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 2004-2018 by */
12/* Albert Chin-A-Young. */
13/* */
14/* based on code in `src/gzip/ftgzip.c' */
15/* */
16/* This file is part of the FreeType project, and may only be used, */
17/* modified, and distributed under the terms of the FreeType project */
18/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
19/* this file you indicate that you have read the license and */
20/* understand and accept it fully. */
21/* */
22/***************************************************************************/
23
24#include <ft2build.h>
25#include FT_INTERNAL_MEMORY_H
26#include FT_INTERNAL_STREAM_H
27#include FT_INTERNAL_DEBUG_H
28#include FT_LZW_H
29#include FT_CONFIG_STANDARD_LIBRARY_H
30
31
32#include FT_MODULE_ERRORS_H
33
34#undef FTERRORS_H_
35
36#undef FT_ERR_PREFIX
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 = FT_THROW( 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;
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 = FT_Err_Ok;
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 = FT_THROW( 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 = FT_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 = FT_THROW( 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 unsigned long
334 ft_lzw_stream_io( FT_Stream stream,
335 unsigned long offset,
336 unsigned char* buffer,
337 unsigned long count )
338 {
339 FT_LZWFile zip = (FT_LZWFile)stream->descriptor.pointer;
340
341
342 return ft_lzw_file_io( zip, offset, 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;
352 FT_LZWFile zip = NULL;
353
354
355 if ( !stream || !source )
356 {
357 error = FT_THROW( Invalid_Stream_Handle );
358 goto Exit;
359 }
360
361 memory = source->memory;
362
363 /*
364 * Check the header right now; this prevents allocation of a huge
365 * LZWFile object (400 KByte of heap memory) if not necessary.
366 *
367 * Did I mention that you should never use .Z compressed font
368 * files?
369 */
370 error = ft_lzw_check_header( source );
371 if ( error )
372 goto Exit;
373
374 FT_ZERO( stream );
375 stream->memory = memory;
376
377 if ( !FT_NEW( zip ) )
378 {
379 error = ft_lzw_file_init( zip, stream, source );
380 if ( error )
381 {
382 FT_FREE( zip );
383 goto Exit;
384 }
385
386 stream->descriptor.pointer = zip;
387 }
388
389 stream->size = 0x7FFFFFFFL; /* don't know the real size! */
390 stream->pos = 0;
391 stream->base = 0;
392 stream->read = ft_lzw_stream_io;
393 stream->close = ft_lzw_stream_close;
394
395 Exit:
396 return error;
397 }
398
399
400#include "ftzopen.c"
401
402
403#else /* !FT_CONFIG_OPTION_USE_LZW */
404
405
406 FT_EXPORT_DEF( FT_Error )
407 FT_Stream_OpenLZW( FT_Stream stream,
408 FT_Stream source )
409 {
410 FT_UNUSED( stream );
411 FT_UNUSED( source );
412
413 return FT_THROW( Unimplemented_Feature );
414 }
415
416
417#endif /* !FT_CONFIG_OPTION_USE_LZW */
418
419
420/* END */
421