137 lines
3.9 KiB
C
137 lines
3.9 KiB
C
/*
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Dictionary decompression
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Educational program using zstd library
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Copyright (C) Yann Collet 2016
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GPL v2 License
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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You can contact the author at :
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- zstd homepage : http://www.zstd.net/
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*/
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#include <stdlib.h> // malloc, exit
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#include <stdio.h> // printf
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#include <string.h> // strerror
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#include <errno.h> // errno
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#include <sys/stat.h> // stat
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#include <zstd.h> // presumes zstd library is installed
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static off_t fsize_X(const char *filename)
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{
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struct stat st;
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if (stat(filename, &st) == 0) return st.st_size;
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/* error */
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printf("stat: %s : %s \n", filename, strerror(errno));
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exit(1);
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}
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static FILE* fopen_X(const char *filename, const char *instruction)
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{
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FILE* const inFile = fopen(filename, instruction);
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if (inFile) return inFile;
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/* error */
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printf("fopen: %s : %s \n", filename, strerror(errno));
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exit(2);
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}
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static void* malloc_X(size_t size)
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{
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void* const buff = malloc(size);
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if (buff) return buff;
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/* error */
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printf("malloc: %s \n", strerror(errno));
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exit(3);
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}
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static void* loadFile_X(const char* fileName, size_t* size)
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{
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off_t const buffSize = fsize_X(fileName);
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FILE* const inFile = fopen_X(fileName, "rb");
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void* const buffer = malloc_X(buffSize);
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size_t const readSize = fread(buffer, 1, buffSize, inFile);
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if (readSize != (size_t)buffSize) {
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printf("fread: %s : %s \n", fileName, strerror(errno));
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exit(4);
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}
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fclose(inFile);
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*size = buffSize;
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return buffer;
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}
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/* createDict() :
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`dictFileName` is supposed to have been created using `zstd --train` */
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static const ZSTD_DDict* createDict(const char* dictFileName)
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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 = loadFile_X(dictFileName, &dictSize);
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const ZSTD_DDict* const ddict = ZSTD_createDDict(dictBuffer, dictSize);
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free(dictBuffer);
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return ddict;
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}
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static void decompress(const char* fname, const ZSTD_DDict* ddict)
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{
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size_t cSize;
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void* const cBuff = loadFile_X(fname, &cSize);
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unsigned long long const rSize = ZSTD_getDecompressedSize(cBuff, cSize);
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if (rSize==0) {
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printf("%s : original size unknown \n", fname);
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exit(5);
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}
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void* const rBuff = malloc_X(rSize);
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ZSTD_DCtx* const dctx = ZSTD_createDCtx();
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size_t const dSize = ZSTD_decompress_usingDDict(dctx, rBuff, rSize, cBuff, cSize, ddict);
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if (dSize != rSize) {
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printf("error decoding %s : %s \n", fname, ZSTD_getErrorName(dSize));
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exit(7);
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}
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/* success */
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printf("%25s : %6u -> %7u \n", fname, (unsigned)cSize, (unsigned)rSize);
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ZSTD_freeDCtx(dctx);
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free(rBuff);
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free(cBuff);
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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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if (argc<3) {
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printf("wrong arguments\n");
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printf("usage:\n");
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printf("%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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const ZSTD_DDict* const dictPtr = createDict(dictName);
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int u;
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for (u=1; u<argc-1; u++) decompress(argv[u], dictPtr);
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printf("All %u files correctly decoded (in memory) \n", argc-2);
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}
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