                return NULL;

        list_entry = udev_device_get_properties_list_entry(udev_device);
        list_entry = udev_list_entry_get_by_name(list_entry, key);
        return udev_list_entry_get_value(list_entry);
}

int udev_device_read_db(struct udev_device *udev_device, const char *dbfile)
{
        char filename[UTIL_PATH_SIZE];
        char line[UTIL_LINE_SIZE];
        FILE *f;

        /* providing a database file will always force-load it */
        if (dbfile == NULL) {
                const char *id;

                if (udev_device->db_loaded)
                        return 0;
                udev_device->db_loaded = true;

                id = udev_device_get_id_filename(udev_device);
                if (id == NULL)
                        return -1;
                util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev_device->udev), "/data/", id, NULL);
                dbfile = filename;
        }

        f = fopen(dbfile, "re");
        if (f == NULL) {
                info(udev_device->udev, "no db file to read %s: %m\n", dbfile);
                return -1;
        }
        udev_device->is_initialized = true;

        while (fgets(line, sizeof(line), f)) {
                ssize_t len;
                const char *val;
                struct udev_list_entry *entry;

                len = strlen(line);
                if (len < 4)
                        break;
                line[len-1] = '\0';
                val = &line[2];
                switch(line[0]) {
                case 'S':
                        util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_device->udev), "/", val, NULL);
                        udev_device_add_devlink(udev_device, filename, 0);
                        break;
                case 'L':
                        udev_device_set_devlink_priority(udev_device, atoi(val));
                        break;
                case 'E':
                        entry = udev_device_add_property_from_string(udev_device, val);
                        udev_list_entry_set_num(entry, true);
                        break;
                case 'G':
                        udev_device_add_tag(udev_device, val);
                        break;
                case 'W':
                        udev_device_set_watch_handle(udev_device, atoi(val));
                        break;
                case 'I':
                        udev_device_set_usec_initialized(udev_device, strtoull(val, NULL, 10));
                        break;
                }
        }
        fclose(f);

        info(udev_device->udev, "device %p filled with db file data\n", udev_device);
        return 0;
}

int udev_device_read_uevent_file(struct udev_device *udev_device)
{
        char filename[UTIL_PATH_SIZE];
        FILE *f;
        char line[UTIL_LINE_SIZE];
        int maj = 0;
        int min = 0;

        if (udev_device->uevent_loaded)
                return 0;

        util_strscpyl(filename, sizeof(filename), udev_device->syspath, "/uevent", NULL);
        f = fopen(filename, "re");
        if (f == NULL)
                return -1;
        udev_device->uevent_loaded = true;

        while (fgets(line, sizeof(line), f)) {
                char *pos;

                pos = strchr(line, '\n');
                if (pos == NULL)
                        continue;
                pos[0] = '\0';

                if (strncmp(line, "DEVTYPE=", 8) == 0) {
                        udev_device_set_devtype(udev_device, &line[8]);
                        continue;
                }
                if (strncmp(line, "IFINDEX=", 8) == 0) {
                        udev_device_set_ifindex(udev_device, strtoull(&line[8], NULL, 10));
                        continue;
                }
                if (strncmp(line, "DEVNAME=", 8) == 0) {
                        udev_device_set_devnode(udev_device, &line[8]);
                        continue;
                }

                if (strncmp(line, "MAJOR=", 6) == 0)
                        maj = strtoull(&line[6], NULL, 10);
                else if (strncmp(line, "MINOR=", 6) == 0)
                        min = strtoull(&line[6], NULL, 10);
                else if (strncmp(line, "DEVMODE=", 8) == 0)
                        udev_device->devnode_mode = strtoul(&line[8], NULL, 8);

                udev_device_add_property_from_string(udev_device, line);
        }

        udev_device->devnum = makedev(maj, min);
        fclose(f);
        return 0;
}

void udev_device_set_info_loaded(struct udev_device *device)
{
        device->info_loaded = true;
}

struct udev_device *udev_device_new(struct udev *udev)
{
        struct udev_device *udev_device;
        struct udev_list_entry *list_entry;

        if (udev == NULL)
                return NULL;

        udev_device = calloc(1, sizeof(struct udev_device));
        if (udev_device == NULL)
                return NULL;
        udev_device->refcount = 1;
        udev_device->udev = udev;
        udev_list_init(udev, &udev_device->devlinks_list, true);
        udev_list_init(udev, &udev_device->properties_list, true);
        udev_list_init(udev, &udev_device->sysattr_value_list, true);
        udev_list_init(udev, &udev_device->sysattr_list, false);
        udev_list_init(udev, &udev_device->tags_list, true);
        udev_device->watch_handle = -1;
        /* copy global properties */
        udev_list_entry_foreach(list_entry, udev_get_properties_list_entry(udev))
                udev_device_add_property(udev_device,
                                         udev_list_entry_get_name(list_entry),
                                         udev_list_entry_get_value(list_entry));
        dbg(udev_device->udev, "udev_device: %p created\n", udev_device);
        return udev_device;
}

/**
 * udev_device_new_from_syspath:
 * @udev: udev library context
 * @syspath: sys device path including sys directory
 *
 * Create new udev device, and fill in information from the sys
 * device and the udev database entry. The syspath is the absolute
 * path to the device, including the sys mount point.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev device.
 *
 * Returns: a new udev device, or #NULL, if it does not exist
 **/
UDEV_EXPORT struct udev_device *udev_device_new_from_syspath(struct udev *udev, const char *syspath)
{
        size_t len;
        const char *subdir;
        char path[UTIL_PATH_SIZE];
        char *pos;
        struct stat statbuf;
        struct udev_device *udev_device;

        if (udev == NULL)
                return NULL;
        if (syspath == NULL)
                return NULL;

        /* path starts in sys */
        len = strlen(udev_get_sys_path(udev));
        if (strncmp(syspath, udev_get_sys_path(udev), len) != 0) {
                info(udev, "not in sys :%s\n", syspath);
                return NULL;
        }

        /* path is not a root directory */
        subdir = &syspath[len+1];
        pos = strrchr(subdir, '/');
        if (pos == NULL || pos[1] == '\0' || pos < &subdir[2]) {
                dbg(udev, "not a subdir :%s\n", syspath);
                return NULL;
        }

        /* resolve possible symlink to real path */
        util_strscpy(path, sizeof(path), syspath);
        util_resolve_sys_link(udev, path, sizeof(path));

        if (strncmp(&path[len], "/devices/", 9) == 0) {
                char file[UTIL_PATH_SIZE];

                /* all "devices" require a "uevent" file */
                util_strscpyl(file, sizeof(file), path, "/uevent", NULL);
                if (stat(file, &statbuf) != 0) {
                        dbg(udev, "not a device: %s\n", syspath);
                        return NULL;
                }
        } else {
                /* everything else just needs to be a directory */
                if (stat(path, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode)) {
                        dbg(udev, "directory not found: %s\n", syspath);
                        return NULL;
                }
        }

        udev_device = udev_device_new(udev);
        if (udev_device == NULL)
                return NULL;

        udev_device_set_syspath(udev_device, path);
        info(udev, "device %p has devpath '%s'\n", udev_device, udev_device_get_devpath(udev_device));

        return udev_device;
}

/**
 * udev_device_new_from_devnum:
 * @udev: udev library context
 * @type: char or block device
 * @devnum: device major/minor number
 *
 * Create new udev device, and fill in information from the sys
 * device and the udev database entry. The device is looked-up
 * by its major/minor number and type. Character and block device
 * numbers are not unique across the two types.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev device.
 *
 * Returns: a new udev device, or #NULL, if it does not exist
 **/
UDEV_EXPORT struct udev_device *udev_device_new_from_devnum(struct udev *udev, char type, dev_t devnum)
{
        char path[UTIL_PATH_SIZE];
        const char *type_str;

        if (type == 'b')
                type_str = "block";
        else if (type == 'c')
                type_str = "char";
        else
                return NULL;

        /* use /sys/dev/{block,char}/<maj>:<min> link */
        snprintf(path, sizeof(path), "%s/dev/%s/%u:%u",
                 udev_get_sys_path(udev), type_str, major(devnum), minor(devnum));
        return udev_device_new_from_syspath(udev, path);
}

struct udev_device *udev_device_new_from_id_filename(struct udev *udev, char *id)
{
        char type;
        int maj, min;
        char subsys[UTIL_PATH_SIZE];
        char *sysname;

        switch(id[0]) {
        case 'b':
        case 'c':
                if (sscanf(id, "%c%i:%i", &type, &maj, &min) != 3)
                        return NULL;
                return udev_device_new_from_devnum(udev, type, makedev(maj, min));
        case 'n': {
                int sk;
                struct ifreq ifr;
                struct udev_device *dev;
                int ifindex;

                ifindex = strtoul(&id[1], NULL, 10);
                if (ifindex <= 0)
                        return NULL;

                sk = socket(PF_INET, SOCK_DGRAM, 0);
                if (sk < 0)
                        return NULL;
                memset(&ifr, 0x00, sizeof(struct ifreq));
                ifr.ifr_ifindex = ifindex;
                if (ioctl(sk, SIOCGIFNAME, &ifr) != 0) {
                        close(sk);
                        return NULL;
                }
                close(sk);

                dev = udev_device_new_from_subsystem_sysname(udev, "net", ifr.ifr_name);
                if (dev == NULL)
                        return NULL;
                if (udev_device_get_ifindex(dev) == ifindex)
                        return dev;
                udev_device_unref(dev);
                return NULL;
        }
        case '+':
                util_strscpy(subsys, sizeof(subsys), &id[1]);
                sysname = strchr(subsys, ':');
                if (sysname == NULL)
                        return NULL;
                sysname[0] = '\0';
                sysname = &sysname[1];
                return udev_device_new_from_subsystem_sysname(udev, subsys, sysname);
        default:
                return NULL;
        }
}

/**
 * udev_device_new_from_subsystem_sysname:
 * @udev: udev library context
 * @subsystem: the subsystem of the device
 * @sysname: the name of the device
 *
 * Create new udev device, and fill in information from the sys device
 * and the udev database entry. The device is looked up by the subsystem
 * and name string of the device, like "mem" / "zero", or "block" / "sda".
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev device.
 *
 * Returns: a new udev device, or #NULL, if it does not exist
 **/
UDEV_EXPORT struct udev_device *udev_device_new_from_subsystem_sysname(struct udev *udev, const char *subsystem, const char *sysname)
{
        char path_full[UTIL_PATH_SIZE];
        char *path;
        size_t l;
        struct stat statbuf;

        path = path_full;
        l = util_strpcpyl(&path, sizeof(path_full), udev_get_sys_path(udev), NULL);

        if (strcmp(subsystem, "subsystem") == 0) {
                util_strscpyl(path, l, "/subsystem/", sysname, NULL);
                if (stat(path_full, &statbuf) == 0)
                        goto found;

                util_strscpyl(path, l, "/bus/", sysname, NULL);
                if (stat(path_full, &statbuf) == 0)
                        goto found;

                util_strscpyl(path, l, "/class/", sysname, NULL);
                if (stat(path_full, &statbuf) == 0)
                        goto found;
                goto out;
        }

        if (strcmp(subsystem, "module") == 0) {
                util_strscpyl(path, l, "/module/", sysname, NULL);
                if (stat(path_full, &statbuf) == 0)
                        goto found;
                goto out;
        }

        if (strcmp(subsystem, "drivers") == 0) {
                char subsys[UTIL_NAME_SIZE];
                char *driver;

                util_strscpy(subsys, sizeof(subsys), sysname);
                driver = strchr(subsys, ':');
                if (driver != NULL) {
                        driver[0] = '\0';
                        driver = &driver[1];

                        util_strscpyl(path, l, "/subsystem/", subsys, "/drivers/", driver, NULL);
                        if (stat(path_full, &statbuf) == 0)
                                goto found;

                        util_strscpyl(path, l, "/bus/", subsys, "/drivers/", driver, NULL);
                        if (stat(path_full, &statbuf) == 0)
                                goto found;
                }
                goto out;
        }

        util_strscpyl(path, l, "/subsystem/", subsystem, "/devices/", sysname, NULL);
        if (stat(path_full, &statbuf) == 0)
                goto found;

        util_strscpyl(path, l, "/bus/", subsystem, "/devices/", sysname, NULL);
        if (stat(path_full, &statbuf) == 0)
                goto found;

        util_strscpyl(path, l, "/class/", subsystem, "/", sysname, NULL);
        if (stat(path_full, &statbuf) == 0)
                goto found;
out:
        return NULL;
found:
        return udev_device_new_from_syspath(udev, path_full);
}

/**
 * udev_device_new_from_environment
 * @udev: udev library context
 *
 * Create new udev device, and fill in information from the
 * current process environment. This only works reliable if
 * the process is called from a udev rule. It is usually used
 * for tools executed from IMPORT= rules.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev device.
 *
 * Returns: a new udev device, or #NULL, if it does not exist
 **/
UDEV_EXPORT struct udev_device *udev_device_new_from_environment(struct udev *udev)
{
        int i;
        struct udev_device *udev_device;

        udev_device = udev_device_new(udev);
        if (udev_device == NULL)
                return NULL;
        udev_device_set_info_loaded(udev_device);

        for (i = 0; environ[i] != NULL; i++)
                udev_device_add_property_from_string_parse(udev_device, environ[i]);

        if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
                info(udev, "missing values, invalid device\n");
                udev_device_unref(udev_device);
                udev_device = NULL;
        }

        return udev_device;
}

static struct udev_device *device_new_from_parent(struct udev_device *udev_device)
{
        struct udev_device *udev_device_parent = NULL;
        char path[UTIL_PATH_SIZE];
        const char *subdir;

        util_strscpy(path, sizeof(path), udev_device->syspath);
        subdir = &path[strlen(udev_get_sys_path(udev_device->udev))+1];
        for (;;) {
                char *pos;

                pos = strrchr(subdir, '/');
                if (pos == NULL || pos < &subdir[2])
                        break;
                pos[0] = '\0';
                udev_device_parent = udev_device_new_from_syspath(udev_device->udev, path);
                if (udev_device_parent != NULL)
                        return udev_device_parent;
        }
        return NULL;
}

/**
 * udev_device_get_parent:
 * @udev_device: the device to start searching from
 *
 * Find the next parent device, and fill in information from the sys
 * device and the udev database entry.
 *
 * The returned the device is not referenced. It is attached to the
 * child device, and will be cleaned up when the child device
 * is cleaned up.
 *
 * It is not necessarily just the upper level directory, empty or not
 * recognized sys directories are ignored.
 *
 * It can be called as many times as needed, without caring about
 * references.
 *
 * Returns: a new udev device, or #NULL, if it no parent exist.
 **/
UDEV_EXPORT struct udev_device *udev_device_get_parent(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        if (!udev_device->parent_set) {
                udev_device->parent_set = true;
                udev_device->parent_device = device_new_from_parent(udev_device);
        }
        if (udev_device->parent_device != NULL)
                dbg(udev_device->udev, "returning existing parent %p\n", udev_device->parent_device);
        return udev_device->parent_device;
}

/**
 * udev_device_get_parent_with_subsystem_devtype:
 * @udev_device: udev device to start searching from
 * @subsystem: the subsystem of the device
 * @devtype: the type (DEVTYPE) of the device
 *
 * Find the next parent device, with a matching subsystem and devtype
 * value, and fill in information from the sys device and the udev
 * database entry.
 *
 * If devtype is #NULL, only subsystem is checked, and any devtype will
 * match.
 *
 * The returned the device is not referenced. It is attached to the
 * child device, and will be cleaned up when the child device
 * is cleaned up.
 *
 * It can be called as many times as needed, without caring about
 * references.
 *
 * Returns: a new udev device, or #NULL if no matching parent exists.
 **/
UDEV_EXPORT struct udev_device *udev_device_get_parent_with_subsystem_devtype(struct udev_device *udev_device, const char *subsystem, const char *devtype)
{
        struct udev_device *parent;

        if (subsystem == NULL)
                return NULL;

        parent = udev_device_get_parent(udev_device);
        while (parent != NULL) {
                const char *parent_subsystem;
                const char *parent_devtype;

                parent_subsystem = udev_device_get_subsystem(parent);
                if (parent_subsystem != NULL && strcmp(parent_subsystem, subsystem) == 0) {
                        if (devtype == NULL)
                                break;
                        parent_devtype = udev_device_get_devtype(parent);
                        if (parent_devtype != NULL && strcmp(parent_devtype, devtype) == 0)
                                break;
                }
                parent = udev_device_get_parent(parent);
        }
        return parent;
}

/**
 * udev_device_get_udev:
 * @udev_device: udev device
 *
 * Retrieve the udev library context the device was created with.
 *
 * Returns: the udev library context
 **/
UDEV_EXPORT struct udev *udev_device_get_udev(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        return udev_device->udev;
}

/**
 * udev_device_ref:
 * @udev_device: udev device
 *
 * Take a reference of a udev device.
 *
 * Returns: the passed udev device
 **/
UDEV_EXPORT struct udev_device *udev_device_ref(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        udev_device->refcount++;
        return udev_device;
}

/**
 * udev_device_unref:
 * @udev_device: udev device
 *
 * Drop a reference of a udev device. If the refcount reaches zero,
 * the resources of the device will be released.
 *
 **/
UDEV_EXPORT void udev_device_unref(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return;
        udev_device->refcount--;
        if (udev_device->refcount > 0)
                return;
        if (udev_device->parent_device != NULL)
                udev_device_unref(udev_device->parent_device);
        free(udev_device->syspath);
        free(udev_device->sysname);
        free(udev_device->devnode);
        free(udev_device->subsystem);
        free(udev_device->devtype);
        udev_list_cleanup(&udev_device->devlinks_list);
        udev_list_cleanup(&udev_device->properties_list);
        udev_list_cleanup(&udev_device->sysattr_value_list);
        udev_list_cleanup(&udev_device->sysattr_list);
        udev_list_cleanup(&udev_device->tags_list);
        free(udev_device->action);
        free(udev_device->driver);
        free(udev_device->devpath_old);
        free(udev_device->id_filename);
        free(udev_device->envp);
        free(udev_device->monitor_buf);
        dbg(udev_device->udev, "udev_device: %p released\n", udev_device);
        free(udev_device);
}

/**
 * udev_device_get_devpath:
 * @udev_device: udev device
 *
 * Retrieve the kernel devpath value of the udev device. The path
 * does not contain the sys mount point, and starts with a '/'.
 *
 * Returns: the devpath of the udev device
 **/
UDEV_EXPORT const char *udev_device_get_devpath(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        return udev_device->devpath;
}

/**
 * udev_device_get_syspath:
 * @udev_device: udev device
 *
 * Retrieve the sys path of the udev device. The path is an
 * absolute path and starts with the sys mount point.
 *
 * Returns: the sys path of the udev device
 **/
UDEV_EXPORT const char *udev_device_get_syspath(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        return udev_device->syspath;
}

/**
 * udev_device_get_sysname:
 * @udev_device: udev device
 *
 * Returns: the sys name of the device device
 **/
UDEV_EXPORT const char *udev_device_get_sysname(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        return udev_device->sysname;
}

/**
 * udev_device_get_sysnum:
 * @udev_device: udev device
 *
 * Returns: the trailing number of of the device name
 **/
UDEV_EXPORT const char *udev_device_get_sysnum(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        return udev_device->sysnum;
}

/**
 * udev_device_get_devnode:
 * @udev_device: udev device
 *
 * Retrieve the device node file name belonging to the udev device.
 * The path is an absolute path, and starts with the device directory.
 *
 * Returns: the device node file name of the udev device, or #NULL if no device node exists
 **/
UDEV_EXPORT const char *udev_device_get_devnode(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        if (udev_device->devnode != NULL)
                return udev_device->devnode;
        if (!udev_device->info_loaded)
                udev_device_read_uevent_file(udev_device);
        return udev_device->devnode;
}

/**
 * udev_device_get_devlinks_list_entry:
 * @udev_device: udev device
 *
 * Retrieve the list of device links pointing to the device file of
 * the udev device. The next list entry can be retrieved with
 * udev_list_entry_next(), which returns #NULL if no more entries exist.
 * The devlink path can be retrieved from the list entry by
 * udev_list_entry_get_name(). The path is an absolute path, and starts with
 * the device directory.
 *
 * Returns: the first entry of the device node link list
 **/
UDEV_EXPORT struct udev_list_entry *udev_device_get_devlinks_list_entry(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        if (!udev_device->info_loaded)
                udev_device_read_db(udev_device, NULL);
        return udev_list_get_entry(&udev_device->devlinks_list);
}

void udev_device_cleanup_devlinks_list(struct udev_device *udev_device)
{
        udev_device->devlinks_uptodate = false;
        udev_list_cleanup(&udev_device->devlinks_list);
}

/**
 * udev_device_get_properties_list_entry:
 * @udev_device: udev device
 *
 * Retrieve the list of key/value device properties of the udev
 * device. The next list entry can be retrieved with udev_list_entry_next(),
 * which returns #NULL if no more entries exist. The property name
 * can be retrieved from the list entry by udev_list_get_name(),
 * the property value by udev_list_get_value().
 *
 * Returns: the first entry of the property list
 **/
UDEV_EXPORT struct udev_list_entry *udev_device_get_properties_list_entry(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        if (!udev_device->info_loaded) {
                udev_device_read_uevent_file(udev_device);
                udev_device_read_db(udev_device, NULL);
        }
        if (!udev_device->devlinks_uptodate) {
                char symlinks[UTIL_PATH_SIZE];
                struct udev_list_entry *list_entry;

                udev_device->devlinks_uptodate = true;
                list_entry = udev_device_get_devlinks_list_entry(udev_device);
                if (list_entry != NULL) {
                        char *s;
                        size_t l;

                        s = symlinks;
                        l = util_strpcpyl(&s, sizeof(symlinks), udev_list_entry_get_name(list_entry), NULL);
                        udev_list_entry_foreach(list_entry, udev_list_entry_get_next(list_entry))
                                l = util_strpcpyl(&s, l, " ", udev_list_entry_get_name(list_entry), NULL);
                        udev_device_add_property(udev_device, "DEVLINKS", symlinks);
                }
        }
        if (!udev_device->tags_uptodate) {
                udev_device->tags_uptodate = true;
                if (udev_device_get_tags_list_entry(udev_device) != NULL) {
                        char tags[UTIL_PATH_SIZE];
                        struct udev_list_entry *list_entry;
                        char *s;
                        size_t l;

                        s = tags;
                        l = util_strpcpyl(&s, sizeof(tags), ":", NULL);
                        udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
                                l = util_strpcpyl(&s, l, udev_list_entry_get_name(list_entry), ":", NULL);
                        udev_device_add_property(udev_device, "TAGS", tags);
                }
        }
        return udev_list_get_entry(&udev_device->properties_list);
}

/**
 * udev_device_get_action:
 * @udev_device: udev device
 *
 * This is only valid if the device was received through a monitor. Devices read from
 * sys do not have an action string. Usual actions are: add, remove, change, online,
 * offline.
 *
 * Returns: the kernel action value, or #NULL if there is no action value available.
 **/
UDEV_EXPORT const char *udev_device_get_action(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        return udev_device->action;
}

/**
 * udev_device_get_usec_since_initialized:
 * @udev_device: udev device
 *
 * Return the number of microseconds passed since udev set up the
 * device for the first time.
 *
 * This is only implemented for devices with need to store properties
 * in the udev database. All other devices return 0 here.
 *
 * Returns: the number of microseconds since the device was first seen.
 **/
UDEV_EXPORT unsigned long long int udev_device_get_usec_since_initialized(struct udev_device *udev_device)
{
        unsigned long long now;

        if (udev_device == NULL)
                return 0;
        if (!udev_device->info_loaded)
                udev_device_read_db(udev_device, NULL);
        if (udev_device->usec_initialized == 0)
                return 0;
        now = now_usec();
        if (now == 0)
                return 0;
        return now - udev_device->usec_initialized;
}

unsigned long long udev_device_get_usec_initialized(struct udev_device *udev_device)
{
        return udev_device->usec_initialized;
}

void udev_device_set_usec_initialized(struct udev_device *udev_device, unsigned long long usec_initialized)
{
        char num[32];

        udev_device->usec_initialized = usec_initialized;
        snprintf(num, sizeof(num), "%llu", usec_initialized);
        udev_device_add_property(udev_device, "USEC_INITIALIZED", num);
}

/**
 * udev_device_get_sysattr_value:
 * @udev_device: udev device
 * @sysattr: attribute name
 *
 * The retrieved value is cached in the device. Repeated calls will return the same
 * value and not open the attribute again.
 *
 * Returns: the content of a sys attribute file, or #NULL if there is no sys attribute value.
 **/
UDEV_EXPORT const char *udev_device_get_sysattr_value(struct udev_device *udev_device, const char *sysattr)
{
        struct udev_list_entry *list_entry;
        char path[UTIL_PATH_SIZE];
        char value[4096];
        struct stat statbuf;
        int fd;
        ssize_t size;
        const char *val = NULL;

        if (udev_device == NULL)
                return NULL;
        if (sysattr == NULL)
                return NULL;

        /* look for possibly already cached result */
        list_entry = udev_list_get_entry(&udev_device->sysattr_value_list);
        list_entry = udev_list_entry_get_by_name(list_entry, sysattr);
        if (list_entry != NULL) {
                dbg(udev_device->udev, "got '%s' (%s) from cache\n",
                    sysattr, udev_list_entry_get_value(list_entry));
                return udev_list_entry_get_value(list_entry);
        }

        util_strscpyl(path, sizeof(path), udev_device_get_syspath(udev_device), "/", sysattr, NULL);
        if (lstat(path, &statbuf) != 0) {
                dbg(udev_device->udev, "no attribute '%s', keep negative entry\n", path);
                udev_list_entry_add(&udev_device->sysattr_value_list, sysattr, NULL);
                goto out;
        }

        if (S_ISLNK(statbuf.st_mode)) {
                struct udev_device *dev;

                /*
                 * Some core links return only the last element of the target path,
                 * these are just values, the paths should not be exposed.
                 */
                if (strcmp(sysattr, "driver") == 0 ||
                    strcmp(sysattr, "subsystem") == 0 ||
                    strcmp(sysattr, "module") == 0) {
                        if (util_get_sys_core_link_value(udev_device->udev, sysattr,
                                                         udev_device->syspath, value, sizeof(value)) < 0)
                                return NULL;
                        dbg(udev_device->udev, "cache '%s' with link value '%s'\n", sysattr, value);
                        list_entry = udev_list_entry_add(&udev_device->sysattr_value_list, sysattr, value);
                        val = udev_list_entry_get_value(list_entry);
                        goto out;
                }

                /* resolve link to a device and return its syspath */
                util_strscpyl(path, sizeof(path), udev_device->syspath, "/", sysattr, NULL);
                dev = udev_device_new_from_syspath(udev_device->udev, path);
                if (dev != NULL) {
                        list_entry = udev_list_entry_add(&udev_device->sysattr_value_list, sysattr,
                                                         udev_device_get_syspath(dev));
                        val = udev_list_entry_get_value(list_entry);
                        udev_device_unref(dev);
                }

                goto out;
        }

        /* skip directories */
        if (S_ISDIR(statbuf.st_mode))
                goto out;

        /* skip non-readable files */
        if ((statbuf.st_mode & S_IRUSR) == 0)
                goto out;

        /* read attribute value */
        fd = open(path, O_RDONLY|O_CLOEXEC);
        if (fd < 0) {
                dbg(udev_device->udev, "attribute '%s' can not be opened\n", path);
                goto out;
        }
        size = read(fd, value, sizeof(value));
        close(fd);
        if (size < 0)
                goto out;
        if (size == sizeof(value))
                goto out;

        /* got a valid value, store it in cache and return it */
        value[size] = '\0';
        util_remove_trailing_chars(value, '\n');
        dbg(udev_device->udev, "'%s' has attribute value '%s'\n", path, value);
        list_entry = udev_list_entry_add(&udev_device->sysattr_value_list, sysattr, value);
        val = udev_list_entry_get_value(list_entry);
out:
        return val;
}

static int udev_device_sysattr_list_read(struct udev_device *udev_device)
{
        struct dirent *dent;
        DIR *dir;
        int num = 0;

        if (udev_device == NULL)
                return -1;
        if (udev_device->sysattr_list_read)
                return 0;

        dir = opendir(udev_device_get_syspath(udev_device));
        if (!dir) {
                dbg(udev_device->udev, "sysfs dir '%s' can not be opened\n",
                                udev_device_get_syspath(udev_device));
                return -1;
        }

        for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
                char path[UTIL_PATH_SIZE];
                struct stat statbuf;

                /* only handle symlinks and regular files */
                if (dent->d_type != DT_LNK && dent->d_type != DT_REG)
                        continue;

                util_strscpyl(path, sizeof(path), udev_device_get_syspath(udev_device), "/", dent->d_name, NULL);
                if (lstat(path, &statbuf) != 0)
                        continue;
                if ((statbuf.st_mode & S_IRUSR) == 0)
                        continue;

                udev_list_entry_add(&udev_device->sysattr_list, dent->d_name, NULL);
                num++;
        }

        closedir(dir);
        dbg(udev_device->udev, "found %d sysattrs for '%s'\n", num, udev_device_get_syspath(udev_device));
        udev_device->sysattr_list_read = true;

        return num;
}

/**
 * udev_device_get_sysattr_list_entry:
 * @udev_device: udev device
 *
 * Retrieve the list of available sysattrs, with value being empty;
 * This just return all available sysfs attributes for a particular
 * device without reading their values.
 *
 * Returns: the first entry of the property list
 **/
UDEV_EXPORT struct udev_list_entry *udev_device_get_sysattr_list_entry(struct udev_device *udev_device)
{
        if (!udev_device->sysattr_list_read) {
                int ret;
                ret = udev_device_sysattr_list_read(udev_device);
                if (0 > ret)
                        return NULL;
        }

        return udev_list_get_entry(&udev_device->sysattr_list);
}

int udev_device_set_syspath(struct udev_device *udev_device, const char *syspath)
{
        const char *pos;
        size_t len;

        free(udev_device->syspath);
        udev_device->syspath = strdup(syspath);
        if (udev_device->syspath ==  NULL)
                return -ENOMEM;
        udev_device->devpath = &udev_device->syspath[strlen(udev_get_sys_path(udev_device->udev))];
        udev_device_add_property(udev_device, "DEVPATH", udev_device->devpath);

        pos = strrchr(udev_device->syspath, '/');
        if (pos == NULL)
                return -EINVAL;
        udev_device->sysname = strdup(&pos[1]);
        if (udev_device->sysname == NULL)
                return -ENOMEM;

        /* some devices have '!' in their name, change that to '/' */
        len = 0;
        while (udev_device->sysname[len] != '\0') {
                if (udev_device->sysname[len] == '!')
                        udev_device->sysname[len] = '/';
                len++;
        }

        /* trailing number */
        while (len > 0 && isdigit(udev_device->sysname[--len]))
                udev_device->sysnum = &udev_device->sysname[len];

        /* sysname is completely numeric */
        if (len == 0)
                udev_device->sysnum = NULL;

        return 0;
}

int udev_device_set_devnode(struct udev_device *udev_device, const char *devnode)
{
        free(udev_device->devnode);
        if (devnode[0] != '/') {
                if (asprintf(&udev_device->devnode, "%s/%s", udev_get_dev_path(udev_device->udev), devnode) < 0)
                        udev_device->devnode = NULL;
        } else {
                udev_device->devnode = strdup(devnode);
        }
        if (udev_device->devnode == NULL)
                return -ENOMEM;
        udev_device_add_property(udev_device, "DEVNAME", udev_device->devnode);
        return 0;
}

int udev_device_add_devlink(struct udev_device *udev_device, const char *devlink, int unique)
{
        struct udev_list_entry *list_entry;

        udev_device->devlinks_uptodate = false;
        list_entry = udev_list_entry_add(&udev_device->devlinks_list, devlink, NULL);
        if (list_entry == NULL)
                return -ENOMEM;
        if (unique)
                udev_list_entry_set_num(list_entry, true);
        return 0;
}

const char *udev_device_get_id_filename(struct udev_device *udev_device)
{
        if (udev_device->id_filename == NULL) {
                if (udev_device_get_subsystem(udev_device) == NULL)
                        return NULL;

                if (major(udev_device_get_devnum(udev_device)) > 0) {
                        /* use dev_t -- b259:131072, c254:0 */
                        if (asprintf(&udev_device->id_filename, "%c%u:%u",
                                     strcmp(udev_device_get_subsystem(udev_device), "block") == 0 ? 'b' : 'c',
                                     major(udev_device_get_devnum(udev_device)),
                                     minor(udev_device_get_devnum(udev_device))) < 0)
                                udev_device->id_filename = NULL;
                } else if (udev_device_get_ifindex(udev_device) > 0) {
                        /* use netdev ifindex -- n3 */
                        if (asprintf(&udev_device->id_filename, "n%u", udev_device_get_ifindex(udev_device)) < 0)
                                udev_device->id_filename = NULL;
                } else {
                        /*
                         * use $subsys:$syname -- pci:0000:00:1f.2
                         * sysname() has '!' translated, get it from devpath
                         */
                        const char *sysname;
                        sysname = strrchr(udev_device->devpath, '/');
                        if (sysname == NULL)
                                return NULL;
                        sysname = &sysname[1];
                        if (asprintf(&udev_device->id_filename, "+%s:%s", udev_device_get_subsystem(udev_device), sysname) < 0)
                                udev_device->id_filename = NULL;
                }
        }
        return udev_device->id_filename;
}

/**
 * udev_device_get_is_initialized:
 * @udev_device: udev device
 *
 * Check if udev has already handled the device and has set up
 * device node permissions and context, or has renamed a network
 * device.
 *
 * This is only implemented for devices with a device node
 * or network interfaces. All other devices return 1 here.
 *
 * Returns: 1 if the device is set up. 0 otherwise.
 **/
UDEV_EXPORT int udev_device_get_is_initialized(struct udev_device *udev_device)
{
        if (!udev_device->info_loaded)
                udev_device_read_db(udev_device, NULL);
        return udev_device->is_initialized;
}

void udev_device_set_is_initialized(struct udev_device *udev_device)
{
        udev_device->is_initialized = true;
}

int udev_device_add_tag(struct udev_device *udev_device, const char *tag)
{
        if (strchr(tag, ':') != NULL || strchr(tag, ' ') != NULL)
                return -EINVAL;
        udev_device->tags_uptodate = false;
        if (udev_list_entry_add(&udev_device->tags_list, tag, NULL) != NULL)
                return 0;
        return -ENOMEM;
}

void udev_device_cleanup_tags_list(struct udev_device *udev_device)
{
        udev_device->tags_uptodate = false;
        udev_list_cleanup(&udev_device->tags_list);
}

/**
 * udev_device_get_tags_list_entry:
 * @udev_device: udev device
 *
 * Retrieve the list of tags attached to the udev device. The next
 * list entry can be retrieved with udev_list_entry_next(),
 * which returns #NULL if no more entries exist. The tag string
 * can be retrieved from the list entry by udev_list_get_name().
 *
 * Returns: the first entry of the tag list
 **/
UDEV_EXPORT struct udev_list_entry *udev_device_get_tags_list_entry(struct udev_device *udev_device)
{
        if (udev_device == NULL)
                return NULL;
        if (!udev_device->info_loaded)
                udev_device_read_db(udev_device, NULL);
        return udev_list_get_entry(&udev_device->tags_list);
}

UDEV_EXPORT int udev_device_has_tag(struct udev_device *udev_device, const char *tag)
{
        struct udev_list_entry *list_entry;

        if (udev_device == NULL)
                return false;
        if (!udev_device->info_loaded)
                udev_device_read_db(udev_device, NULL);
        list_entry = udev_device_get_tags_list_entry(udev_device);
        if (udev_list_entry_get_by_name(list_entry, tag) != NULL)
                return true;
        return false;
}

#define ENVP_SIZE                        128
#define MONITOR_BUF_SIZE                4096
static int update_envp_monitor_buf(struct udev_device *udev_device)
{
        struct udev_list_entry *list_entry;
        char *s;
        size_t l;
        unsigned int i;

        /* monitor buffer of property strings */
        free(udev_device->monitor_buf);
        udev_device->monitor_buf_len = 0;
        udev_device->monitor_buf = malloc(MONITOR_BUF_SIZE);
        if (udev_device->monitor_buf == NULL)
                return -ENOMEM;

        /* envp array, strings will point into monitor buffer */
        if (udev_device->envp == NULL)
                udev_device->envp = malloc(sizeof(char *) * ENVP_SIZE);
        if (udev_device->envp == NULL)
                return -ENOMEM;

        i = 0;
        s = udev_device->monitor_buf;
        l = MONITOR_BUF_SIZE;
        udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(udev_device)) {
                const char *key;

                key = udev_list_entry_get_name(list_entry);
                /* skip private variables */
                if (key[0] == '.')
                        continue;

                /* add string to envp array */
                udev_device->envp[i++] = s;
                if (i+1 >= ENVP_SIZE)
                        return -EINVAL;

                /* add property string to monitor buffer */
                l = util_strpcpyl(&s, l, key, "=", udev_list_entry_get_value(list_entry), NULL);
                if (l == 0)
                        return -EINVAL;
                /* advance past the trailing '\0' that util_strpcpyl() guarantees */
                s++;
                l--;
        }
        udev_device->envp[i] = NULL;
        udev_device->monitor_buf_len = s - udev_device->monitor_buf;
        udev_device->envp_uptodate = true;
        dbg(udev_device->udev, "filled envp/monitor buffer, %u properties, %zu bytes\n",
            i, udev_device->monitor_buf_len);
        return 0;
}

char **udev_device_get_properties_envp(struct udev_device *udev_device)
{
        if (!udev_device->envp_uptodate)
                if (update_envp_monitor_buf(udev_device) != 0)
                        return NULL;
        return udev_device->envp;
}

ssize_t udev_device_get_properties_monitor_buf(struct udev_device *udev_device, const char **buf)
{
        if (!udev_device->envp_uptodate)
                if (update_envp_monitor_buf(udev_device) != 0)
                        return -EINVAL;
        *buf = udev_device->monitor_buf;
        return udev_device->monitor_buf_len;
}

int udev_device_set_action(struct udev_device *udev_device, const char *action)
{
        free(udev_device->action);
        udev_device->action = strdup(action);
        if (udev_device->action == NULL)
                return -ENOMEM;
        udev_device_add_property(udev_device, "ACTION", udev_device->action);
        return 0;
}

int udev_device_get_devlink_priority(struct udev_device *udev_device)
{
        if (!udev_device->info_loaded)
                udev_device_read_db(udev_device, NULL);
        return udev_device->devlink_priority;
}

int udev_device_set_devlink_priority(struct udev_device *udev_device, int prio)
{
         udev_device->devlink_priority = prio;
        return 0;
}

int udev_device_get_watch_handle(struct udev_device *udev_device)
{
        if (!udev_device->info_loaded)
                udev_device_read_db(udev_device, NULL);
        return udev_device->watch_handle;
}

int udev_device_set_watch_handle(struct udev_device *udev_device, int handle)
{
        udev_device->watch_handle = handle;
        return 0;
}

bool udev_device_get_db_persist(struct udev_device *udev_device)
{
        return udev_device->db_persist;
}

void udev_device_set_db_persist(struct udev_device *udev_device)
{
        udev_device->db_persist = true;
}