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 | #include <stdio.h> // printf |
13 | #include <stdlib.h> // free |
14 | #include <zstd.h> // presumes zstd library is installed |
15 | #include "common.h" // Helper functions, CHECK(), and CHECK_ZSTD() |
16 | |
17 | /* createDict() : |
18 | `dictFileName` is supposed to have been created using `zstd --train` */ |
19 | static ZSTD_DDict* createDict_orDie(const char* dictFileName) |
20 | { |
21 | size_t dictSize; |
22 | printf("loading dictionary %s \n", dictFileName); |
23 | void* const dictBuffer = mallocAndLoadFile_orDie(dictFileName, &dictSize); |
24 | ZSTD_DDict* const ddict = ZSTD_createDDict(dictBuffer, dictSize); |
25 | CHECK(ddict != NULL, "ZSTD_createDDict() failed!"); |
26 | free(dictBuffer); |
27 | return ddict; |
28 | } |
29 | |
30 | static void decompress(const char* fname, const ZSTD_DDict* ddict) |
31 | { |
32 | size_t cSize; |
33 | void* const cBuff = mallocAndLoadFile_orDie(fname, &cSize); |
34 | /* Read the content size from the frame header. For simplicity we require |
35 | * that it is always present. By default, zstd will write the content size |
36 | * in the header when it is known. If you can't guarantee that the frame |
37 | * content size is always written into the header, either use streaming |
38 | * decompression, or ZSTD_decompressBound(). |
39 | */ |
40 | unsigned long long const rSize = ZSTD_getFrameContentSize(cBuff, cSize); |
41 | CHECK(rSize != ZSTD_CONTENTSIZE_ERROR, "%s: not compressed by zstd!", fname); |
42 | CHECK(rSize != ZSTD_CONTENTSIZE_UNKNOWN, "%s: original size unknown!", fname); |
43 | void* const rBuff = malloc_orDie((size_t)rSize); |
44 | |
45 | /* Check that the dictionary ID matches. |
46 | * If a non-zstd dictionary is used, then both will be zero. |
47 | * By default zstd always writes the dictionary ID into the frame. |
48 | * Zstd will check if there is a dictionary ID mismatch as well. |
49 | */ |
50 | unsigned const expectedDictID = ZSTD_getDictID_fromDDict(ddict); |
51 | unsigned const actualDictID = ZSTD_getDictID_fromFrame(cBuff, cSize); |
52 | CHECK(actualDictID == expectedDictID, |
53 | "DictID mismatch: expected %u got %u", |
54 | expectedDictID, |
55 | actualDictID); |
56 | |
57 | /* Decompress using the dictionary. |
58 | * If you need to control the decompression parameters, then use the |
59 | * advanced API: ZSTD_DCtx_setParameter(), ZSTD_DCtx_refDDict(), and |
60 | * ZSTD_decompressDCtx(). |
61 | */ |
62 | ZSTD_DCtx* const dctx = ZSTD_createDCtx(); |
63 | CHECK(dctx != NULL, "ZSTD_createDCtx() failed!"); |
64 | size_t const dSize = ZSTD_decompress_usingDDict(dctx, rBuff, rSize, cBuff, cSize, ddict); |
65 | CHECK_ZSTD(dSize); |
66 | /* When zstd knows the content size, it will error if it doesn't match. */ |
67 | CHECK(dSize == rSize, "Impossible because zstd will check this condition!"); |
68 | |
69 | /* success */ |
70 | printf("%25s : %6u -> %7u \n", fname, (unsigned)cSize, (unsigned)rSize); |
71 | |
72 | ZSTD_freeDCtx(dctx); |
73 | free(rBuff); |
74 | free(cBuff); |
75 | } |
76 | |
77 | |
78 | int main(int argc, const char** argv) |
79 | { |
80 | const char* const exeName = argv[0]; |
81 | |
82 | if (argc<3) { |
83 | printf("wrong arguments\n"); |
84 | printf("usage:\n"); |
85 | printf("%s [FILES] dictionary\n", exeName); |
86 | return 1; |
87 | } |
88 | |
89 | /* load dictionary only once */ |
90 | const char* const dictName = argv[argc-1]; |
91 | ZSTD_DDict* const dictPtr = createDict_orDie(dictName); |
92 | |
93 | int u; |
94 | for (u=1; u<argc-1; u++) decompress(argv[u], dictPtr); |
95 | |
96 | ZSTD_freeDDict(dictPtr); |
97 | printf("All %u files correctly decoded (in memory) \n", argc-2); |
98 | return 0; |
99 | } |