aboutsummaryrefslogtreecommitdiff
path: root/lib/libmtd.c
blob: 654490edbee9c64246e2d1cd24c027f4ba1203e4 (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
/*
 * Copyright (c) International Business Machines Corp., 2006
 * Copyright (C) 2009 Nokia Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Author: Artem Bityutskiy
 *
 * MTD library.
 */

#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <inttypes.h>

#include <mtd/mtd-user.h>
#include <libmtd.h>

#include "libmtd_int.h"
#include "common.h"

/**
 * mkpath - compose full path from 2 given components.
 * @path: the first component
 * @name: the second component
 *
 * This function returns the resulting path in case of success and %NULL in
 * case of failure.
 */
static char *mkpath(const char *path, const char *name)
{
	char *n;
	size_t len1 = strlen(path);
	size_t len2 = strlen(name);

	n = xmalloc(len1 + len2 + 2);

	memcpy(n, path, len1);
	if (n[len1 - 1] != '/')
		n[len1++] = '/';

	memcpy(n + len1, name, len2 + 1);
	return n;
}

/**
 * read_data - read data from a file.
 * @file: the file to read from
 * @buf: the buffer to read to
 * @buf_len: buffer length
 *
 * This function returns number of read bytes in case of success and %-1 in
 * case of failure. Note, if the file contains more then @buf_len bytes of
 * date, this function fails with %EINVAL error code.
 */
static int read_data(const char *file, void *buf, int buf_len)
{
	int fd, rd, tmp, tmp1;

	fd = open(file, O_RDONLY | O_CLOEXEC);
	if (fd == -1)
		return -1;

	rd = read(fd, buf, buf_len);
	if (rd == -1) {
		sys_errmsg("cannot read \"%s\"", file);
		goto out_error;
	}

	if (rd == buf_len) {
		errmsg("contents of \"%s\" is too long", file);
		errno = EINVAL;
		goto out_error;
	}

	((char *)buf)[rd] = '\0';

	/* Make sure all data is read */
	tmp1 = read(fd, &tmp, 1);
	if (tmp1 == 1) {
		sys_errmsg("cannot read \"%s\"", file);
		goto out_error;
	}
	if (tmp1) {
		errmsg("file \"%s\" contains too much data (> %d bytes)",
		       file, buf_len);
		errno = EINVAL;
		goto out_error;
	}

	if (close(fd)) {
		sys_errmsg("close failed on \"%s\"", file);
		return -1;
	}

	return rd;

out_error:
	close(fd);
	return -1;
}

/**
 * read_major - read major and minor numbers from a file.
 * @file: name of the file to read from
 * @major: major number is returned here
 * @minor: minor number is returned here
 *
 * This function returns % in case of success, and %-1 in case of failure.
 */
static int read_major(const char *file, int *major, int *minor)
{
	int ret;
	char buf[50];

	ret = read_data(file, buf, 50);
	if (ret < 0)
		return ret;

	ret = sscanf(buf, "%d:%d\n", major, minor);
	if (ret != 2) {
		errno = EINVAL;
		return errmsg("\"%s\" does not have major:minor format", file);
	}

	if (*major < 0 || *minor < 0) {
		errno = EINVAL;
		return errmsg("bad major:minor %d:%d in \"%s\"",
			      *major, *minor, file);
	}

	return 0;
}

/**
 * dev_get_major - get major and minor numbers of an MTD device.
 * @lib: libmtd descriptor
 * @mtd_num: MTD device number
 * @major: major number is returned here
 * @minor: minor number is returned here
 *
 * This function returns zero in case of success and %-1 in case of failure.
 */
static int dev_get_major(struct libmtd *lib, int mtd_num, int *major, int *minor)
{
	char file[strlen(lib->mtd_dev) + 50];

	sprintf(file, lib->mtd_dev, mtd_num);
	return read_major(file, major, minor);
}

/**
 * dev_read_data - read data from an MTD device's sysfs file.
 * @patt: file pattern to read from
 * @mtd_num: MTD device number
 * @buf: buffer to read to
 * @buf_len: buffer length
 *
 * This function returns number of read bytes in case of success and %-1 in
 * case of failure.
 */
static int dev_read_data(const char *patt, int mtd_num, void *buf, int buf_len)
{
	char file[strlen(patt) + 100];

	sprintf(file, patt, mtd_num);
	return read_data(file, buf, buf_len);
}

/**
 * read_hex_ll - read a hex 'long long' value from a file.
 * @file: the file to read from
 * @value: the result is stored here
 *
 * This function reads file @file and interprets its contents as hexadecimal
 * 'long long' integer. If this is not true, it fails with %EINVAL error code.
 * Returns %0 in case of success and %-1 in case of failure.
 */
static int read_hex_ll(const char *file, long long *value)
{
	int fd, rd;
	char buf[50];

	fd = open(file, O_RDONLY | O_CLOEXEC);
	if (fd == -1)
		return -1;

	rd = read(fd, buf, sizeof(buf));
	if (rd == -1) {
		sys_errmsg("cannot read \"%s\"", file);
		goto out_error;
	}
	if (rd == sizeof(buf)) {
		errmsg("contents of \"%s\" is too long", file);
		errno = EINVAL;
		goto out_error;
	}
	buf[rd] = '\0';

	if (sscanf(buf, "%llx\n", value) != 1) {
		errmsg("cannot read integer from \"%s\"\n", file);
		errno = EINVAL;
		goto out_error;
	}

	if (*value < 0) {
		errmsg("negative value %lld in \"%s\"", *value, file);
		errno = EINVAL;
		goto out_error;
	}

	if (close(fd))
		return sys_errmsg("close failed on \"%s\"", file);

	return 0;

out_error:
	close(fd);
	return -1;
}

/**
 * read_pos_ll - read a positive 'long long' value from a file.
 * @file: the file to read from
 * @value: the result is stored here
 *
 * This function reads file @file and interprets its contents as a positive
 * 'long long' integer. If this is not true, it fails with %EINVAL error code.
 * Returns %0 in case of success and %-1 in case of failure.
 */
static int read_pos_ll(const char *file, long long *value)
{
	int fd, rd;
	char buf[50];

	fd = open(file, O_RDONLY | O_CLOEXEC);
	if (fd == -1)
		return -1;

	rd = read(fd, buf, 50);
	if (rd == -1) {
		sys_errmsg("cannot read \"%s\"", file);
		goto out_error;
	}
	if (rd == 50) {
		errmsg("contents of \"%s\" is too long", file);
		errno = EINVAL;
		goto out_error;
	}

	if (sscanf(buf, "%lld\n", value) != 1) {
		errmsg("cannot read integer from \"%s\"\n", file);
		errno = EINVAL;
		goto out_error;
	}

	if (*value < 0) {
		errmsg("negative value %lld in \"%s\"", *value, file);
		errno = EINVAL;
		goto out_error;
	}

	if (close(fd))
		return sys_errmsg("close failed on \"%s\"", file);

	return 0;

out_error:
	close(fd);
	return -1;
}

/**
 * read_hex_int - read an 'int' value from a file.
 * @file: the file to read from
 * @value: the result is stored here
 *
 * This function is the same as 'read_pos_ll()', but it reads an 'int'
 * value, not 'long long'.
 */
static int read_hex_int(const char *file, int *value)
{
	long long res;

	if (read_hex_ll(file, &res))
		return -1;

	/* Make sure the value has correct range */
	if (res > INT_MAX || res < INT_MIN) {
		errmsg("value %lld read from file \"%s\" is out of range",
		       res, file);
		errno = EINVAL;
		return -1;
	}

	*value = res;
	return 0;
}

/**
 * read_pos_int - read a positive 'int' value from a file.
 * @file: the file to read from
 * @value: the result is stored here
 *
 * This function is the same as 'read_pos_ll()', but it reads an 'int'
 * value, not 'long long'.
 */
static int read_pos_int(const char *file, int *value)
{
	long long res;

	if (read_pos_ll(file, &res))
		return -1;

	/* Make sure the value is not too big */
	if (res > INT_MAX) {
		errmsg("value %lld read from file \"%s\" is out of range",
		       res, file);
		errno = EINVAL;
		return -1;
	}

	*value = res;
	return 0;
}

/**
 * dev_read_hex_int - read an hex 'int' value from an MTD device sysfs file.
 * @patt: file pattern to read from
 * @mtd_num: MTD device number
 * @value: the result is stored here
 *
 * This function returns %0 in case of success and %-1 in case of failure.
 */
static int dev_read_hex_int(const char *patt, int mtd_num, int *value)
{
	char file[strlen(patt) + 50];

	sprintf(file, patt, mtd_num);
	return read_hex_int(file, value);
}

/**
 * dev_read_pos_int - read a positive 'int' value from an MTD device sysfs file.
 * @patt: file pattern to read from
 * @mtd_num: MTD device number
 * @value: the result is stored here
 *
 * This function returns %0 in case of success and %-1 in case of failure.
 */
static int dev_read_pos_int(const char *patt, int mtd_num, int *value)
{
	char file[strlen(patt) + 50];

	sprintf(file, patt, mtd_num);
	return read_pos_int(file, value);
}

/**
 * dev_read_pos_ll - read a positive 'long long' value from an MTD device sysfs file.
 * @patt: file pattern to read from
 * @mtd_num: MTD device number
 * @value: the result is stored here
 *
 * This function returns %0 in case of success and %-1 in case of failure.
 */
static int dev_read_pos_ll(const char *patt, int mtd_num, long long *value)
{
	char file[strlen(patt) + 50];

	sprintf(file, patt, mtd_num);
	return read_pos_ll(file, value);
}

/**
 * type_str2int - convert MTD device type to integer.
 * @str: MTD device type string to convert
 *
 * This function converts MTD device type string @str, read from sysfs, into an
 * integer.
 */
static int type_str2int(const char *str)
{
	if (!strcmp(str, "nand"))
		return MTD_NANDFLASH;
	if (!strcmp(str, "nor"))
		return MTD_NORFLASH;
	if (!strcmp(str, "rom"))
		return MTD_ROM;
	if (!strcmp(str, "absent"))
		return MTD_ABSENT;
	if (!strcmp(str, "dataflash"))
		return MTD_DATAFLASH;
	if (!strcmp(str, "ram"))
		return MTD_RAM;
	if (!strcmp(str, "ubi"))
		return MTD_UBIVOLUME;
	return -1;
}

/**
 * dev_node2num - find UBI device number by its character device node.
 * @lib: MTD library descriptor
 * @node: name of the MTD device node
 * @mtd_num: MTD device number is returned here
 *
 * This function returns %0 in case of success and %-1 in case of failure.
 */
static int dev_node2num(struct libmtd *lib, const char *node, int *mtd_num)
{
	struct stat st;
	int i, mjr, mnr;
	struct mtd_info info;

	if (stat(node, &st))
		return sys_errmsg("cannot get information about \"%s\"", node);

	if (!S_ISCHR(st.st_mode)) {
		errmsg("\"%s\" is not a character device", node);
		errno = EINVAL;
		return -1;
	}

	mjr = major(st.st_rdev);
	mnr = minor(st.st_rdev);

	if (mtd_get_info((libmtd_t *)lib, &info))
		return -1;

	for (i = info.lowest_mtd_num; i <= info.highest_mtd_num; i++) {
		int mjr1, mnr1, ret;

		ret = dev_get_major(lib, i, &mjr1, &mnr1);
		if (ret) {
			if (errno == ENOENT)
				continue;
			if (!errno)
				break;
			return -1;
		}

		if (mjr1 == mjr && mnr1 == mnr) {
			errno = 0;
			*mtd_num = i;
			return 0;
		}
	}

	errno = ENODEV;
	return -1;
}

/**
 * sysfs_is_supported - check whether the MTD sub-system supports MTD.
 * @lib: MTD library descriptor
 *
 * The Linux kernel MTD subsystem gained MTD support starting from kernel
 * 2.6.30 and libmtd tries to use sysfs interface if possible, because the NAND
 * sub-page size is available there (and not available at all in pre-sysfs
 * kernels).
 *
 * Very old kernels did not have "/sys/class/mtd" directory. Not very old
 * kernels (e.g., 2.6.29) did have "/sys/class/mtd/mtdX" directories, by there
 * were no files there, e.g., the "name" file was not present. So all we can do
 * is to check for a "/sys/class/mtd/mtdX/name" file. But this is not a
 * reliable check, because if this is a new system with no MTD devices - we'll
 * treat it as a pre-sysfs system.
 */
static int sysfs_is_supported(struct libmtd *lib)
{
	int fd, num = -1;
	DIR *sysfs_mtd;
	char file[strlen(lib->mtd_name) + 10];

	sysfs_mtd = opendir(lib->sysfs_mtd);
	if (!sysfs_mtd) {
		if (errno == ENOENT) {
			errno = 0;
			return 0;
		}
		return sys_errmsg("cannot open \"%s\"", lib->sysfs_mtd);
	}

	/*
	 * First of all find an "mtdX" directory. This is needed because there
	 * may be, for example, mtd1 but no mtd0.
	 */
	while (1) {
		int ret, mtd_num;
		char tmp_buf[256];
		struct dirent *dirent;

		dirent = readdir(sysfs_mtd);
		if (!dirent)
			break;

		if (strlen(dirent->d_name) >= 255) {
			errmsg("invalid entry in %s: \"%s\"",
			       lib->sysfs_mtd, dirent->d_name);
			errno = EINVAL;
			closedir(sysfs_mtd);
			return -1;
		}

		ret = sscanf(dirent->d_name, MTD_NAME_PATT"%s",
			     &mtd_num, tmp_buf);
		if (ret == 1) {
			num = mtd_num;
			break;
		}
	}

	if (closedir(sysfs_mtd))
		return sys_errmsg("closedir failed on \"%s\"", lib->sysfs_mtd);

	if (num == -1)
		/* No mtd device, treat this as pre-sysfs system */
		return 0;

	sprintf(file, lib->mtd_name, num);
	fd = open(file, O_RDONLY | O_CLOEXEC);
	if (fd == -1)
		return 0;

	if (close(fd)) {
		sys_errmsg("close failed on \"%s\"", file);
		return -1;
	}

	return 1;
}

libmtd_t libmtd_open(void)
{
	struct libmtd *lib;

	lib = xzalloc(sizeof(*lib));

	lib->offs64_ioctls = OFFS64_IOCTLS_UNKNOWN;

	lib->sysfs_mtd = mkpath("/sys", SYSFS_MTD);
	if (!lib->sysfs_mtd)
		goto out_error;

	lib->mtd = mkpath(lib->sysfs_mtd, MTD_NAME_PATT);
	if (!lib->mtd)
		goto out_error;

	lib->mtd_name = mkpath(lib->mtd, MTD_NAME);
	if (!lib->mtd_name)
		goto out_error;

	if (!sysfs_is_supported(lib)) {
		free(lib->mtd);
		free(lib->sysfs_mtd);
		free(lib->mtd_name);
		lib->mtd_name = lib->mtd = lib->sysfs_mtd = NULL;
		return lib;
	}

	lib->mtd_dev = mkpath(lib->mtd, MTD_DEV);
	if (!lib->mtd_dev)
		goto out_error;

	lib->mtd_type = mkpath(lib->mtd, MTD_TYPE);
	if (!lib->mtd_type)
		goto out_error;

	lib->mtd_eb_size = mkpath(lib->mtd, MTD_EB_SIZE);
	if (!lib->mtd_eb_size)
		goto out_error;

	lib->mtd_size = mkpath(lib->mtd, MTD_SIZE);
	if (!lib->mtd_size)
		goto out_error;

	lib->mtd_min_io_size = mkpath(lib->mtd, MTD_MIN_IO_SIZE);
	if (!lib->mtd_min_io_size)
		goto out_error;

	lib->mtd_subpage_size = mkpath(lib->mtd, MTD_SUBPAGE_SIZE);
	if (!lib->mtd_subpage_size)
		goto out_error;

	lib->mtd_oob_size = mkpath(lib->mtd, MTD_OOB_SIZE);
	if (!lib->mtd_oob_size)
		goto out_error;

	lib->mtd_region_cnt = mkpath(lib->mtd, MTD_REGION_CNT);
	if (!lib->mtd_region_cnt)
		goto out_error;

	lib->mtd_flags = mkpath(lib->mtd, MTD_FLAGS);
	if (!lib->mtd_flags)
		goto out_error;

	lib->sysfs_supported = 1;
	return lib;

out_error:
	libmtd_close((libmtd_t)lib);
	return NULL;
}

void libmtd_close(libmtd_t desc)
{
	struct libmtd *lib = (struct libmtd *)desc;

	free(lib->mtd_flags);
	free(lib->mtd_region_cnt);
	free(lib->mtd_oob_size);
	free(lib->mtd_subpage_size);
	free(lib->mtd_min_io_size);
	free(lib->mtd_size);
	free(lib->mtd_eb_size);
	free(lib->mtd_type);
	free(lib->mtd_dev);
	free(lib->mtd_name);
	free(lib->mtd);
	free(lib->sysfs_mtd);
	free(lib);
}

int mtd_dev_present(libmtd_t desc, int mtd_num) {
	struct stat st;
	struct libmtd *lib = (struct libmtd *)desc;

	if (!lib->sysfs_supported)
		return legacy_dev_present(mtd_num);
	else {
		char file[strlen(lib->mtd) + 10];

		sprintf(file, lib->mtd, mtd_num);
		return !stat(file, &st);
	}
}

int mtd_get_info(libmtd_t desc, struct mtd_info *info)
{
	DIR *sysfs_mtd;
	struct dirent *dirent;
	struct libmtd *lib = (struct libmtd *)desc;

	memset(info, 0, sizeof(struct mtd_info));

	if (!lib->sysfs_supported)
		return legacy_mtd_get_info(info);

	info->sysfs_supported = 1;

	/*
	 * We have to scan the MTD sysfs directory to identify how many MTD
	 * devices are present.
	 */
	sysfs_mtd = opendir(lib->sysfs_mtd);
	if (!sysfs_mtd) {
		if (errno == ENOENT) {
			errno = ENODEV;
			return -1;
		}
		return sys_errmsg("cannot open \"%s\"", lib->sysfs_mtd);
	}

	info->lowest_mtd_num = INT_MAX;
	while (1) {
		int mtd_num, ret;
		char tmp_buf[256];

		errno = 0;
		dirent = readdir(sysfs_mtd);
		if (!dirent)
			break;

		if (strlen(dirent->d_name) >= 255) {
			errmsg("invalid entry in %s: \"%s\"",
			       lib->sysfs_mtd, dirent->d_name);
			errno = EINVAL;
			goto out_close;
		}

		ret = sscanf(dirent->d_name, MTD_NAME_PATT"%s",
			     &mtd_num, tmp_buf);
		if (ret == 1) {
			info->mtd_dev_cnt += 1;
			if (mtd_num > info->highest_mtd_num)
				info->highest_mtd_num = mtd_num;
			if (mtd_num < info->lowest_mtd_num)
				info->lowest_mtd_num = mtd_num;
		}
	}

	if (!dirent && errno) {
		sys_errmsg("readdir failed on \"%s\"", lib->sysfs_mtd);
		goto out_close;
	}

	if (closedir(sysfs_mtd))
		return sys_errmsg("closedir failed on \"%s\"", lib->sysfs_mtd);

	if (info->lowest_mtd_num == INT_MAX)
		info->lowest_mtd_num = 0;

	return 0;

out_close:
	closedir(sysfs_mtd);
	return -1;
}

int mtd_get_dev_info1(libmtd_t desc, int mtd_num, struct mtd_dev_info *mtd)
{
	int ret;
	struct libmtd *lib = (struct libmtd *)desc;

	memset(mtd, 0, sizeof(struct mtd_dev_info));
	mtd->mtd_num = mtd_num;

	if (!mtd_dev_present(desc, mtd_num)) {
		errno = ENODEV;
		return -1;
	} else if (!lib->sysfs_supported)
		return legacy_get_dev_info1(mtd_num, mtd);

	if (dev_get_major(lib, mtd_num, &mtd->major, &mtd->minor))
		return -1;

	ret = dev_read_data(lib->mtd_name, mtd_num, &mtd->name,
			    MTD_NAME_MAX + 1);
	if (ret < 0)
		return -1;
	((char *)mtd->name)[ret - 1] = '\0';

	ret = dev_read_data(lib->mtd_type, mtd_num, &mtd->type_str,
			    MTD_TYPE_MAX + 1);
	if (ret < 0)
		return -1;
	((char *)mtd->type_str)[ret - 1] = '\0';

	if (dev_read_pos_int(lib->mtd_eb_size, mtd_num, &mtd->eb_size))
		return -1;
	if (dev_read_pos_ll(lib->mtd_size, mtd_num, &mtd->size))
		return -1;
	if (dev_read_pos_int(lib->mtd_min_io_size, mtd_num, &mtd->min_io_size))
		return -1;
	if (dev_read_pos_int(lib->mtd_subpage_size, mtd_num, &mtd->subpage_size))
		return -1;
	if (dev_read_pos_int(lib->mtd_oob_size, mtd_num, &mtd->oob_size))
		return -1;
	if (dev_read_pos_int(lib->mtd_region_cnt, mtd_num, &mtd->region_cnt))
		return -1;
	if (dev_read_hex_int(lib->mtd_flags, mtd_num, &ret))
		return -1;
	mtd->writable = !!(ret & MTD_WRITEABLE);

	mtd->eb_cnt = mtd->size / mtd->eb_size;
	mtd->type = type_str2int(mtd->type_str);
	mtd->bb_allowed = !!(mtd->type == MTD_NANDFLASH);

	return 0;
}

int mtd_get_dev_info(libmtd_t desc, const char *node, struct mtd_dev_info *mtd)
{
	int mtd_num;
	struct libmtd *lib = (struct libmtd *)desc;

	if (!lib->sysfs_supported)
		return legacy_get_dev_info(node, mtd);

	if (dev_node2num(lib, node, &mtd_num))
		return -1;

	return mtd_get_dev_info1(desc, mtd_num, mtd);
}

static inline int mtd_ioctl_error(const struct mtd_dev_info *mtd, int eb,
				  const char *sreq)
{
	return sys_errmsg("%s ioctl failed for eraseblock %d (mtd%d)",
			  sreq, eb, mtd->mtd_num);
}

static int mtd_valid_erase_block(const struct mtd_dev_info *mtd, int eb)
{
	if (eb < 0 || eb >= mtd->eb_cnt) {
		errmsg("bad eraseblock number %d, mtd%d has %d eraseblocks",
		       eb, mtd->mtd_num, mtd->eb_cnt);
		errno = EINVAL;
		return -1;
	}
	return 0;
}

static int mtd_xlock(const struct mtd_dev_info *mtd, int fd, int eb, int req,
		     const char *sreq)
{
	int ret;
	struct erase_info_user ei;

	ret = mtd_valid_erase_block(mtd, eb);
	if (ret)
		return ret;

	ei.start = eb * mtd->eb_size;
	ei.length = mtd->eb_size;

	ret = ioctl(fd, req, &ei);
	if (ret < 0)
		return mtd_ioctl_error(mtd, eb, sreq);

	return 0;
}
#define mtd_xlock(mtd, fd, eb, req) mtd_xlock(mtd, fd, eb, req, #req)

int mtd_lock(const struct mtd_dev_info *mtd, int fd, int eb)
{
	return mtd_xlock(mtd, fd, eb, MEMLOCK);
}

int mtd_unlock(const struct mtd_dev_info *mtd, int fd, int eb)
{
	return mtd_xlock(mtd, fd, eb, MEMUNLOCK);
}

int mtd_erase(libmtd_t desc, const struct mtd_dev_info *mtd, int fd, int eb)
{
	int ret;
	struct libmtd *lib = (struct libmtd *)desc;
	struct erase_info_user64 ei64;
	struct erase_info_user ei;

	ret = mtd_valid_erase_block(mtd, eb);
	if (ret)
		return ret;

	ei64.start = (__u64)eb * mtd->eb_size;
	ei64.length = mtd->eb_size;

	if (lib->offs64_ioctls == OFFS64_IOCTLS_SUPPORTED ||
	    lib->offs64_ioctls == OFFS64_IOCTLS_UNKNOWN) {
		ret = ioctl(fd, MEMERASE64, &ei64);
		if (ret == 0)
			return ret;

		if (errno != ENOTTY ||
		    lib->offs64_ioctls != OFFS64_IOCTLS_UNKNOWN)
			return mtd_ioctl_error(mtd, eb, "MEMERASE64");

		/*
		 * MEMERASE64 support was added in kernel version 2.6.31, so
		 * probably we are working with older kernel and this ioctl is
		 * not supported.
		 */
		lib->offs64_ioctls = OFFS64_IOCTLS_NOT_SUPPORTED;
	}

	if (ei64.start + ei64.length > 0xFFFFFFFF) {
		errmsg("this system can address only %u eraseblocks",
		       0xFFFFFFFFU / mtd->eb_size);
		errno = EINVAL;
		return -1;
	}

	ei.start = ei64.start;
	ei.length = ei64.length;
	ret = ioctl(fd, MEMERASE, &ei);
	if (ret < 0)
		return mtd_ioctl_error(mtd, eb, "MEMERASE");
	return 0;
}

int mtd_regioninfo(int fd, int regidx, struct region_info_user *reginfo)
{
	int ret;

	if (regidx < 0) {
		errno = ENODEV;
		return -1;
	}

	ret = ioctl(fd, MEMGETREGIONINFO, reginfo);
	if (ret < 0)
		return sys_errmsg("%s ioctl failed for erase region %d",
			"MEMGETREGIONINFO", regidx);

	return 0;
}

int mtd_is_locked(const struct mtd_dev_info *mtd, int fd, int eb)
{
	int ret;
	erase_info_t ei;

	ei.start = eb * mtd->eb_size;
	ei.length = mtd->eb_size;

	ret = ioctl(fd, MEMISLOCKED, &ei);
	if (ret < 0) {
		if (errno != ENOTTY && errno != EOPNOTSUPP)
			return mtd_ioctl_error(mtd, eb, "MEMISLOCKED");
		else
			errno = EOPNOTSUPP;
	}

	return ret;
}

/* Patterns to write to a physical eraseblock when torturing it */
static uint8_t patterns[] = {0xa5, 0x5a, 0x0};

/**
 * check_pattern - check if buffer contains only a certain byte pattern.
 * @buf: buffer to check
 * @patt: the pattern to check
 * @size: buffer size in bytes
 *
 * This function returns %1 in there are only @patt bytes in @buf, and %0 if
 * something else was also found.
 */
static int check_pattern(const void *buf, uint8_t patt, int size)
{
	int i;

	for (i = 0; i < size; i++)
		if (((const uint8_t *)buf)[i] != patt)
			return 0;
	return 1;
}

int mtd_torture(libmtd_t desc, const struct mtd_dev_info *mtd, int fd, int eb)
{
	int err, i, patt_count;
	void *buf;

	normsg("run torture test for PEB %d", eb);
	patt_count = ARRAY_SIZE(patterns);

	buf = xmalloc(mtd->eb_size);

	for (i = 0; i < patt_count; i++) {
		err = mtd_erase(desc, mtd, fd, eb);
		if (err)
			goto out;

		/* Make sure the PEB contains only 0xFF bytes */
		err = mtd_read(mtd, fd, eb, 0, buf, mtd->eb_size);
		if (err)
			goto out;

		err = check_pattern(buf, 0xFF, mtd->eb_size);
		if (err == 0) {
			errmsg("erased PEB %d, but a non-0xFF byte found", eb);
			errno = EIO;
			goto out;
		}

		/* Write a pattern and check it */
		memset(buf, patterns[i], mtd->eb_size);
		err = mtd_write(desc, mtd, fd, eb, 0, buf, mtd->eb_size, NULL,
				0, 0);
		if (err)
			goto out;

		memset(buf, ~patterns[i], mtd->eb_size);
		err = mtd_read(mtd, fd, eb, 0, buf, mtd->eb_size);
		if (err)
			goto out;

		err = check_pattern(buf, patterns[i], mtd->eb_size);
		if (err == 0) {
			errmsg("pattern %x checking failed for PEB %d",
				patterns[i], eb);
			errno = EIO;
			goto out;
		}
	}

	err = 0;
	normsg("PEB %d passed torture test, do not mark it a bad", eb);

out:
	free(buf);
	return -1;
}

int mtd_is_bad(const struct mtd_dev_info *mtd, int fd, int eb)
{
	int ret;
	loff_t seek;

	ret = mtd_valid_erase_block(mtd, eb);
	if (ret)
		return ret;

	if (!mtd->bb_allowed)
		return 0;

	seek = (loff_t)eb * mtd->eb_size;
	ret = ioctl(fd, MEMGETBADBLOCK, &seek);
	if (ret == -1)
		return mtd_ioctl_error(mtd, eb, "MEMGETBADBLOCK");
	return ret;
}

int mtd_mark_bad(const struct mtd_dev_info *mtd, int fd, int eb)
{
	int ret;
	loff_t seek;

	if (!mtd->bb_allowed) {
		errno = EINVAL;
		return -1;
	}

	ret = mtd_valid_erase_block(mtd, eb);
	if (ret)
		return ret;

	seek = (loff_t)eb * mtd->eb_size;
	ret = ioctl(fd, MEMSETBADBLOCK, &seek);
	if (ret == -1)
		return mtd_ioctl_error(mtd, eb, "MEMSETBADBLOCK");
	return 0;
}

int mtd_read(const struct mtd_dev_info *mtd, int fd, int eb, int offs,
	     void *buf, int len)
{
	int ret, rd = 0;
	off_t seek;

	ret = mtd_valid_erase_block(mtd, eb);
	if (ret)
		return ret;

	if (offs < 0 || offs + len > mtd->eb_size) {
		errmsg("bad offset %d or length %d, mtd%d eraseblock size is %d",
		       offs, len, mtd->mtd_num, mtd->eb_size);
		errno = EINVAL;
		return -1;
	}

	/* Seek to the beginning of the eraseblock */
	seek = (off_t)eb * mtd->eb_size + offs;
	if (lseek(fd, seek, SEEK_SET) != seek)
		return sys_errmsg("cannot seek mtd%d to offset %"PRIdoff_t,
				  mtd->mtd_num, seek);

	while (rd < len) {
		ret = read(fd, buf, len);
		if (ret < 0)
			return sys_errmsg("cannot read %d bytes from mtd%d (eraseblock %d, offset %d)",
					  len, mtd->mtd_num, eb, offs);
		rd += ret;
	}

	return 0;
}

static int legacy_auto_oob_layout(const struct mtd_dev_info *mtd, int fd,
				  int ooblen, void *oob) {
	struct nand_oobinfo old_oobinfo;
	int start, len;
	uint8_t *tmp_buf;

	/* Read the current oob info */
	if (ioctl(fd, MEMGETOOBSEL, &old_oobinfo))
		return sys_errmsg("MEMGETOOBSEL failed");

	tmp_buf = malloc(ooblen);
	memcpy(tmp_buf, oob, ooblen);

	/*
	 * We use autoplacement and have the oobinfo with the autoplacement
	 * information from the kernel available
	 */
	if (old_oobinfo.useecc == MTD_NANDECC_AUTOPLACE) {
		int i, tags_pos = 0;
		for (i = 0; old_oobinfo.oobfree[i][1]; i++) {
			/* Set the reserved bytes to 0xff */
			start = old_oobinfo.oobfree[i][0];
			len = old_oobinfo.oobfree[i][1];
			memcpy(oob + start, tmp_buf + tags_pos, len);
			tags_pos += len;
		}
	} else {
		/* Set at least the ecc byte positions to 0xff */
		start = old_oobinfo.eccbytes;
		len = mtd->oob_size - start;
		memcpy(oob + start, tmp_buf + start, len);
	}

	return 0;
}

int mtd_write(libmtd_t desc, const struct mtd_dev_info *mtd, int fd, int eb,
	      int offs, void *data, int len, void *oob, int ooblen,
	      uint8_t mode)
{
	int ret;
	off_t seek;
	struct mtd_write_req ops;

	ret = mtd_valid_erase_block(mtd, eb);
	if (ret)
		return ret;

	if (offs < 0 || offs + len > mtd->eb_size) {
		errmsg("bad offset %d or length %d, mtd%d eraseblock size is %d",
		       offs, len, mtd->mtd_num, mtd->eb_size);
		errno = EINVAL;
		return -1;
	}
	if (offs % mtd->subpage_size) {
		errmsg("write offset %d is not aligned to mtd%d min. I/O size %d",
		       offs, mtd->mtd_num, mtd->subpage_size);
		errno = EINVAL;
		return -1;
	}
	if (len % mtd->subpage_size) {
		errmsg("write length %d is not aligned to mtd%d min. I/O size %d",
		       len, mtd->mtd_num, mtd->subpage_size);
		errno = EINVAL;
		return -1;
	}

	/* Calculate seek address */
	seek = (off_t)eb * mtd->eb_size + offs;

	if (oob) {
		ops.start = seek;
		ops.len = len;
		ops.ooblen = ooblen;
		ops.usr_data = (uint64_t)(unsigned long)data;
		ops.usr_oob = (uint64_t)(unsigned long)oob;
		ops.mode = mode;

		ret = ioctl(fd, MEMWRITE, &ops);
		if (ret == 0)
			return 0;
		else if (errno != ENOTTY && errno != EOPNOTSUPP)
			return mtd_ioctl_error(mtd, eb, "MEMWRITE");

		/* Fall back to old OOB ioctl() if necessary */
		if (mode == MTD_OPS_AUTO_OOB)
			if (legacy_auto_oob_layout(mtd, fd, ooblen, oob))
				return -1;
		if (mtd_write_oob(desc, mtd, fd, seek, ooblen, oob) < 0)
			return sys_errmsg("cannot write to OOB");
	}
	if (data) {
		/* Seek to the beginning of the eraseblock */
		if (lseek(fd, seek, SEEK_SET) != seek)
			return sys_errmsg("cannot seek mtd%d to offset %"PRIdoff_t,
					mtd->mtd_num, seek);
		ret = write(fd, data, len);
		if (ret != len)
			return sys_errmsg("cannot write %d bytes to mtd%d "
					  "(eraseblock %d, offset %d)",
					  len, mtd->mtd_num, eb, offs);
	}

	return 0;
}

int do_oob_op(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
	      uint64_t start, uint64_t length, void *data, unsigned int cmd64,
	      unsigned int cmd)
{
	int ret, oob_offs;
	struct mtd_oob_buf64 oob64;
	struct mtd_oob_buf oob;
	unsigned long long max_offs;
	const char *cmd64_str, *cmd_str;
	struct libmtd *lib = (struct libmtd *)desc;

	if (cmd64 ==  MEMREADOOB64) {
		cmd64_str = "MEMREADOOB64";
		cmd_str   = "MEMREADOOB";
	} else {
		cmd64_str = "MEMWRITEOOB64";
		cmd_str   = "MEMWRITEOOB";
	}

	max_offs = (unsigned long long)mtd->eb_cnt * mtd->eb_size;
	if (start >= max_offs) {
		errmsg("bad page address %" PRIu64 ", mtd%d has %d eraseblocks (%llu bytes)",
		       start, mtd->mtd_num, mtd->eb_cnt, max_offs);
		errno = EINVAL;
		return -1;
	}

	oob_offs = start & (mtd->min_io_size - 1);
	if (oob_offs + length > mtd->oob_size || length == 0) {
		errmsg("Cannot write %" PRIu64 " OOB bytes to address %" PRIu64 " (OOB offset %u) - mtd%d OOB size is only %d bytes",
		       length, start, oob_offs, mtd->mtd_num,  mtd->oob_size);
		errno = EINVAL;
		return -1;
	}

	oob64.start = start;
	oob64.length = length;
	oob64.usr_ptr = (uint64_t)(unsigned long)data;

	if (lib->offs64_ioctls == OFFS64_IOCTLS_SUPPORTED ||
	    lib->offs64_ioctls == OFFS64_IOCTLS_UNKNOWN) {
		ret = ioctl(fd, cmd64, &oob64);
		if (ret == 0)
			return ret;

		if (errno != ENOTTY ||
		    lib->offs64_ioctls != OFFS64_IOCTLS_UNKNOWN) {
			sys_errmsg("%s ioctl failed for mtd%d, offset %" PRIu64 " (eraseblock %" PRIu64 ")",
				   cmd64_str, mtd->mtd_num, start, start / mtd->eb_size);
		}

		/*
		 * MEMREADOOB64/MEMWRITEOOB64 support was added in kernel
		 * version 2.6.31, so probably we are working with older kernel
		 * and these ioctls are not supported.
		 */
		lib->offs64_ioctls = OFFS64_IOCTLS_NOT_SUPPORTED;
	}

	if (oob64.start > 0xFFFFFFFFULL) {
		errmsg("this system can address only up to address %lu",
		       0xFFFFFFFFUL);
		errno = EINVAL;
		return -1;
	}

	oob.start = oob64.start;
	oob.length = oob64.length;
	oob.ptr = data;

	ret = ioctl(fd, cmd, &oob);
	if (ret < 0)
		sys_errmsg("%s ioctl failed for mtd%d, offset %" PRIu64 " (eraseblock %" PRIu64 ")",
			   cmd_str, mtd->mtd_num, start, start / mtd->eb_size);
	return ret;
}

int mtd_read_oob(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
		 uint64_t start, uint64_t length, void *data)
{
	return do_oob_op(desc, mtd, fd, start, length, data,
			 MEMREADOOB64, MEMREADOOB);
}

int mtd_write_oob(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
		  uint64_t start, uint64_t length, void *data)
{
	return do_oob_op(desc, mtd, fd, start, length, data,
			 MEMWRITEOOB64, MEMWRITEOOB);
}

int mtd_write_img(const struct mtd_dev_info *mtd, int fd, int eb, int offs,
		  const char *img_name)
{
	int tmp, ret, in_fd, len, written = 0;
	off_t seek;
	struct stat st;
	char *buf;

	ret = mtd_valid_erase_block(mtd, eb);
	if (ret)
		return ret;

	if (offs < 0 || offs >= mtd->eb_size) {
		errmsg("bad offset %d, mtd%d eraseblock size is %d",
		       offs, mtd->mtd_num, mtd->eb_size);
		errno = EINVAL;
		return -1;
	}
	if (offs % mtd->subpage_size) {
		errmsg("write offset %d is not aligned to mtd%d min. I/O size %d",
		       offs, mtd->mtd_num, mtd->subpage_size);
		errno = EINVAL;
		return -1;
	}

	in_fd = open(img_name, O_RDONLY | O_CLOEXEC);
	if (in_fd == -1)
		return sys_errmsg("cannot open \"%s\"", img_name);

	if (fstat(in_fd, &st)) {
		sys_errmsg("cannot stat %s", img_name);
		goto out_close;
	}

	len = st.st_size;
	if (len % mtd->subpage_size) {
		errmsg("size of \"%s\" is %d byte, which is not aligned to "
		       "mtd%d min. I/O size %d", img_name, len, mtd->mtd_num,
		       mtd->subpage_size);
		errno = EINVAL;
		goto out_close;
	}
	tmp = (offs + len + mtd->eb_size - 1) / mtd->eb_size;
	if (eb + tmp > mtd->eb_cnt) {
		errmsg("\"%s\" image size is %d bytes, mtd%d size is %d "
		       "eraseblocks, the image does not fit if we write it "
		       "starting from eraseblock %d, offset %d",
		       img_name, len, mtd->mtd_num, mtd->eb_cnt, eb, offs);
		errno = EINVAL;
		goto out_close;
	}

	/* Seek to the beginning of the eraseblock */
	seek = (off_t)eb * mtd->eb_size + offs;
	if (lseek(fd, seek, SEEK_SET) != seek) {
		sys_errmsg("cannot seek mtd%d to offset %"PRIdoff_t,
			    mtd->mtd_num, seek);
		goto out_close;
	}

	buf = xmalloc(mtd->eb_size);

	while (written < len) {
		int rd = 0;

		do {
			ret = read(in_fd, buf, mtd->eb_size - offs - rd);
			if (ret == -1) {
				sys_errmsg("cannot read \"%s\"", img_name);
				goto out_free;
			}
			rd += ret;
		} while (ret && rd < mtd->eb_size - offs);

		ret = write(fd, buf, rd);
		if (ret != rd) {
			sys_errmsg("cannot write %d bytes to mtd%d (eraseblock %d, offset %d)",
				   len, mtd->mtd_num, eb, offs);
			goto out_free;
		}

		offs = 0;
		eb += 1;
		written += rd;
	}

	free(buf);
	close(in_fd);
	return 0;

out_free:
	free(buf);
out_close:
	close(in_fd);
	return -1;
}

int mtd_probe_node(libmtd_t desc, const char *node)
{
	struct stat st;
	struct mtd_info info;
	int i, mjr, mnr;
	struct libmtd *lib = (struct libmtd *)desc;

	if (stat(node, &st))
		return sys_errmsg("cannot get information about \"%s\"", node);

	if (!S_ISCHR(st.st_mode)) {
		errmsg("\"%s\" is not a character device", node);
		errno = EINVAL;
		return -1;
	}

	mjr = major(st.st_rdev);
	mnr = minor(st.st_rdev);

	if (mtd_get_info((libmtd_t *)lib, &info))
		return -1;

	if (!lib->sysfs_supported)
		return 0;

	for (i = info.lowest_mtd_num; i <= info.highest_mtd_num; i++) {
		int mjr1, mnr1, ret;

		ret = dev_get_major(lib, i, &mjr1, &mnr1);
		if (ret) {
			if (errno == ENOENT)
				continue;
			if (!errno)
				break;
			return -1;
		}

		if (mjr1 == mjr && mnr1 == mnr)
			return 1;
	}

	errno = 0;
	return -1;
}