ftpatent.c revision 049d6fea481044fcc000e7782e5bc7046fc70844 
1/***************************************************************************/
2/*                                                                         */
3/*  ftpatent.c                                                             */
4/*                                                                         */
5/*    FreeType API for checking patented TrueType bytecode instructions    */
6/*    (body).                                                              */
7/*                                                                         */
8/*  Copyright 2007 by David Turner.                                        */
9/*                                                                         */
10/*  This file is part of the FreeType project, and may only be used,       */
11/*  modified, and distributed under the terms of the FreeType project      */
12/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
13/*  this file you indicate that you have read the license and              */
14/*  understand and accept it fully.                                        */
15/*                                                                         */
16/***************************************************************************/
17
18#include <ft2build.h>
19#include FT_FREETYPE_H
20#include FT_TRUETYPE_TAGS_H
21#include FT_INTERNAL_OBJECTS_H
22#include FT_INTERNAL_STREAM_H
23#include FT_SERVICE_SFNT_H
24#include FT_SERVICE_TRUETYPE_GLYF_H
25
26
27  static FT_Bool
28  _tt_check_patents_in_range( FT_Stream  stream,
29                              FT_ULong   size )
30  {
31    FT_Bool   result = FALSE;
32    FT_Error  error;
33    FT_Bytes  p, end;
34
35
36    if ( FT_FRAME_ENTER( size ) )
37      return 0;
38
39    p   = stream->cursor;
40    end = p + size;
41
42    while ( p < end )
43    {
44      switch (p[0])
45      {
46      case 0x06:  /* SPvTL // */
47      case 0x07:  /* SPvTL +  */
48      case 0x08:  /* SFvTL // */
49      case 0x09:  /* SFvTL +  */
50      case 0x0A:  /* SPvFS    */
51      case 0x0B:  /* SFvFS    */
52        result = TRUE;
53        goto Exit;
54
55      case 0x40:
56        if ( p + 1 >= end )
57          goto Exit;
58
59        p += p[1] + 2;
60        break;
61
62      case 0x41:
63        if ( p + 1 >= end )
64          goto Exit;
65
66        p += p[1] * 2 + 2;
67        break;
68
69      case 0x71:  /* DELTAP2 */
70      case 0x72:  /* DELTAP3 */
71      case 0x73:  /* DELTAC0 */
72      case 0x74:  /* DELTAC1 */
73      case 0x75:  /* DELTAC2 */
74        result = TRUE;
75        goto Exit;
76
77      case 0xB0:
78      case 0xB1:
79      case 0xB2:
80      case 0xB3:
81      case 0xB4:
82      case 0xB5:
83      case 0xB6:
84      case 0xB7:
85        p += ( p[0] - 0xB0 ) + 2;
86        break;
87
88      case 0xB8:
89      case 0xB9:
90      case 0xBA:
91      case 0xBB:
92      case 0xBC:
93      case 0xBD:
94      case 0xBE:
95      case 0xBF:
96        p += ( p[0] - 0xB8 ) * 2 + 3;
97        break;
98
99      default:
100        p += 1;
101        break;
102      }
103    }
104
105  Exit:
106    FT_FRAME_EXIT();
107    return result;
108  }
109
110
111  static FT_Bool
112  _tt_check_patents_in_table( FT_Face   face,
113                              FT_ULong  tag )
114  {
115    FT_Stream              stream = face->stream;
116    FT_Error               error;
117    FT_Service_SFNT_Table  service;
118    FT_Bool                result = FALSE;
119
120
121    FT_FACE_FIND_SERVICE( face, service, SFNT_TABLE );
122
123    if ( service )
124    {
125      FT_ULong  offset, size;
126
127
128      error = service->table_info( face, tag, &offset, &size );
129      if ( error                    ||
130           FT_STREAM_SEEK( offset ) )
131        goto Exit;
132
133      result = _tt_check_patents_in_range( stream, size );
134    }
135
136  Exit:
137    return result;
138  }
139
140
141  static FT_Bool
142  _tt_face_check_patents( FT_Face  face )
143  {
144    FT_Stream  stream = face->stream;
145    FT_UInt    gindex;
146    FT_Error   error;
147    FT_Bool    result;
148
149    FT_Service_TTGlyf  service;
150
151
152    result = _tt_check_patents_in_table( face, TTAG_fpgm );
153    if ( result )
154      goto Exit;
155
156    result = _tt_check_patents_in_table( face, TTAG_prep );
157    if ( result )
158      goto Exit;
159
160    FT_FACE_FIND_SERVICE( face, service, TT_GLYF );
161    if ( service == NULL )
162      goto Exit;
163
164    for ( gindex = 0; gindex < (FT_UInt)face->num_glyphs; gindex++ )
165    {
166      FT_ULong  offset, num_ins, size;
167      FT_Int    num_contours;
168
169
170      offset = service->get_location( face, gindex, &size );
171      if ( size == 0 )
172        continue;
173
174      if ( FT_STREAM_SEEK( offset )      ||
175           FT_READ_SHORT( num_contours ) )
176        continue;
177
178      if ( num_contours >= 0 )  /* simple glyph */
179      {
180        if ( FT_STREAM_SKIP( 8 + num_contours * 2 ) )
181          continue;
182      }
183      else  /* compound glyph */
184      {
185        FT_Bool  has_instr = 0;
186
187
188        if ( FT_STREAM_SKIP( 8 ) )
189          continue;
190
191        /* now read each component */
192        for (;;)
193        {
194          FT_UInt  flags, toskip;
195
196
197          if( FT_READ_USHORT( flags ) )
198            break;
199
200          toskip = 2 + 1 + 1;
201
202          if ( ( flags & ( 1 << 0 ) ) != 0 )       /* ARGS_ARE_WORDS */
203            toskip += 2;
204
205          if ( ( flags & ( 1 << 3 ) ) != 0 )       /* WE_HAVE_A_SCALE */
206            toskip += 2;
207          else if ( ( flags & ( 1 << 6 ) ) != 0 )  /* WE_HAVE_X_Y_SCALE */
208            toskip += 4;
209          else if ( ( flags & ( 1 << 7 ) ) != 0 )  /* WE_HAVE_A_2x2 */
210            toskip += 8;
211
212          if ( ( flags & ( 1 << 8 ) ) != 0 )       /* WE_HAVE_INSTRUCTIONS */
213            has_instr = 1;
214
215          if ( FT_STREAM_SKIP( toskip ) )
216            goto NextGlyph;
217
218          if ( ( flags & ( 1 << 5 ) ) == 0 )       /* MORE_COMPONENTS */
219            break;
220        }
221
222        if ( !has_instr )
223          goto NextGlyph;
224      }
225
226      if ( FT_READ_USHORT( num_ins ) )
227        continue;
228
229      result = _tt_check_patents_in_range( stream, num_ins );
230      if ( result )
231        goto Exit;
232
233    NextGlyph:
234      ;
235    }
236
237  Exit:
238    return result;
239  }
240
241
242  /* documentation is in freetype.h */
243
244  FT_EXPORT_DEF( FT_Bool )
245  FT_Face_CheckTrueTypePatents( FT_Face  face )
246  {
247    FT_Bool  result = FALSE;
248
249
250    if ( face && FT_IS_SFNT( face ) )
251      result = _tt_face_check_patents( face );
252
253    return result;
254  }
255
256
257  /* documentation is in freetype.h */
258
259  FT_EXPORT_DEF( FT_Bool )
260  FT_Face_SetUnpatentedHinting( FT_Face  face,
261                                FT_Bool  value )
262  {
263    FT_Bool  result = 0;
264
265
266#if defined( TT_CONFIG_OPTION_UNPATENTED_HINTING ) && \
267    !defined( TT_CONFIG_OPTION_BYTECODE_INTEPRETER )
268    if ( face && FT_IS_SFNT( face ) )
269    {
270      result = !face->internal->ignore_unpatented_hinter;
271      face->internal->ignore_unpatented_hinter = !value;
272    }
273#else
274    FT_UNUSED( face );
275    FT_UNUSED( value );
276#endif
277
278    return result;
279  }
280
281/* END */
282