库Linux中zlib库的优秀性能（linux中zlib）
Zlib库是一个开源的压缩解压库，它具备良好的速度和准确性，为Linux系统中 Linux zib库提供了优秀的性能。
首先，zlib库为Linux系统中 Linux zib库提供了强大的压缩机制，使得Linux系统的资源消耗得到明显的减少。使用zlib库，可以将大量的数据压缩到更小的空间，从而节省了系统的存储空间，减少了系统的资源消耗，提高了系统的效率。例如，下面的代码可以使用zlib库来压缩一个文件：
// 将一个文件压缩
#include
#include
int compress_file(char* filename, char* compress_filename)
{
int ret, flush;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
FILE *source = fopen(filename, “rb”);
FILE *compress_file = fopen(compress_filename, “wb”);
if (source == NULL) {
printf(“Can’t open %s\n”, filename);
return -1;
}
if (compress_file == NULL) {
printf(“Can’t open %s\n”, compress_filename);
return -1;
}
/* allocate deflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = deflateInit(&strm, Z_BEST_COMPRESSION);
if (ret != Z_OK)
return ret;
/* compress until end of file */
do {
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source)) {
(void)deflateEnd(&strm);
return Z_ERRNO;
}
flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
strm.next_in = in;
/* run deflate() on input until output buffer not full, finish
compression if all of source has been read in */
do {
strm.avail_out = CHUNK;
strm.next_out = out;
ret = deflate(&strm, flush); /* no bad return value */
if (ret == Z_STREAM_ERROR) { /* state not clobbered */
(void)deflateEnd(&strm);
return Z_ERRNO;
}
have = CHUNK – strm.avail_out;
if (fwrite(out, 1, have, compress_file) != have || ferror(compress_file)) {
(void)deflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
/* done when last data in file processed */
} while (flush != Z_FINISH);
/* clean up and return */
(void)deflateEnd(&strm);
return Z_OK;
}
此外，zlib库有一个非常快的解压缩速度，使得Linux系统在解压缩过程中能够得到较高的效率。比如，下面的代码可以使用zlib库解压缩文件：
// 将一个文件解压缩
#include
#include
int uncompress_file(char* compress_filename, char* filename)
{
int ret;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
FILE *compress_file = fopen(compress_filename, “rb”);
FILE *source = fopen(filename, “wb”);
if (source == NULL) {
printf(“Can’t open %s\n”, filename);
return -1;
}
/* allocate inflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit(&strm);
if (ret != Z_OK)
return ret;
/* decompress until deflate stream ends or end of file */
do {
strm.avail_in = fread(in, 1, CHUNK, compress_file);
if (ferror(compress_file)) {
(void)inflateEnd(&strm);
return Z_ERRNO;
}
if (strm.avail_in == 0)
break;
strm.next_in = in;
/* run inflate() on input until output buffer not full */
do {
strm.avail_out = CHUNK;
strm.next_out = out;
ret = inflate(&strm, Z_NO_FLUSH);
if (ret == Z_STREAM_ERROR) { /* state not clobbered */
(void)inflateEnd(&strm);
return Z_ERRNO;
}
switch (ret) {
case Z_NEED_DICT:
case Z_DATA_ERROR:
case Z_MEM_ERROR:
(void)inflateEnd(&strm);
return Z_ERRNO;
}
have = CHUNK – strm.avail_out;
if (fwrite(out, 1, have, source) != have || ferror(source)) {
(void)inflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
/* done when inflate() says it’s done */
} while (ret != Z_STREAM_END);
/* clean up and return */
(void)inflateEnd(&strm);
return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}
总的来说，Linux zib库作为Linux系统的组成部分，它给Linux系统带来了良好的压缩和解压缩性能，并且使用非常简便，从而优化了Linux系统，增加了系统的灵活性。
