648db22b |
1 | /* |
2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
3 | * All rights reserved. |
4 | * |
5 | * This source code is licensed under both the BSD-style license (found in the |
6 | * LICENSE file in the root directory of this source tree) and the GPLv2 (found |
7 | * in the COPYING file in the root directory of this source tree). |
8 | * You may select, at your option, one of the above-listed licenses. |
9 | */ |
10 | |
11 | /* ********************************************************* |
12 | * Turn on Large Files support (>4GB) for 32-bit Linux/Unix |
13 | ***********************************************************/ |
14 | #if !defined(__64BIT__) || defined(__MINGW32__) /* No point defining Large file for 64 bit but MinGW-w64 requires it */ |
15 | # if !defined(_FILE_OFFSET_BITS) |
16 | # define _FILE_OFFSET_BITS 64 /* turn off_t into a 64-bit type for ftello, fseeko */ |
17 | # endif |
18 | # if !defined(_LARGEFILE_SOURCE) /* obsolete macro, replaced with _FILE_OFFSET_BITS */ |
19 | # define _LARGEFILE_SOURCE 1 /* Large File Support extension (LFS) - fseeko, ftello */ |
20 | # endif |
21 | # if defined(_AIX) || defined(__hpux) |
22 | # define _LARGE_FILES /* Large file support on 32-bits AIX and HP-UX */ |
23 | # endif |
24 | #endif |
25 | |
26 | /* ************************************************************ |
27 | * Detect POSIX version |
28 | * PLATFORM_POSIX_VERSION = 0 for non-Unix e.g. Windows |
29 | * PLATFORM_POSIX_VERSION = 1 for Unix-like but non-POSIX |
30 | * PLATFORM_POSIX_VERSION > 1 is equal to found _POSIX_VERSION |
31 | * Value of PLATFORM_POSIX_VERSION can be forced on command line |
32 | ***************************************************************/ |
33 | #ifndef PLATFORM_POSIX_VERSION |
34 | |
35 | # if (defined(__APPLE__) && defined(__MACH__)) || defined(__SVR4) || defined(_AIX) || defined(__hpux) /* POSIX.1-2001 (SUSv3) conformant */ \ |
36 | || defined(__DragonFly__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) /* BSD distros */ |
37 | /* exception rule : force posix version to 200112L, |
38 | * note: it's better to use unistd.h's _POSIX_VERSION whenever possible */ |
39 | # define PLATFORM_POSIX_VERSION 200112L |
40 | |
41 | /* try to determine posix version through official unistd.h's _POSIX_VERSION (https://pubs.opengroup.org/onlinepubs/7908799/xsh/unistd.h.html). |
42 | * note : there is no simple way to know in advance if <unistd.h> is present or not on target system, |
43 | * Posix specification mandates its presence and its content, but target system must respect this spec. |
44 | * It's necessary to _not_ #include <unistd.h> whenever target OS is not unix-like |
45 | * otherwise it will block preprocessing stage. |
46 | * The following list of build macros tries to "guess" if target OS is likely unix-like, and therefore can #include <unistd.h> |
47 | */ |
48 | # elif !defined(_WIN32) \ |
49 | && ( defined(__unix__) || defined(__unix) \ |
50 | || defined(__midipix__) || defined(__VMS) || defined(__HAIKU__) ) |
51 | |
52 | # if defined(__linux__) || defined(__linux) || defined(__CYGWIN__) |
53 | # ifndef _POSIX_C_SOURCE |
54 | # define _POSIX_C_SOURCE 200809L /* feature test macro : https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html */ |
55 | # endif |
56 | # endif |
57 | # include <unistd.h> /* declares _POSIX_VERSION */ |
58 | # if defined(_POSIX_VERSION) /* POSIX compliant */ |
59 | # define PLATFORM_POSIX_VERSION _POSIX_VERSION |
60 | # else |
61 | # define PLATFORM_POSIX_VERSION 1 |
62 | # endif |
63 | |
64 | # ifdef __UCLIBC__ |
65 | # ifndef __USE_MISC |
66 | # define __USE_MISC /* enable st_mtim on uclibc */ |
67 | # endif |
68 | # endif |
69 | |
70 | # else /* non-unix target platform (like Windows) */ |
71 | # define PLATFORM_POSIX_VERSION 0 |
72 | # endif |
73 | |
74 | #endif /* PLATFORM_POSIX_VERSION */ |
75 | |
76 | |
77 | /* ************************************************************ |
78 | * Avoid fseek()'s 2GiB barrier with MSVC, macOS, *BSD, MinGW |
79 | ***************************************************************/ |
80 | #if defined(_MSC_VER) && _MSC_VER >= 1400 |
81 | # define LONG_SEEK _fseeki64 |
82 | #elif !defined(__64BIT__) && (PLATFORM_POSIX_VERSION >= 200112L) /* No point defining Large file for 64 bit */ |
83 | # define LONG_SEEK fseeko |
84 | #elif defined(__MINGW32__) && !defined(__STRICT_ANSI__) && !defined(__NO_MINGW_LFS) && defined(__MSVCRT__) |
85 | # define LONG_SEEK fseeko64 |
86 | #elif defined(_WIN32) && !defined(__DJGPP__) |
87 | # include <windows.h> |
88 | static int LONG_SEEK(FILE* file, __int64 offset, int origin) { |
89 | LARGE_INTEGER off; |
90 | DWORD method; |
91 | off.QuadPart = offset; |
92 | if (origin == SEEK_END) |
93 | method = FILE_END; |
94 | else if (origin == SEEK_CUR) |
95 | method = FILE_CURRENT; |
96 | else |
97 | method = FILE_BEGIN; |
98 | |
99 | if (SetFilePointerEx((HANDLE) _get_osfhandle(_fileno(file)), off, NULL, method)) |
100 | return 0; |
101 | else |
102 | return -1; |
103 | } |
104 | #else |
105 | # define LONG_SEEK fseek |
106 | #endif |
107 | |
108 | #include <stdlib.h> /* malloc, free */ |
109 | #include <stdio.h> /* FILE* */ |
110 | #include <limits.h> /* UNIT_MAX */ |
111 | #include <assert.h> |
112 | |
113 | #define XXH_STATIC_LINKING_ONLY |
114 | #include "xxhash.h" |
115 | |
116 | #define ZSTD_STATIC_LINKING_ONLY |
117 | #include "zstd.h" |
118 | #include "zstd_errors.h" |
119 | #include "mem.h" |
120 | #include "zstd_seekable.h" |
121 | |
122 | #undef ERROR |
123 | #define ERROR(name) ((size_t)-ZSTD_error_##name) |
124 | |
125 | #define CHECK_IO(f) { int const errcod = (f); if (errcod < 0) return ERROR(seekableIO); } |
126 | |
127 | #undef MIN |
128 | #undef MAX |
129 | #define MIN(a, b) ((a) < (b) ? (a) : (b)) |
130 | #define MAX(a, b) ((a) > (b) ? (a) : (b)) |
131 | |
132 | #define ZSTD_SEEKABLE_NO_OUTPUT_PROGRESS_MAX 16 |
133 | |
134 | /* Special-case callbacks for FILE* and in-memory modes, so that we can treat |
135 | * them the same way as the advanced API */ |
136 | static int ZSTD_seekable_read_FILE(void* opaque, void* buffer, size_t n) |
137 | { |
138 | size_t const result = fread(buffer, 1, n, (FILE*)opaque); |
139 | if (result != n) { |
140 | return -1; |
141 | } |
142 | return 0; |
143 | } |
144 | |
145 | static int ZSTD_seekable_seek_FILE(void* opaque, long long offset, int origin) |
146 | { |
147 | int const ret = LONG_SEEK((FILE*)opaque, offset, origin); |
148 | if (ret) return ret; |
149 | return fflush((FILE*)opaque); |
150 | } |
151 | |
152 | typedef struct { |
153 | const void *ptr; |
154 | size_t size; |
155 | size_t pos; |
156 | } buffWrapper_t; |
157 | |
158 | static int ZSTD_seekable_read_buff(void* opaque, void* buffer, size_t n) |
159 | { |
160 | buffWrapper_t* const buff = (buffWrapper_t*)opaque; |
161 | assert(buff != NULL); |
162 | if (buff->pos + n > buff->size) return -1; |
163 | memcpy(buffer, (const BYTE*)buff->ptr + buff->pos, n); |
164 | buff->pos += n; |
165 | return 0; |
166 | } |
167 | |
168 | static int ZSTD_seekable_seek_buff(void* opaque, long long offset, int origin) |
169 | { |
170 | buffWrapper_t* const buff = (buffWrapper_t*) opaque; |
171 | unsigned long long newOffset; |
172 | assert(buff != NULL); |
173 | switch (origin) { |
174 | case SEEK_SET: |
175 | assert(offset >= 0); |
176 | newOffset = (unsigned long long)offset; |
177 | break; |
178 | case SEEK_CUR: |
179 | newOffset = (unsigned long long)((long long)buff->pos + offset); |
180 | break; |
181 | case SEEK_END: |
182 | newOffset = (unsigned long long)((long long)buff->size + offset); |
183 | break; |
184 | default: |
185 | assert(0); /* not possible */ |
186 | } |
187 | if (newOffset > buff->size) { |
188 | return -1; |
189 | } |
190 | buff->pos = newOffset; |
191 | return 0; |
192 | } |
193 | |
194 | typedef struct { |
195 | U64 cOffset; |
196 | U64 dOffset; |
197 | U32 checksum; |
198 | } seekEntry_t; |
199 | |
200 | struct ZSTD_seekTable_s { |
201 | seekEntry_t* entries; |
202 | size_t tableLen; |
203 | |
204 | int checksumFlag; |
205 | }; |
206 | |
207 | #define SEEKABLE_BUFF_SIZE ZSTD_BLOCKSIZE_MAX |
208 | |
209 | struct ZSTD_seekable_s { |
210 | ZSTD_DStream* dstream; |
211 | ZSTD_seekTable seekTable; |
212 | ZSTD_seekable_customFile src; |
213 | |
214 | U64 decompressedOffset; |
215 | U32 curFrame; |
216 | |
217 | BYTE inBuff[SEEKABLE_BUFF_SIZE]; /* need to do our own input buffering */ |
218 | BYTE outBuff[SEEKABLE_BUFF_SIZE]; /* so we can efficiently decompress the |
219 | starts of chunks before we get to the |
220 | desired section */ |
221 | ZSTD_inBuffer in; /* maintain continuity across ZSTD_seekable_decompress operations */ |
222 | buffWrapper_t buffWrapper; /* for `src.opaque` in in-memory mode */ |
223 | |
224 | XXH64_state_t xxhState; |
225 | }; |
226 | |
227 | ZSTD_seekable* ZSTD_seekable_create(void) |
228 | { |
229 | ZSTD_seekable* const zs = (ZSTD_seekable*)malloc(sizeof(ZSTD_seekable)); |
230 | if (zs == NULL) return NULL; |
231 | |
232 | /* also initializes stage to zsds_init */ |
233 | memset(zs, 0, sizeof(*zs)); |
234 | |
235 | zs->dstream = ZSTD_createDStream(); |
236 | if (zs->dstream == NULL) { |
237 | free(zs); |
238 | return NULL; |
239 | } |
240 | |
241 | return zs; |
242 | } |
243 | |
244 | size_t ZSTD_seekable_free(ZSTD_seekable* zs) |
245 | { |
246 | if (zs == NULL) return 0; /* support free on null */ |
247 | ZSTD_freeDStream(zs->dstream); |
248 | free(zs->seekTable.entries); |
249 | free(zs); |
250 | return 0; |
251 | } |
252 | |
253 | ZSTD_seekTable* ZSTD_seekTable_create_fromSeekable(const ZSTD_seekable* zs) |
254 | { |
255 | ZSTD_seekTable* const st = (ZSTD_seekTable*)malloc(sizeof(ZSTD_seekTable)); |
256 | if (st==NULL) return NULL; |
257 | |
258 | st->checksumFlag = zs->seekTable.checksumFlag; |
259 | st->tableLen = zs->seekTable.tableLen; |
260 | |
261 | /* Allocate an extra entry at the end to match logic of initial allocation */ |
262 | size_t const entriesSize = sizeof(seekEntry_t) * (zs->seekTable.tableLen + 1); |
263 | seekEntry_t* const entries = (seekEntry_t*)malloc(entriesSize); |
264 | if (entries==NULL) { |
265 | free(st); |
266 | return NULL; |
267 | } |
268 | |
269 | memcpy(entries, zs->seekTable.entries, entriesSize); |
270 | st->entries = entries; |
271 | return st; |
272 | } |
273 | |
274 | size_t ZSTD_seekTable_free(ZSTD_seekTable* st) |
275 | { |
276 | if (st == NULL) return 0; /* support free on null */ |
277 | free(st->entries); |
278 | free(st); |
279 | return 0; |
280 | } |
281 | |
282 | /** ZSTD_seekable_offsetToFrameIndex() : |
283 | * Performs a binary search to find the last frame with a decompressed offset |
284 | * <= pos |
285 | * @return : the frame's index */ |
286 | unsigned ZSTD_seekable_offsetToFrameIndex(const ZSTD_seekable* zs, unsigned long long pos) |
287 | { |
288 | return ZSTD_seekTable_offsetToFrameIndex(&zs->seekTable, pos); |
289 | } |
290 | |
291 | unsigned ZSTD_seekTable_offsetToFrameIndex(const ZSTD_seekTable* st, unsigned long long pos) |
292 | { |
293 | U32 lo = 0; |
294 | U32 hi = (U32)st->tableLen; |
295 | assert(st->tableLen <= UINT_MAX); |
296 | |
297 | if (pos >= st->entries[st->tableLen].dOffset) { |
298 | return (unsigned)st->tableLen; |
299 | } |
300 | |
301 | while (lo + 1 < hi) { |
302 | U32 const mid = lo + ((hi - lo) >> 1); |
303 | if (st->entries[mid].dOffset <= pos) { |
304 | lo = mid; |
305 | } else { |
306 | hi = mid; |
307 | } |
308 | } |
309 | return lo; |
310 | } |
311 | |
312 | unsigned ZSTD_seekable_getNumFrames(const ZSTD_seekable* zs) |
313 | { |
314 | return ZSTD_seekTable_getNumFrames(&zs->seekTable); |
315 | } |
316 | |
317 | unsigned ZSTD_seekTable_getNumFrames(const ZSTD_seekTable* st) |
318 | { |
319 | assert(st->tableLen <= UINT_MAX); |
320 | return (unsigned)st->tableLen; |
321 | } |
322 | |
323 | unsigned long long ZSTD_seekable_getFrameCompressedOffset(const ZSTD_seekable* zs, unsigned frameIndex) |
324 | { |
325 | return ZSTD_seekTable_getFrameCompressedOffset(&zs->seekTable, frameIndex); |
326 | } |
327 | |
328 | unsigned long long ZSTD_seekTable_getFrameCompressedOffset(const ZSTD_seekTable* st, unsigned frameIndex) |
329 | { |
330 | if (frameIndex >= st->tableLen) return ZSTD_SEEKABLE_FRAMEINDEX_TOOLARGE; |
331 | return st->entries[frameIndex].cOffset; |
332 | } |
333 | |
334 | unsigned long long ZSTD_seekable_getFrameDecompressedOffset(const ZSTD_seekable* zs, unsigned frameIndex) |
335 | { |
336 | return ZSTD_seekTable_getFrameDecompressedOffset(&zs->seekTable, frameIndex); |
337 | } |
338 | |
339 | unsigned long long ZSTD_seekTable_getFrameDecompressedOffset(const ZSTD_seekTable* st, unsigned frameIndex) |
340 | { |
341 | if (frameIndex >= st->tableLen) return ZSTD_SEEKABLE_FRAMEINDEX_TOOLARGE; |
342 | return st->entries[frameIndex].dOffset; |
343 | } |
344 | |
345 | size_t ZSTD_seekable_getFrameCompressedSize(const ZSTD_seekable* zs, unsigned frameIndex) |
346 | { |
347 | return ZSTD_seekTable_getFrameCompressedSize(&zs->seekTable, frameIndex); |
348 | } |
349 | |
350 | size_t ZSTD_seekTable_getFrameCompressedSize(const ZSTD_seekTable* st, unsigned frameIndex) |
351 | { |
352 | if (frameIndex >= st->tableLen) return ERROR(frameIndex_tooLarge); |
353 | return st->entries[frameIndex + 1].cOffset - |
354 | st->entries[frameIndex].cOffset; |
355 | } |
356 | |
357 | size_t ZSTD_seekable_getFrameDecompressedSize(const ZSTD_seekable* zs, unsigned frameIndex) |
358 | { |
359 | return ZSTD_seekTable_getFrameDecompressedSize(&zs->seekTable, frameIndex); |
360 | } |
361 | |
362 | size_t ZSTD_seekTable_getFrameDecompressedSize(const ZSTD_seekTable* st, unsigned frameIndex) |
363 | { |
364 | if (frameIndex > st->tableLen) return ERROR(frameIndex_tooLarge); |
365 | return st->entries[frameIndex + 1].dOffset - |
366 | st->entries[frameIndex].dOffset; |
367 | } |
368 | |
369 | static size_t ZSTD_seekable_loadSeekTable(ZSTD_seekable* zs) |
370 | { |
371 | int checksumFlag; |
372 | ZSTD_seekable_customFile src = zs->src; |
373 | /* read the footer, fixed size */ |
374 | CHECK_IO(src.seek(src.opaque, -(int)ZSTD_seekTableFooterSize, SEEK_END)); |
375 | CHECK_IO(src.read(src.opaque, zs->inBuff, ZSTD_seekTableFooterSize)); |
376 | |
377 | if (MEM_readLE32(zs->inBuff + 5) != ZSTD_SEEKABLE_MAGICNUMBER) { |
378 | return ERROR(prefix_unknown); |
379 | } |
380 | |
381 | { BYTE const sfd = zs->inBuff[4]; |
382 | checksumFlag = sfd >> 7; |
383 | |
384 | /* check reserved bits */ |
385 | if ((sfd >> 2) & 0x1f) { |
386 | return ERROR(corruption_detected); |
387 | } } |
388 | |
389 | { U32 const numFrames = MEM_readLE32(zs->inBuff); |
390 | U32 const sizePerEntry = 8 + (checksumFlag?4:0); |
391 | U32 const tableSize = sizePerEntry * numFrames; |
392 | U32 const frameSize = tableSize + ZSTD_seekTableFooterSize + ZSTD_SKIPPABLEHEADERSIZE; |
393 | |
394 | U32 remaining = frameSize - ZSTD_seekTableFooterSize; /* don't need to re-read footer */ |
395 | { U32 const toRead = MIN(remaining, SEEKABLE_BUFF_SIZE); |
396 | CHECK_IO(src.seek(src.opaque, -(S64)frameSize, SEEK_END)); |
397 | CHECK_IO(src.read(src.opaque, zs->inBuff, toRead)); |
398 | remaining -= toRead; |
399 | } |
400 | |
401 | if (MEM_readLE32(zs->inBuff) != (ZSTD_MAGIC_SKIPPABLE_START | 0xE)) { |
402 | return ERROR(prefix_unknown); |
403 | } |
404 | if (MEM_readLE32(zs->inBuff+4) + ZSTD_SKIPPABLEHEADERSIZE != frameSize) { |
405 | return ERROR(prefix_unknown); |
406 | } |
407 | |
408 | { /* Allocate an extra entry at the end so that we can do size |
409 | * computations on the last element without special case */ |
410 | seekEntry_t* const entries = (seekEntry_t*)malloc(sizeof(seekEntry_t) * (numFrames + 1)); |
411 | |
412 | U32 idx = 0; |
413 | U32 pos = 8; |
414 | |
415 | U64 cOffset = 0; |
416 | U64 dOffset = 0; |
417 | |
418 | if (entries == NULL) return ERROR(memory_allocation); |
419 | |
420 | /* compute cumulative positions */ |
421 | for (; idx < numFrames; idx++) { |
422 | if (pos + sizePerEntry > SEEKABLE_BUFF_SIZE) { |
423 | U32 const offset = SEEKABLE_BUFF_SIZE - pos; |
424 | U32 const toRead = MIN(remaining, SEEKABLE_BUFF_SIZE - offset); |
425 | memmove(zs->inBuff, zs->inBuff + pos, offset); /* move any data we haven't read yet */ |
426 | CHECK_IO(src.read(src.opaque, zs->inBuff+offset, toRead)); |
427 | remaining -= toRead; |
428 | pos = 0; |
429 | } |
430 | entries[idx].cOffset = cOffset; |
431 | entries[idx].dOffset = dOffset; |
432 | |
433 | cOffset += MEM_readLE32(zs->inBuff + pos); |
434 | pos += 4; |
435 | dOffset += MEM_readLE32(zs->inBuff + pos); |
436 | pos += 4; |
437 | if (checksumFlag) { |
438 | entries[idx].checksum = MEM_readLE32(zs->inBuff + pos); |
439 | pos += 4; |
440 | } |
441 | } |
442 | entries[numFrames].cOffset = cOffset; |
443 | entries[numFrames].dOffset = dOffset; |
444 | |
445 | zs->seekTable.entries = entries; |
446 | zs->seekTable.tableLen = numFrames; |
447 | zs->seekTable.checksumFlag = checksumFlag; |
448 | return 0; |
449 | } |
450 | } |
451 | } |
452 | |
453 | size_t ZSTD_seekable_initBuff(ZSTD_seekable* zs, const void* src, size_t srcSize) |
454 | { |
455 | zs->buffWrapper = (buffWrapper_t){src, srcSize, 0}; |
456 | { ZSTD_seekable_customFile srcFile = {&zs->buffWrapper, |
457 | &ZSTD_seekable_read_buff, |
458 | &ZSTD_seekable_seek_buff}; |
459 | return ZSTD_seekable_initAdvanced(zs, srcFile); } |
460 | } |
461 | |
462 | size_t ZSTD_seekable_initFile(ZSTD_seekable* zs, FILE* src) |
463 | { |
464 | ZSTD_seekable_customFile srcFile = {src, &ZSTD_seekable_read_FILE, |
465 | &ZSTD_seekable_seek_FILE}; |
466 | return ZSTD_seekable_initAdvanced(zs, srcFile); |
467 | } |
468 | |
469 | size_t ZSTD_seekable_initAdvanced(ZSTD_seekable* zs, ZSTD_seekable_customFile src) |
470 | { |
471 | zs->src = src; |
472 | |
473 | { const size_t seekTableInit = ZSTD_seekable_loadSeekTable(zs); |
474 | if (ZSTD_isError(seekTableInit)) return seekTableInit; } |
475 | |
476 | zs->decompressedOffset = (U64)-1; |
477 | zs->curFrame = (U32)-1; |
478 | |
479 | { const size_t dstreamInit = ZSTD_initDStream(zs->dstream); |
480 | if (ZSTD_isError(dstreamInit)) return dstreamInit; } |
481 | return 0; |
482 | } |
483 | |
484 | size_t ZSTD_seekable_decompress(ZSTD_seekable* zs, void* dst, size_t len, unsigned long long offset) |
485 | { |
486 | unsigned long long const eos = zs->seekTable.entries[zs->seekTable.tableLen].dOffset; |
487 | if (offset + len > eos) { |
488 | len = eos - offset; |
489 | } |
490 | |
491 | U32 targetFrame = ZSTD_seekable_offsetToFrameIndex(zs, offset); |
492 | U32 noOutputProgressCount = 0; |
493 | size_t srcBytesRead = 0; |
494 | do { |
495 | /* check if we can continue from a previous decompress job */ |
496 | if (targetFrame != zs->curFrame || offset < zs->decompressedOffset) { |
497 | zs->decompressedOffset = zs->seekTable.entries[targetFrame].dOffset; |
498 | zs->curFrame = targetFrame; |
499 | |
500 | assert(zs->seekTable.entries[targetFrame].cOffset < LLONG_MAX); |
501 | CHECK_IO(zs->src.seek(zs->src.opaque, |
502 | (long long)zs->seekTable.entries[targetFrame].cOffset, |
503 | SEEK_SET)); |
504 | zs->in = (ZSTD_inBuffer){zs->inBuff, 0, 0}; |
505 | XXH64_reset(&zs->xxhState, 0); |
506 | ZSTD_DCtx_reset(zs->dstream, ZSTD_reset_session_only); |
507 | if (zs->buffWrapper.size && srcBytesRead > zs->buffWrapper.size) { |
508 | return ERROR(seekableIO); |
509 | } |
510 | } |
511 | |
512 | while (zs->decompressedOffset < offset + len) { |
513 | size_t toRead; |
514 | ZSTD_outBuffer outTmp; |
515 | size_t prevOutPos; |
516 | size_t prevInPos; |
517 | size_t forwardProgress; |
518 | if (zs->decompressedOffset < offset) { |
519 | /* dummy decompressions until we get to the target offset */ |
520 | outTmp = (ZSTD_outBuffer){zs->outBuff, (size_t) (MIN(SEEKABLE_BUFF_SIZE, offset - zs->decompressedOffset)), 0}; |
521 | } else { |
522 | outTmp = (ZSTD_outBuffer){dst, len, (size_t) (zs->decompressedOffset - offset)}; |
523 | } |
524 | |
525 | prevOutPos = outTmp.pos; |
526 | prevInPos = zs->in.pos; |
527 | toRead = ZSTD_decompressStream(zs->dstream, &outTmp, &zs->in); |
528 | if (ZSTD_isError(toRead)) { |
529 | return toRead; |
530 | } |
531 | |
532 | if (zs->seekTable.checksumFlag) { |
533 | XXH64_update(&zs->xxhState, (BYTE*)outTmp.dst + prevOutPos, |
534 | outTmp.pos - prevOutPos); |
535 | } |
536 | forwardProgress = outTmp.pos - prevOutPos; |
537 | if (forwardProgress == 0) { |
538 | if (noOutputProgressCount++ > ZSTD_SEEKABLE_NO_OUTPUT_PROGRESS_MAX) { |
539 | return ERROR(seekableIO); |
540 | } |
541 | } else { |
542 | noOutputProgressCount = 0; |
543 | } |
544 | zs->decompressedOffset += forwardProgress; |
545 | srcBytesRead += zs->in.pos - prevInPos; |
546 | |
547 | if (toRead == 0) { |
548 | /* frame complete */ |
549 | |
550 | /* verify checksum */ |
551 | if (zs->seekTable.checksumFlag && |
552 | (XXH64_digest(&zs->xxhState) & 0xFFFFFFFFU) != |
553 | zs->seekTable.entries[targetFrame].checksum) { |
554 | return ERROR(corruption_detected); |
555 | } |
556 | |
557 | if (zs->decompressedOffset < offset + len) { |
558 | /* go back to the start and force a reset of the stream */ |
559 | targetFrame = ZSTD_seekable_offsetToFrameIndex(zs, zs->decompressedOffset); |
560 | /* in this case it will fail later with corruption_detected, since last block does not have checksum */ |
561 | assert(targetFrame != zs->seekTable.tableLen); |
562 | } |
563 | break; |
564 | } |
565 | |
566 | /* read in more data if we're done with this buffer */ |
567 | if (zs->in.pos == zs->in.size) { |
568 | toRead = MIN(toRead, SEEKABLE_BUFF_SIZE); |
569 | CHECK_IO(zs->src.read(zs->src.opaque, zs->inBuff, toRead)); |
570 | zs->in.size = toRead; |
571 | zs->in.pos = 0; |
572 | } |
573 | } /* while (zs->decompressedOffset < offset + len) */ |
574 | } while (zs->decompressedOffset != offset + len); |
575 | |
576 | return len; |
577 | } |
578 | |
579 | size_t ZSTD_seekable_decompressFrame(ZSTD_seekable* zs, void* dst, size_t dstSize, unsigned frameIndex) |
580 | { |
581 | if (frameIndex >= zs->seekTable.tableLen) { |
582 | return ERROR(frameIndex_tooLarge); |
583 | } |
584 | |
585 | { size_t const decompressedSize = |
586 | zs->seekTable.entries[frameIndex + 1].dOffset - |
587 | zs->seekTable.entries[frameIndex].dOffset; |
588 | if (dstSize < decompressedSize) { |
589 | return ERROR(dstSize_tooSmall); |
590 | } |
591 | return ZSTD_seekable_decompress( |
592 | zs, dst, decompressedSize, |
593 | zs->seekTable.entries[frameIndex].dOffset); |
594 | } |
595 | } |