108 lines
3.5 KiB
C
108 lines
3.5 KiB
C
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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**/
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/* This example deals with Dictionary compression,
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* its counterpart is `examples/dictionary_decompression.c` .
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* These examples presume that a dictionary already exists.
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* The main method to create a dictionary is `zstd --train`,
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* look at the CLI documentation for details.
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* Another possible method is to employ dictionary training API,
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* published in `lib/zdict.h` .
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**/
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#include <stdio.h> // printf
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#include <stdlib.h> // free
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#include <string.h> // memset, strcat
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#include <zstd.h> // presumes zstd library is installed
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#include "common.h" // Helper functions, CHECK(), and CHECK_ZSTD()
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/* createDict() :
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** `dictFileName` is supposed already created using `zstd --train` */
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static ZSTD_CDict* createCDict_orDie(const char* dictFileName, int cLevel)
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{
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size_t dictSize;
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printf("loading dictionary %s \n", dictFileName);
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void* const dictBuffer = mallocAndLoadFile_orDie(dictFileName, &dictSize);
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ZSTD_CDict* const cdict = ZSTD_createCDict(dictBuffer, dictSize, cLevel);
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CHECK(cdict != NULL, "ZSTD_createCDict() failed!");
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free(dictBuffer);
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return cdict;
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}
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static void compress(const char* fname, const char* oname, const ZSTD_CDict* cdict)
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{
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size_t fSize;
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void* const fBuff = mallocAndLoadFile_orDie(fname, &fSize);
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size_t const cBuffSize = ZSTD_compressBound(fSize);
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void* const cBuff = malloc_orDie(cBuffSize);
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/* Compress using the dictionary.
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* This function writes the dictionary id, and content size into the header.
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* But, it doesn't use a checksum. You can control these options using the
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* advanced API: ZSTD_CCtx_setParameter(), ZSTD_CCtx_refCDict(),
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* and ZSTD_compress2().
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*/
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ZSTD_CCtx* const cctx = ZSTD_createCCtx();
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CHECK(cctx != NULL, "ZSTD_createCCtx() failed!");
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size_t const cSize = ZSTD_compress_usingCDict(cctx, cBuff, cBuffSize, fBuff, fSize, cdict);
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CHECK_ZSTD(cSize);
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saveFile_orDie(oname, cBuff, cSize);
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/* success */
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printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
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ZSTD_freeCCtx(cctx); /* never fails */
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free(fBuff);
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free(cBuff);
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}
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static char* createOutFilename_orDie(const char* filename)
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{
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size_t const inL = strlen(filename);
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size_t const outL = inL + 5;
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void* outSpace = malloc_orDie(outL);
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memset(outSpace, 0, outL);
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strcat(outSpace, filename);
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strcat(outSpace, ".zst");
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return (char*)outSpace;
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}
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int main(int argc, const char** argv)
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{
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const char* const exeName = argv[0];
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int const cLevel = 3;
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if (argc<3) {
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fprintf(stderr, "wrong arguments\n");
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fprintf(stderr, "usage:\n");
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fprintf(stderr, "%s [FILES] dictionary\n", exeName);
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return 1;
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}
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/* load dictionary only once */
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const char* const dictName = argv[argc-1];
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ZSTD_CDict* const dictPtr = createCDict_orDie(dictName, cLevel);
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int u;
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for (u=1; u<argc-1; u++) {
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const char* inFilename = argv[u];
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char* const outFilename = createOutFilename_orDie(inFilename);
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compress(inFilename, outFilename, dictPtr);
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free(outFilename);
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}
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ZSTD_freeCDict(dictPtr);
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printf("All %u files compressed. \n", argc-2);
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return 0;
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}
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