1/*
2 * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
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/* zstd_decompress_internal:
13 * objects and definitions shared within lib/decompress modules */
14
15 #ifndef ZSTD_DECOMPRESS_INTERNAL_H
16 #define ZSTD_DECOMPRESS_INTERNAL_H
17
18
19/*-*******************************************************
20 *  Dependencies
21 *********************************************************/
22#include "../common/mem.h"             /* BYTE, U16, U32 */
23#include "../common/zstd_internal.h"   /* ZSTD_seqSymbol */
24
25
26
27/*-*******************************************************
28 *  Constants
29 *********************************************************/
30static const U32 LL_base[MaxLL+1] = {
31                 0,    1,    2,     3,     4,     5,     6,      7,
32                 8,    9,   10,    11,    12,    13,    14,     15,
33                16,   18,   20,    22,    24,    28,    32,     40,
34                48,   64, 0x80, 0x100, 0x200, 0x400, 0x800, 0x1000,
35                0x2000, 0x4000, 0x8000, 0x10000 };
36
37static const U32 OF_base[MaxOff+1] = {
38                 0,        1,       1,       5,     0xD,     0x1D,     0x3D,     0x7D,
39                 0xFD,   0x1FD,   0x3FD,   0x7FD,   0xFFD,   0x1FFD,   0x3FFD,   0x7FFD,
40                 0xFFFD, 0x1FFFD, 0x3FFFD, 0x7FFFD, 0xFFFFD, 0x1FFFFD, 0x3FFFFD, 0x7FFFFD,
41                 0xFFFFFD, 0x1FFFFFD, 0x3FFFFFD, 0x7FFFFFD, 0xFFFFFFD, 0x1FFFFFFD, 0x3FFFFFFD, 0x7FFFFFFD };
42
43static const U32 OF_bits[MaxOff+1] = {
44                     0,  1,  2,  3,  4,  5,  6,  7,
45                     8,  9, 10, 11, 12, 13, 14, 15,
46                    16, 17, 18, 19, 20, 21, 22, 23,
47                    24, 25, 26, 27, 28, 29, 30, 31 };
48
49static const U32 ML_base[MaxML+1] = {
50                     3,  4,  5,    6,     7,     8,     9,    10,
51                    11, 12, 13,   14,    15,    16,    17,    18,
52                    19, 20, 21,   22,    23,    24,    25,    26,
53                    27, 28, 29,   30,    31,    32,    33,    34,
54                    35, 37, 39,   41,    43,    47,    51,    59,
55                    67, 83, 99, 0x83, 0x103, 0x203, 0x403, 0x803,
56                    0x1003, 0x2003, 0x4003, 0x8003, 0x10003 };
57
58
59/*-*******************************************************
60 *  Decompression types
61 *********************************************************/
62 typedef struct {
63     U32 fastMode;
64     U32 tableLog;
65 } ZSTD_seqSymbol_header;
66
67 typedef struct {
68     U16  nextState;
69     BYTE nbAdditionalBits;
70     BYTE nbBits;
71     U32  baseValue;
72 } ZSTD_seqSymbol;
73
74 #define SEQSYMBOL_TABLE_SIZE(log)   (1 + (1 << (log)))
75
76typedef struct {
77    ZSTD_seqSymbol LLTable[SEQSYMBOL_TABLE_SIZE(LLFSELog)];    /* Note : Space reserved for FSE Tables */
78    ZSTD_seqSymbol OFTable[SEQSYMBOL_TABLE_SIZE(OffFSELog)];   /* is also used as temporary workspace while building hufTable during DDict creation */
79    ZSTD_seqSymbol MLTable[SEQSYMBOL_TABLE_SIZE(MLFSELog)];    /* and therefore must be at least HUF_DECOMPRESS_WORKSPACE_SIZE large */
80    HUF_DTable hufTable[HUF_DTABLE_SIZE(HufLog)];  /* can accommodate HUF_decompress4X */
81    U32 rep[ZSTD_REP_NUM];
82} ZSTD_entropyDTables_t;
83
84typedef enum { ZSTDds_getFrameHeaderSize, ZSTDds_decodeFrameHeader,
85               ZSTDds_decodeBlockHeader, ZSTDds_decompressBlock,
86               ZSTDds_decompressLastBlock, ZSTDds_checkChecksum,
87               ZSTDds_decodeSkippableHeader, ZSTDds_skipFrame } ZSTD_dStage;
88
89typedef enum { zdss_init=0, zdss_loadHeader,
90               zdss_read, zdss_load, zdss_flush } ZSTD_dStreamStage;
91
92typedef enum {
93    ZSTD_use_indefinitely = -1,  /* Use the dictionary indefinitely */
94    ZSTD_dont_use = 0,           /* Do not use the dictionary (if one exists free it) */
95    ZSTD_use_once = 1            /* Use the dictionary once and set to ZSTD_dont_use */
96} ZSTD_dictUses_e;
97
98typedef enum {
99    ZSTD_obm_buffered = 0,  /* Buffer the output */
100    ZSTD_obm_stable = 1     /* ZSTD_outBuffer is stable */
101} ZSTD_outBufferMode_e;
102
103struct ZSTD_DCtx_s
104{
105    const ZSTD_seqSymbol* LLTptr;
106    const ZSTD_seqSymbol* MLTptr;
107    const ZSTD_seqSymbol* OFTptr;
108    const HUF_DTable* HUFptr;
109    ZSTD_entropyDTables_t entropy;
110    U32 workspace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];   /* space needed when building huffman tables */
111    const void* previousDstEnd;   /* detect continuity */
112    const void* prefixStart;      /* start of current segment */
113    const void* virtualStart;     /* virtual start of previous segment if it was just before current one */
114    const void* dictEnd;          /* end of previous segment */
115    size_t expected;
116    ZSTD_frameHeader fParams;
117    U64 decodedSize;
118    blockType_e bType;            /* used in ZSTD_decompressContinue(), store blockType between block header decoding and block decompression stages */
119    ZSTD_dStage stage;
120    U32 litEntropy;
121    U32 fseEntropy;
122    XXH64_state_t xxhState;
123    size_t headerSize;
124    ZSTD_format_e format;
125    const BYTE* litPtr;
126    ZSTD_customMem customMem;
127    size_t litSize;
128    size_t rleSize;
129    size_t staticSize;
130    int bmi2;                     /* == 1 if the CPU supports BMI2 and 0 otherwise. CPU support is determined dynamically once per context lifetime. */
131
132    /* dictionary */
133    ZSTD_DDict* ddictLocal;
134    const ZSTD_DDict* ddict;     /* set by ZSTD_initDStream_usingDDict(), or ZSTD_DCtx_refDDict() */
135    U32 dictID;
136    int ddictIsCold;             /* if == 1 : dictionary is "new" for working context, and presumed "cold" (not in cpu cache) */
137    ZSTD_dictUses_e dictUses;
138
139    /* streaming */
140    ZSTD_dStreamStage streamStage;
141    char*  inBuff;
142    size_t inBuffSize;
143    size_t inPos;
144    size_t maxWindowSize;
145    char*  outBuff;
146    size_t outBuffSize;
147    size_t outStart;
148    size_t outEnd;
149    size_t lhSize;
150    void* legacyContext;
151    U32 previousLegacyVersion;
152    U32 legacyVersion;
153    U32 hostageByte;
154    int noForwardProgress;
155    ZSTD_outBufferMode_e outBufferMode;
156    ZSTD_outBuffer expectedOutBuffer;
157
158    /* workspace */
159    BYTE litBuffer[ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH];
160    BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX];
161
162    size_t oversizedDuration;
163
164#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
165    void const* dictContentBeginForFuzzing;
166    void const* dictContentEndForFuzzing;
167#endif
168};  /* typedef'd to ZSTD_DCtx within "zstd.h" */
169
170
171/*-*******************************************************
172 *  Shared internal functions
173 *********************************************************/
174
175/*! ZSTD_loadDEntropy() :
176 *  dict : must point at beginning of a valid zstd dictionary.
177 * @return : size of dictionary header (size of magic number + dict ID + entropy tables) */
178size_t ZSTD_loadDEntropy(ZSTD_entropyDTables_t* entropy,
179                   const void* const dict, size_t const dictSize);
180
181/*! ZSTD_checkContinuity() :
182 *  check if next `dst` follows previous position, where decompression ended.
183 *  If yes, do nothing (continue on current segment).
184 *  If not, classify previous segment as "external dictionary", and start a new segment.
185 *  This function cannot fail. */
186void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst);
187
188
189#endif /* ZSTD_DECOMPRESS_INTERNAL_H */
190