summaryrefslogtreecommitdiffstats
path: root/mtdutils/mtdutils.c
blob: 3e354e3340845e415fc6663068ce6b7edbdeea7b (plain) (blame)
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
/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/mount.h>  // for _IOW, _IOR, mount()
#include <sys/stat.h>
#include <mtd/mtd-user.h>
#undef NDEBUG
#include <assert.h>

#include "mtdutils.h"

struct MtdPartition {
    int device_index;
    unsigned int size;
    unsigned int erase_size;
    char *name;
};

struct MtdReadContext {
    const MtdPartition *partition;
    char *buffer;
    size_t consumed;
    int fd;
};

struct MtdWriteContext {
    const MtdPartition *partition;
    char *buffer;
    size_t stored;
    int fd;

    off_t* bad_block_offsets;
    int bad_block_alloc;
    int bad_block_count;
};

typedef struct {
    MtdPartition *partitions;
    int partitions_allocd;
    int partition_count;
} MtdState;

static MtdState g_mtd_state = {
    NULL,   // partitions
    0,      // partitions_allocd
    -1      // partition_count
};

#define MTD_PROC_FILENAME   "/proc/mtd"

int
mtd_scan_partitions()
{
    char buf[2048];
    const char *bufp;
    int fd;
    int i;
    ssize_t nbytes;

    if (g_mtd_state.partitions == NULL) {
        const int nump = 32;
        MtdPartition *partitions = malloc(nump * sizeof(*partitions));
        if (partitions == NULL) {
            errno = ENOMEM;
            return -1;
        }
        g_mtd_state.partitions = partitions;
        g_mtd_state.partitions_allocd = nump;
        memset(partitions, 0, nump * sizeof(*partitions));
    }
    g_mtd_state.partition_count = 0;

    /* Initialize all of the entries to make things easier later.
     * (Lets us handle sparsely-numbered partitions, which
     * may not even be possible.)
     */
    for (i = 0; i < g_mtd_state.partitions_allocd; i++) {
        MtdPartition *p = &g_mtd_state.partitions[i];
        if (p->name != NULL) {
            free(p->name);
            p->name = NULL;
        }
        p->device_index = -1;
    }

    /* Open and read the file contents.
     */
    fd = open(MTD_PROC_FILENAME, O_RDONLY);
    if (fd < 0) {
        goto bail;
    }
    nbytes = read(fd, buf, sizeof(buf) - 1);
    close(fd);
    if (nbytes < 0) {
        goto bail;
    }
    buf[nbytes] = '\0';

    /* Parse the contents of the file, which looks like:
     *
     *     # cat /proc/mtd
     *     dev:    size   erasesize  name
     *     mtd0: 00080000 00020000 "bootloader"
     *     mtd1: 00400000 00020000 "mfg_and_gsm"
     *     mtd2: 00400000 00020000 "0000000c"
     *     mtd3: 00200000 00020000 "0000000d"
     *     mtd4: 04000000 00020000 "system"
     *     mtd5: 03280000 00020000 "userdata"
     */
    bufp = buf;
    while (nbytes > 0) {
        int mtdnum, mtdsize, mtderasesize;
        int matches;
        char mtdname[64];
        mtdname[0] = '\0';
        mtdnum = -1;

        matches = sscanf(bufp, "mtd%d: %x %x \"%63[^\"]",
                &mtdnum, &mtdsize, &mtderasesize, mtdname);
        /* This will fail on the first line, which just contains
         * column headers.
         */
        if (matches == 4) {
            MtdPartition *p = &g_mtd_state.partitions[mtdnum];
            p->device_index = mtdnum;
            p->size = mtdsize;
            p->erase_size = mtderasesize;
            p->name = strdup(mtdname);
            if (p->name == NULL) {
                errno = ENOMEM;
                goto bail;
            }
            g_mtd_state.partition_count++;
        }

        /* Eat the line.
         */
        while (nbytes > 0 && *bufp != '\n') {
            bufp++;
            nbytes--;
        }
        if (nbytes > 0) {
            bufp++;
            nbytes--;
        }
    }

    return g_mtd_state.partition_count;

bail:
    // keep "partitions" around so we can free the names on a rescan.
    g_mtd_state.partition_count = -1;
    return -1;
}

const MtdPartition *
mtd_find_partition_by_name(const char *name)
{
    if (g_mtd_state.partitions != NULL) {
        int i;
        for (i = 0; i < g_mtd_state.partitions_allocd; i++) {
            MtdPartition *p = &g_mtd_state.partitions[i];
            if (p->device_index >= 0 && p->name != NULL) {
                if (strcmp(p->name, name) == 0) {
                    return p;
                }
            }
        }
    }
    return NULL;
}

int
mtd_mount_partition(const MtdPartition *partition, const char *mount_point,
        const char *filesystem, int read_only)
{
    const unsigned long flags = MS_NOATIME | MS_NODEV | MS_NODIRATIME;
    char devname[64];
    int rv = -1;

    sprintf(devname, "/dev/block/mtdblock%d", partition->device_index);
    if (!read_only) {
        rv = mount(devname, mount_point, filesystem, flags, NULL);
    }
    if (read_only || rv < 0) {
        rv = mount(devname, mount_point, filesystem, flags | MS_RDONLY, 0);
        if (rv < 0) {
            printf("Failed to mount %s on %s: %s\n",
                    devname, mount_point, strerror(errno));
        } else {
            printf("Mount %s on %s read-only\n", devname, mount_point);
        }
    }
#if 1   //TODO: figure out why this is happening; remove include of stat.h
    if (rv >= 0) {
        /* For some reason, the x bits sometimes aren't set on the root
         * of mounted volumes.
         */
        struct stat st;
        rv = stat(mount_point, &st);
        if (rv < 0) {
            return rv;
        }
        mode_t new_mode = st.st_mode | S_IXUSR | S_IXGRP | S_IXOTH;
        if (new_mode != st.st_mode) {
printf("Fixing execute permissions for %s\n", mount_point);
            rv = chmod(mount_point, new_mode);
            if (rv < 0) {
                printf("Couldn't fix permissions for %s: %s\n",
                        mount_point, strerror(errno));
            }
        }
    }
#endif
    return rv;
}

int
mtd_partition_info(const MtdPartition *partition,
        size_t *total_size, size_t *erase_size, size_t *write_size)
{
    char mtddevname[32];
    sprintf(mtddevname, "/dev/mtd/mtd%d", partition->device_index);
    int fd = open(mtddevname, O_RDONLY);
    if (fd < 0) return -1;

    struct mtd_info_user mtd_info;
    int ret = ioctl(fd, MEMGETINFO, &mtd_info);
    close(fd);
    if (ret < 0) return -1;

    if (total_size != NULL) *total_size = mtd_info.size;
    if (erase_size != NULL) *erase_size = mtd_info.erasesize;
    if (write_size != NULL) *write_size = mtd_info.writesize;
    return 0;
}

MtdReadContext *mtd_read_partition(const MtdPartition *partition)
{
    MtdReadContext *ctx = (MtdReadContext*) malloc(sizeof(MtdReadContext));
    if (ctx == NULL) return NULL;

    ctx->buffer = malloc(partition->erase_size);
    if (ctx->buffer == NULL) {
        free(ctx);
        return NULL;
    }

    char mtddevname[32];
    sprintf(mtddevname, "/dev/mtd/mtd%d", partition->device_index);
    ctx->fd = open(mtddevname, O_RDONLY);
    if (ctx->fd < 0) {
        free(ctx);
        free(ctx->buffer);
        return NULL;
    }

    ctx->partition = partition;
    ctx->consumed = partition->erase_size;
    return ctx;
}

static int read_block(const MtdPartition *partition, int fd, char *data)
{
    struct mtd_ecc_stats before, after;
    if (ioctl(fd, ECCGETSTATS, &before)) {
        fprintf(stderr, "mtd: ECCGETSTATS error (%s)\n", strerror(errno));
        return -1;
    }

    loff_t pos = lseek64(fd, 0, SEEK_CUR);

    ssize_t size = partition->erase_size;
    int mgbb;

    while (pos + size <= (int) partition->size) {
        if (lseek64(fd, pos, SEEK_SET) != pos || read(fd, data, size) != size) {
            fprintf(stderr, "mtd: read error at 0x%08llx (%s)\n",
                    pos, strerror(errno));
        } else if (ioctl(fd, ECCGETSTATS, &after)) {
            fprintf(stderr, "mtd: ECCGETSTATS error (%s)\n", strerror(errno));
            return -1;
        } else if (after.failed != before.failed) {
            fprintf(stderr, "mtd: ECC errors (%d soft, %d hard) at 0x%08llx\n",
                    after.corrected - before.corrected,
                    after.failed - before.failed, pos);
        } else if ((mgbb = ioctl(fd, MEMGETBADBLOCK, &pos))) {
            fprintf(stderr,
                    "mtd: MEMGETBADBLOCK returned %d at 0x%08llx (errno=%d)\n",
                    mgbb, pos, errno);
        } else {
            int i;
            for (i = 0; i < size; ++i) {
                if (data[i] != 0) {
                    return 0;  // Success!
                }
            }
            fprintf(stderr, "mtd: read all-zero block at 0x%08llx; skipping\n",
                    pos);
        }

        pos += partition->erase_size;
    }

    errno = ENOSPC;
    return -1;
}

ssize_t mtd_read_data(MtdReadContext *ctx, char *data, size_t len)
{
    ssize_t read = 0;
    while (read < (int) len) {
        if (ctx->consumed < ctx->partition->erase_size) {
            size_t avail = ctx->partition->erase_size - ctx->consumed;
            size_t copy = len - read < avail ? len - read : avail;
            memcpy(data + read, ctx->buffer + ctx->consumed, copy);
            ctx->consumed += copy;
            read += copy;
        }

        // Read complete blocks directly into the user's buffer
        while (ctx->consumed == ctx->partition->erase_size &&
               len - read >= ctx->partition->erase_size) {
            if (read_block(ctx->partition, ctx->fd, data + read)) return -1;
            read += ctx->partition->erase_size;
        }

        if (read >= len) {
            return read;
        }

        // Read the next block into the buffer
        if (ctx->consumed == ctx->partition->erase_size && read < (int) len) {
            if (read_block(ctx->partition, ctx->fd, ctx->buffer)) return -1;
            ctx->consumed = 0;
        }
    }

    return read;
}

void mtd_read_close(MtdReadContext *ctx)
{
    close(ctx->fd);
    free(ctx->buffer);
    free(ctx);
}

MtdWriteContext *mtd_write_partition(const MtdPartition *partition)
{
    MtdWriteContext *ctx = (MtdWriteContext*) malloc(sizeof(MtdWriteContext));
    if (ctx == NULL) return NULL;

    ctx->bad_block_offsets = NULL;
    ctx->bad_block_alloc = 0;
    ctx->bad_block_count = 0;

    ctx->buffer = malloc(partition->erase_size);
    if (ctx->buffer == NULL) {
        free(ctx);
        return NULL;
    }

    char mtddevname[32];
    sprintf(mtddevname, "/dev/mtd/mtd%d", partition->device_index);
    ctx->fd = open(mtddevname, O_RDWR);
    if (ctx->fd < 0) {
        free(ctx->buffer);
        free(ctx);
        return NULL;
    }

    ctx->partition = partition;
    ctx->stored = 0;
    return ctx;
}

static void add_bad_block_offset(MtdWriteContext *ctx, off_t pos) {
    if (ctx->bad_block_count + 1 > ctx->bad_block_alloc) {
        ctx->bad_block_alloc = (ctx->bad_block_alloc*2) + 1;
        ctx->bad_block_offsets = realloc(ctx->bad_block_offsets,
                                         ctx->bad_block_alloc * sizeof(off_t));
    }
    ctx->bad_block_offsets[ctx->bad_block_count++] = pos;
}

static int write_block(MtdWriteContext *ctx, const char *data)
{
    const MtdPartition *partition = ctx->partition;
    int fd = ctx->fd;

    off_t pos = lseek(fd, 0, SEEK_CUR);
    if (pos == (off_t) -1) return 1;

    ssize_t size = partition->erase_size;
    while (pos + size <= (int) partition->size) {
        loff_t bpos = pos;
        int ret = ioctl(fd, MEMGETBADBLOCK, &bpos);
        if (ret != 0 && !(ret == -1 && errno == EOPNOTSUPP)) {
            add_bad_block_offset(ctx, pos);
            fprintf(stderr,
                    "mtd: not writing bad block at 0x%08lx (ret %d errno %d)\n",
                    pos, ret, errno);
            pos += partition->erase_size;
            continue;  // Don't try to erase known factory-bad blocks.
        }

        struct erase_info_user erase_info;
        erase_info.start = pos;
        erase_info.length = size;
        int retry;
        for (retry = 0; retry < 2; ++retry) {
            if (ioctl(fd, MEMERASE, &erase_info) < 0) {
                fprintf(stderr, "mtd: erase failure at 0x%08lx (%s)\n",
                        pos, strerror(errno));
                continue;
            }
            if (lseek(fd, pos, SEEK_SET) != pos ||
                write(fd, data, size) != size) {
                fprintf(stderr, "mtd: write error at 0x%08lx (%s)\n",
                        pos, strerror(errno));
            }

            char verify[size];
            if (lseek(fd, pos, SEEK_SET) != pos ||
                read(fd, verify, size) != size) {
                fprintf(stderr, "mtd: re-read error at 0x%08lx (%s)\n",
                        pos, strerror(errno));
                continue;
            }
            if (memcmp(data, verify, size) != 0) {
                fprintf(stderr, "mtd: verification error at 0x%08lx (%s)\n",
                        pos, strerror(errno));
                continue;
            }

            if (retry > 0) {
                fprintf(stderr, "mtd: wrote block after %d retries\n", retry);
            }
            return 0;  // Success!
        }

        // Try to erase it once more as we give up on this block
        add_bad_block_offset(ctx, pos);
        fprintf(stderr, "mtd: skipping write block at 0x%08lx\n", pos);
        ioctl(fd, MEMERASE, &erase_info);
        pos += partition->erase_size;
    }

    // Ran out of space on the device
    errno = ENOSPC;
    return -1;
}

ssize_t mtd_write_data(MtdWriteContext *ctx, const char *data, size_t len)
{
    size_t wrote = 0;
    while (wrote < len) {
        // Coalesce partial writes into complete blocks
        if (ctx->stored > 0 || len - wrote < ctx->partition->erase_size) {
            size_t avail = ctx->partition->erase_size - ctx->stored;
            size_t copy = len - wrote < avail ? len - wrote : avail;
            memcpy(ctx->buffer + ctx->stored, data + wrote, copy);
            ctx->stored += copy;
            wrote += copy;
        }

        // If a complete block was accumulated, write it
        if (ctx->stored == ctx->partition->erase_size) {
            if (write_block(ctx, ctx->buffer)) return -1;
            ctx->stored = 0;
        }

        // Write complete blocks directly from the user's buffer
        while (ctx->stored == 0 && len - wrote >= ctx->partition->erase_size) {
            if (write_block(ctx, data + wrote)) return -1;
            wrote += ctx->partition->erase_size;
        }
    }

    return wrote;
}

off_t mtd_erase_blocks(MtdWriteContext *ctx, int blocks)
{
    // Zero-pad and write any pending data to get us to a block boundary
    if (ctx->stored > 0) {
        size_t zero = ctx->partition->erase_size - ctx->stored;
        memset(ctx->buffer + ctx->stored, 0, zero);
        if (write_block(ctx, ctx->buffer)) return -1;
        ctx->stored = 0;
    }

    off_t pos = lseek(ctx->fd, 0, SEEK_CUR);
    if ((off_t) pos == (off_t) -1) return pos;

    const int total = (ctx->partition->size - pos) / ctx->partition->erase_size;
    if (blocks < 0) blocks = total;
    if (blocks > total) {
        errno = ENOSPC;
        return -1;
    }

    // Erase the specified number of blocks
    while (blocks-- > 0) {
        loff_t bpos = pos;
        if (ioctl(ctx->fd, MEMGETBADBLOCK, &bpos) > 0) {
            fprintf(stderr, "mtd: not erasing bad block at 0x%08lx\n", pos);
            pos += ctx->partition->erase_size;
            continue;  // Don't try to erase known factory-bad blocks.
        }

        struct erase_info_user erase_info;
        erase_info.start = pos;
        erase_info.length = ctx->partition->erase_size;
        if (ioctl(ctx->fd, MEMERASE, &erase_info) < 0) {
            fprintf(stderr, "mtd: erase failure at 0x%08lx\n", pos);
        }
        pos += ctx->partition->erase_size;
    }

    return pos;
}

int mtd_write_close(MtdWriteContext *ctx)
{
    int r = 0;
    // Make sure any pending data gets written
    if (mtd_erase_blocks(ctx, 0) == (off_t) -1) r = -1;
    if (close(ctx->fd)) r = -1;
    free(ctx->bad_block_offsets);
    free(ctx->buffer);
    free(ctx);
    return r;
}

/* Return the offset of the first good block at or after pos (which
 * might be pos itself).
 */
off_t mtd_find_write_start(MtdWriteContext *ctx, off_t pos) {
    int i;
    for (i = 0; i < ctx->bad_block_count; ++i) {
        if (ctx->bad_block_offsets[i] == pos) {
            pos += ctx->partition->erase_size;
        } else if (ctx->bad_block_offsets[i] > pos) {
            return pos;
        }
    }
    return pos;
}