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 2005, 2006, 2007, 2009 by David Turner. */ 12 /* */ 13 /* This file is part of the FreeType project, and may only be used, */ 14 /* modified, and distributed under the terms of the FreeType project */ 15 /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ 16 /* this file you indicate that you have read the license and */ 17 /* understand and accept it fully. */ 18 /* */ 19 /***************************************************************************/ 20 21 #include "ftzopen.h" 22 #include FT_INTERNAL_MEMORY_H 23 #include FT_INTERNAL_STREAM_H 24 #include FT_INTERNAL_DEBUG_H 25 26 27 static int ft_lzwstate_refill(FT_LzwState state)28 ft_lzwstate_refill( FT_LzwState state ) 29 { 30 FT_ULong count; 31 32 33 if ( state->in_eof ) 34 return -1; 35 36 count = FT_Stream_TryRead( state->source, 37 state->buf_tab, 38 state->num_bits ); /* WHY? */ 39 40 state->buf_size = (FT_UInt)count; 41 state->buf_total += count; 42 state->in_eof = FT_BOOL( count < state->num_bits ); 43 state->buf_offset = 0; 44 state->buf_size = ( state->buf_size << 3 ) - ( state->num_bits - 1 ); 45 46 if ( count == 0 ) /* end of file */ 47 return -1; 48 49 return 0; 50 } 51 52 53 static FT_Int32 ft_lzwstate_get_code(FT_LzwState state)54 ft_lzwstate_get_code( FT_LzwState state ) 55 { 56 FT_UInt num_bits = state->num_bits; 57 FT_Int offset = state->buf_offset; 58 FT_Byte* p; 59 FT_Int result; 60 61 62 if ( state->buf_clear || 63 offset >= state->buf_size || 64 state->free_ent >= state->free_bits ) 65 { 66 if ( state->free_ent >= state->free_bits ) 67 { 68 state->num_bits = ++num_bits; 69 state->free_bits = state->num_bits < state->max_bits 70 ? (FT_UInt)( ( 1UL << num_bits ) - 256 ) 71 : state->max_free + 1; 72 } 73 74 if ( state->buf_clear ) 75 { 76 state->num_bits = num_bits = LZW_INIT_BITS; 77 state->free_bits = (FT_UInt)( ( 1UL << num_bits ) - 256 ); 78 state->buf_clear = 0; 79 } 80 81 if ( ft_lzwstate_refill( state ) < 0 ) 82 return -1; 83 84 offset = 0; 85 } 86 87 state->buf_offset = offset + num_bits; 88 89 p = &state->buf_tab[offset >> 3]; 90 offset &= 7; 91 result = *p++ >> offset; 92 offset = 8 - offset; 93 num_bits -= offset; 94 95 if ( num_bits >= 8 ) 96 { 97 result |= *p++ << offset; 98 offset += 8; 99 num_bits -= 8; 100 } 101 if ( num_bits > 0 ) 102 result |= ( *p & LZW_MASK( num_bits ) ) << offset; 103 104 return result; 105 } 106 107 108 /* grow the character stack */ 109 static int ft_lzwstate_stack_grow(FT_LzwState state)110 ft_lzwstate_stack_grow( FT_LzwState state ) 111 { 112 if ( state->stack_top >= state->stack_size ) 113 { 114 FT_Memory memory = state->memory; 115 FT_Error error; 116 FT_Offset old_size = state->stack_size; 117 FT_Offset new_size = old_size; 118 119 new_size = new_size + ( new_size >> 1 ) + 4; 120 121 if ( state->stack == state->stack_0 ) 122 { 123 state->stack = NULL; 124 old_size = 0; 125 } 126 127 if ( FT_RENEW_ARRAY( state->stack, old_size, new_size ) ) 128 return -1; 129 130 state->stack_size = new_size; 131 } 132 return 0; 133 } 134 135 136 /* grow the prefix/suffix arrays */ 137 static int ft_lzwstate_prefix_grow(FT_LzwState state)138 ft_lzwstate_prefix_grow( FT_LzwState state ) 139 { 140 FT_UInt old_size = state->prefix_size; 141 FT_UInt new_size = old_size; 142 FT_Memory memory = state->memory; 143 FT_Error error; 144 145 146 if ( new_size == 0 ) /* first allocation -> 9 bits */ 147 new_size = 512; 148 else 149 new_size += new_size >> 2; /* don't grow too fast */ 150 151 /* 152 * Note that the `suffix' array is located in the same memory block 153 * pointed to by `prefix'. 154 * 155 * I know that sizeof(FT_Byte) == 1 by definition, but it is clearer 156 * to write it literally. 157 * 158 */ 159 if ( FT_REALLOC_MULT( state->prefix, old_size, new_size, 160 sizeof ( FT_UShort ) + sizeof ( FT_Byte ) ) ) 161 return -1; 162 163 /* now adjust `suffix' and move the data accordingly */ 164 state->suffix = (FT_Byte*)( state->prefix + new_size ); 165 166 FT_MEM_MOVE( state->suffix, 167 state->prefix + old_size, 168 old_size * sizeof ( FT_Byte ) ); 169 170 state->prefix_size = new_size; 171 return 0; 172 } 173 174 175 FT_LOCAL_DEF( void ) ft_lzwstate_reset(FT_LzwState state)176 ft_lzwstate_reset( FT_LzwState state ) 177 { 178 state->in_eof = 0; 179 state->buf_offset = 0; 180 state->buf_size = 0; 181 state->buf_clear = 0; 182 state->buf_total = 0; 183 state->stack_top = 0; 184 state->num_bits = LZW_INIT_BITS; 185 state->phase = FT_LZW_PHASE_START; 186 } 187 188 189 FT_LOCAL_DEF( void ) ft_lzwstate_init(FT_LzwState state,FT_Stream source)190 ft_lzwstate_init( FT_LzwState state, 191 FT_Stream source ) 192 { 193 FT_ZERO( state ); 194 195 state->source = source; 196 state->memory = source->memory; 197 198 state->prefix = NULL; 199 state->suffix = NULL; 200 state->prefix_size = 0; 201 202 state->stack = state->stack_0; 203 state->stack_size = sizeof ( state->stack_0 ); 204 205 ft_lzwstate_reset( state ); 206 } 207 208 209 FT_LOCAL_DEF( void ) ft_lzwstate_done(FT_LzwState state)210 ft_lzwstate_done( FT_LzwState state ) 211 { 212 FT_Memory memory = state->memory; 213 214 215 ft_lzwstate_reset( state ); 216 217 if ( state->stack != state->stack_0 ) 218 FT_FREE( state->stack ); 219 220 FT_FREE( state->prefix ); 221 state->suffix = NULL; 222 223 FT_ZERO( state ); 224 } 225 226 227 #define FTLZW_STACK_PUSH( c ) \ 228 FT_BEGIN_STMNT \ 229 if ( state->stack_top >= state->stack_size && \ 230 ft_lzwstate_stack_grow( state ) < 0 ) \ 231 goto Eof; \ 232 \ 233 state->stack[state->stack_top++] = (FT_Byte)(c); \ 234 FT_END_STMNT 235 236 237 FT_LOCAL_DEF( FT_ULong ) ft_lzwstate_io(FT_LzwState state,FT_Byte * buffer,FT_ULong out_size)238 ft_lzwstate_io( FT_LzwState state, 239 FT_Byte* buffer, 240 FT_ULong out_size ) 241 { 242 FT_ULong result = 0; 243 244 FT_UInt old_char = state->old_char; 245 FT_UInt old_code = state->old_code; 246 FT_UInt in_code = state->in_code; 247 248 249 if ( out_size == 0 ) 250 goto Exit; 251 252 switch ( state->phase ) 253 { 254 case FT_LZW_PHASE_START: 255 { 256 FT_Byte max_bits; 257 FT_Int32 c; 258 259 260 /* skip magic bytes, and read max_bits + block_flag */ 261 if ( FT_Stream_Seek( state->source, 2 ) != 0 || 262 FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 ) 263 goto Eof; 264 265 state->max_bits = max_bits & LZW_BIT_MASK; 266 state->block_mode = max_bits & LZW_BLOCK_MASK; 267 state->max_free = (FT_UInt)( ( 1UL << state->max_bits ) - 256 ); 268 269 if ( state->max_bits > LZW_MAX_BITS ) 270 goto Eof; 271 272 state->num_bits = LZW_INIT_BITS; 273 state->free_ent = ( state->block_mode ? LZW_FIRST 274 : LZW_CLEAR ) - 256; 275 in_code = 0; 276 277 state->free_bits = state->num_bits < state->max_bits 278 ? (FT_UInt)( ( 1UL << state->num_bits ) - 256 ) 279 : state->max_free + 1; 280 281 c = ft_lzwstate_get_code( state ); 282 if ( c < 0 ) 283 goto Eof; 284 285 old_code = old_char = (FT_UInt)c; 286 287 if ( buffer ) 288 buffer[result] = (FT_Byte)old_char; 289 290 if ( ++result >= out_size ) 291 goto Exit; 292 293 state->phase = FT_LZW_PHASE_CODE; 294 } 295 /* fall-through */ 296 297 case FT_LZW_PHASE_CODE: 298 { 299 FT_Int32 c; 300 FT_UInt code; 301 302 303 NextCode: 304 c = ft_lzwstate_get_code( state ); 305 if ( c < 0 ) 306 goto Eof; 307 308 code = (FT_UInt)c; 309 310 if ( code == LZW_CLEAR && state->block_mode ) 311 { 312 /* why not LZW_FIRST-256 ? */ 313 state->free_ent = ( LZW_FIRST - 1 ) - 256; 314 state->buf_clear = 1; 315 c = ft_lzwstate_get_code( state ); 316 if ( c < 0 ) 317 goto Eof; 318 319 code = (FT_UInt)c; 320 } 321 322 in_code = code; /* save code for later */ 323 324 if ( code >= 256U ) 325 { 326 /* special case for KwKwKwK */ 327 if ( code - 256U >= state->free_ent ) 328 { 329 FTLZW_STACK_PUSH( old_char ); 330 code = old_code; 331 } 332 333 while ( code >= 256U ) 334 { 335 if ( !state->prefix ) 336 goto Eof; 337 338 FTLZW_STACK_PUSH( state->suffix[code - 256] ); 339 code = state->prefix[code - 256]; 340 } 341 } 342 343 old_char = code; 344 FTLZW_STACK_PUSH( old_char ); 345 346 state->phase = FT_LZW_PHASE_STACK; 347 } 348 /* fall-through */ 349 350 case FT_LZW_PHASE_STACK: 351 { 352 while ( state->stack_top > 0 ) 353 { 354 --state->stack_top; 355 356 if ( buffer ) 357 buffer[result] = state->stack[state->stack_top]; 358 359 if ( ++result == out_size ) 360 goto Exit; 361 } 362 363 /* now create new entry */ 364 if ( state->free_ent < state->max_free ) 365 { 366 if ( state->free_ent >= state->prefix_size && 367 ft_lzwstate_prefix_grow( state ) < 0 ) 368 goto Eof; 369 370 FT_ASSERT( state->free_ent < state->prefix_size ); 371 372 state->prefix[state->free_ent] = (FT_UShort)old_code; 373 state->suffix[state->free_ent] = (FT_Byte) old_char; 374 375 state->free_ent += 1; 376 } 377 378 old_code = in_code; 379 380 state->phase = FT_LZW_PHASE_CODE; 381 goto NextCode; 382 } 383 384 default: /* state == EOF */ 385 ; 386 } 387 388 Exit: 389 state->old_code = old_code; 390 state->old_char = old_char; 391 state->in_code = in_code; 392 393 return result; 394 395 Eof: 396 state->phase = FT_LZW_PHASE_EOF; 397 goto Exit; 398 } 399 400 401 /* END */ 402