summaryrefslogtreecommitdiffstats
path: root/updater/blockimg.c
blob: 555230dd3c7095f3522af4c0910351f94321229b (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
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
/*
 * Copyright (C) 2014 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 <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <pthread.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <time.h>
#include <unistd.h>

#include "applypatch/applypatch.h"
#include "edify/expr.h"
#include "mincrypt/sha.h"
#include "minzip/DirUtil.h"
#include "updater.h"

#define BLOCKSIZE 4096

// Set this to 0 to interpret 'erase' transfers to mean do a
// BLKDISCARD ioctl (the normal behavior).  Set to 1 to interpret
// erase to mean fill the region with zeroes.
#define DEBUG_ERASE  0

#ifndef BLKDISCARD
#define BLKDISCARD _IO(0x12,119)
#endif

char* PrintSha1(const uint8_t* digest);

typedef struct {
    int count;
    int size;
    int pos[0];
} RangeSet;

static RangeSet* parse_range(char* text) {
    char* save;
    int num;
    num = strtol(strtok_r(text, ",", &save), NULL, 0);

    RangeSet* out = malloc(sizeof(RangeSet) + num * sizeof(int));
    if (out == NULL) {
        fprintf(stderr, "failed to allocate range of %lu bytes\n",
                sizeof(RangeSet) + num * sizeof(int));
        exit(1);
    }
    out->count = num / 2;
    out->size = 0;
    int i;
    for (i = 0; i < num; ++i) {
        out->pos[i] = strtol(strtok_r(NULL, ",", &save), NULL, 0);
        if (i%2) {
            out->size += out->pos[i];
        } else {
            out->size -= out->pos[i];
        }
    }

    return out;
}

static void readblock(int fd, uint8_t* data, size_t size) {
    size_t so_far = 0;
    while (so_far < size) {
        ssize_t r = read(fd, data+so_far, size-so_far);
        if (r < 0 && errno != EINTR) {
            fprintf(stderr, "read failed: %s\n", strerror(errno));
            return;
        } else {
            so_far += r;
        }
    }
}

static void writeblock(int fd, const uint8_t* data, size_t size) {
    size_t written = 0;
    while (written < size) {
        ssize_t w = write(fd, data+written, size-written);
        if (w < 0 && errno != EINTR) {
            fprintf(stderr, "write failed: %s\n", strerror(errno));
            return;
        } else {
            written += w;
        }
    }
}

static void check_lseek(int fd, off_t offset, int whence) {
    while (true) {
        off_t ret = lseek(fd, offset, whence);
        if (ret < 0) {
            if (errno != EINTR) {
                fprintf(stderr, "lseek failed: %s\n", strerror(errno));
                exit(1);
            }
        } else {
            break;
        }
    }
}

static void allocate(size_t size, uint8_t** buffer, size_t* buffer_alloc) {
    // if the buffer's big enough, reuse it.
    if (size <= *buffer_alloc) return;

    free(*buffer);

    *buffer = (uint8_t*) malloc(size);
    if (*buffer == NULL) {
        fprintf(stderr, "failed to allocate %zu bytes\n", size);
        exit(1);
    }
    *buffer_alloc = size;
}

typedef struct {
    int fd;
    RangeSet* tgt;
    int p_block;
    size_t p_remain;
} RangeSinkState;

static ssize_t RangeSinkWrite(const uint8_t* data, ssize_t size, void* token) {
    RangeSinkState* rss = (RangeSinkState*) token;

    if (rss->p_remain <= 0) {
        fprintf(stderr, "range sink write overrun");
        exit(1);
    }

    ssize_t written = 0;
    while (size > 0) {
        size_t write_now = size;
        if (rss->p_remain < write_now) write_now = rss->p_remain;
        writeblock(rss->fd, data, write_now);
        data += write_now;
        size -= write_now;

        rss->p_remain -= write_now;
        written += write_now;

        if (rss->p_remain == 0) {
            // move to the next block
            ++rss->p_block;
            if (rss->p_block < rss->tgt->count) {
                rss->p_remain = (rss->tgt->pos[rss->p_block*2+1] - rss->tgt->pos[rss->p_block*2]) * BLOCKSIZE;
                check_lseek(rss->fd, rss->tgt->pos[rss->p_block*2] * (off_t)BLOCKSIZE, SEEK_SET);
            } else {
                // we can't write any more; return how many bytes have
                // been written so far.
                return written;
            }
        }
    }

    return written;
}

// All of the data for all the 'new' transfers is contained in one
// file in the update package, concatenated together in the order in
// which transfers.list will need it.  We want to stream it out of the
// archive (it's compressed) without writing it to a temp file, but we
// can't write each section until it's that transfer's turn to go.
//
// To achieve this, we expand the new data from the archive in a
// background thread, and block that threads 'receive uncompressed
// data' function until the main thread has reached a point where we
// want some new data to be written.  We signal the background thread
// with the destination for the data and block the main thread,
// waiting for the background thread to complete writing that section.
// Then it signals the main thread to wake up and goes back to
// blocking waiting for a transfer.
//
// NewThreadInfo is the struct used to pass information back and forth
// between the two threads.  When the main thread wants some data
// written, it sets rss to the destination location and signals the
// condition.  When the background thread is done writing, it clears
// rss and signals the condition again.

typedef struct {
    ZipArchive* za;
    const ZipEntry* entry;

    RangeSinkState* rss;

    pthread_mutex_t mu;
    pthread_cond_t cv;
} NewThreadInfo;

static bool receive_new_data(const unsigned char* data, int size, void* cookie) {
    NewThreadInfo* nti = (NewThreadInfo*) cookie;

    while (size > 0) {
        // Wait for nti->rss to be non-NULL, indicating some of this
        // data is wanted.
        pthread_mutex_lock(&nti->mu);
        while (nti->rss == NULL) {
            pthread_cond_wait(&nti->cv, &nti->mu);
        }
        pthread_mutex_unlock(&nti->mu);

        // At this point nti->rss is set, and we own it.  The main
        // thread is waiting for it to disappear from nti.
        ssize_t written = RangeSinkWrite(data, size, nti->rss);
        data += written;
        size -= written;

        if (nti->rss->p_block == nti->rss->tgt->count) {
            // we have written all the bytes desired by this rss.

            pthread_mutex_lock(&nti->mu);
            nti->rss = NULL;
            pthread_cond_broadcast(&nti->cv);
            pthread_mutex_unlock(&nti->mu);
        }
    }

    return true;
}

static void* unzip_new_data(void* cookie) {
    NewThreadInfo* nti = (NewThreadInfo*) cookie;
    mzProcessZipEntryContents(nti->za, nti->entry, receive_new_data, nti);
    return NULL;
}

// args:
//    - block device (or file) to modify in-place
//    - transfer list (blob)
//    - new data stream (filename within package.zip)
//    - patch stream (filename within package.zip, must be uncompressed)

Value* BlockImageUpdateFn(const char* name, State* state, int argc, Expr* argv[]) {
    Value* blockdev_filename;
    Value* transfer_list_value;
    char* transfer_list = NULL;
    Value* new_data_fn;
    Value* patch_data_fn;
    bool success = false;

    if (ReadValueArgs(state, argv, 4, &blockdev_filename, &transfer_list_value,
                      &new_data_fn, &patch_data_fn) < 0) {
        return NULL;
    }

    if (blockdev_filename->type != VAL_STRING) {
        ErrorAbort(state, "blockdev_filename argument to %s must be string", name);
        goto done;
    }
    if (transfer_list_value->type != VAL_BLOB) {
        ErrorAbort(state, "transfer_list argument to %s must be blob", name);
        goto done;
    }
    if (new_data_fn->type != VAL_STRING) {
        ErrorAbort(state, "new_data_fn argument to %s must be string", name);
        goto done;
    }
    if (patch_data_fn->type != VAL_STRING) {
        ErrorAbort(state, "patch_data_fn argument to %s must be string", name);
        goto done;
    }

    UpdaterInfo* ui = (UpdaterInfo*)(state->cookie);
    FILE* cmd_pipe = ui->cmd_pipe;

    ZipArchive* za = ((UpdaterInfo*)(state->cookie))->package_zip;

    const ZipEntry* patch_entry = mzFindZipEntry(za, patch_data_fn->data);
    if (patch_entry == NULL) {
        ErrorAbort(state, "%s(): no file \"%s\" in package", name, patch_data_fn->data);
        goto done;
    }

    uint8_t* patch_start = ((UpdaterInfo*)(state->cookie))->package_zip_addr +
        mzGetZipEntryOffset(patch_entry);

    const ZipEntry* new_entry = mzFindZipEntry(za, new_data_fn->data);
    if (new_entry == NULL) {
        ErrorAbort(state, "%s(): no file \"%s\" in package", name, new_data_fn->data);
        goto done;
    }

    // The transfer list is a text file containing commands to
    // transfer data from one place to another on the target
    // partition.  We parse it and execute the commands in order:
    //
    //    zero [rangeset]
    //      - fill the indicated blocks with zeros
    //
    //    new [rangeset]
    //      - fill the blocks with data read from the new_data file
    //
    //    bsdiff patchstart patchlen [src rangeset] [tgt rangeset]
    //    imgdiff patchstart patchlen [src rangeset] [tgt rangeset]
    //      - read the source blocks, apply a patch, write result to
    //        target blocks.  bsdiff or imgdiff specifies the type of
    //        patch.
    //
    //    move [src rangeset] [tgt rangeset]
    //      - copy data from source blocks to target blocks (no patch
    //        needed; rangesets are the same size)
    //
    //    erase [rangeset]
    //      - mark the given blocks as empty
    //
    // The creator of the transfer list will guarantee that no block
    // is read (ie, used as the source for a patch or move) after it
    // has been written.
    //
    // Within one command the source and target ranges may overlap so
    // in general we need to read the entire source into memory before
    // writing anything to the target blocks.
    //
    // All the patch data is concatenated into one patch_data file in
    // the update package.  It must be stored uncompressed because we
    // memory-map it in directly from the archive.  (Since patches are
    // already compressed, we lose very little by not compressing
    // their concatenation.)

    pthread_t new_data_thread;
    NewThreadInfo nti;
    nti.za = za;
    nti.entry = new_entry;
    nti.rss = NULL;
    pthread_mutex_init(&nti.mu, NULL);
    pthread_cond_init(&nti.cv, NULL);

    pthread_attr_t attr;
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    pthread_create(&new_data_thread, &attr, unzip_new_data, &nti);

    int i, j;

    char* linesave;
    char* wordsave;

    int fd = open(blockdev_filename->data, O_RDWR);
    if (fd < 0) {
        ErrorAbort(state, "failed to open %s: %s", blockdev_filename->data, strerror(errno));
        goto done;
    }

    char* line;
    char* word;

    // The data in transfer_list_value is not necessarily
    // null-terminated, so we need to copy it to a new buffer and add
    // the null that strtok_r will need.
    transfer_list = malloc(transfer_list_value->size+1);
    if (transfer_list == NULL) {
        fprintf(stderr, "failed to allocate %zd bytes for transfer list\n",
                transfer_list_value->size+1);
        exit(1);
    }
    memcpy(transfer_list, transfer_list_value->data, transfer_list_value->size);
    transfer_list[transfer_list_value->size] = '\0';

    line = strtok_r(transfer_list, "\n", &linesave);

    // first line in transfer list is the version number; currently
    // there's only version 1.
    if (strcmp(line, "1") != 0) {
        ErrorAbort(state, "unexpected transfer list version [%s]\n", line);
        goto done;
    }

    // second line in transfer list is the total number of blocks we
    // expect to write.
    line = strtok_r(NULL, "\n", &linesave);
    int total_blocks = strtol(line, NULL, 0);
    // shouldn't happen, but avoid divide by zero.
    if (total_blocks == 0) ++total_blocks;
    int blocks_so_far = 0;

    uint8_t* buffer = NULL;
    size_t buffer_alloc = 0;

    // third and subsequent lines are all individual transfer commands.
    for (line = strtok_r(NULL, "\n", &linesave); line;
         line = strtok_r(NULL, "\n", &linesave)) {
        char* style;
        style = strtok_r(line, " ", &wordsave);

        if (strcmp("move", style) == 0) {
            word = strtok_r(NULL, " ", &wordsave);
            RangeSet* src = parse_range(word);
            word = strtok_r(NULL, " ", &wordsave);
            RangeSet* tgt = parse_range(word);

            printf("  moving %d blocks\n", src->size);

            allocate(src->size * BLOCKSIZE, &buffer, &buffer_alloc);
            size_t p = 0;
            for (i = 0; i < src->count; ++i) {
                check_lseek(fd, src->pos[i*2] * (off_t)BLOCKSIZE, SEEK_SET);
                size_t sz = (src->pos[i*2+1] - src->pos[i*2]) * BLOCKSIZE;
                readblock(fd, buffer+p, sz);
                p += sz;
            }

            p = 0;
            for (i = 0; i < tgt->count; ++i) {
                check_lseek(fd, tgt->pos[i*2] * (off_t)BLOCKSIZE, SEEK_SET);
                size_t sz = (tgt->pos[i*2+1] - tgt->pos[i*2]) * BLOCKSIZE;
                writeblock(fd, buffer+p, sz);
                p += sz;
            }

            blocks_so_far += tgt->size;
            fprintf(cmd_pipe, "set_progress %.4f\n", (double)blocks_so_far / total_blocks);
            fflush(cmd_pipe);

            free(src);
            free(tgt);

        } else if (strcmp("zero", style) == 0 ||
                   (DEBUG_ERASE && strcmp("erase", style) == 0)) {
            word = strtok_r(NULL, " ", &wordsave);
            RangeSet* tgt = parse_range(word);

            printf("  zeroing %d blocks\n", tgt->size);

            allocate(BLOCKSIZE, &buffer, &buffer_alloc);
            memset(buffer, 0, BLOCKSIZE);
            for (i = 0; i < tgt->count; ++i) {
                check_lseek(fd, tgt->pos[i*2] * (off_t)BLOCKSIZE, SEEK_SET);
                for (j = tgt->pos[i*2]; j < tgt->pos[i*2+1]; ++j) {
                    writeblock(fd, buffer, BLOCKSIZE);
                }
            }

            if (style[0] == 'z') {   // "zero" but not "erase"
                blocks_so_far += tgt->size;
                fprintf(cmd_pipe, "set_progress %.4f\n", (double)blocks_so_far / total_blocks);
                fflush(cmd_pipe);
            }

            free(tgt);
        } else if (strcmp("new", style) == 0) {

            word = strtok_r(NULL, " ", &wordsave);
            RangeSet* tgt = parse_range(word);

            printf("  writing %d blocks of new data\n", tgt->size);

            RangeSinkState rss;
            rss.fd = fd;
            rss.tgt = tgt;
            rss.p_block = 0;
            rss.p_remain = (tgt->pos[1] - tgt->pos[0]) * BLOCKSIZE;
            check_lseek(fd, tgt->pos[0] * (off_t)BLOCKSIZE, SEEK_SET);

            pthread_mutex_lock(&nti.mu);
            nti.rss = &rss;
            pthread_cond_broadcast(&nti.cv);
            while (nti.rss) {
                pthread_cond_wait(&nti.cv, &nti.mu);
            }
            pthread_mutex_unlock(&nti.mu);

            blocks_so_far += tgt->size;
            fprintf(cmd_pipe, "set_progress %.4f\n", (double)blocks_so_far / total_blocks);
            fflush(cmd_pipe);

            free(tgt);

        } else if (strcmp("bsdiff", style) == 0 ||
                   strcmp("imgdiff", style) == 0) {
            word = strtok_r(NULL, " ", &wordsave);
            size_t patch_offset = strtoul(word, NULL, 0);
            word = strtok_r(NULL, " ", &wordsave);
            size_t patch_len = strtoul(word, NULL, 0);

            word = strtok_r(NULL, " ", &wordsave);
            RangeSet* src = parse_range(word);
            word = strtok_r(NULL, " ", &wordsave);
            RangeSet* tgt = parse_range(word);

            printf("  patching %d blocks to %d\n", src->size, tgt->size);

            // Read the source into memory.
            allocate(src->size * BLOCKSIZE, &buffer, &buffer_alloc);
            size_t p = 0;
            for (i = 0; i < src->count; ++i) {
                check_lseek(fd, src->pos[i*2] * (off_t)BLOCKSIZE, SEEK_SET);
                size_t sz = (src->pos[i*2+1] - src->pos[i*2]) * BLOCKSIZE;
                readblock(fd, buffer+p, sz);
                p += sz;
            }

            Value patch_value;
            patch_value.type = VAL_BLOB;
            patch_value.size = patch_len;
            patch_value.data = (char*)(patch_start + patch_offset);

            RangeSinkState rss;
            rss.fd = fd;
            rss.tgt = tgt;
            rss.p_block = 0;
            rss.p_remain = (tgt->pos[1] - tgt->pos[0]) * BLOCKSIZE;
            check_lseek(fd, tgt->pos[0] * (off_t)BLOCKSIZE, SEEK_SET);

            if (style[0] == 'i') {      // imgdiff
                ApplyImagePatch(buffer, src->size * BLOCKSIZE,
                                &patch_value,
                                &RangeSinkWrite, &rss, NULL, NULL);
            } else {
                ApplyBSDiffPatch(buffer, src->size * BLOCKSIZE,
                                 &patch_value, 0,
                                 &RangeSinkWrite, &rss, NULL);
            }

            // We expect the output of the patcher to fill the tgt ranges exactly.
            if (rss.p_block != tgt->count || rss.p_remain != 0) {
                fprintf(stderr, "range sink underrun?\n");
            }

            blocks_so_far += tgt->size;
            fprintf(cmd_pipe, "set_progress %.4f\n", (double)blocks_so_far / total_blocks);
            fflush(cmd_pipe);

            free(src);
            free(tgt);
        } else if (!DEBUG_ERASE && strcmp("erase", style) == 0) {
            struct stat st;
            if (fstat(fd, &st) == 0 && S_ISBLK(st.st_mode)) {
                word = strtok_r(NULL, " ", &wordsave);
                RangeSet* tgt = parse_range(word);

                printf("  erasing %d blocks\n", tgt->size);

                for (i = 0; i < tgt->count; ++i) {
                    uint64_t range[2];
                    // offset in bytes
                    range[0] = tgt->pos[i*2] * (uint64_t)BLOCKSIZE;
                    // len in bytes
                    range[1] = (tgt->pos[i*2+1] - tgt->pos[i*2]) * (uint64_t)BLOCKSIZE;

                    if (ioctl(fd, BLKDISCARD, &range) < 0) {
                        printf("    blkdiscard failed: %s\n", strerror(errno));
                    }
                }

                free(tgt);
            } else {
                printf("  ignoring erase (not block device)\n");
            }
        } else {
            fprintf(stderr, "unknown transfer style \"%s\"\n", style);
            exit(1);
        }
    }

    pthread_join(new_data_thread, NULL);
    success = true;

    free(buffer);
    printf("wrote %d blocks; expected %d\n", blocks_so_far, total_blocks);
    printf("max alloc needed was %zu\n", buffer_alloc);

  done:
    free(transfer_list);
    FreeValue(blockdev_filename);
    FreeValue(transfer_list_value);
    FreeValue(new_data_fn);
    FreeValue(patch_data_fn);
    return StringValue(success ? strdup("t") : strdup(""));
}

Value* RangeSha1Fn(const char* name, State* state, int argc, Expr* argv[]) {
    Value* blockdev_filename;
    Value* ranges;
    const uint8_t* digest = NULL;
    if (ReadValueArgs(state, argv, 2, &blockdev_filename, &ranges) < 0) {
        return NULL;
    }

    if (blockdev_filename->type != VAL_STRING) {
        ErrorAbort(state, "blockdev_filename argument to %s must be string", name);
        goto done;
    }
    if (ranges->type != VAL_STRING) {
        ErrorAbort(state, "ranges argument to %s must be string", name);
        goto done;
    }

    int fd = open(blockdev_filename->data, O_RDWR);
    if (fd < 0) {
        ErrorAbort(state, "failed to open %s: %s", blockdev_filename->data, strerror(errno));
        goto done;
    }

    RangeSet* rs = parse_range(ranges->data);
    uint8_t buffer[BLOCKSIZE];

    SHA_CTX ctx;
    SHA_init(&ctx);

    int i, j;
    for (i = 0; i < rs->count; ++i) {
        check_lseek(fd, rs->pos[i*2] * (off_t)BLOCKSIZE, SEEK_SET);
        for (j = rs->pos[i*2]; j < rs->pos[i*2+1]; ++j) {
            readblock(fd, buffer, BLOCKSIZE);
            SHA_update(&ctx, buffer, BLOCKSIZE);
        }
    }
    digest = SHA_final(&ctx);
    close(fd);

  done:
    FreeValue(blockdev_filename);
    FreeValue(ranges);
    if (digest == NULL) {
        return StringValue(strdup(""));
    } else {
        return StringValue(PrintSha1(digest));
    }
}

void RegisterBlockImageFunctions() {
    RegisterFunction("block_image_update", BlockImageUpdateFn);
    RegisterFunction("range_sha1", RangeSha1Fn);
}