425 lines
10 KiB
C
425 lines
10 KiB
C
/****************************************************************************
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*
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* ftzopen.c
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*
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* FreeType support for .Z compressed files.
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*
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* This optional component relies on NetBSD's zopen(). It should mainly
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* be used to parse compressed PCF fonts, as found with many X11 server
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* distributions.
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*
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* Copyright (C) 2005-2021 by
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* David Turner.
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*
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* This file is part of the FreeType project, and may only be used,
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* modified, and distributed under the terms of the FreeType project
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* license, LICENSE.TXT. By continuing to use, modify, or distribute
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* this file you indicate that you have read the license and
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* understand and accept it fully.
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*
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*/
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#include "ftzopen.h"
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#include <freetype/internal/ftmemory.h>
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#include <freetype/internal/ftstream.h>
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#include <freetype/internal/ftdebug.h>
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static int
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ft_lzwstate_refill( FT_LzwState state )
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{
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FT_ULong count;
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if ( state->in_eof )
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return -1;
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count = FT_Stream_TryRead( state->source,
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state->buf_tab,
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state->num_bits ); /* WHY? */
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state->buf_size = (FT_UInt)count;
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state->buf_total += count;
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state->in_eof = FT_BOOL( count < state->num_bits );
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state->buf_offset = 0;
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state->buf_size <<= 3;
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if ( state->buf_size > state->num_bits )
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state->buf_size -= state->num_bits - 1;
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else
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return -1; /* not enough data */
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if ( count == 0 ) /* end of file */
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return -1;
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return 0;
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}
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static FT_Int32
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ft_lzwstate_get_code( FT_LzwState state )
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{
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FT_UInt num_bits = state->num_bits;
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FT_UInt offset = state->buf_offset;
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FT_Byte* p;
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FT_Int result;
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if ( state->buf_clear ||
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offset >= state->buf_size ||
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state->free_ent >= state->free_bits )
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{
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if ( state->free_ent >= state->free_bits )
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{
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state->num_bits = ++num_bits;
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if ( num_bits > LZW_MAX_BITS )
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return -1;
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state->free_bits = state->num_bits < state->max_bits
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? (FT_UInt)( ( 1UL << num_bits ) - 256 )
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: state->max_free + 1;
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}
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if ( state->buf_clear )
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{
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state->num_bits = num_bits = LZW_INIT_BITS;
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state->free_bits = (FT_UInt)( ( 1UL << num_bits ) - 256 );
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state->buf_clear = 0;
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}
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if ( ft_lzwstate_refill( state ) < 0 )
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return -1;
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offset = 0;
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}
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state->buf_offset = offset + num_bits;
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p = &state->buf_tab[offset >> 3];
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offset &= 7;
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result = *p++ >> offset;
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offset = 8 - offset;
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num_bits -= offset;
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if ( num_bits >= 8 )
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{
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result |= *p++ << offset;
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offset += 8;
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num_bits -= 8;
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}
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if ( num_bits > 0 )
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result |= ( *p & LZW_MASK( num_bits ) ) << offset;
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return result;
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}
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/* grow the character stack */
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static int
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ft_lzwstate_stack_grow( FT_LzwState state )
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{
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if ( state->stack_top >= state->stack_size )
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{
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FT_Memory memory = state->memory;
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FT_Error error;
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FT_Offset old_size = state->stack_size;
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FT_Offset new_size = old_size;
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new_size = new_size + ( new_size >> 1 ) + 4;
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if ( state->stack == state->stack_0 )
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{
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state->stack = NULL;
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old_size = 0;
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}
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/* requirement of the character stack larger than 1<<LZW_MAX_BITS */
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/* implies bug in the decompression code */
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if ( new_size > ( 1 << LZW_MAX_BITS ) )
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{
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new_size = 1 << LZW_MAX_BITS;
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if ( new_size == old_size )
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return -1;
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}
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if ( FT_RENEW_ARRAY( state->stack, old_size, new_size ) )
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return -1;
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state->stack_size = new_size;
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}
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return 0;
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}
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/* grow the prefix/suffix arrays */
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static int
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ft_lzwstate_prefix_grow( FT_LzwState state )
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{
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FT_UInt old_size = state->prefix_size;
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FT_UInt new_size = old_size;
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FT_Memory memory = state->memory;
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FT_Error error;
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if ( new_size == 0 ) /* first allocation -> 9 bits */
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new_size = 512;
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else
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new_size += new_size >> 2; /* don't grow too fast */
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/*
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* Note that the `suffix' array is located in the same memory block
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* pointed to by `prefix'.
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*
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* I know that sizeof(FT_Byte) == 1 by definition, but it is clearer
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* to write it literally.
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*
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*/
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if ( FT_REALLOC_MULT( state->prefix, old_size, new_size,
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sizeof ( FT_UShort ) + sizeof ( FT_Byte ) ) )
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return -1;
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/* now adjust `suffix' and move the data accordingly */
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state->suffix = (FT_Byte*)( state->prefix + new_size );
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FT_MEM_MOVE( state->suffix,
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state->prefix + old_size,
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old_size * sizeof ( FT_Byte ) );
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state->prefix_size = new_size;
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return 0;
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}
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FT_LOCAL_DEF( void )
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ft_lzwstate_reset( FT_LzwState state )
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{
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state->in_eof = 0;
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state->buf_offset = 0;
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state->buf_size = 0;
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state->buf_clear = 0;
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state->buf_total = 0;
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state->stack_top = 0;
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state->num_bits = LZW_INIT_BITS;
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state->phase = FT_LZW_PHASE_START;
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}
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FT_LOCAL_DEF( void )
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ft_lzwstate_init( FT_LzwState state,
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FT_Stream source )
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{
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FT_ZERO( state );
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state->source = source;
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state->memory = source->memory;
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state->prefix = NULL;
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state->suffix = NULL;
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state->prefix_size = 0;
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state->stack = state->stack_0;
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state->stack_size = sizeof ( state->stack_0 );
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ft_lzwstate_reset( state );
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}
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FT_LOCAL_DEF( void )
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ft_lzwstate_done( FT_LzwState state )
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{
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FT_Memory memory = state->memory;
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ft_lzwstate_reset( state );
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if ( state->stack != state->stack_0 )
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FT_FREE( state->stack );
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FT_FREE( state->prefix );
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state->suffix = NULL;
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FT_ZERO( state );
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}
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#define FTLZW_STACK_PUSH( c ) \
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FT_BEGIN_STMNT \
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if ( state->stack_top >= state->stack_size && \
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ft_lzwstate_stack_grow( state ) < 0 ) \
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goto Eof; \
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\
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state->stack[state->stack_top++] = (FT_Byte)(c); \
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FT_END_STMNT
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FT_LOCAL_DEF( FT_ULong )
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ft_lzwstate_io( FT_LzwState state,
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FT_Byte* buffer,
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FT_ULong out_size )
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{
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FT_ULong result = 0;
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FT_UInt old_char = state->old_char;
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FT_UInt old_code = state->old_code;
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FT_UInt in_code = state->in_code;
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if ( out_size == 0 )
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goto Exit;
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switch ( state->phase )
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{
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case FT_LZW_PHASE_START:
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{
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FT_Byte max_bits;
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FT_Int32 c;
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/* skip magic bytes, and read max_bits + block_flag */
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if ( FT_Stream_Seek( state->source, 2 ) != 0 ||
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FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 )
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goto Eof;
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state->max_bits = max_bits & LZW_BIT_MASK;
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state->block_mode = max_bits & LZW_BLOCK_MASK;
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state->max_free = (FT_UInt)( ( 1UL << state->max_bits ) - 256 );
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if ( state->max_bits > LZW_MAX_BITS )
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goto Eof;
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state->num_bits = LZW_INIT_BITS;
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state->free_ent = ( state->block_mode ? LZW_FIRST
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: LZW_CLEAR ) - 256;
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in_code = 0;
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state->free_bits = state->num_bits < state->max_bits
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? (FT_UInt)( ( 1UL << state->num_bits ) - 256 )
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: state->max_free + 1;
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c = ft_lzwstate_get_code( state );
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if ( c < 0 || c > 255 )
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goto Eof;
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old_code = old_char = (FT_UInt)c;
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if ( buffer )
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buffer[result] = (FT_Byte)old_char;
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if ( ++result >= out_size )
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goto Exit;
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state->phase = FT_LZW_PHASE_CODE;
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}
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/* fall-through */
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case FT_LZW_PHASE_CODE:
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{
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FT_Int32 c;
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FT_UInt code;
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NextCode:
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c = ft_lzwstate_get_code( state );
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if ( c < 0 )
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goto Eof;
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code = (FT_UInt)c;
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if ( code == LZW_CLEAR && state->block_mode )
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{
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/* why not LZW_FIRST-256 ? */
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state->free_ent = ( LZW_FIRST - 1 ) - 256;
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state->buf_clear = 1;
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/* not quite right, but at least more predictable */
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old_code = 0;
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old_char = 0;
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goto NextCode;
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}
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in_code = code; /* save code for later */
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if ( code >= 256U )
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{
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/* special case for KwKwKwK */
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if ( code - 256U >= state->free_ent )
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{
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/* corrupted LZW stream */
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if ( code - 256U > state->free_ent )
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goto Eof;
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FTLZW_STACK_PUSH( old_char );
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code = old_code;
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}
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while ( code >= 256U )
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{
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if ( !state->prefix )
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goto Eof;
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FTLZW_STACK_PUSH( state->suffix[code - 256] );
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code = state->prefix[code - 256];
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}
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}
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old_char = code;
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FTLZW_STACK_PUSH( old_char );
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state->phase = FT_LZW_PHASE_STACK;
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}
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/* fall-through */
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case FT_LZW_PHASE_STACK:
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{
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while ( state->stack_top > 0 )
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{
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state->stack_top--;
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if ( buffer )
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buffer[result] = state->stack[state->stack_top];
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if ( ++result == out_size )
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goto Exit;
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}
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/* now create new entry */
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if ( state->free_ent < state->max_free )
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{
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if ( state->free_ent >= state->prefix_size &&
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ft_lzwstate_prefix_grow( state ) < 0 )
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goto Eof;
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FT_ASSERT( state->free_ent < state->prefix_size );
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state->prefix[state->free_ent] = (FT_UShort)old_code;
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state->suffix[state->free_ent] = (FT_Byte) old_char;
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state->free_ent += 1;
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}
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old_code = in_code;
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state->phase = FT_LZW_PHASE_CODE;
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goto NextCode;
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}
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default: /* state == EOF */
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;
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}
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Exit:
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state->old_code = old_code;
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state->old_char = old_char;
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state->in_code = in_code;
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return result;
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Eof:
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state->phase = FT_LZW_PHASE_EOF;
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goto Exit;
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}
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/* END */
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