?? ftlzw.c
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/***************************************************************************//* *//* 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 2004, 2005, 2006 by *//* Albert Chin-A-Young. *//* *//* Based on code in src/gzip/ftgzip.c, Copyright 2004 by *//* David Turner, Robert Wilhelm, and Werner Lemberg. *//* *//* 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 <ft2build.h>#include FT_INTERNAL_MEMORY_H#include FT_INTERNAL_STREAM_H#include FT_INTERNAL_DEBUG_H#include FT_LZW_H#include <string.h>#include <stdio.h>#include FT_MODULE_ERRORS_H#undef __FTERRORS_H__#define FT_ERR_PREFIX LZW_Err_#define FT_ERR_BASE FT_Mod_Err_LZW#include FT_ERRORS_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 = LZW_Err_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 = LZW_Err_Ok; 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 */ { stream = source; 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 = 0; zip->cursor = zip->buffer; count = ft_lzwstate_io( lzw, zip->buffer, FT_LZW_BUFFER_SIZE ); zip->limit = zip->cursor + count; if ( count == 0 ) error = LZW_Err_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 = LZW_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 = LZW_Err_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 FT_ULong ft_lzw_stream_io( FT_Stream stream, FT_ULong pos, FT_Byte* buffer, FT_ULong count ) { FT_LZWFile zip = (FT_LZWFile)stream->descriptor.pointer; return ft_lzw_file_io( zip, pos, buffer, count ); } FT_EXPORT_DEF( FT_Error ) FT_Stream_OpenLZW( FT_Stream stream, FT_Stream source ) { FT_Error error; FT_Memory memory = source->memory; FT_LZWFile zip; /* * 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 = 0; 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 LZW_Err_Unimplemented_Feature; }#endif /* !FT_CONFIG_OPTION_USE_LZW *//* END */?? 快捷鍵說明
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