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 }