1 /****************************************************************************
5 * FreeType support for .Z compressed files.
7 * This optional component relies on NetBSD's zopen(). It should mainly
8 * be used to parse compressed PCF fonts, as found with many X11 server
11 * Copyright (C) 2005-2020 by
14 * This file is part of the FreeType project, and may only be used,
15 * modified, and distributed under the terms of the FreeType project
16 * license, LICENSE.TXT. By continuing to use, modify, or distribute
17 * this file you indicate that you have read the license and
18 * understand and accept it fully.
23 #include <freetype/internal/ftmemory.h>
24 #include <freetype/internal/ftstream.h>
25 #include <freetype/internal/ftdebug.h>
29 ft_lzwstate_refill( FT_LzwState state )
37 count = FT_Stream_TryRead( state->source,
39 state->num_bits ); /* WHY? */
41 state->buf_size = (FT_UInt)count;
42 state->buf_total += count;
43 state->in_eof = FT_BOOL( count < state->num_bits );
44 state->buf_offset = 0;
46 state->buf_size <<= 3;
47 if ( state->buf_size > state->num_bits )
48 state->buf_size -= state->num_bits - 1;
50 return -1; /* not enough data */
52 if ( count == 0 ) /* end of file */
60 ft_lzwstate_get_code( FT_LzwState state )
62 FT_UInt num_bits = state->num_bits;
63 FT_UInt offset = state->buf_offset;
68 if ( state->buf_clear ||
69 offset >= state->buf_size ||
70 state->free_ent >= state->free_bits )
72 if ( state->free_ent >= state->free_bits )
74 state->num_bits = ++num_bits;
75 if ( num_bits > LZW_MAX_BITS )
78 state->free_bits = state->num_bits < state->max_bits
79 ? (FT_UInt)( ( 1UL << num_bits ) - 256 )
80 : state->max_free + 1;
83 if ( state->buf_clear )
85 state->num_bits = num_bits = LZW_INIT_BITS;
86 state->free_bits = (FT_UInt)( ( 1UL << num_bits ) - 256 );
90 if ( ft_lzwstate_refill( state ) < 0 )
96 state->buf_offset = offset + num_bits;
98 p = &state->buf_tab[offset >> 3];
100 result = *p++ >> offset;
106 result |= *p++ << offset;
111 result |= ( *p & LZW_MASK( num_bits ) ) << offset;
117 /* grow the character stack */
119 ft_lzwstate_stack_grow( FT_LzwState state )
121 if ( state->stack_top >= state->stack_size )
123 FT_Memory memory = state->memory;
125 FT_Offset old_size = state->stack_size;
126 FT_Offset new_size = old_size;
128 new_size = new_size + ( new_size >> 1 ) + 4;
130 if ( state->stack == state->stack_0 )
136 /* requirement of the character stack larger than 1<<LZW_MAX_BITS */
137 /* implies bug in the decompression code */
138 if ( new_size > ( 1 << LZW_MAX_BITS ) )
140 new_size = 1 << LZW_MAX_BITS;
141 if ( new_size == old_size )
145 if ( FT_RENEW_ARRAY( state->stack, old_size, new_size ) )
148 state->stack_size = new_size;
154 /* grow the prefix/suffix arrays */
156 ft_lzwstate_prefix_grow( FT_LzwState state )
158 FT_UInt old_size = state->prefix_size;
159 FT_UInt new_size = old_size;
160 FT_Memory memory = state->memory;
164 if ( new_size == 0 ) /* first allocation -> 9 bits */
167 new_size += new_size >> 2; /* don't grow too fast */
170 * Note that the `suffix' array is located in the same memory block
171 * pointed to by `prefix'.
173 * I know that sizeof(FT_Byte) == 1 by definition, but it is clearer
174 * to write it literally.
177 if ( FT_REALLOC_MULT( state->prefix, old_size, new_size,
178 sizeof ( FT_UShort ) + sizeof ( FT_Byte ) ) )
181 /* now adjust `suffix' and move the data accordingly */
182 state->suffix = (FT_Byte*)( state->prefix + new_size );
184 FT_MEM_MOVE( state->suffix,
185 state->prefix + old_size,
186 old_size * sizeof ( FT_Byte ) );
188 state->prefix_size = new_size;
194 ft_lzwstate_reset( FT_LzwState state )
197 state->buf_offset = 0;
199 state->buf_clear = 0;
200 state->buf_total = 0;
201 state->stack_top = 0;
202 state->num_bits = LZW_INIT_BITS;
203 state->phase = FT_LZW_PHASE_START;
208 ft_lzwstate_init( FT_LzwState state,
213 state->source = source;
214 state->memory = source->memory;
216 state->prefix = NULL;
217 state->suffix = NULL;
218 state->prefix_size = 0;
220 state->stack = state->stack_0;
221 state->stack_size = sizeof ( state->stack_0 );
223 ft_lzwstate_reset( state );
228 ft_lzwstate_done( FT_LzwState state )
230 FT_Memory memory = state->memory;
233 ft_lzwstate_reset( state );
235 if ( state->stack != state->stack_0 )
236 FT_FREE( state->stack );
238 FT_FREE( state->prefix );
239 state->suffix = NULL;
245 #define FTLZW_STACK_PUSH( c ) \
247 if ( state->stack_top >= state->stack_size && \
248 ft_lzwstate_stack_grow( state ) < 0 ) \
251 state->stack[state->stack_top++] = (FT_Byte)(c); \
255 FT_LOCAL_DEF( FT_ULong )
256 ft_lzwstate_io( FT_LzwState state,
262 FT_UInt old_char = state->old_char;
263 FT_UInt old_code = state->old_code;
264 FT_UInt in_code = state->in_code;
270 switch ( state->phase )
272 case FT_LZW_PHASE_START:
278 /* skip magic bytes, and read max_bits + block_flag */
279 if ( FT_Stream_Seek( state->source, 2 ) != 0 ||
280 FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 )
283 state->max_bits = max_bits & LZW_BIT_MASK;
284 state->block_mode = max_bits & LZW_BLOCK_MASK;
285 state->max_free = (FT_UInt)( ( 1UL << state->max_bits ) - 256 );
287 if ( state->max_bits > LZW_MAX_BITS )
290 state->num_bits = LZW_INIT_BITS;
291 state->free_ent = ( state->block_mode ? LZW_FIRST
295 state->free_bits = state->num_bits < state->max_bits
296 ? (FT_UInt)( ( 1UL << state->num_bits ) - 256 )
297 : state->max_free + 1;
299 c = ft_lzwstate_get_code( state );
300 if ( c < 0 || c > 255 )
303 old_code = old_char = (FT_UInt)c;
306 buffer[result] = (FT_Byte)old_char;
308 if ( ++result >= out_size )
311 state->phase = FT_LZW_PHASE_CODE;
315 case FT_LZW_PHASE_CODE:
322 c = ft_lzwstate_get_code( state );
328 if ( code == LZW_CLEAR && state->block_mode )
330 /* why not LZW_FIRST-256 ? */
331 state->free_ent = ( LZW_FIRST - 1 ) - 256;
332 state->buf_clear = 1;
334 /* not quite right, but at least more predictable */
341 in_code = code; /* save code for later */
345 /* special case for KwKwKwK */
346 if ( code - 256U >= state->free_ent )
348 /* corrupted LZW stream */
349 if ( code - 256U > state->free_ent )
352 FTLZW_STACK_PUSH( old_char );
356 while ( code >= 256U )
358 if ( !state->prefix )
361 FTLZW_STACK_PUSH( state->suffix[code - 256] );
362 code = state->prefix[code - 256];
367 FTLZW_STACK_PUSH( old_char );
369 state->phase = FT_LZW_PHASE_STACK;
373 case FT_LZW_PHASE_STACK:
375 while ( state->stack_top > 0 )
380 buffer[result] = state->stack[state->stack_top];
382 if ( ++result == out_size )
386 /* now create new entry */
387 if ( state->free_ent < state->max_free )
389 if ( state->free_ent >= state->prefix_size &&
390 ft_lzwstate_prefix_grow( state ) < 0 )
393 FT_ASSERT( state->free_ent < state->prefix_size );
395 state->prefix[state->free_ent] = (FT_UShort)old_code;
396 state->suffix[state->free_ent] = (FT_Byte) old_char;
398 state->free_ent += 1;
403 state->phase = FT_LZW_PHASE_CODE;
407 default: /* state == EOF */
412 state->old_code = old_code;
413 state->old_char = old_char;
414 state->in_code = in_code;
419 state->phase = FT_LZW_PHASE_EOF;