ref: d6a5c57727643fc7a0d30e10776edf9c2c5956ae
dir: /src/lzw/ftlzw.c/
/****************************************************************************
*
* ftlzw.c
*
* FreeType support for .Z compressed files.
*
* This optional component relies on NetBSD's zopen(). It should mainly
* be used to parse compressed PCF fonts, as found with many X11 server
* distributions.
*
* Copyright (C) 2004-2021 by
* Albert Chin-A-Young.
*
* based on code in `src/gzip/ftgzip.c'
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
#include <freetype/internal/ftmemory.h>
#include <freetype/internal/ftstream.h>
#include <freetype/internal/ftdebug.h>
#include <freetype/ftlzw.h>
#include FT_CONFIG_STANDARD_LIBRARY_H
#include <freetype/ftmoderr.h>
#undef FTERRORS_H_
#undef FT_ERR_PREFIX
#define FT_ERR_PREFIX LZW_Err_
#define FT_ERR_BASE FT_Mod_Err_LZW
#include <freetype/fterrors.h>
#ifdef FT_CONFIG_OPTION_USE_LZW
#include "ftzopen.h"
/***************************************************************************/
/***************************************************************************/
/***** *****/
/***** M E M O R Y M A N A G E M E N T *****/
/***** *****/
/***************************************************************************/
/***************************************************************************/
/***************************************************************************/
/***************************************************************************/
/***** *****/
/***** F I L E D E S C R I P T O R *****/
/***** *****/
/***************************************************************************/
/***************************************************************************/
#define FT_LZW_BUFFER_SIZE 4096
typedef struct FT_LZWFileRec_
{
FT_Stream source; /* parent/source stream */
FT_Stream stream; /* embedding stream */
FT_Memory memory; /* memory allocator */
FT_LzwStateRec lzw; /* lzw decompressor state */
FT_Byte buffer[FT_LZW_BUFFER_SIZE]; /* output buffer */
FT_ULong pos; /* position in output */
FT_Byte* cursor;
FT_Byte* limit;
} FT_LZWFileRec, *FT_LZWFile;
/* check and skip .Z header */
static FT_Error
ft_lzw_check_header( FT_Stream stream )
{
FT_Error error;
FT_Byte head[2];
if ( FT_STREAM_SEEK( 0 ) ||
FT_STREAM_READ( head, 2 ) )
goto Exit;
/* head[0] && head[1] are the magic numbers */
if ( head[0] != 0x1F ||
head[1] != 0x9D )
error = FT_THROW( Invalid_File_Format );
Exit:
return error;
}
static FT_Error
ft_lzw_file_init( FT_LZWFile zip,
FT_Stream stream,
FT_Stream source )
{
FT_LzwState lzw = &zip->lzw;
FT_Error error;
zip->stream = stream;
zip->source = source;
zip->memory = stream->memory;
zip->limit = zip->buffer + FT_LZW_BUFFER_SIZE;
zip->cursor = zip->limit;
zip->pos = 0;
/* check and skip .Z header */
error = ft_lzw_check_header( source );
if ( error )
goto Exit;
/* initialize internal lzw variable */
ft_lzwstate_init( lzw, source );
Exit:
return error;
}
static void
ft_lzw_file_done( FT_LZWFile zip )
{
/* clear the rest */
ft_lzwstate_done( &zip->lzw );
zip->memory = NULL;
zip->source = NULL;
zip->stream = NULL;
}
static FT_Error
ft_lzw_file_reset( FT_LZWFile zip )
{
FT_Stream stream = zip->source;
FT_Error error;
if ( !FT_STREAM_SEEK( 0 ) )
{
ft_lzwstate_reset( &zip->lzw );
zip->limit = zip->buffer + FT_LZW_BUFFER_SIZE;
zip->cursor = zip->limit;
zip->pos = 0;
}
return error;
}
static FT_Error
ft_lzw_file_fill_output( FT_LZWFile zip )
{
FT_LzwState lzw = &zip->lzw;
FT_ULong count;
FT_Error error = FT_Err_Ok;
zip->cursor = zip->buffer;
count = ft_lzwstate_io( lzw, zip->buffer, FT_LZW_BUFFER_SIZE );
zip->limit = zip->cursor + count;
if ( count == 0 )
error = FT_THROW( Invalid_Stream_Operation );
return error;
}
/* fill output buffer; `count' must be <= FT_LZW_BUFFER_SIZE */
static FT_Error
ft_lzw_file_skip_output( FT_LZWFile zip,
FT_ULong count )
{
FT_Error error = FT_Err_Ok;
/* first, we skip what we can from the output buffer */
{
FT_ULong delta = (FT_ULong)( zip->limit - zip->cursor );
if ( delta >= count )
delta = count;
zip->cursor += delta;
zip->pos += delta;
count -= delta;
}
/* next, we skip as many bytes remaining as possible */
while ( count > 0 )
{
FT_ULong delta = FT_LZW_BUFFER_SIZE;
FT_ULong numread;
if ( delta > count )
delta = count;
numread = ft_lzwstate_io( &zip->lzw, NULL, delta );
if ( numread < delta )
{
/* not enough bytes */
error = FT_THROW( Invalid_Stream_Operation );
break;
}
zip->pos += delta;
count -= delta;
}
return error;
}
static FT_ULong
ft_lzw_file_io( FT_LZWFile zip,
FT_ULong pos,
FT_Byte* buffer,
FT_ULong count )
{
FT_ULong result = 0;
FT_Error error;
/* seeking backwards. */
if ( pos < zip->pos )
{
/* If the new position is within the output buffer, simply */
/* decrement pointers, otherwise we reset the stream completely! */
if ( ( zip->pos - pos ) <= (FT_ULong)( zip->cursor - zip->buffer ) )
{
zip->cursor -= zip->pos - pos;
zip->pos = pos;
}
else
{
error = ft_lzw_file_reset( zip );
if ( error )
goto Exit;
}
}
/* skip unwanted bytes */
if ( pos > zip->pos )
{
error = ft_lzw_file_skip_output( zip, (FT_ULong)( pos - zip->pos ) );
if ( error )
goto Exit;
}
if ( count == 0 )
goto Exit;
/* now read the data */
for (;;)
{
FT_ULong delta;
delta = (FT_ULong)( zip->limit - zip->cursor );
if ( delta >= count )
delta = count;
FT_MEM_COPY( buffer + result, zip->cursor, delta );
result += delta;
zip->cursor += delta;
zip->pos += delta;
count -= delta;
if ( count == 0 )
break;
error = ft_lzw_file_fill_output( zip );
if ( error )
break;
}
Exit:
return result;
}
/***************************************************************************/
/***************************************************************************/
/***** *****/
/***** L Z W E M B E D D I N G S T R E A M *****/
/***** *****/
/***************************************************************************/
/***************************************************************************/
static void
ft_lzw_stream_close( FT_Stream stream )
{
FT_LZWFile zip = (FT_LZWFile)stream->descriptor.pointer;
FT_Memory memory = stream->memory;
if ( zip )
{
/* finalize lzw file descriptor */
ft_lzw_file_done( zip );
FT_FREE( zip );
stream->descriptor.pointer = NULL;
}
}
static unsigned long
ft_lzw_stream_io( FT_Stream stream,
unsigned long offset,
unsigned char* buffer,
unsigned long count )
{
FT_LZWFile zip = (FT_LZWFile)stream->descriptor.pointer;
return ft_lzw_file_io( zip, offset, buffer, count );
}
FT_EXPORT_DEF( FT_Error )
FT_Stream_OpenLZW( FT_Stream stream,
FT_Stream source )
{
FT_Error error;
FT_Memory memory;
FT_LZWFile zip = NULL;
if ( !stream || !source )
{
error = FT_THROW( Invalid_Stream_Handle );
goto Exit;
}
memory = source->memory;
/*
* Check the header right now; this prevents allocation of a huge
* LZWFile object (400 KByte of heap memory) if not necessary.
*
* Did I mention that you should never use .Z compressed font
* files?
*/
error = ft_lzw_check_header( source );
if ( error )
goto Exit;
FT_ZERO( stream );
stream->memory = memory;
if ( !FT_NEW( zip ) )
{
error = ft_lzw_file_init( zip, stream, source );
if ( error )
{
FT_FREE( zip );
goto Exit;
}
stream->descriptor.pointer = zip;
}
stream->size = 0x7FFFFFFFL; /* don't know the real size! */
stream->pos = 0;
stream->base = NULL;
stream->read = ft_lzw_stream_io;
stream->close = ft_lzw_stream_close;
Exit:
return error;
}
#include "ftzopen.c"
#else /* !FT_CONFIG_OPTION_USE_LZW */
FT_EXPORT_DEF( FT_Error )
FT_Stream_OpenLZW( FT_Stream stream,
FT_Stream source )
{
FT_UNUSED( stream );
FT_UNUSED( source );
return FT_THROW( Unimplemented_Feature );
}
#endif /* !FT_CONFIG_OPTION_USE_LZW */
/* END */