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 #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 } 100