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2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
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.
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()
18 `dictFileName` is supposed to have been created using `zstd --train` */
19 static ZSTD_DDict
* createDict_orDie(const char* dictFileName
)
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!");
30 static void decompress(const char* fname
, const ZSTD_DDict
* ddict
)
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().
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
);
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.
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",
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().
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
);
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!");
70 printf("%25s : %6u -> %7u \n", fname
, (unsigned)cSize
, (unsigned)rSize
);
78 int main(int argc
, const char** argv
)
80 const char* const exeName
= argv
[0];
83 printf("wrong arguments\n");
85 printf("%s [FILES] dictionary\n", exeName
);
89 /* load dictionary only once */
90 const char* const dictName
= argv
[argc
-1];
91 ZSTD_DDict
* const dictPtr
= createDict_orDie(dictName
);
94 for (u
=1; u
<argc
-1; u
++) decompress(argv
[u
], dictPtr
);
96 ZSTD_freeDDict(dictPtr
);
97 printf("All %u files correctly decoded (in memory) \n", argc
-2);