CentrED/Imaging/ZLib/imzinflate.pas

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Unit imzinflate;
{ inflate.c -- zlib interface to inflate modules
Copyright (C) 1995-1998 Mark Adler
Pascal tranlastion
Copyright (C) 1998 by Jacques Nomssi Nzali
For conditions of distribution and use, see copyright notice in readme.txt
}
interface
{$I imzconf.inc}
uses
imzutil, impaszlib, iminfblock, iminfutil;
function inflateInit(var z : z_stream) : int;
{ Initializes the internal stream state for decompression. The fields
zalloc, zfree and opaque must be initialized before by the caller. If
zalloc and zfree are set to Z_NULL, inflateInit updates them to use default
allocation functions.
inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
enough memory, Z_VERSION_ERROR if the zlib library version is incompatible
with the version assumed by the caller. msg is set to null if there is no
error message. inflateInit does not perform any decompression: this will be
done by inflate(). }
function inflateInit_(z : z_streamp;
const version : string;
stream_size : int) : int;
function inflateInit2_(var z: z_stream;
w : int;
const version : string;
stream_size : int) : int;
function inflateInit2(var z: z_stream;
windowBits : int) : int;
{
This is another version of inflateInit with an extra parameter. The
fields next_in, avail_in, zalloc, zfree and opaque must be initialized
before by the caller.
The windowBits parameter is the base two logarithm of the maximum window
size (the size of the history buffer). It should be in the range 8..15 for
this version of the library. The default value is 15 if inflateInit is used
instead. If a compressed stream with a larger window size is given as
input, inflate() will return with the error code Z_DATA_ERROR instead of
trying to allocate a larger window.
inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
memLevel). msg is set to null if there is no error message. inflateInit2
does not perform any decompression apart from reading the zlib header if
present: this will be done by inflate(). (So next_in and avail_in may be
modified, but next_out and avail_out are unchanged.)
}
function inflateEnd(var z : z_stream) : int;
{
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).
}
function inflateReset(var z : z_stream) : int;
{
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).
}
function inflate(var z : z_stream;
f : int) : int;
{
inflate decompresses as much data as possible, and stops when the input
buffer becomes empty or the output buffer becomes full. It may 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.
}
function inflateSetDictionary(var z : z_stream;
dictionary : pBytef; {const array of byte}
dictLength : uInt) : int;
{
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 (see deflateSetDictionary).
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().
}
function inflateSync(var z : z_stream) : int;
{
Skips invalid compressed data until a full flush point (see above the
description of deflate with Z_FULL_FLUSH) 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.
}
function inflateSyncPoint(var z : z_stream) : int;
implementation
uses
imadler;
function inflateReset(var z : z_stream) : int;
begin
if (z.state = Z_NULL) then
begin
inflateReset := Z_STREAM_ERROR;
exit;
end;
z.total_out := 0;
z.total_in := 0;
z.msg := '';
if z.state^.nowrap then
z.state^.mode := BLOCKS
else
z.state^.mode := METHOD;
inflate_blocks_reset(z.state^.blocks^, z, Z_NULL);
{$IFDEF DEBUG}
Tracev('inflate: reset');
{$ENDIF}
inflateReset := Z_OK;
end;
function inflateEnd(var z : z_stream) : int;
begin
if (z.state = Z_NULL) or not Assigned(z.zfree) then
begin
inflateEnd := Z_STREAM_ERROR;
exit;
end;
if (z.state^.blocks <> Z_NULL) then
inflate_blocks_free(z.state^.blocks, z);
ZFREE(z, z.state);
z.state := Z_NULL;
{$IFDEF DEBUG}
Tracev('inflate: end');
{$ENDIF}
inflateEnd := Z_OK;
end;
function inflateInit2_(var z: z_stream;
w : int;
const version : string;
stream_size : int) : int;
begin
if (version = '') or (version[1] <> ZLIB_VERSION[1]) or
(stream_size <> sizeof(z_stream)) then
begin
inflateInit2_ := Z_VERSION_ERROR;
exit;
end;
{ initialize state }
{ SetLength(strm.msg, 255); }
z.msg := '';
if not Assigned(z.zalloc) then
begin
{$IFDEF FPC} z.zalloc := @zcalloc; {$ELSE}
z.zalloc := zcalloc;
{$endif}
z.opaque := voidpf(0);
end;
if not Assigned(z.zfree) then
{$IFDEF FPC} z.zfree := @zcfree; {$ELSE}
z.zfree := zcfree;
{$ENDIF}
z.state := pInternal_state( ZALLOC(z,1,sizeof(internal_state)) );
if (z.state = Z_NULL) then
begin
inflateInit2_ := Z_MEM_ERROR;
exit;
end;
z.state^.blocks := Z_NULL;
{ handle undocumented nowrap option (no zlib header or check) }
z.state^.nowrap := FALSE;
if (w < 0) then
begin
w := - w;
z.state^.nowrap := TRUE;
end;
{ set window size }
if (w < 8) or (w > 15) then
begin
inflateEnd(z);
inflateInit2_ := Z_STREAM_ERROR;
exit;
end;
z.state^.wbits := uInt(w);
{ create inflate_blocks state }
if z.state^.nowrap then
z.state^.blocks := inflate_blocks_new(z, NIL, uInt(1) shl w)
else
{$IFDEF FPC}
z.state^.blocks := inflate_blocks_new(z, @adler32, uInt(1) shl w);
{$ELSE}
z.state^.blocks := inflate_blocks_new(z, adler32, uInt(1) shl w);
{$ENDIF}
if (z.state^.blocks = Z_NULL) then
begin
inflateEnd(z);
inflateInit2_ := Z_MEM_ERROR;
exit;
end;
{$IFDEF DEBUG}
Tracev('inflate: allocated');
{$ENDIF}
{ reset state }
inflateReset(z);
inflateInit2_ := Z_OK;
end;
function inflateInit2(var z: z_stream; windowBits : int) : int;
begin
inflateInit2 := inflateInit2_(z, windowBits, ZLIB_VERSION, sizeof(z_stream));
end;
function inflateInit(var z : z_stream) : int;
{ inflateInit is a macro to allow checking the zlib version
and the compiler's view of z_stream: }
begin
inflateInit := inflateInit2_(z, DEF_WBITS, ZLIB_VERSION, sizeof(z_stream));
end;
function inflateInit_(z : z_streamp;
const version : string;
stream_size : int) : int;
begin
{ initialize state }
if (z = Z_NULL) then
inflateInit_ := Z_STREAM_ERROR
else
inflateInit_ := inflateInit2_(z^, DEF_WBITS, version, stream_size);
end;
function inflate(var z : z_stream;
f : int) : int;
var
r : int;
b : uInt;
begin
if (z.state = Z_NULL) or (z.next_in = Z_NULL) then
begin
inflate := Z_STREAM_ERROR;
exit;
end;
if f = Z_FINISH then
f := Z_BUF_ERROR
else
f := Z_OK;
r := Z_BUF_ERROR;
while True do
case (z.state^.mode) of
BLOCKS:
begin
r := inflate_blocks(z.state^.blocks^, z, r);
if (r = Z_DATA_ERROR) then
begin
z.state^.mode := BAD;
z.state^.sub.marker := 0; { can try inflateSync }
continue; { break C-switch }
end;
if (r = Z_OK) then
r := f;
if (r <> Z_STREAM_END) then
begin
inflate := r;
exit;
end;
r := f;
inflate_blocks_reset(z.state^.blocks^, z, @z.state^.sub.check.was);
if (z.state^.nowrap) then
begin
z.state^.mode := DONE;
continue; { break C-switch }
end;
z.state^.mode := CHECK4; { falltrough }
end;
CHECK4:
begin
{NEEDBYTE}
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f;
{z.state^.sub.check.need := uLong(NEXTBYTE(z)) shl 24;}
Dec(z.avail_in);
Inc(z.total_in);
z.state^.sub.check.need := uLong(z.next_in^) shl 24;
Inc(z.next_in);
z.state^.mode := CHECK3; { falltrough }
end;
CHECK3:
begin
{NEEDBYTE}
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f;
{Inc( z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 16);}
Dec(z.avail_in);
Inc(z.total_in);
Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 16);
Inc(z.next_in);
z.state^.mode := CHECK2; { falltrough }
end;
CHECK2:
begin
{NEEDBYTE}
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f;
{Inc( z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 8);}
Dec(z.avail_in);
Inc(z.total_in);
Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 8);
Inc(z.next_in);
z.state^.mode := CHECK1; { falltrough }
end;
CHECK1:
begin
{NEEDBYTE}
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f;
{Inc( z.state^.sub.check.need, uLong(NEXTBYTE(z)) );}
Dec(z.avail_in);
Inc(z.total_in);
Inc(z.state^.sub.check.need, uLong(z.next_in^) );
Inc(z.next_in);
if (z.state^.sub.check.was <> z.state^.sub.check.need) then
begin
z.state^.mode := BAD;
z.msg := 'incorrect data check';
z.state^.sub.marker := 5; { can't try inflateSync }
continue; { break C-switch }
end;
{$IFDEF DEBUG}
Tracev('inflate: zlib check ok');
{$ENDIF}
z.state^.mode := DONE; { falltrough }
end;
DONE:
begin
inflate := Z_STREAM_END;
exit;
end;
METHOD:
begin
{NEEDBYTE}
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f; {}
{z.state^.sub.method := NEXTBYTE(z);}
Dec(z.avail_in);
Inc(z.total_in);
z.state^.sub.method := z.next_in^;
Inc(z.next_in);
if ((z.state^.sub.method and $0f) <> Z_DEFLATED) then
begin
z.state^.mode := BAD;
z.msg := 'unknown compression method';
z.state^.sub.marker := 5; { can't try inflateSync }
continue; { break C-switch }
end;
if ((z.state^.sub.method shr 4) + 8 > z.state^.wbits) then
begin
z.state^.mode := BAD;
z.msg := 'invalid window size';
z.state^.sub.marker := 5; { can't try inflateSync }
continue; { break C-switch }
end;
z.state^.mode := FLAG;
{ fall trough }
end;
FLAG:
begin
{NEEDBYTE}
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f; {}
{b := NEXTBYTE(z);}
Dec(z.avail_in);
Inc(z.total_in);
b := z.next_in^;
Inc(z.next_in);
if (((z.state^.sub.method shl 8) + b) mod 31) <> 0 then {% mod ?}
begin
z.state^.mode := BAD;
z.msg := 'incorrect header check';
z.state^.sub.marker := 5; { can't try inflateSync }
continue; { break C-switch }
end;
{$IFDEF DEBUG}
Tracev('inflate: zlib header ok');
{$ENDIF}
if ((b and PRESET_DICT) = 0) then
begin
z.state^.mode := BLOCKS;
continue; { break C-switch }
end;
z.state^.mode := DICT4;
{ falltrough }
end;
DICT4:
begin
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f;
{z.state^.sub.check.need := uLong(NEXTBYTE(z)) shl 24;}
Dec(z.avail_in);
Inc(z.total_in);
z.state^.sub.check.need := uLong(z.next_in^) shl 24;
Inc(z.next_in);
z.state^.mode := DICT3; { falltrough }
end;
DICT3:
begin
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f;
{Inc(z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 16);}
Dec(z.avail_in);
Inc(z.total_in);
Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 16);
Inc(z.next_in);
z.state^.mode := DICT2; { falltrough }
end;
DICT2:
begin
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
r := f;
{Inc(z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 8);}
Dec(z.avail_in);
Inc(z.total_in);
Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 8);
Inc(z.next_in);
z.state^.mode := DICT1; { falltrough }
end;
DICT1:
begin
if (z.avail_in = 0) then
begin
inflate := r;
exit;
end;
{ r := f; --- wird niemals benutzt }
{Inc(z.state^.sub.check.need, uLong(NEXTBYTE(z)) );}
Dec(z.avail_in);
Inc(z.total_in);
Inc(z.state^.sub.check.need, uLong(z.next_in^) );
Inc(z.next_in);
z.adler := z.state^.sub.check.need;
z.state^.mode := DICT0;
inflate := Z_NEED_DICT;
exit;
end;
DICT0:
begin
z.state^.mode := BAD;
z.msg := 'need dictionary';
z.state^.sub.marker := 0; { can try inflateSync }
inflate := Z_STREAM_ERROR;
exit;
end;
BAD:
begin
inflate := Z_DATA_ERROR;
exit;
end;
else
begin
inflate := Z_STREAM_ERROR;
exit;
end;
end;
{$ifdef NEED_DUMMY_result}
result := Z_STREAM_ERROR; { Some dumb compilers complain without this }
{$endif}
end;
function inflateSetDictionary(var z : z_stream;
dictionary : pBytef; {const array of byte}
dictLength : uInt) : int;
var
length : uInt;
begin
length := dictLength;
if (z.state = Z_NULL) or (z.state^.mode <> DICT0) then
begin
inflateSetDictionary := Z_STREAM_ERROR;
exit;
end;
if (adler32(Long(1), dictionary, dictLength) <> z.adler) then
begin
inflateSetDictionary := Z_DATA_ERROR;
exit;
end;
z.adler := Long(1);
if (length >= (uInt(1) shl z.state^.wbits)) then
begin
length := (1 shl z.state^.wbits)-1;
Inc( dictionary, dictLength - length);
end;
inflate_set_dictionary(z.state^.blocks^, dictionary^, length);
z.state^.mode := BLOCKS;
inflateSetDictionary := Z_OK;
end;
function inflateSync(var z : z_stream) : int;
const
mark : packed array[0..3] of byte = (0, 0, $ff, $ff);
var
n : uInt; { number of bytes to look at }
p : pBytef; { pointer to bytes }
m : uInt; { number of marker bytes found in a row }
r, w : uLong; { temporaries to save total_in and total_out }
begin
{ set up }
if (z.state = Z_NULL) then
begin
inflateSync := Z_STREAM_ERROR;
exit;
end;
if (z.state^.mode <> BAD) then
begin
z.state^.mode := BAD;
z.state^.sub.marker := 0;
end;
n := z.avail_in;
if (n = 0) then
begin
inflateSync := Z_BUF_ERROR;
exit;
end;
p := z.next_in;
m := z.state^.sub.marker;
{ search }
while (n <> 0) and (m < 4) do
begin
if (p^ = mark[m]) then
Inc(m)
else
if (p^ <> 0) then
m := 0
else
m := 4 - m;
Inc(p);
Dec(n);
end;
{ restore }
Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
z.next_in := p;
z.avail_in := n;
z.state^.sub.marker := m;
{ return no joy or set up to restart on a new block }
if (m <> 4) then
begin
inflateSync := Z_DATA_ERROR;
exit;
end;
r := z.total_in;
w := z.total_out;
inflateReset(z);
z.total_in := r;
z.total_out := w;
z.state^.mode := BLOCKS;
inflateSync := Z_OK;
end;
{
returns true if inflate is currently at the end of a block generated
by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
but removes the length bytes of the resulting empty stored block. When
decompressing, PPP checks that at the end of input packet, inflate is
waiting for these length bytes.
}
function inflateSyncPoint(var z : z_stream) : int;
begin
if (z.state = Z_NULL) or (z.state^.blocks = Z_NULL) then
begin
inflateSyncPoint := Z_STREAM_ERROR;
exit;
end;
inflateSyncPoint := inflate_blocks_sync_point(z.state^.blocks^);
end;
end.