📄 example.c
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/* example.c -- usage example of the zlib compression library * Copyright (C) 1995-2004 Jean-loup Gailly. * For conditions of distribution and use, see copyright notice in zlib.h *//* @(#) $Id: example.c,v 1.1 2006/01/03 15:27:03 robilad Exp $ */#include <stdio.h>#include "zlib.h"#ifdef STDC# include <string.h># include <stdlib.h>#endif#if defined(VMS) || defined(RISCOS)# define TESTFILE "foo-gz"#else# define TESTFILE "foo.gz"#endif#define CHECK_ERR(err, msg) { \ if (err != Z_OK) { \ fprintf(stderr, "%s error: %d\n", msg, err); \ exit(1); \ } \}const char hello[] = "hello, hello!";/* "hello world" would be more standard, but the repeated "hello" * stresses the compression code better, sorry... */const char dictionary[] = "hello";uLong dictId; /* Adler32 value of the dictionary */void test_compress OF((Byte *compr, uLong comprLen, Byte *uncompr, uLong uncomprLen));void test_gzio OF((const char *fname, Byte *uncompr, uLong uncomprLen));void test_deflate OF((Byte *compr, uLong comprLen));void test_inflate OF((Byte *compr, uLong comprLen, Byte *uncompr, uLong uncomprLen));void test_large_deflate OF((Byte *compr, uLong comprLen, Byte *uncompr, uLong uncomprLen));void test_large_inflate OF((Byte *compr, uLong comprLen, Byte *uncompr, uLong uncomprLen));void test_flush OF((Byte *compr, uLong *comprLen));void test_sync OF((Byte *compr, uLong comprLen, Byte *uncompr, uLong uncomprLen));void test_dict_deflate OF((Byte *compr, uLong comprLen));void test_dict_inflate OF((Byte *compr, uLong comprLen, Byte *uncompr, uLong uncomprLen));int main OF((int argc, char *argv[]));/* =========================================================================== * Test compress() and uncompress() */void test_compress(compr, comprLen, uncompr, uncomprLen) Byte *compr, *uncompr; uLong comprLen, uncomprLen;{ int err; uLong len = (uLong)strlen(hello)+1; err = compress(compr, &comprLen, (const Bytef*)hello, len); CHECK_ERR(err, "compress"); strcpy((char*)uncompr, "garbage"); err = uncompress(uncompr, &uncomprLen, compr, comprLen); CHECK_ERR(err, "uncompress"); if (strcmp((char*)uncompr, hello)) { fprintf(stderr, "bad uncompress\n"); exit(1); } else { printf("uncompress(): %s\n", (char *)uncompr); }}/* =========================================================================== * Test read/write of .gz files */void test_gzio(fname, uncompr, uncomprLen) const char *fname; /* compressed file name */ Byte *uncompr; uLong uncomprLen;{#ifdef NO_GZCOMPRESS fprintf(stderr, "NO_GZCOMPRESS -- gz* functions cannot compress\n");#else int err; int len = (int)strlen(hello)+1; gzFile file; z_off_t pos; file = gzopen(fname, "wb"); if (file == NULL) { fprintf(stderr, "gzopen error\n"); exit(1); } gzputc(file, 'h'); if (gzputs(file, "ello") != 4) { fprintf(stderr, "gzputs err: %s\n", gzerror(file, &err)); exit(1); } if (gzprintf(file, ", %s!", "hello") != 8) { fprintf(stderr, "gzprintf err: %s\n", gzerror(file, &err)); exit(1); } gzseek(file, 1L, SEEK_CUR); /* add one zero byte */ gzclose(file); file = gzopen(fname, "rb"); if (file == NULL) { fprintf(stderr, "gzopen error\n"); exit(1); } strcpy((char*)uncompr, "garbage"); if (gzread(file, uncompr, (unsigned)uncomprLen) != len) { fprintf(stderr, "gzread err: %s\n", gzerror(file, &err)); exit(1); } if (strcmp((char*)uncompr, hello)) { fprintf(stderr, "bad gzread: %s\n", (char*)uncompr); exit(1); } else { printf("gzread(): %s\n", (char*)uncompr); } pos = gzseek(file, -8L, SEEK_CUR); if (pos != 6 || gztell(file) != pos) { fprintf(stderr, "gzseek error, pos=%ld, gztell=%ld\n", (long)pos, (long)gztell(file)); exit(1); } if (gzgetc(file) != ' ') { fprintf(stderr, "gzgetc error\n"); exit(1); } if (gzungetc(' ', file) != ' ') { fprintf(stderr, "gzungetc error\n"); exit(1); } gzgets(file, (char*)uncompr, (int)uncomprLen); if (strlen((char*)uncompr) != 7) { /* " hello!" */ fprintf(stderr, "gzgets err after gzseek: %s\n", gzerror(file, &err)); exit(1); } if (strcmp((char*)uncompr, hello + 6)) { fprintf(stderr, "bad gzgets after gzseek\n"); exit(1); } else { printf("gzgets() after gzseek: %s\n", (char*)uncompr); } gzclose(file);#endif}/* =========================================================================== * Test deflate() with small buffers */void test_deflate(compr, comprLen) Byte *compr; uLong comprLen;{ z_stream c_stream; /* compression stream */ int err; uLong len = (uLong)strlen(hello)+1; c_stream.zalloc = (alloc_func)0; c_stream.zfree = (free_func)0; c_stream.opaque = (voidpf)0; err = deflateInit(&c_stream, Z_DEFAULT_COMPRESSION); CHECK_ERR(err, "deflateInit"); c_stream.next_in = (Bytef*)hello; c_stream.next_out = compr; while (c_stream.total_in != len && c_stream.total_out < comprLen) { c_stream.avail_in = c_stream.avail_out = 1; /* force small buffers */ err = deflate(&c_stream, Z_NO_FLUSH); CHECK_ERR(err, "deflate"); } /* Finish the stream, still forcing small buffers: */ for (;;) { c_stream.avail_out = 1; err = deflate(&c_stream, Z_FINISH); if (err == Z_STREAM_END) break; CHECK_ERR(err, "deflate"); } err = deflateEnd(&c_stream); CHECK_ERR(err, "deflateEnd");}/* =========================================================================== * Test inflate() with small buffers */void test_inflate(compr, comprLen, uncompr, uncomprLen) Byte *compr, *uncompr; uLong comprLen, uncomprLen;{ int err; z_stream d_stream; /* decompression stream */ strcpy((char*)uncompr, "garbage"); d_stream.zalloc = (alloc_func)0; d_stream.zfree = (free_func)0; d_stream.opaque = (voidpf)0; d_stream.next_in = compr; d_stream.avail_in = 0; d_stream.next_out = uncompr; err = inflateInit(&d_stream); CHECK_ERR(err, "inflateInit"); while (d_stream.total_out < uncomprLen && d_stream.total_in < comprLen) { d_stream.avail_in = d_stream.avail_out = 1; /* force small buffers */ err = inflate(&d_stream, Z_NO_FLUSH); if (err == Z_STREAM_END) break; CHECK_ERR(err, "inflate"); } err = inflateEnd(&d_stream); CHECK_ERR(err, "inflateEnd"); if (strcmp((char*)uncompr, hello)) { fprintf(stderr, "bad inflate\n"); exit(1); } else { printf("inflate(): %s\n", (char *)uncompr); }}/* =========================================================================== * Test deflate() with large buffers and dynamic change of compression level */void test_large_deflate(compr, comprLen, uncompr, uncomprLen) Byte *compr, *uncompr; uLong comprLen, uncomprLen;{ z_stream c_stream; /* compression stream */ int err; c_stream.zalloc = (alloc_func)0; c_stream.zfree = (free_func)0; c_stream.opaque = (voidpf)0; err = deflateInit(&c_stream, Z_BEST_SPEED); CHECK_ERR(err, "deflateInit"); c_stream.next_out = compr; c_stream.avail_out = (uInt)comprLen; /* At this point, uncompr is still mostly zeroes, so it should compress * very well: */ c_stream.next_in = uncompr; c_stream.avail_in = (uInt)uncomprLen; err = deflate(&c_stream, Z_NO_FLUSH); CHECK_ERR(err, "deflate"); if (c_stream.avail_in != 0) { fprintf(stderr, "deflate not greedy\n"); exit(1); } /* Feed in already compressed data and switch to no compression: */ deflateParams(&c_stream, Z_NO_COMPRESSION, Z_DEFAULT_STRATEGY); c_stream.next_in = compr; c_stream.avail_in = (uInt)comprLen/2; err = deflate(&c_stream, Z_NO_FLUSH); CHECK_ERR(err, "deflate");
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