462 lines
15 KiB
C
462 lines
15 KiB
C
/*
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* Copyright (c) 2017-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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/* *********************************************************
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* Turn on Large Files support (>4GB) for 32-bit Linux/Unix
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***********************************************************/
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#if !defined(__64BIT__) || defined(__MINGW32__) /* No point defining Large file for 64 bit but MinGW-w64 requires it */
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# if !defined(_FILE_OFFSET_BITS)
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# define _FILE_OFFSET_BITS 64 /* turn off_t into a 64-bit type for ftello, fseeko */
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# endif
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# if !defined(_LARGEFILE_SOURCE) /* obsolete macro, replaced with _FILE_OFFSET_BITS */
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# define _LARGEFILE_SOURCE 1 /* Large File Support extension (LFS) - fseeko, ftello */
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# endif
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# if defined(_AIX) || defined(__hpux)
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# define _LARGE_FILES /* Large file support on 32-bits AIX and HP-UX */
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# endif
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#endif
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/* ************************************************************
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* Avoid fseek()'s 2GiB barrier with MSVC, MacOS, *BSD, MinGW
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***************************************************************/
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#if defined(_MSC_VER) && _MSC_VER >= 1400
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# define LONG_SEEK _fseeki64
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#elif !defined(__64BIT__) && (PLATFORM_POSIX_VERSION >= 200112L) /* No point defining Large file for 64 bit */
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# define LONG_SEEK fseeko
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#elif defined(__MINGW32__) && !defined(__STRICT_ANSI__) && !defined(__NO_MINGW_LFS) && defined(__MSVCRT__)
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# define LONG_SEEK fseeko64
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#elif defined(_WIN32) && !defined(__DJGPP__)
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# include <windows.h>
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static int LONG_SEEK(FILE* file, __int64 offset, int origin) {
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LARGE_INTEGER off;
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DWORD method;
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off.QuadPart = offset;
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if (origin == SEEK_END)
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method = FILE_END;
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else if (origin == SEEK_CUR)
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method = FILE_CURRENT;
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else
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method = FILE_BEGIN;
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if (SetFilePointerEx((HANDLE) _get_osfhandle(_fileno(file)), off, NULL, method))
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return 0;
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else
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return -1;
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}
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#else
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# define LONG_SEEK fseek
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#endif
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#include <stdlib.h> /* malloc, free */
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#include <stdio.h> /* FILE* */
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#define XXH_STATIC_LINKING_ONLY
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#define XXH_NAMESPACE ZSTD_
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#include "xxhash.h"
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#define ZSTD_STATIC_LINKING_ONLY
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#include "zstd.h"
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#include "zstd_errors.h"
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#include "mem.h"
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#include "zstd_seekable.h"
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#undef ERROR
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#define ERROR(name) ((size_t)-ZSTD_error_##name)
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#define CHECK_IO(f) { int const errcod = (f); if (errcod < 0) return ERROR(seekableIO); }
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#undef MIN
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#undef MAX
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#define MIN(a, b) ((a) < (b) ? (a) : (b))
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#define MAX(a, b) ((a) > (b) ? (a) : (b))
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/* Special-case callbacks for FILE* and in-memory modes, so that we can treat
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* them the same way as the advanced API */
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static int ZSTD_seekable_read_FILE(void* opaque, void* buffer, size_t n)
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{
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size_t const result = fread(buffer, 1, n, (FILE*)opaque);
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if (result != n) {
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return -1;
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}
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return 0;
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}
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static int ZSTD_seekable_seek_FILE(void* opaque, S64 offset, int origin)
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{
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int const ret = LONG_SEEK((FILE*)opaque, offset, origin);
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if (ret) return ret;
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return fflush((FILE*)opaque);
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}
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typedef struct {
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const void *ptr;
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size_t size;
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size_t pos;
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} buffWrapper_t;
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static int ZSTD_seekable_read_buff(void* opaque, void* buffer, size_t n)
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{
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buffWrapper_t* buff = (buffWrapper_t*) opaque;
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if (buff->size + n > buff->pos) return -1;
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memcpy(buffer, (const BYTE*)buff->ptr + buff->pos, n);
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buff->pos += n;
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return 0;
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}
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static int ZSTD_seekable_seek_buff(void* opaque, S64 offset, int origin)
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{
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buffWrapper_t* buff = (buffWrapper_t*) opaque;
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unsigned long long newOffset;
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switch (origin) {
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case SEEK_SET:
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newOffset = offset;
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break;
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case SEEK_CUR:
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newOffset = (unsigned long long)buff->pos + offset;
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break;
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case SEEK_END:
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newOffset = (unsigned long long)buff->size - offset;
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break;
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}
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if (newOffset < 0 || newOffset > buff->size) {
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return -1;
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}
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buff->pos = newOffset;
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return 0;
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}
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typedef struct {
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U64 cOffset;
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U64 dOffset;
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U32 checksum;
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} seekEntry_t;
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typedef struct {
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seekEntry_t* entries;
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size_t tableLen;
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int checksumFlag;
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} seekTable_t;
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#define SEEKABLE_BUFF_SIZE ZSTD_BLOCKSIZE_ABSOLUTEMAX
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struct ZSTD_seekable_s {
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ZSTD_DStream* dstream;
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seekTable_t seekTable;
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ZSTD_seekable_customFile src;
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U64 decompressedOffset;
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U32 curFrame;
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BYTE inBuff[SEEKABLE_BUFF_SIZE]; /* need to do our own input buffering */
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BYTE outBuff[SEEKABLE_BUFF_SIZE]; /* so we can efficiently decompress the
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starts of chunks before we get to the
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desired section */
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ZSTD_inBuffer in; /* maintain continuity across ZSTD_seekable_decompress operations */
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buffWrapper_t buffWrapper; /* for `src.opaque` in in-memory mode */
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XXH64_state_t xxhState;
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};
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ZSTD_seekable* ZSTD_seekable_create(void)
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{
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ZSTD_seekable* zs = malloc(sizeof(ZSTD_seekable));
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if (zs == NULL) return NULL;
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/* also initializes stage to zsds_init */
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memset(zs, 0, sizeof(*zs));
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zs->dstream = ZSTD_createDStream();
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if (zs->dstream == NULL) {
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free(zs);
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return NULL;
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}
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return zs;
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}
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size_t ZSTD_seekable_free(ZSTD_seekable* zs)
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{
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if (zs == NULL) return 0; /* support free on null */
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ZSTD_freeDStream(zs->dstream);
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free(zs->seekTable.entries);
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free(zs);
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return 0;
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}
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/** ZSTD_seekable_offsetToFrameIndex() :
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* Performs a binary search to find the last frame with a decompressed offset
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* <= pos
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* @return : the frame's index */
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U32 ZSTD_seekable_offsetToFrameIndex(ZSTD_seekable* const zs, U64 pos)
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{
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U32 lo = 0;
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U32 hi = zs->seekTable.tableLen;
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if (pos >= zs->seekTable.entries[zs->seekTable.tableLen].dOffset) {
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return zs->seekTable.tableLen;
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}
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while (lo + 1 < hi) {
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U32 const mid = lo + ((hi - lo) >> 1);
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if (zs->seekTable.entries[mid].dOffset <= pos) {
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lo = mid;
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} else {
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hi = mid;
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}
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}
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return lo;
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}
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U32 ZSTD_seekable_getNumFrames(ZSTD_seekable* const zs)
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{
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return zs->seekTable.tableLen;
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}
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U64 ZSTD_seekable_getFrameCompressedOffset(ZSTD_seekable* const zs, U32 frameIndex)
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{
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if (frameIndex >= zs->seekTable.tableLen) return ZSTD_SEEKABLE_FRAMEINDEX_TOOLARGE;
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return zs->seekTable.entries[frameIndex].cOffset;
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}
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U64 ZSTD_seekable_getFrameDecompressedOffset(ZSTD_seekable* const zs, U32 frameIndex)
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{
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if (frameIndex >= zs->seekTable.tableLen) return ZSTD_SEEKABLE_FRAMEINDEX_TOOLARGE;
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return zs->seekTable.entries[frameIndex].dOffset;
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}
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size_t ZSTD_seekable_getFrameCompressedSize(ZSTD_seekable* const zs, U32 frameIndex)
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{
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if (frameIndex >= zs->seekTable.tableLen) return ERROR(frameIndex_tooLarge);
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return zs->seekTable.entries[frameIndex + 1].cOffset -
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zs->seekTable.entries[frameIndex].cOffset;
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}
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size_t ZSTD_seekable_getFrameDecompressedSize(ZSTD_seekable* const zs, U32 frameIndex)
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{
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if (frameIndex > zs->seekTable.tableLen) return ERROR(frameIndex_tooLarge);
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return zs->seekTable.entries[frameIndex + 1].dOffset -
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zs->seekTable.entries[frameIndex].dOffset;
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}
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static size_t ZSTD_seekable_loadSeekTable(ZSTD_seekable* zs)
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{
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int checksumFlag;
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ZSTD_seekable_customFile src = zs->src;
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/* read the footer, fixed size */
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CHECK_IO(src.seek(src.opaque, -(int)ZSTD_seekTableFooterSize, SEEK_END));
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CHECK_IO(src.read(src.opaque, zs->inBuff, ZSTD_seekTableFooterSize));
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if (MEM_readLE32(zs->inBuff + 5) != ZSTD_SEEKABLE_MAGICNUMBER) {
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return ERROR(prefix_unknown);
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}
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{ BYTE const sfd = zs->inBuff[4];
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checksumFlag = sfd >> 7;
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/* check reserved bits */
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if ((checksumFlag >> 2) & 0x1f) {
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return ERROR(corruption_detected);
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}
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}
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{ U32 const numFrames = MEM_readLE32(zs->inBuff);
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U32 const sizePerEntry = 8 + (checksumFlag?4:0);
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U32 const tableSize = sizePerEntry * numFrames;
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U32 const frameSize = tableSize + ZSTD_seekTableFooterSize + ZSTD_skippableHeaderSize;
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U32 remaining = frameSize - ZSTD_seekTableFooterSize; /* don't need to re-read footer */
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{
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U32 const toRead = MIN(remaining, SEEKABLE_BUFF_SIZE);
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CHECK_IO(src.seek(src.opaque, -(S64)frameSize, SEEK_END));
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CHECK_IO(src.read(src.opaque, zs->inBuff, toRead));
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remaining -= toRead;
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}
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if (MEM_readLE32(zs->inBuff) != (ZSTD_MAGIC_SKIPPABLE_START | 0xE)) {
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return ERROR(prefix_unknown);
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}
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if (MEM_readLE32(zs->inBuff+4) + ZSTD_skippableHeaderSize != frameSize) {
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return ERROR(prefix_unknown);
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}
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{ /* Allocate an extra entry at the end so that we can do size
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* computations on the last element without special case */
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seekEntry_t* entries = (seekEntry_t*)malloc(sizeof(seekEntry_t) * (numFrames + 1));
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const BYTE* tableBase = zs->inBuff + ZSTD_skippableHeaderSize;
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U32 idx = 0;
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U32 pos = 8;
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U64 cOffset = 0;
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U64 dOffset = 0;
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if (!entries) {
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free(entries);
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return ERROR(memory_allocation);
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}
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/* compute cumulative positions */
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for (; idx < numFrames; idx++) {
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if (pos + sizePerEntry > SEEKABLE_BUFF_SIZE) {
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U32 const toRead = MIN(remaining, SEEKABLE_BUFF_SIZE);
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U32 const offset = SEEKABLE_BUFF_SIZE - pos;
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memmove(zs->inBuff, zs->inBuff + pos, offset); /* move any data we haven't read yet */
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CHECK_IO(src.read(src.opaque, zs->inBuff+offset, toRead));
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remaining -= toRead;
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pos = 0;
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}
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entries[idx].cOffset = cOffset;
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entries[idx].dOffset = dOffset;
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cOffset += MEM_readLE32(zs->inBuff + pos);
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pos += 4;
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dOffset += MEM_readLE32(zs->inBuff + pos);
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pos += 4;
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if (checksumFlag) {
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entries[idx].checksum = MEM_readLE32(zs->inBuff + pos);
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pos += 4;
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}
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}
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entries[numFrames].cOffset = cOffset;
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entries[numFrames].dOffset = dOffset;
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zs->seekTable.entries = entries;
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zs->seekTable.tableLen = numFrames;
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zs->seekTable.checksumFlag = checksumFlag;
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return 0;
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}
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}
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}
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size_t ZSTD_seekable_initBuff(ZSTD_seekable* zs, const void* src, size_t srcSize)
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{
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zs->buffWrapper = (buffWrapper_t){src, srcSize, 0};
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{ ZSTD_seekable_customFile srcFile = {&zs->buffWrapper,
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&ZSTD_seekable_read_buff,
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&ZSTD_seekable_seek_buff};
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return ZSTD_seekable_initAdvanced(zs, srcFile); }
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}
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size_t ZSTD_seekable_initFile(ZSTD_seekable* zs, FILE* src)
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{
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ZSTD_seekable_customFile srcFile = {src, &ZSTD_seekable_read_FILE,
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&ZSTD_seekable_seek_FILE};
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return ZSTD_seekable_initAdvanced(zs, srcFile);
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}
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size_t ZSTD_seekable_initAdvanced(ZSTD_seekable* zs, ZSTD_seekable_customFile src)
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{
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zs->src = src;
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{ const size_t seekTableInit = ZSTD_seekable_loadSeekTable(zs);
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if (ZSTD_isError(seekTableInit)) return seekTableInit; }
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zs->decompressedOffset = (U64)-1;
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zs->curFrame = (U32)-1;
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{ const size_t dstreamInit = ZSTD_initDStream(zs->dstream);
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if (ZSTD_isError(dstreamInit)) return dstreamInit; }
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return 0;
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}
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size_t ZSTD_seekable_decompress(ZSTD_seekable* zs, void* dst, size_t len, U64 offset)
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{
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U32 targetFrame = ZSTD_seekable_offsetToFrameIndex(zs, offset);
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do {
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/* check if we can continue from a previous decompress job */
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if (targetFrame != zs->curFrame || offset != zs->decompressedOffset) {
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zs->decompressedOffset = zs->seekTable.entries[targetFrame].dOffset;
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zs->curFrame = targetFrame;
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CHECK_IO(zs->src.seek(zs->src.opaque,
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zs->seekTable.entries[targetFrame].cOffset,
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SEEK_SET));
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zs->in = (ZSTD_inBuffer){zs->inBuff, 0, 0};
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XXH64_reset(&zs->xxhState, 0);
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ZSTD_resetDStream(zs->dstream);
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}
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while (zs->decompressedOffset < offset + len) {
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size_t toRead;
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ZSTD_outBuffer outTmp;
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size_t prevOutPos;
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if (zs->decompressedOffset < offset) {
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/* dummy decompressions until we get to the target offset */
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outTmp = (ZSTD_outBuffer){zs->outBuff, MIN(SEEKABLE_BUFF_SIZE, offset - zs->decompressedOffset), 0};
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} else {
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outTmp = (ZSTD_outBuffer){dst, len, zs->decompressedOffset - offset};
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}
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prevOutPos = outTmp.pos;
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toRead = ZSTD_decompressStream(zs->dstream, &outTmp, &zs->in);
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if (ZSTD_isError(toRead)) {
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return toRead;
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}
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if (zs->seekTable.checksumFlag) {
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XXH64_update(&zs->xxhState, (BYTE*)outTmp.dst + prevOutPos,
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outTmp.pos - prevOutPos);
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}
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zs->decompressedOffset += outTmp.pos - prevOutPos;
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if (toRead == 0) {
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/* frame complete */
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/* verify checksum */
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if (zs->seekTable.checksumFlag &&
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(XXH64_digest(&zs->xxhState) & 0xFFFFFFFFU) !=
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zs->seekTable.entries[targetFrame].checksum) {
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return ERROR(corruption_detected);
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}
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if (zs->decompressedOffset < offset + len) {
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/* go back to the start and force a reset of the stream */
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targetFrame = ZSTD_seekable_offsetToFrameIndex(zs, zs->decompressedOffset);
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}
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break;
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}
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/* read in more data if we're done with this buffer */
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if (zs->in.pos == zs->in.size) {
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toRead = MIN(toRead, SEEKABLE_BUFF_SIZE);
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CHECK_IO(zs->src.read(zs->src.opaque, zs->inBuff, toRead));
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zs->in.size = toRead;
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zs->in.pos = 0;
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}
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}
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} while (zs->decompressedOffset != offset + len);
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return len;
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}
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size_t ZSTD_seekable_decompressFrame(ZSTD_seekable* zs, void* dst, size_t dstSize, U32 frameIndex)
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{
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if (frameIndex >= zs->seekTable.tableLen) {
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return ERROR(frameIndex_tooLarge);
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}
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{
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size_t const decompressedSize =
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zs->seekTable.entries[frameIndex + 1].dOffset -
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zs->seekTable.entries[frameIndex].dOffset;
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if (dstSize < decompressedSize) {
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return ERROR(dstSize_tooSmall);
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}
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return ZSTD_seekable_decompress(
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zs, dst, decompressedSize,
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zs->seekTable.entries[frameIndex].dOffset);
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}
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}
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