gzip c语言开发,【C/C++】C实现gzip格式的压缩与解压Demo

参考链接:

http://www.codeproject.com/Questions/341319/C-Decompress-Gzipped-http-response

http://www.cppblog.com/woaidongmao/archive/2011/06/05/148089.html

http://stackoverflow.com/questions/13762918/setup-zlib-to-generate-gzipped-data

基于原有的代码整理后, 实现基础的gzip格式字节流压缩与解压, 代码如下：

#include

#include

#include

#include

// gzCompress: do the compressing

int gzCompress(const char *src, int srcLen, char *dest, int destLen)

{

z_stream c_stream;

int err = 0;

int windowBits = 15;

int GZIP_ENCODING = 16;

if(src && srcLen > 0)

{

c_stream.zalloc = (alloc_func)0;

c_stream.zfree = (free_func)0;

c_stream.opaque = (voidpf)0;

if(deflateInit2(&c_stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,

windowBits | GZIP_ENCODING, 8, Z_DEFAULT_STRATEGY) != Z_OK) return -1;

c_stream.next_in = (Bytef *)src;

c_stream.avail_in = srcLen;

c_stream.next_out = (Bytef *)dest;

c_stream.avail_out = destLen;

while (c_stream.avail_in != 0 && c_stream.total_out < destLen)

{

if(deflate(&c_stream, Z_NO_FLUSH) != Z_OK) return -1;

}

if(c_stream.avail_in != 0) return c_stream.avail_in;

for (;;) {

if((err = deflate(&c_stream, Z_FINISH)) == Z_STREAM_END) break;

if(err != Z_OK) return -1;

}

if(deflateEnd(&c_stream) != Z_OK) return -1;

return c_stream.total_out;

}

return -1;

}

// gzDecompress: do the decompressing

int gzDecompress(const char *src, int srcLen, const char *dst, int dstLen){

z_stream strm;

strm.zalloc=NULL;

strm.zfree=NULL;

strm.opaque=NULL;

strm.avail_in = srcLen;

strm.avail_out = dstLen;

strm.next_in = (Bytef *)src;

strm.next_out = (Bytef *)dst;

int err=-1, ret=-1;

err = inflateInit2(&strm, MAX_WBITS+16);

if (err == Z_OK){

err = inflate(&strm, Z_FINISH);

if (err == Z_STREAM_END){

ret = strm.total_out;

}

else{

inflateEnd(&strm);

return err;

}

}

else{

inflateEnd(&strm);

return err;

}

inflateEnd(&strm);

return err;

}

int main()

{

char* src = "just for test, dd, dd, dd";

int size_src = strlen(src);

char* compressed = malloc(size_src*2);

memset(compressed, 0, size_src*2);

printf("to compress src: %s\n", src);

printf("to compress src size: %d\n", size_src);

int gzSize = gzCompress(src, size_src, compressed, size_src*2);

if (gzSize <= 0)

{

printf("compress error.\n");

return -1;

}

printf("compressed: ");

int i = 0;

for (; i

{

printf("%02x ", compressed[i]);

}

printf("\ncompressed size: %d\n", gzSize);

char* uncompressed = malloc(size_src*2);

memset(uncompressed, 0, size_src*2);

int ret = gzDecompress(compressed, gzSize, uncompressed, size_src*2);

printf("uncompressed: %s\n", uncompressed);

printf("uncompressed size: %d\n", strlen(uncompressed));

free(compressed);

free(uncompressed);

return 0;

}运行效果:

root@xiaomo:/data/apps/# ./zlib_test

to compress src: just for test, dd, dd, dd

to compress src size: 25

compressed: 1f 8b 08 00 00 00 00 00 00 03 cb 2a 2d 2e 51 48 cb 2f 52 28 49 2d 2e d1 51 48 49 81 61 00 33 c3 e2 f3 19 00 00 00

compressed size: 38

uncompressed: just for test, dd, dd, dd

uncompressed size: 25