1/*
2 * Copyright (c) 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#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` */
19static 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
30static 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
78int 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}
100