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 /* This example deals with Dictionary compression, 12 * its counterpart is `examples/dictionary_decompression.c` . 13 * These examples presume that a dictionary already exists. 14 * The main method to create a dictionary is `zstd --train`, 15 * look at the CLI documentation for details. 16 * Another possible method is to employ dictionary training API, 17 * published in `lib/zdict.h` . 18 **/ 19 20 #include <stdio.h> // printf 21 #include <stdlib.h> // free 22 #include <string.h> // memset, strcat 23 #include <zstd.h> // presumes zstd library is installed 24 #include "common.h" // Helper functions, CHECK(), and CHECK_ZSTD() 25 26 /* createDict() : 27 ** `dictFileName` is supposed already created using `zstd --train` */ 28 static ZSTD_CDict* createCDict_orDie(const char* dictFileName, int cLevel) 29 { 30 size_t dictSize; 31 printf("loading dictionary %s \n", dictFileName); 32 void* const dictBuffer = mallocAndLoadFile_orDie(dictFileName, &dictSize); 33 ZSTD_CDict* const cdict = ZSTD_createCDict(dictBuffer, dictSize, cLevel); 34 CHECK(cdict != NULL, "ZSTD_createCDict() failed!"); 35 free(dictBuffer); 36 return cdict; 37 } 38 39 40 static void compress(const char* fname, const char* oname, const ZSTD_CDict* cdict) 41 { 42 size_t fSize; 43 void* const fBuff = mallocAndLoadFile_orDie(fname, &fSize); 44 size_t const cBuffSize = ZSTD_compressBound(fSize); 45 void* const cBuff = malloc_orDie(cBuffSize); 46 47 /* Compress using the dictionary. 48 * This function writes the dictionary id, and content size into the header. 49 * But, it doesn't use a checksum. You can control these options using the 50 * advanced API: ZSTD_CCtx_setParameter(), ZSTD_CCtx_refCDict(), 51 * and ZSTD_compress2(). 52 */ 53 ZSTD_CCtx* const cctx = ZSTD_createCCtx(); 54 CHECK(cctx != NULL, "ZSTD_createCCtx() failed!"); 55 size_t const cSize = ZSTD_compress_usingCDict(cctx, cBuff, cBuffSize, fBuff, fSize, cdict); 56 CHECK_ZSTD(cSize); 57 58 saveFile_orDie(oname, cBuff, cSize); 59 60 /* success */ 61 printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname); 62 63 ZSTD_freeCCtx(cctx); /* never fails */ 64 free(fBuff); 65 free(cBuff); 66 } 67 68 69 static char* createOutFilename_orDie(const char* filename) 70 { 71 size_t const inL = strlen(filename); 72 size_t const outL = inL + 5; 73 void* outSpace = malloc_orDie(outL); 74 memset(outSpace, 0, outL); 75 strcat(outSpace, filename); 76 strcat(outSpace, ".zst"); 77 return (char*)outSpace; 78 } 79 80 int main(int argc, const char** argv) 81 { 82 const char* const exeName = argv[0]; 83 int const cLevel = 3; 84 85 if (argc<3) { 86 fprintf(stderr, "wrong arguments\n"); 87 fprintf(stderr, "usage:\n"); 88 fprintf(stderr, "%s [FILES] dictionary\n", exeName); 89 return 1; 90 } 91 92 /* load dictionary only once */ 93 const char* const dictName = argv[argc-1]; 94 ZSTD_CDict* const dictPtr = createCDict_orDie(dictName, cLevel); 95 96 int u; 97 for (u=1; u<argc-1; u++) { 98 const char* inFilename = argv[u]; 99 char* const outFilename = createOutFilename_orDie(inFilename); 100 compress(inFilename, outFilename, dictPtr); 101 free(outFilename); 102 } 103 104 ZSTD_freeCDict(dictPtr); 105 printf("All %u files compressed. \n", argc-2); 106 return 0; 107 } 108