由于要用程序压缩一个文件夹，因此选用zlib库。
在zlib中的例子程序zpipe.c中，给出了如何压缩一个文件，这里稍加扩展，对一个文件夹进行压缩。
说来也简单，就是将文件夹/目录下的每个文件找到并压缩到一个文件中。
源代码如下：
#include
<
stdio.h
>
#include
<
string
.h
>
#include
<
assert.h
>
#include
<
dos.h
>
#include
<
direct.h
>
#include
<
zlib.h
>
#if
defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
# include
<
fcntl.h
>
# include
<
io.h
>
# define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
# define SET_BINARY_MODE(file)
#endif
#define
CHUNK 16384
//
#define USE_TAG
#ifdef USE_TAG
#define
COMPRESS_FILE_TAG_HEAD "<<<"
#define
COMPRESS_FILE_TAG_TAIL ">>>"
#define
COMPRESS_FILE_TAG_END_LEN 3
//
must be strlen(COMPRESS_FILE_TAG_HEAD) = strlen(COMPRESS_FILE_TAG_TAIL)
#else
#define
COMPRESS_FILE_TAG_HEAD ""
#define
COMPRESS_FILE_TAG_TAIL ""
#define
COMPRESS_FILE_TAG_END_LEN 0
//
must be strlen(COMPRESS_FILE_TAG_HEAD) = strlen(COMPRESS_FILE_TAG_TAIL)
#endif
/**/
/**/
/**/
/* Compress from file source to file dest until EOF on source.
def() returns Z_OK on success, Z_MEM_ERROR if memory could not be allocated for processing, Z_STREAM_ERROR if an invalid compression level is supplied, Z_VERSION_ERROR if the version of zlib.h and the version of the library linked do not match, or Z_ERRNO if there is
an error reading or writing the files. */
static
int
def(FILE
*
source, FILE
*
dest,
int
level)...
...
{
int ret, flush; unsigned have; z_stream strm; unsigned char in[CHUNK]; unsigned char out[CHUNK];
/**//**//**//* allocate deflate state */ strm.zalloc = Z_NULL; strm.zfree = Z_NULL; strm.opaque = Z_NULL; ret = deflateInit(&strm, level); 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 */ assert(ret != Z_STREAM_ERROR); /**//**//**//* state not clobbered */ have = CHUNK - strm.avail_out; if (fwrite(out, 1, have, dest) != have || ferror(dest)) ......{
(void)deflateEnd(&strm); return Z_ERRNO; } } while (strm.avail_out == 0); assert(strm.avail_in == 0); /**//**//**//* all input will be used */ /**//**//**//* done when last data in file processed */ } while (flush != Z_FINISH); assert(ret == Z_STREAM_END); /**//**//**//* stream will be complete */ /**//**//**//* clean up and return */ (void)deflateEnd(&strm); return Z_OK;}
/**/
/**/
/**/
/* Decompress from file source to file dest until stream ends or EOF. inf() returns Z_OK on success, Z_MEM_ERROR if memory could not be allocated for processing, Z_DATA_ERROR if the deflate data is invalid or incomplete, Z_VERSION_ERROR if the version of zlib.h and the version of the library linked do not match, or Z_ERRNO if there is an error reading or writing the files. */
static
int
inf(FILE
*
source, FILE
*
dest)...
...
{
int ret; unsigned have; z_stream strm; unsigned char in[CHUNK]; unsigned char out[CHUNK]; /**//**//**//* 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, source); if (ferror(source)) ......{
(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); assert(ret != Z_STREAM_ERROR); /**//**//**//* state not clobbered */ switch (ret) ......{
case Z_NEED_DICT: ret = Z_DATA_ERROR; /**//**//**//* and fall through */ case Z_DATA_ERROR: case Z_MEM_ERROR: (void)inflateEnd(&strm); return ret; } have = CHUNK - strm.avail_out; if (fwrite(out, 1, have, dest) != have || ferror(dest)) ......{
(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;}
/**/
/**/
/**/
/* report a zlib or i/o error */
static
void
zerr(
int
ret)...
...
{
fputs("zpipe: ", stderr); switch (ret) ......{
case Z_ERRNO: if (ferror(stdin)) fputs("error reading stdin ", stderr); if (ferror(stdout)) fputs("error writing stdout ", stderr); break; case Z_STREAM_ERROR: fputs("invalid compression level ", stderr); break; case Z_DATA_ERROR: fputs("invalid or incomplete deflate data ", stderr); break; case Z_MEM_ERROR: fputs("out of memory ", stderr); break; case Z_VERSION_ERROR: fputs("zlib version mismatch! ", stderr); }}
以上就是zpipe.c的几个主要函数：def()、inf()和zerr()，def()是压缩函数，主要使用了zlib的deflate()接口；inf()是压缩函数，主要使用了zlib的inflate()接口；zerr()是错误打印函数。
static
int
write_zfile_file_header(
const
char
*
file,FILE
*
zfile)
...
{
int len; len = strlen(file); if (fwrite(COMPRESS_FILE_TAG_HEAD, 1, COMPRESS_FILE_TAG_END_LEN, zfile) != COMPRESS_FILE_TAG_END_LEN || ferror(zfile)) ...{
fprintf(stderr,"When writing file or dir header to zfile: write error. "); return 1; } if (fwrite(file, 1, len, zfile) != len|| ferror(zfile)) ...{
fprintf(stderr,"When writing file or dir header to zfile: write error. "); return 1; } if (fwrite(COMPRESS_FILE_TAG_TAIL, 1, COMPRESS_FILE_TAG_END_LEN, zfile) != COMPRESS_FILE_TAG_END_LEN || ferror(zfile)) ...{
fprintf(stderr,"When writing file or dir header to zfile: write error. "); return 1; } return 0;}
/**/
/* compress or decompress from stdin to stdout */
static
int
compress_dir(
char
*
file_in,FILE
*
fd_out)
...
{
FILE *fd_in; struct _finddata_t find_data; char file[128]; long lf; int ret; write_zfile_file_header(file_in,fd_out); sprintf(file,"%s%s",file_in,"/*"); if((lf = _findfirst(file,&find_data))==-1l) // LOOKOUT: not eleven, but one and lowercase 'L' ...{
fprintf(stdout,"file not found. "); } else ...{
do ...{
if(!strcmp(find_data.name,".") || !strcmp(find_data.name,"..")) continue; fprintf(stdout,"%s",find_data.name); sprintf(file,"%s%s%s",file_in,"/",find_data.name); if(find_data.attrib & _A_SUBDIR) ...{
fprintf(stdout," ---directory--- "); ret = compress_dir(file,fd_out); } else ...{
write_zfile_file_header(file,fd_out); if(access(file, 2) != 0) //W_OK=2 ...{
int attrib; attrib = _chmod(file,0); _chmod(file,1,attrib & ~_A_RDONLY); fprintf(stderr,"When writing file: No privilege to write file %s. ",file); return -1; } fd_in = fopen(file,"rb+"); SET_BINARY_MODE(fd_in); ret = def(fd_in, fd_out, Z_DEFAULT_COMPRESSION); if (ret != Z_OK) zerr(ret); else fprintf(stdout," zip over "); fclose(fd_in); } }while( _findnext(lf, &find_data ) == 0 ); } return 0;}
int
main(
int
argc,
char
**
argv)
...
{
struct _finddata_t find_data; FILE *fd_in; FILE *fd_out; const char *file_dir; char file_out[100]; int ret; if (argc == 2) ...{
file_dir = argv[1]; if(_findfirst(file_dir,&find_data)==-1l) // LOOKOUT: not eleven, but one and lowercase 'L' ...{
fprintf(stderr,"File or dir %s not found. ",file_dir); return 1; } if(find_data.attrib & _A_SUBDIR) ...{
sprintf(file_out,"%s%s",file_dir,".z"); fd_out = fopen(file_out,"wb+"); SET_BINARY_MODE(fd_out); fprintf(stdout,"Dir %s being Compressed ... ",file_dir); ret = compress_dir(file_dir,fd_out); fclose(fd_out); } else ...{
fprintf(stdout,"File %s being Compressed ... ",file_dir); sprintf(file_out,"%s%s",file_dir,".z"); fd_in = fopen(file_dir,"rb+"); fd_out = fopen(file_out,"wb+"); SET_BINARY_MODE(fd_in); SET_BINARY_MODE(fd_out); ret = def(fd_in, fd_out, Z_DEFAULT_COMPRESSION); fclose(fd_in); fclose(fd_out); } if (ret != 0) ...{
fprintf(stderr,"Compress Error !!!!!!!!!!!!!! "); zerr(ret); } else fprintf(stdout,"Compress OK--------------- "); } else ...{
fprintf(stdout,"zod usage: zod [file]/[directory] "); } getch(); return 0;}
以上就是主要的目录压缩代码，主要是将目录/文件的名称写入后，紧跟着压缩后的数据。
这里只提供了压缩代码，解压代码也依次逆向做出；在解压的时候，有个问题：怎样知道压缩数据开始？这里提供了USE_TAG进行分隔，若诸位有更好的方法，请告诉我。
注意：这种格式并不通用，要根据你的实际格式要求进行压缩！
仅供参考。