lib/zlib/uncompr.c

   1 /* uncompr.c -- decompress a memory buffer
   2  * Copyright (C) 1995-2003 Jean-loup Gailly.
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 /* @(#) $Id$ */
   7
   8 #include "zutil.h"
   9
  10 /* ===========================================================================
  11      Decompresses the source buffer into the destination buffer.  sourceLen is
  12    the byte length of the source buffer. Upon entry, destLen is the total
  13    size of the destination buffer, which must be large enough to hold the
  14    entire uncompressed data. (The size of the uncompressed data must have
  15    been saved previously by the compressor and transmitted to the decompressor
  16    by some mechanism outside the scope of this compression library.)
  17    Upon exit, destLen is the actual size of the compressed buffer.
  18      This function can be used to decompress a whole file at once if the
  19    input file is mmap'ed.
  20
  21      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
  22    enough memory, Z_BUF_ERROR if there was not enough room in the output
  23    buffer, or Z_DATA_ERROR if the input data was corrupted.
  24 */
  25 int ZEXPORT uncompress (dest, destLen, source, sourceLen)
  26     Bytef *dest;
  27     uLongf *destLen;
  28     const Bytef *source;
  29     uLong sourceLen;
  30 {
  31     z_stream stream;
  32     int err;
  33
  34     stream.next_in = source;
  35     stream.avail_in = (uInt)sourceLen;
  36     /* Check for source > 64K on 16-bit machine: */
  37     if ((uLong)stream.avail_in != sourceLen) return Z_BUF_ERROR;
  38
  39     stream.next_out = dest;
  40     stream.avail_out = (uInt)*destLen;
  41     if ((uLong)stream.avail_out != *destLen) return Z_BUF_ERROR;
  42
  43     stream.zalloc = (alloc_func)0;
  44     stream.zfree = (free_func)0;
  45
  46     err = inflateInit(&stream);
  47     if (err != Z_OK) return err;
  48
  49     err = inflate(&stream, Z_FINISH);
  50     if (err != Z_STREAM_END) {
  51         inflateEnd(&stream);
  52         if (err == Z_NEED_DICT || (err == Z_BUF_ERROR && stream.avail_in == 0))
  53             return Z_DATA_ERROR;
  54         return err;
  55     }
  56     *destLen = stream.total_out;
  57
  58     err = inflateEnd(&stream);
  59     return err;
  60 }