1 /**************************************************************************** 2 * 3 * ftzopen.c 4 * 5 * FreeType support for .Z compressed files. 6 * 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 9 * distributions. 10 * 11 * Copyright (C) 2005-2021 by 12 * David Turner. 13 * 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. 19 * 20 */ 21 22 #include "ftzopen.h" 23 #include <freetype/internal/ftmemory.h> 24 #include <freetype/internal/ftstream.h> 25 #include <freetype/internal/ftdebug.h> 26 27 28 static int ft_lzwstate_refill(FT_LzwState state)29 ft_lzwstate_refill( FT_LzwState state ) 30 { 31 FT_ULong count; 32 33 34 if ( state->in_eof ) 35 return -1; 36 37 count = FT_Stream_TryRead( state->source, 38 state->buf_tab, 39 state->num_bits ); /* WHY? */ 40 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; 45 46 state->buf_size <<= 3; 47 if ( state->buf_size > state->num_bits ) 48 state->buf_size -= state->num_bits - 1; 49 else 50 return -1; /* not enough data */ 51 52 if ( count == 0 ) /* end of file */ 53 return -1; 54 55 return 0; 56 } 57 58 59 static FT_Int32 ft_lzwstate_get_code(FT_LzwState state)60 ft_lzwstate_get_code( FT_LzwState state ) 61 { 62 FT_UInt num_bits = state->num_bits; 63 FT_UInt offset = state->buf_offset; 64 FT_Byte* p; 65 FT_Int result; 66 67 68 if ( state->buf_clear || 69 offset >= state->buf_size || 70 state->free_ent >= state->free_bits ) 71 { 72 if ( state->free_ent >= state->free_bits ) 73 { 74 state->num_bits = ++num_bits; 75 if ( num_bits > LZW_MAX_BITS ) 76 return -1; 77 78 state->free_bits = state->num_bits < state->max_bits 79 ? (FT_UInt)( ( 1UL << num_bits ) - 256 ) 80 : state->max_free + 1; 81 } 82 83 if ( state->buf_clear ) 84 { 85 state->num_bits = num_bits = LZW_INIT_BITS; 86 state->free_bits = (FT_UInt)( ( 1UL << num_bits ) - 256 ); 87 state->buf_clear = 0; 88 } 89 90 if ( ft_lzwstate_refill( state ) < 0 ) 91 return -1; 92 93 offset = 0; 94 } 95 96 state->buf_offset = offset + num_bits; 97 98 p = &state->buf_tab[offset >> 3]; 99 offset &= 7; 100 result = *p++ >> offset; 101 offset = 8 - offset; 102 num_bits -= offset; 103 104 if ( num_bits >= 8 ) 105 { 106 result |= *p++ << offset; 107 offset += 8; 108 num_bits -= 8; 109 } 110 if ( num_bits > 0 ) 111 result |= ( *p & LZW_MASK( num_bits ) ) << offset; 112 113 return result; 114 } 115 116 117 /* grow the character stack */ 118 static int ft_lzwstate_stack_grow(FT_LzwState state)119 ft_lzwstate_stack_grow( FT_LzwState state ) 120 { 121 if ( state->stack_top >= state->stack_size ) 122 { 123 FT_Memory memory = state->memory; 124 FT_Error error; 125 FT_Offset old_size = state->stack_size; 126 FT_Offset new_size = old_size; 127 128 new_size = new_size + ( new_size >> 1 ) + 4; 129 130 /* if relocating to heap */ 131 if ( state->stack == state->stack_0 ) 132 { 133 state->stack = NULL; 134 old_size = 0; 135 } 136 137 /* requirement of the character stack larger than 1<<LZW_MAX_BITS */ 138 /* implies bug in the decompression code */ 139 if ( new_size > ( 1 << LZW_MAX_BITS ) ) 140 { 141 new_size = 1 << LZW_MAX_BITS; 142 if ( new_size == old_size ) 143 return -1; 144 } 145 146 if ( FT_QRENEW_ARRAY( state->stack, old_size, new_size ) ) 147 return -1; 148 149 /* if relocating to heap */ 150 if ( old_size == 0 ) 151 FT_MEM_COPY( state->stack, state->stack_0, FT_LZW_DEFAULT_STACK_SIZE ); 152 153 state->stack_size = new_size; 154 } 155 return 0; 156 } 157 158 159 /* grow the prefix/suffix arrays */ 160 static int ft_lzwstate_prefix_grow(FT_LzwState state)161 ft_lzwstate_prefix_grow( FT_LzwState state ) 162 { 163 FT_UInt old_size = state->prefix_size; 164 FT_UInt new_size = old_size; 165 FT_Memory memory = state->memory; 166 FT_Error error; 167 168 169 if ( new_size == 0 ) /* first allocation -> 9 bits */ 170 new_size = 512; 171 else 172 new_size += new_size >> 2; /* don't grow too fast */ 173 174 /* 175 * Note that the `suffix' array is located in the same memory block 176 * pointed to by `prefix'. 177 * 178 * I know that sizeof(FT_Byte) == 1 by definition, but it is clearer 179 * to write it literally. 180 * 181 */ 182 if ( FT_REALLOC_MULT( state->prefix, old_size, new_size, 183 sizeof ( FT_UShort ) + sizeof ( FT_Byte ) ) ) 184 return -1; 185 186 /* now adjust `suffix' and move the data accordingly */ 187 state->suffix = (FT_Byte*)( state->prefix + new_size ); 188 189 FT_MEM_MOVE( state->suffix, 190 state->prefix + old_size, 191 old_size * sizeof ( FT_Byte ) ); 192 193 state->prefix_size = new_size; 194 return 0; 195 } 196 197 198 FT_LOCAL_DEF( void ) ft_lzwstate_reset(FT_LzwState state)199 ft_lzwstate_reset( FT_LzwState state ) 200 { 201 state->in_eof = 0; 202 state->buf_offset = 0; 203 state->buf_size = 0; 204 state->buf_clear = 0; 205 state->buf_total = 0; 206 state->stack_top = 0; 207 state->num_bits = LZW_INIT_BITS; 208 state->phase = FT_LZW_PHASE_START; 209 } 210 211 212 FT_LOCAL_DEF( void ) ft_lzwstate_init(FT_LzwState state,FT_Stream source)213 ft_lzwstate_init( FT_LzwState state, 214 FT_Stream source ) 215 { 216 FT_ZERO( state ); 217 218 state->source = source; 219 state->memory = source->memory; 220 221 state->prefix = NULL; 222 state->suffix = NULL; 223 state->prefix_size = 0; 224 225 state->stack = state->stack_0; 226 state->stack_size = sizeof ( state->stack_0 ); 227 228 ft_lzwstate_reset( state ); 229 } 230 231 232 FT_LOCAL_DEF( void ) ft_lzwstate_done(FT_LzwState state)233 ft_lzwstate_done( FT_LzwState state ) 234 { 235 FT_Memory memory = state->memory; 236 237 238 ft_lzwstate_reset( state ); 239 240 if ( state->stack != state->stack_0 ) 241 FT_FREE( state->stack ); 242 243 FT_FREE( state->prefix ); 244 state->suffix = NULL; 245 246 FT_ZERO( state ); 247 } 248 249 250 #define FTLZW_STACK_PUSH( c ) \ 251 FT_BEGIN_STMNT \ 252 if ( state->stack_top >= state->stack_size && \ 253 ft_lzwstate_stack_grow( state ) < 0 ) \ 254 goto Eof; \ 255 \ 256 state->stack[state->stack_top++] = (FT_Byte)(c); \ 257 FT_END_STMNT 258 259 260 FT_LOCAL_DEF( FT_ULong ) ft_lzwstate_io(FT_LzwState state,FT_Byte * buffer,FT_ULong out_size)261 ft_lzwstate_io( FT_LzwState state, 262 FT_Byte* buffer, 263 FT_ULong out_size ) 264 { 265 FT_ULong result = 0; 266 267 FT_UInt old_char = state->old_char; 268 FT_UInt old_code = state->old_code; 269 FT_UInt in_code = state->in_code; 270 271 272 if ( out_size == 0 ) 273 goto Exit; 274 275 switch ( state->phase ) 276 { 277 case FT_LZW_PHASE_START: 278 { 279 FT_Byte max_bits; 280 FT_Int32 c; 281 282 283 /* skip magic bytes, and read max_bits + block_flag */ 284 if ( FT_Stream_Seek( state->source, 2 ) != 0 || 285 FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 ) 286 goto Eof; 287 288 state->max_bits = max_bits & LZW_BIT_MASK; 289 state->block_mode = max_bits & LZW_BLOCK_MASK; 290 state->max_free = (FT_UInt)( ( 1UL << state->max_bits ) - 256 ); 291 292 if ( state->max_bits > LZW_MAX_BITS ) 293 goto Eof; 294 295 state->num_bits = LZW_INIT_BITS; 296 state->free_ent = ( state->block_mode ? LZW_FIRST 297 : LZW_CLEAR ) - 256; 298 in_code = 0; 299 300 state->free_bits = state->num_bits < state->max_bits 301 ? (FT_UInt)( ( 1UL << state->num_bits ) - 256 ) 302 : state->max_free + 1; 303 304 c = ft_lzwstate_get_code( state ); 305 if ( c < 0 || c > 255 ) 306 goto Eof; 307 308 old_code = old_char = (FT_UInt)c; 309 310 if ( buffer ) 311 buffer[result] = (FT_Byte)old_char; 312 313 if ( ++result >= out_size ) 314 goto Exit; 315 316 state->phase = FT_LZW_PHASE_CODE; 317 } 318 /* fall-through */ 319 320 case FT_LZW_PHASE_CODE: 321 { 322 FT_Int32 c; 323 FT_UInt code; 324 325 326 NextCode: 327 c = ft_lzwstate_get_code( state ); 328 if ( c < 0 ) 329 goto Eof; 330 331 code = (FT_UInt)c; 332 333 if ( code == LZW_CLEAR && state->block_mode ) 334 { 335 /* why not LZW_FIRST-256 ? */ 336 state->free_ent = ( LZW_FIRST - 1 ) - 256; 337 state->buf_clear = 1; 338 339 /* not quite right, but at least more predictable */ 340 old_code = 0; 341 old_char = 0; 342 343 goto NextCode; 344 } 345 346 in_code = code; /* save code for later */ 347 348 if ( code >= 256U ) 349 { 350 /* special case for KwKwKwK */ 351 if ( code - 256U >= state->free_ent ) 352 { 353 /* corrupted LZW stream */ 354 if ( code - 256U > state->free_ent ) 355 goto Eof; 356 357 FTLZW_STACK_PUSH( old_char ); 358 code = old_code; 359 } 360 361 while ( code >= 256U ) 362 { 363 if ( !state->prefix ) 364 goto Eof; 365 366 FTLZW_STACK_PUSH( state->suffix[code - 256] ); 367 code = state->prefix[code - 256]; 368 } 369 } 370 371 old_char = code; 372 FTLZW_STACK_PUSH( old_char ); 373 374 state->phase = FT_LZW_PHASE_STACK; 375 } 376 /* fall-through */ 377 378 case FT_LZW_PHASE_STACK: 379 { 380 while ( state->stack_top > 0 ) 381 { 382 state->stack_top--; 383 384 if ( buffer ) 385 buffer[result] = state->stack[state->stack_top]; 386 387 if ( ++result == out_size ) 388 goto Exit; 389 } 390 391 /* now create new entry */ 392 if ( state->free_ent < state->max_free ) 393 { 394 if ( state->free_ent >= state->prefix_size && 395 ft_lzwstate_prefix_grow( state ) < 0 ) 396 goto Eof; 397 398 FT_ASSERT( state->free_ent < state->prefix_size ); 399 400 state->prefix[state->free_ent] = (FT_UShort)old_code; 401 state->suffix[state->free_ent] = (FT_Byte) old_char; 402 403 state->free_ent += 1; 404 } 405 406 old_code = in_code; 407 408 state->phase = FT_LZW_PHASE_CODE; 409 goto NextCode; 410 } 411 412 default: /* state == EOF */ 413 ; 414 } 415 416 Exit: 417 state->old_code = old_code; 418 state->old_char = old_char; 419 state->in_code = in_code; 420 421 return result; 422 423 Eof: 424 state->phase = FT_LZW_PHASE_EOF; 425 goto Exit; 426 } 427 428 429 /* END */ 430