zlib/examples/zpipe.c

   1 /* zpipe.c: example of proper use of zlib's inflate() and deflate()
   2    Not copyrighted -- provided to the public domain
   3    Version 1.2  9 November 2004  Mark Adler */
   4
   5 /* Version history:
   6    1.0  30 Oct 2004  First version
   7    1.1   8 Nov 2004  Add void casting for unused return values
   8                      Use switch statement for inflate() return values
   9    1.2   9 Nov 2004  Add assertions to document zlib guarantees
  10    1.3   6 Apr 2005  Remove incorrect assertion in inf()
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #include <assert.h>
  16 #include "zlib.h"
  17
  18 #define CHUNK 16384
  19
  20 /* Compress from file source to file dest until EOF on source.
  21    def() returns Z_OK on success, Z_MEM_ERROR if memory could not be
  22    allocated for processing, Z_STREAM_ERROR if an invalid compression
  23    level is supplied, Z_VERSION_ERROR if the version of zlib.h and the
  24    version of the library linked do not match, or Z_ERRNO if there is
  25    an error reading or writing the files. */
  26 int def(FILE *source, FILE *dest, int level)
  27 {
  28     int ret, flush;
  29     unsigned have;
  30     z_stream strm;
  31     char in[CHUNK];
  32     char out[CHUNK];
  33
  34     /* allocate deflate state */
  35     strm.zalloc = Z_NULL;
  36     strm.zfree = Z_NULL;
  37     strm.opaque = Z_NULL;
  38     ret = deflateInit(&strm, level);
  39     if (ret != Z_OK)
  40         return ret;
  41
  42     /* compress until end of file */
  43     do {
  44         strm.avail_in = fread(in, 1, CHUNK, source);
  45         if (ferror(source)) {
  46             (void)deflateEnd(&strm);
  47             return Z_ERRNO;
  48         }
  49         flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
  50         strm.next_in = in;
  51
  52         /* run deflate() on input until output buffer not full, finish
  53            compression if all of source has been read in */
  54         do {
  55             strm.avail_out = CHUNK;
  56             strm.next_out = out;
  57             ret = deflate(&strm, flush);    /* no bad return value */
  58             assert(ret != Z_STREAM_ERROR);  /* state not clobbered */
  59             have = CHUNK - strm.avail_out;
  60             if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
  61                 (void)deflateEnd(&strm);
  62                 return Z_ERRNO;
  63             }
  64         } while (strm.avail_out == 0);
  65         assert(strm.avail_in == 0);     /* all input will be used */
  66
  67         /* done when last data in file processed */
  68     } while (flush != Z_FINISH);
  69     assert(ret == Z_STREAM_END);        /* stream will be complete */
  70
  71     /* clean up and return */
  72     (void)deflateEnd(&strm);
  73     return Z_OK;
  74 }
  75
  76 /* Decompress from file source to file dest until stream ends or EOF.
  77    inf() returns Z_OK on success, Z_MEM_ERROR if memory could not be
  78    allocated for processing, Z_DATA_ERROR if the deflate data is
  79    invalid or incomplete, Z_VERSION_ERROR if the version of zlib.h and
  80    the version of the library linked do not match, or Z_ERRNO if there
  81    is an error reading or writing the files. */
  82 int inf(FILE *source, FILE *dest)
  83 {
  84     int ret;
  85     unsigned have;
  86     z_stream strm;
  87     char in[CHUNK];
  88     char out[CHUNK];
  89
  90     /* allocate inflate state */
  91     strm.zalloc = Z_NULL;
  92     strm.zfree = Z_NULL;
  93     strm.opaque = Z_NULL;
  94     strm.avail_in = 0;
  95     strm.next_in = Z_NULL;
  96     ret = inflateInit(&strm);
  97     if (ret != Z_OK)
  98         return ret;
  99
 100     /* decompress until deflate stream ends or end of file */
 101     do {
 102         strm.avail_in = fread(in, 1, CHUNK, source);
 103         if (ferror(source)) {
 104             (void)inflateEnd(&strm);
 105             return Z_ERRNO;
 106         }
 107         if (strm.avail_in == 0)
 108             break;
 109         strm.next_in = in;
 110
 111         /* run inflate() on input until output buffer not full */
 112         do {
 113             strm.avail_out = CHUNK;
 114             strm.next_out = out;
 115             ret = inflate(&strm, Z_NO_FLUSH);
 116             assert(ret != Z_STREAM_ERROR);  /* state not clobbered */
 117             switch (ret) {
 118             case Z_NEED_DICT:
 119                 ret = Z_DATA_ERROR;     /* and fall through */
 120             case Z_DATA_ERROR:
 121             case Z_MEM_ERROR:
 122                 (void)inflateEnd(&strm);
 123                 return ret;
 124             }
 125             have = CHUNK - strm.avail_out;
 126             if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
 127                 (void)inflateEnd(&strm);
 128                 return Z_ERRNO;
 129             }
 130         } while (strm.avail_out == 0);
 131
 132         /* done when inflate() says it's done */
 133     } while (ret != Z_STREAM_END);
 134
 135     /* clean up and return */
 136     (void)inflateEnd(&strm);
 137     return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
 138 }
 139
 140 /* report a zlib or i/o error */
 141 void zerr(int ret)
 142 {
 143     fputs("zpipe: ", stderr);
 144     switch (ret) {
 145     case Z_ERRNO:
 146         if (ferror(stdin))
 147             fputs("error reading stdin\n", stderr);
 148         if (ferror(stdout))
 149             fputs("error writing stdout\n", stderr);
 150         break;
 151     case Z_STREAM_ERROR:
 152         fputs("invalid compression level\n", stderr);
 153         break;
 154     case Z_DATA_ERROR:
 155         fputs("invalid or incomplete deflate data\n", stderr);
 156         break;
 157     case Z_MEM_ERROR:
 158         fputs("out of memory\n", stderr);
 159         break;
 160     case Z_VERSION_ERROR:
 161         fputs("zlib version mismatch!\n", stderr);
 162     }
 163 }
 164
 165 /* compress or decompress from stdin to stdout */
 166 int main(int argc, char **argv)
 167 {
 168     int ret;
 169
 170     /* do compression if no arguments */
 171     if (argc == 1) {
 172         ret = def(stdin, stdout, Z_DEFAULT_COMPRESSION);
 173         if (ret != Z_OK)
 174             zerr(ret);
 175         return ret;
 176     }
 177
 178     /* do decompression if -d specified */
 179     else if (argc == 2 && strcmp(argv[1], "-d") == 0) {
 180         ret = inf(stdin, stdout);
 181         if (ret != Z_OK)
 182             zerr(ret);
 183         return ret;
 184     }
 185
 186     /* otherwise, report usage */
 187     else {
 188         fputs("zpipe usage: zpipe [-d] < source > dest\n", stderr);
 189         return 1;
 190     }
 191 }