thirdparty/freetype-2.3.12/src/lzw/ftlzw.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ftlzw.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 2004, 2005, 2006, 2009, 2010 by                              */
  12 /*  Albert Chin-A-Young.                                                   */
  13 /*                                                                         */
  14 /*  Based on code in src/gzip/ftgzip.c, Copyright 2004 by                  */
  15 /*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
  16 /*                                                                         */
  17 /*  This file is part of the FreeType project, and may only be used,       */
  18 /*  modified, and distributed under the terms of the FreeType project      */
  19 /*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
  20 /*  this file you indicate that you have read the license and              */
  21 /*  understand and accept it fully.                                        */
  22 /*                                                                         */
  23 /***************************************************************************/
  24
  25 #include <ft2build.h>
  26 #include FT_INTERNAL_MEMORY_H
  27 #include FT_INTERNAL_STREAM_H
  28 #include FT_INTERNAL_DEBUG_H
  29 #include FT_LZW_H
  30 #include FT_CONFIG_STANDARD_LIBRARY_H
  31
  32
  33 #include FT_MODULE_ERRORS_H
  34
  35 #undef __FTERRORS_H__
  36
  37 #define FT_ERR_PREFIX  LZW_Err_
  38 #define FT_ERR_BASE    FT_Mod_Err_LZW
  39
  40 #include FT_ERRORS_H
  41
  42
  43 #ifdef FT_CONFIG_OPTION_USE_LZW
  44
  45 #ifdef FT_CONFIG_OPTION_PIC
  46 #error "lzw code does not support PIC yet"
  47 #endif
  48
  49 #include "ftzopen.h"
  50
  51
  52 /***************************************************************************/
  53 /***************************************************************************/
  54 /*****                                                                 *****/
  55 /*****                  M E M O R Y   M A N A G E M E N T              *****/
  56 /*****                                                                 *****/
  57 /***************************************************************************/
  58 /***************************************************************************/
  59
  60 /***************************************************************************/
  61 /***************************************************************************/
  62 /*****                                                                 *****/
  63 /*****                   F I L E   D E S C R I P T O R                 *****/
  64 /*****                                                                 *****/
  65 /***************************************************************************/
  66 /***************************************************************************/
  67
  68 #define FT_LZW_BUFFER_SIZE  4096
  69
  70   typedef struct  FT_LZWFileRec_
  71   {
  72     FT_Stream       source;         /* parent/source stream        */
  73     FT_Stream       stream;         /* embedding stream            */
  74     FT_Memory       memory;         /* memory allocator            */
  75     FT_LzwStateRec  lzw;            /* lzw decompressor state      */
  76
  77     FT_Byte         buffer[FT_LZW_BUFFER_SIZE]; /* output buffer      */
  78     FT_ULong        pos;                        /* position in output */
  79     FT_Byte*        cursor;
  80     FT_Byte*        limit;
  81
  82   } FT_LZWFileRec, *FT_LZWFile;
  83
  84
  85   /* check and skip .Z header */
  86   static FT_Error
  87   ft_lzw_check_header( FT_Stream  stream )
  88   {
  89     FT_Error  error;
  90     FT_Byte   head[2];
  91
  92
  93     if ( FT_STREAM_SEEK( 0 )       ||
  94          FT_STREAM_READ( head, 2 ) )
  95       goto Exit;
  96
  97     /* head[0] && head[1] are the magic numbers */
  98     if ( head[0] != 0x1f ||
  99          head[1] != 0x9d )
 100       error = LZW_Err_Invalid_File_Format;
 101
 102   Exit:
 103     return error;
 104   }
 105
 106
 107   static FT_Error
 108   ft_lzw_file_init( FT_LZWFile  zip,
 109                     FT_Stream   stream,
 110                     FT_Stream   source )
 111   {
 112     FT_LzwState  lzw   = &zip->lzw;
 113     FT_Error     error = LZW_Err_Ok;
 114
 115
 116     zip->stream = stream;
 117     zip->source = source;
 118     zip->memory = stream->memory;
 119
 120     zip->limit  = zip->buffer + FT_LZW_BUFFER_SIZE;
 121     zip->cursor = zip->limit;
 122     zip->pos    = 0;
 123
 124     /* check and skip .Z header */
 125     error = ft_lzw_check_header( source );
 126     if ( error )
 127       goto Exit;
 128
 129     /* initialize internal lzw variable */
 130     ft_lzwstate_init( lzw, source );
 131
 132   Exit:
 133     return error;
 134   }
 135
 136
 137   static void
 138   ft_lzw_file_done( FT_LZWFile  zip )
 139   {
 140     /* clear the rest */
 141     ft_lzwstate_done( &zip->lzw );
 142
 143     zip->memory = NULL;
 144     zip->source = NULL;
 145     zip->stream = NULL;
 146   }
 147
 148
 149   static FT_Error
 150   ft_lzw_file_reset( FT_LZWFile  zip )
 151   {
 152     FT_Stream  stream = zip->source;
 153     FT_Error   error;
 154
 155
 156     if ( !FT_STREAM_SEEK( 0 ) )
 157     {
 158       ft_lzwstate_reset( &zip->lzw );
 159
 160       zip->limit  = zip->buffer + FT_LZW_BUFFER_SIZE;
 161       zip->cursor = zip->limit;
 162       zip->pos    = 0;
 163     }
 164
 165     return error;
 166   }
 167
 168
 169   static FT_Error
 170   ft_lzw_file_fill_output( FT_LZWFile  zip )
 171   {
 172     FT_LzwState  lzw = &zip->lzw;
 173     FT_ULong     count;
 174     FT_Error     error   = 0;
 175
 176
 177     zip->cursor = zip->buffer;
 178
 179     count = ft_lzwstate_io( lzw, zip->buffer, FT_LZW_BUFFER_SIZE );
 180
 181     zip->limit = zip->cursor + count;
 182
 183     if ( count == 0 )
 184       error = LZW_Err_Invalid_Stream_Operation;
 185
 186     return error;
 187   }
 188
 189
 190   /* fill output buffer; `count' must be <= FT_LZW_BUFFER_SIZE */
 191   static FT_Error
 192   ft_lzw_file_skip_output( FT_LZWFile  zip,
 193                            FT_ULong    count )
 194   {
 195     FT_Error  error = LZW_Err_Ok;
 196
 197
 198     /* first, we skip what we can from the output buffer */
 199     {
 200       FT_ULong  delta = (FT_ULong)( zip->limit - zip->cursor );
 201
 202
 203       if ( delta >= count )
 204         delta = count;
 205
 206       zip->cursor += delta;
 207       zip->pos    += delta;
 208
 209       count -= delta;
 210     }
 211
 212     /* next, we skip as many bytes remaining as possible */
 213     while ( count > 0 )
 214     {
 215       FT_ULong  delta = FT_LZW_BUFFER_SIZE;
 216       FT_ULong  numread;
 217
 218
 219       if ( delta > count )
 220         delta = count;
 221
 222       numread = ft_lzwstate_io( &zip->lzw, NULL, delta );
 223       if ( numread < delta )
 224       {
 225         /* not enough bytes */
 226         error = LZW_Err_Invalid_Stream_Operation;
 227         break;
 228       }
 229
 230       zip->pos += delta;
 231       count    -= delta;
 232     }
 233
 234     return error;
 235   }
 236
 237
 238   static FT_ULong
 239   ft_lzw_file_io( FT_LZWFile  zip,
 240                   FT_ULong    pos,
 241                   FT_Byte*    buffer,
 242                   FT_ULong    count )
 243   {
 244     FT_ULong  result = 0;
 245     FT_Error  error;
 246
 247
 248     /* seeking backwards. */
 249     if ( pos < zip->pos )
 250     {
 251       /* If the new position is within the output buffer, simply       */
 252       /* decrement pointers, otherwise we reset the stream completely! */
 253       if ( ( zip->pos - pos ) <= (FT_ULong)( zip->cursor - zip->buffer ) )
 254       {
 255         zip->cursor -= zip->pos - pos;
 256         zip->pos     = pos;
 257       }
 258       else
 259       {
 260         error = ft_lzw_file_reset( zip );
 261         if ( error )
 262           goto Exit;
 263       }
 264     }
 265
 266     /* skip unwanted bytes */
 267     if ( pos > zip->pos )
 268     {
 269       error = ft_lzw_file_skip_output( zip, (FT_ULong)( pos - zip->pos ) );
 270       if ( error )
 271         goto Exit;
 272     }
 273
 274     if ( count == 0 )
 275       goto Exit;
 276
 277     /* now read the data */
 278     for (;;)
 279     {
 280       FT_ULong  delta;
 281
 282
 283       delta = (FT_ULong)( zip->limit - zip->cursor );
 284       if ( delta >= count )
 285         delta = count;
 286
 287       FT_MEM_COPY( buffer + result, zip->cursor, delta );
 288       result      += delta;
 289       zip->cursor += delta;
 290       zip->pos    += delta;
 291
 292       count -= delta;
 293       if ( count == 0 )
 294         break;
 295
 296       error = ft_lzw_file_fill_output( zip );
 297       if ( error )
 298         break;
 299     }
 300
 301   Exit:
 302     return result;
 303   }
 304
 305
 306 /***************************************************************************/
 307 /***************************************************************************/
 308 /*****                                                                 *****/
 309 /*****            L Z W   E M B E D D I N G   S T R E A M              *****/
 310 /*****                                                                 *****/
 311 /***************************************************************************/
 312 /***************************************************************************/
 313
 314   static void
 315   ft_lzw_stream_close( FT_Stream  stream )
 316   {
 317     FT_LZWFile  zip    = (FT_LZWFile)stream->descriptor.pointer;
 318     FT_Memory   memory = stream->memory;
 319
 320
 321     if ( zip )
 322     {
 323       /* finalize lzw file descriptor */
 324       ft_lzw_file_done( zip );
 325
 326       FT_FREE( zip );
 327
 328       stream->descriptor.pointer = NULL;
 329     }
 330   }
 331
 332
 333   static FT_ULong
 334   ft_lzw_stream_io( FT_Stream  stream,
 335                     FT_ULong   pos,
 336                     FT_Byte*   buffer,
 337                     FT_ULong   count )
 338   {
 339     FT_LZWFile  zip = (FT_LZWFile)stream->descriptor.pointer;
 340
 341
 342     return ft_lzw_file_io( zip, pos, buffer, count );
 343   }
 344
 345
 346   FT_EXPORT_DEF( FT_Error )
 347   FT_Stream_OpenLZW( FT_Stream  stream,
 348                      FT_Stream  source )
 349   {
 350     FT_Error    error;
 351     FT_Memory   memory = source->memory;
 352     FT_LZWFile  zip;
 353
 354
 355     /*
 356      *  Check the header right now; this prevents allocation of a huge
 357      *  LZWFile object (400 KByte of heap memory) if not necessary.
 358      *
 359      *  Did I mention that you should never use .Z compressed font
 360      *  files?
 361      */
 362     error = ft_lzw_check_header( source );
 363     if ( error )
 364       goto Exit;
 365
 366     FT_ZERO( stream );
 367     stream->memory = memory;
 368
 369     if ( !FT_NEW( zip ) )
 370     {
 371       error = ft_lzw_file_init( zip, stream, source );
 372       if ( error )
 373       {
 374         FT_FREE( zip );
 375         goto Exit;
 376       }
 377
 378       stream->descriptor.pointer = zip;
 379     }
 380
 381     stream->size  = 0x7FFFFFFFL;  /* don't know the real size! */
 382     stream->pos   = 0;
 383     stream->base  = 0;
 384     stream->read  = ft_lzw_stream_io;
 385     stream->close = ft_lzw_stream_close;
 386
 387   Exit:
 388     return error;
 389   }
 390
 391
 392 #include "ftzopen.c"
 393
 394
 395 #else  /* !FT_CONFIG_OPTION_USE_LZW */
 396
 397
 398   FT_EXPORT_DEF( FT_Error )
 399   FT_Stream_OpenLZW( FT_Stream  stream,
 400                      FT_Stream  source )
 401   {
 402     FT_UNUSED( stream );
 403     FT_UNUSED( source );
 404
 405     return LZW_Err_Unimplemented_Feature;
 406   }
 407
 408
 409 #endif /* !FT_CONFIG_OPTION_USE_LZW */
 410
 411
 412 /* END */