1 /****************************************************************************
2 *
3 * t1parse.c
4 *
5 * Type 1 parser (body).
6 *
7 * Copyright (C) 1996-2023 by
8 * David Turner, Robert Wilhelm, and Werner Lemberg.
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
19 /**************************************************************************
20 *
21 * The Type 1 parser is in charge of the following:
22 *
23 * - provide an implementation of a growing sequence of objects called
24 * a `T1_Table' (used to build various tables needed by the loader).
25 *
26 * - opening .pfb and .pfa files to extract their top-level and private
27 * dictionaries.
28 *
29 * - read numbers, arrays & strings from any dictionary.
30 *
31 * See `t1load.c' to see how data is loaded from the font file.
32 *
33 */
34
35
36 #include <freetype/internal/ftdebug.h>
37 #include <freetype/internal/ftstream.h>
38 #include <freetype/internal/psaux.h>
39
40 #include "t1parse.h"
41
42 #include "t1errors.h"
43
44
45 /**************************************************************************
46 *
47 * The macro FT_COMPONENT is used in trace mode. It is an implicit
48 * parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log
49 * messages during execution.
50 */
51 #undef FT_COMPONENT
52 #define FT_COMPONENT t1parse
53
54
55 /*************************************************************************/
56 /*************************************************************************/
57 /*************************************************************************/
58 /***** *****/
59 /***** INPUT STREAM PARSER *****/
60 /***** *****/
61 /*************************************************************************/
62 /*************************************************************************/
63 /*************************************************************************/
64
65
66 /* see Adobe Technical Note 5040.Download_Fonts.pdf */
67
68 static FT_Error
69 read_pfb_tag( FT_Stream stream,
70 FT_UShort *atag,
71 FT_ULong *asize )
72 {
73 FT_Error error;
74 FT_UShort tag;
75 FT_ULong size;
76
77
78 *atag = 0;
79 *asize = 0;
80
81 if ( !FT_READ_USHORT( tag ) )
82 {
83 if ( tag == 0x8001U || tag == 0x8002U )
84 {
85 if ( !FT_READ_ULONG_LE( size ) )
86 *asize = size;
87 }
88
89 *atag = tag;
90 }
91
92 return error;
93 }
94
95
96 static FT_Error
97 check_type1_format( FT_Stream stream,
98 const char* header_string,
99 size_t header_length )
100 {
101 FT_Error error;
102 FT_UShort tag;
103 FT_ULong dummy;
104
105
106 if ( FT_STREAM_SEEK( 0 ) )
107 goto Exit;
108
109 error = read_pfb_tag( stream, &tag, &dummy );
110 if ( error )
111 goto Exit;
112
113 /* We assume that the first segment in a PFB is always encoded as */
114 /* text. This might be wrong (and the specification doesn't insist */
115 /* on that), but we have never seen a counterexample. */
116 if ( tag != 0x8001U && FT_STREAM_SEEK( 0 ) )
117 goto Exit;
118
119 if ( !FT_FRAME_ENTER( header_length ) )
120 {
121 error = FT_Err_Ok;
122
123 if ( ft_memcmp( stream->cursor, header_string, header_length ) != 0 )
124 error = FT_THROW( Unknown_File_Format );
125
126 FT_FRAME_EXIT();
127 }
128
129 Exit:
130 return error;
131 }
132
133
134 FT_LOCAL_DEF( FT_Error )
135 T1_New_Parser( T1_Parser parser,
136 FT_Stream stream,
137 FT_Memory memory,
138 PSAux_Service psaux )
139 {
140 FT_Error error;
141 FT_UShort tag;
142 FT_ULong size;
143
144
145 psaux->ps_parser_funcs->init( &parser->root, NULL, NULL, memory );
146
147 parser->stream = stream;
148 parser->base_len = 0;
149 parser->base_dict = NULL;
150 parser->private_len = 0;
151 parser->private_dict = NULL;
152 parser->in_pfb = 0;
153 parser->in_memory = 0;
154 parser->single_block = 0;
155
156 /* check the header format */
157 error = check_type1_format( stream, "%!PS-AdobeFont", 14 );
158 if ( error )
159 {
160 if ( FT_ERR_NEQ( error, Unknown_File_Format ) )
161 goto Exit;
162
163 error = check_type1_format( stream, "%!FontType", 10 );
164 if ( error )
165 {
166 FT_TRACE2(( " not a Type 1 font\n" ));
167 goto Exit;
168 }
169 }
170
171 /*******************************************************************
172 *
173 * Here a short summary of what is going on:
174 *
175 * When creating a new Type 1 parser, we try to locate and load
176 * the base dictionary if this is possible (i.e., for PFB
177 * files). Otherwise, we load the whole font into memory.
178 *
179 * When `loading' the base dictionary, we only setup pointers
180 * in the case of a memory-based stream. Otherwise, we
181 * allocate and load the base dictionary in it.
182 *
183 * parser->in_pfb is set if we are in a binary (`.pfb') font.
184 * parser->in_memory is set if we have a memory stream.
185 */
186
187 /* try to compute the size of the base dictionary; */
188 /* look for a Postscript binary file tag, i.e., 0x8001 */
189 if ( FT_STREAM_SEEK( 0L ) )
190 goto Exit;
191
192 error = read_pfb_tag( stream, &tag, &size );
193 if ( error )
194 goto Exit;
195
196 if ( tag != 0x8001U )
197 {
198 /* assume that this is a PFA file for now; an error will */
199 /* be produced later when more things are checked */
200 if ( FT_STREAM_SEEK( 0L ) )
201 goto Exit;
202 size = stream->size;
203 }
204 else
205 parser->in_pfb = 1;
206
207 /* now, try to load `size' bytes of the `base' dictionary we */
208 /* found previously */
209
210 /* if it is a memory-based resource, set up pointers */
211 if ( !stream->read )
212 {
213 parser->base_dict = (FT_Byte*)stream->base + stream->pos;
214 parser->base_len = size;
215 parser->in_memory = 1;
216
217 /* check that the `size' field is valid */
218 if ( FT_STREAM_SKIP( size ) )
219 goto Exit;
220 }
221 else
222 {
223 /* read segment in memory -- this is clumsy, but so does the format */
224 if ( FT_QALLOC( parser->base_dict, size ) ||
225 FT_STREAM_READ( parser->base_dict, size ) )
226 goto Exit;
227 parser->base_len = size;
228 }
229
230 parser->root.base = parser->base_dict;
231 parser->root.cursor = parser->base_dict;
232 parser->root.limit = parser->root.cursor + parser->base_len;
233
234 Exit:
235 if ( error && !parser->in_memory )
236 FT_FREE( parser->base_dict );
237
238 return error;
239 }
240
241
242 FT_LOCAL_DEF( void )
243 T1_Finalize_Parser( T1_Parser parser )
244 {
245 FT_Memory memory = parser->root.memory;
246
247
248 /* always free the private dictionary */
249 FT_FREE( parser->private_dict );
250
251 /* free the base dictionary only when we have a disk stream */
252 if ( !parser->in_memory )
253 FT_FREE( parser->base_dict );
254
255 parser->root.funcs.done( &parser->root );
256 }
257
258
259 FT_LOCAL_DEF( FT_Error )
260 T1_Get_Private_Dict( T1_Parser parser,
261 PSAux_Service psaux )
262 {
263 FT_Stream stream = parser->stream;
264 FT_Memory memory = parser->root.memory;
265 FT_Error error = FT_Err_Ok;
266 FT_ULong size;
267
268
269 if ( parser->in_pfb )
270 {
271 /* in the case of the PFB format, the private dictionary can be */
272 /* made of several segments. We thus first read the number of */
273 /* segments to compute the total size of the private dictionary */
274 /* then re-read them into memory. */
275 FT_ULong start_pos = FT_STREAM_POS();
276 FT_UShort tag;
277
278
279 parser->private_len = 0;
280 for (;;)
281 {
282 error = read_pfb_tag( stream, &tag, &size );
283 if ( error )
284 goto Fail;
285
286 if ( tag != 0x8002U )
287 break;
288
289 parser->private_len += size;
290
291 if ( FT_STREAM_SKIP( size ) )
292 goto Fail;
293 }
294
295 /* Check that we have a private dictionary there */
296 /* and allocate private dictionary buffer */
297 if ( parser->private_len == 0 )
298 {
299 FT_ERROR(( "T1_Get_Private_Dict:"
300 " invalid private dictionary section\n" ));
301 error = FT_THROW( Invalid_File_Format );
302 goto Fail;
303 }
304
305 if ( FT_STREAM_SEEK( start_pos ) ||
306 FT_QALLOC( parser->private_dict, parser->private_len ) )
307 goto Fail;
308
309 parser->private_len = 0;
310 for (;;)
311 {
312 error = read_pfb_tag( stream, &tag, &size );
313 if ( error || tag != 0x8002U )
314 {
315 error = FT_Err_Ok;
316 break;
317 }
318
319 if ( FT_STREAM_READ( parser->private_dict + parser->private_len,
320 size ) )
321 goto Fail;
322
323 parser->private_len += size;
324 }
325 }
326 else
327 {
328 /* We have already `loaded' the whole PFA font file into memory; */
329 /* if this is a memory resource, allocate a new block to hold */
330 /* the private dict. Otherwise, simply overwrite into the base */
331 /* dictionary block in the heap. */
332
333 /* First look for the `eexec' keyword. Ensure `eexec' is real -- */
334 /* it could be in a comment or string (as e.g. in u003043t.gsf */
335 /* from ghostscript). */
336 FT_Byte* cur = parser->base_dict;
337 FT_Byte* limit = cur + parser->base_len;
338 FT_Pointer pos_lf;
339 FT_Bool test_cr;
340
341
342 parser->root.cursor = parser->base_dict;
343 parser->root.limit = parser->base_dict + parser->base_len;
344
345 cur = parser->root.cursor;
346 limit = parser->root.limit;
347
348 while ( cur < limit )
349 {
350 /* 9 = 5 letters for `eexec' + whitespace + 4 chars */
351 if ( cur[0] == 'e' && cur + 9 < limit )
352 {
353 if ( cur[1] == 'e' &&
354 cur[2] == 'x' &&
355 cur[3] == 'e' &&
356 cur[4] == 'c' )
357 goto Found;
358 }
359
360 T1_Skip_PS_Token( parser );
361 if ( parser->root.error )
362 break;
363 T1_Skip_Spaces ( parser );
364 cur = parser->root.cursor;
365 }
366
367 FT_ERROR(( "T1_Get_Private_Dict: could not find `eexec' keyword\n" ));
368 error = FT_THROW( Invalid_File_Format );
369 goto Exit;
370
371 /* now determine where to write the _encrypted_ binary private */
372 /* dictionary. We overwrite the base dictionary for disk-based */
373 /* resources and allocate a new block otherwise */
374
375 Found:
376 parser->root.limit = parser->base_dict + parser->base_len;
377
378 T1_Skip_PS_Token( parser );
379 cur = parser->root.cursor;
380 limit = parser->root.limit;
381
382 /* According to the Type 1 spec, the first cipher byte must not be */
383 /* an ASCII whitespace character code (blank, tab, carriage return */
384 /* or line feed). We have seen Type 1 fonts with two line feed */
385 /* characters... So skip now all whitespace character codes. */
386 /* */
387 /* On the other hand, Adobe's Type 1 parser handles fonts just */
388 /* fine that are violating this limitation, so we add a heuristic */
389 /* test to stop at \r only if it is not used for EOL. */
390
391 pos_lf = ft_memchr( cur, '\n', (size_t)( limit - cur ) );
392 test_cr = FT_BOOL( !pos_lf ||
393 pos_lf > ft_memchr( cur,
394 '\r',
395 (size_t)( limit - cur ) ) );
396
397 while ( cur < limit &&
398 ( *cur == ' ' ||
399 *cur == '\t' ||
400 (test_cr && *cur == '\r' ) ||
401 *cur == '\n' ) )
402 cur++;
403 if ( cur >= limit )
404 {
405 FT_ERROR(( "T1_Get_Private_Dict:"
406 " `eexec' not properly terminated\n" ));
407 error = FT_THROW( Invalid_File_Format );
408 goto Exit;
409 }
410
411 size = parser->base_len - (FT_ULong)( cur - parser->base_dict );
412
413 if ( parser->in_memory )
414 {
415 /* note that we allocate one more byte to put a terminating `0' */
416 if ( FT_QALLOC( parser->private_dict, size + 1 ) )
417 goto Fail;
418 parser->private_len = size;
419 }
420 else
421 {
422 parser->single_block = 1;
423 parser->private_dict = parser->base_dict;
424 parser->private_len = size;
425 parser->base_dict = NULL;
426 parser->base_len = 0;
427 }
428
429 /* now determine whether the private dictionary is encoded in binary */
430 /* or hexadecimal ASCII format -- decode it accordingly */
431
432 /* we need to access the next 4 bytes (after the final whitespace */
433 /* following the `eexec' keyword); if they all are hexadecimal */
434 /* digits, then we have a case of ASCII storage */
435
436 if ( cur + 3 < limit &&
437 ft_isxdigit( cur[0] ) && ft_isxdigit( cur[1] ) &&
438 ft_isxdigit( cur[2] ) && ft_isxdigit( cur[3] ) )
439 {
440 /* ASCII hexadecimal encoding */
441 FT_ULong len;
442
443
444 parser->root.cursor = cur;
445 (void)psaux->ps_parser_funcs->to_bytes( &parser->root,
446 parser->private_dict,
447 parser->private_len,
448 &len,
449 0 );
450 parser->private_len = len;
451
452 /* put a safeguard */
453 parser->private_dict[len] = '\0';
454 }
455 else
456 /* binary encoding -- copy the private dict */
457 FT_MEM_MOVE( parser->private_dict, cur, size );
458 }
459
460 /* we now decrypt the encoded binary private dictionary */
461 psaux->t1_decrypt( parser->private_dict, parser->private_len, 55665U );
462
463 if ( parser->private_len < 4 )
464 {
465 FT_ERROR(( "T1_Get_Private_Dict:"
466 " invalid private dictionary section\n" ));
467 error = FT_THROW( Invalid_File_Format );
468 goto Fail;
469 }
470
471 /* replace the four random bytes at the beginning with whitespace */
472 parser->private_dict[0] = ' ';
473 parser->private_dict[1] = ' ';
474 parser->private_dict[2] = ' ';
475 parser->private_dict[3] = ' ';
476
477 parser->root.base = parser->private_dict;
478 parser->root.cursor = parser->private_dict;
479 parser->root.limit = parser->root.cursor + parser->private_len;
480
481 Fail:
482 Exit:
483 return error;
484 }
485
486
487 /* END */