xunzip.cpp

压缩/解压缩类源码

//   The application must update next_in and avail_in when avail_in has
//   dropped to zero. It must update next_out and avail_out when avail_out
//   has dropped to zero. The application must initialize zalloc, zfree and
//   opaque before calling the init function. All other fields are set by the
//   compression library and must not be updated by the application.
//
//   The opaque value provided by the application will be passed as the first
//   parameter for calls of zalloc and zfree. This can be useful for custom
//   memory management. The compression library attaches no meaning to the
//   opaque value.
//
//   zalloc must return Z_NULL if there is not enough memory for the object.
//   If zlib is used in a multi-threaded application, zalloc and zfree must be
//   thread safe.
//
//   The fields total_in and total_out can be used for statistics or
//   progress reports. After compression, total_in holds the total size of
//   the uncompressed data and may be saved for use in the decompressor
//   (particularly if the decompressor wants to decompress everything in
//   a single step).
//


// basic functions

const char *zlibVersion ();
// The application can compare zlibVersion and ZLIB_VERSION for consistency.
// If the first character differs, the library code actually used is
// not compatible with the zlib.h header file used by the application.
// This check is automatically made by inflateInit.






int inflate (z_streamp strm, int flush);
//
//    inflate decompresses as much data as possible, and stops when the input
//  buffer becomes empty or the output buffer becomes full. It may some
//  introduce some output latency (reading input without producing any output)
//  except when forced to flush.
//
//  The detailed semantics are as follows. inflate performs one or both of the
//  following actions:
//
//  - Decompress more input starting at next_in and update next_in and avail_in
//    accordingly. If not all input can be processed (because there is not
//    enough room in the output buffer), next_in is updated and processing
//    will resume at this point for the next call of inflate().
//
//  - Provide more output starting at next_out and update next_out and avail_out
//    accordingly.  inflate() provides as much output as possible, until there
//    is no more input data or no more space in the output buffer (see below
//    about the flush parameter).
//
//  Before the call of inflate(), the application should ensure that at least
//  one of the actions is possible, by providing more input and/or consuming
//  more output, and updating the next_* and avail_* values accordingly.
//  The application can consume the uncompressed output when it wants, for
//  example when the output buffer is full (avail_out == 0), or after each
//  call of inflate(). If inflate returns Z_OK and with zero avail_out, it
//  must be called again after making room in the output buffer because there
//  might be more output pending.
//
//    If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
//  output as possible to the output buffer. The flushing behavior of inflate is
//  not specified for values of the flush parameter other than Z_SYNC_FLUSH
//  and Z_FINISH, but the current implementation actually flushes as much output
//  as possible anyway.
//
//    inflate() should normally be called until it returns Z_STREAM_END or an
//  error. However if all decompression is to be performed in a single step
//  (a single call of inflate), the parameter flush should be set to
//  Z_FINISH. In this case all pending input is processed and all pending
//  output is flushed; avail_out must be large enough to hold all the
//  uncompressed data. (The size of the uncompressed data may have been saved
//  by the compressor for this purpose.) The next operation on this stream must
//  be inflateEnd to deallocate the decompression state. The use of Z_FINISH
//  is never required, but can be used to inform inflate that a faster routine
//  may be used for the single inflate() call.
//
//     If a preset dictionary is needed at this point (see inflateSetDictionary
//  below), inflate sets strm-adler to the adler32 checksum of the
//  dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
//  it sets strm->adler to the adler32 checksum of all output produced
//  so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
//  an error code as described below. At the end of the stream, inflate()
//  checks that its computed adler32 checksum is equal to that saved by the
//  compressor and returns Z_STREAM_END only if the checksum is correct.
//
//    inflate() returns Z_OK if some progress has been made (more input processed
//  or more output produced), Z_STREAM_END if the end of the compressed data has
//  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
//  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
//  corrupted (input stream not conforming to the zlib format or incorrect
//  adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
//  (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
//  enough memory, Z_BUF_ERROR if no progress is possible or if there was not
//  enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
//  case, the application may then call inflateSync to look for a good
//  compression block.
//


int inflateEnd (z_streamp strm);
//
//     All dynamically allocated data structures for this stream are freed.
//   This function discards any unprocessed input and does not flush any
//   pending output.
//
//     inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
//   was inconsistent. In the error case, msg may be set but then points to a
//   static string (which must not be deallocated).

                        // Advanced functions 

//  The following functions are needed only in some special applications.





int inflateSetDictionary (z_streamp strm,
                                             const Byte *dictionary,
                                             uInt  dictLength);
//
//     Initializes the decompression dictionary from the given uncompressed byte
//   sequence. This function must be called immediately after a call of inflate
//   if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
//   can be determined from the Adler32 value returned by this call of
//   inflate. The compressor and decompressor must use exactly the same
//   dictionary. 
//
//     inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
//   parameter is invalid (such as NULL dictionary) or the stream state is
//   inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
//   expected one (incorrect Adler32 value). inflateSetDictionary does not
//   perform any decompression: this will be done by subsequent calls of
//   inflate().


int inflateSync (z_streamp strm);
// 
//    Skips invalid compressed data until a full flush point can be found, or until all
//  available input is skipped. No output is provided.
//
//    inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
//  if no more input was provided, Z_DATA_ERROR if no flush point has been found,
//  or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
//  case, the application may save the current current value of total_in which
//  indicates where valid compressed data was found. In the error case, the
//  application may repeatedly call inflateSync, providing more input each time,
//  until success or end of the input data.


int inflateReset (z_streamp strm);
//     This function is equivalent to inflateEnd followed by inflateInit,
//   but does not free and reallocate all the internal decompression state.
//   The stream will keep attributes that may have been set by inflateInit2.
//
//      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
//   stream state was inconsistent (such as zalloc or state being NULL).
//



// checksum functions
// These functions are not related to compression but are exported
// anyway because they might be useful in applications using the
// compression library.

uLong adler32 (uLong adler, const Byte *buf, uInt len);
//     Update a running Adler-32 checksum with the bytes buf[0..len-1] and
//   return the updated checksum. If buf is NULL, this function returns
//   the required initial value for the checksum.
//   An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
//   much faster. Usage example:
//
//     uLong adler = adler32(0L, Z_NULL, 0);
//
//     while (read_buffer(buffer, length) != EOF) {
//       adler = adler32(adler, buffer, length);
//     }
//     if (adler != original_adler) error();

uLong ucrc32   (uLong crc, const Byte *buf, uInt len);
//     Update a running crc with the bytes buf[0..len-1] and return the updated
//   crc. If buf is NULL, this function returns the required initial value
//   for the crc. Pre- and post-conditioning (one's complement) is performed
//   within this function so it shouldn't be done by the application.
//   Usage example:
//
//     uLong crc = crc32(0L, Z_NULL, 0);
//
//     while (read_buffer(buffer, length) != EOF) {
//       crc = crc32(crc, buffer, length);
//     }
//     if (crc != original_crc) error();




const char   *zError           (int err);
int           inflateSyncPoint (z_streamp z);
const uLong *get_crc_table    (void);



typedef unsigned char  uch;
typedef uch uchf;
typedef unsigned short ush;
typedef ush ushf;
typedef unsigned long  ulg;



const char * const z_errmsg[10] = { // indexed by 2-zlib_error
"need dictionary",     // Z_NEED_DICT       2
"stream end",          // Z_STREAM_END      1
"",                    // Z_OK              0
"file error",          // Z_ERRNO         (-1)
"stream error",        // Z_STREAM_ERROR  (-2)
"data error",          // Z_DATA_ERROR    (-3)
"insufficient memory", // Z_MEM_ERROR     (-4)
"buffer error",        // Z_BUF_ERROR     (-5)
"incompatible version",// Z_VERSION_ERROR (-6)
""};


#define ERR_MSG(err) z_errmsg[Z_NEED_DICT-(err)]

#define ERR_RETURN(strm,err) \
  return (strm->msg = (char*)ERR_MSG(err), (err))
// To be used only when the state is known to be valid 

        // common constants


#define STORED_BLOCK 0
#define STATIC_TREES 1
#define DYN_TREES    2
// The three kinds of block type 

#define MIN_MATCH  3
#define MAX_MATCH  258
// The minimum and maximum match lengths 

#define PRESET_DICT 0x20 // preset dictionary flag in zlib header 

        // target dependencies 

#define OS_CODE  0x0b  // Window 95 & Windows NT



         // functions 

#define zmemzero(dest, len) memset(dest, 0, len)

// Diagnostic functions
#undef Assert
#undef Trace
#undef Tracev
#undef Tracevv
#undef Tracec
#undef Tracecv

#ifdef DEBUG
  int z_verbose = 0;
  void z_error (char *m) {fprintf(stderr, "%s\n", m); exit(1);}
#  define Assert(cond,msg) {if(!(cond)) z_error(msg);}
#  define Trace(x) {if (z_verbose>=0) fprintf x ;}
#  define Tracev(x) {if (z_verbose>0) fprintf x ;}
#  define Tracevv(x) {if (z_verbose>1) fprintf x ;}
#  define Tracec(c,x) {if (z_verbose>0 && (c)) fprintf x ;}
#  define Tracecv(c,x) {if (z_verbose>1 && (c)) fprintf x ;}
#else
#  define Assert(cond,msg)
#  define Trace(x)
#  define Tracev(x)
#  define Tracevv(x)
#  define Tracec(c,x)
#  define Tracecv(c,x)
#endif


typedef uLong (*check_func) (uLong check, const Byte *buf, uInt len);
voidpf zcalloc (voidpf opaque, unsigned items, unsigned size);
void   zcfree  (voidpf opaque, voidpf ptr);

#define ZALLOC(strm, items, size) \
           (*((strm)->zalloc))((strm)->opaque, (items), (size))
#define ZFREE(strm, addr)  (*((strm)->zfree))((strm)->opaque, (voidpf)(addr))

//void ZFREE(z_streamp strm,voidpf addr)
//{ *((strm)->zfree))((strm)->opaque, addr);
//}

#define TRY_FREE(s, p) {if (p) ZFREE(s, p);}




// Huffman code lookup table entry--this entry is four bytes for machines
// that have 16-bit pointers (e.g. PC's in the small or medium model).


typedef struct inflate_huft_s inflate_huft;

struct inflate_huft_s {
  union {
    struct {
      Byte Exop;        // number of extra bits or operation
      Byte Bits;        // number of bits in this code or subcode
    } what;
    uInt pad;           // pad structure to a power of 2 (4 bytes for
  } word;               //  16-bit, 8 bytes for 32-bit int's)
  uInt base;            // literal, length base, distance base, or table offset
};

// Maximum size of dynamic tree.  The maximum found in a long but non-
//   exhaustive search was 1004 huft structures (850 for length/literals
//   and 154 for distances, the latter actually the result of an
//   exhaustive search).  The actual maximum is not known, but the
//   value below is more than safe.
#define MANY 1440

int inflate_trees_bits (
    uInt *,                    // 19 code lengths
    uInt *,                    // bits tree desired/actual depth
    inflate_huft * *,       // bits tree result
    inflate_huft *,             // space for trees
    z_streamp);                // for messages

int inflate_trees_dynamic (
    uInt,                       // number of literal/length codes
    uInt,                       // number of distance codes
    uInt *,                    // that many (total) code lengths
    uInt *,                    // literal desired/actual bit depth
    uInt *,                    // distance desired/actual bit depth
    inflate_huft * *,       // literal/length tree result
    inflate_huft * *,       // distance tree result