1 /*
2 * Copyright (c) Ian F. Darwin 1986-1995.
3 * Software written by Ian F. Darwin and others;
4 * maintained 1995-present by Christos Zoulas and others.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice immediately at the beginning of the file, without modification,
11 * this list of conditions, and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28 /*
29 * ASCII magic -- try to detect text encoding.
30 *
31 * Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000,
32 * to handle character codes other than ASCII on a unified basis.
33 */
34
35 #include "file.h"
36
37 #ifndef lint
38 FILE_RCSID("@(#)$File: ascmagic.c,v 1.109 2021/02/05 23:01:40 christos Exp $")
39 #endif /* lint */
40
41 #include "magic.h"
42 #include <string.h>
43 #include <ctype.h>
44 #include <stdlib.h>
45 #ifdef HAVE_UNISTD_H
46 #include <unistd.h>
47 #endif
48
49 #define MAXLINELEN 300 /* longest sane line length */
50 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \
51 || (x) == 0x85 || (x) == '\f')
52
53 private unsigned char *encode_utf8(unsigned char *, size_t, file_unichar_t *,
54 size_t);
55 private size_t trim_nuls(const unsigned char *, size_t);
56
57 /*
58 * Undo the NUL-termination kindly provided by process()
59 * but leave at least one byte to look at
60 */
61 private size_t
trim_nuls(const unsigned char * buf,size_t nbytes)62 trim_nuls(const unsigned char *buf, size_t nbytes)
63 {
64 while (nbytes > 1 && buf[nbytes - 1] == '\0')
65 nbytes--;
66
67 return nbytes;
68 }
69
70 protected int
file_ascmagic(struct magic_set * ms,const struct buffer * b,int text)71 file_ascmagic(struct magic_set *ms, const struct buffer *b, int text)
72 {
73 file_unichar_t *ubuf = NULL;
74 size_t ulen = 0;
75 int rv = 1;
76 struct buffer bb;
77
78 const char *code = NULL;
79 const char *code_mime = NULL;
80 const char *type = NULL;
81
82 bb = *b;
83 bb.flen = trim_nuls(CAST(const unsigned char *, b->fbuf), b->flen);
84 /*
85 * Avoid trimming at an odd byte if the original buffer was evenly
86 * sized; this avoids losing the last character on UTF-16 LE text
87 */
88 if ((bb.flen & 1) && !(b->flen & 1))
89 bb.flen++;
90
91 /* If file doesn't look like any sort of text, give up. */
92 if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime,
93 &type) == 0)
94 rv = 0;
95 else
96 rv = file_ascmagic_with_encoding(ms, &bb,
97 ubuf, ulen, code, type, text);
98
99 efree(ubuf);
100
101 return rv;
102 }
103
104 protected int
file_ascmagic_with_encoding(struct magic_set * ms,const struct buffer * b,file_unichar_t * ubuf,size_t ulen,const char * code,const char * type,int text)105 file_ascmagic_with_encoding(struct magic_set *ms, const struct buffer *b,
106 file_unichar_t *ubuf, size_t ulen, const char *code, const char *type,
107 int text)
108 {
109 struct buffer bb;
110 const unsigned char *buf = CAST(const unsigned char *, b->fbuf);
111 size_t nbytes = b->flen;
112 unsigned char *utf8_buf = NULL, *utf8_end;
113 size_t mlen, i, len;
114 int rv = -1;
115 int mime = ms->flags & MAGIC_MIME;
116 int need_separator = 0;
117
118 const char *subtype = NULL;
119
120 int has_escapes = 0;
121 int has_backspace = 0;
122 int seen_cr = 0;
123
124 int n_crlf = 0;
125 int n_lf = 0;
126 int n_cr = 0;
127 int n_nel = 0;
128 int executable = 0;
129
130 size_t last_line_end = CAST(size_t, -1);
131 size_t has_long_lines = 0;
132
133 nbytes = trim_nuls(buf, nbytes);
134
135 /* If we have fewer than 2 bytes, give up. */
136 if (nbytes <= 1) {
137 rv = 0;
138 goto done;
139 }
140
141 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) {
142 /* Convert ubuf to UTF-8 and try text soft magic */
143 /* malloc size is a conservative overestimate; could be
144 improved, or at least realloced after conversion. */
145 mlen = ulen * 6;
146 if ((utf8_buf = CAST(unsigned char *, emalloc(mlen))) == NULL) {
147 file_oomem(ms, mlen);
148 goto done;
149 }
150 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen))
151 == NULL)
152 goto done;
153 buffer_init(&bb, b->fd, &b->st, utf8_buf,
154 CAST(size_t, utf8_end - utf8_buf));
155
156 if ((rv = file_softmagic(ms, &bb, NULL, NULL,
157 TEXTTEST, text)) == 0)
158 rv = -1;
159 else
160 need_separator = 1;
161 buffer_fini(&bb);
162 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) {
163 rv = rv == -1 ? 0 : 1;
164 goto done;
165 }
166 }
167
168 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) {
169 rv = 0;
170 goto done;
171 }
172
173 /* Now try to discover other details about the file. */
174 for (i = 0; i < ulen; i++) {
175 if (ubuf[i] == '\n') {
176 if (seen_cr)
177 n_crlf++;
178 else
179 n_lf++;
180 last_line_end = i;
181 } else if (seen_cr)
182 n_cr++;
183
184 seen_cr = (ubuf[i] == '\r');
185 if (seen_cr)
186 last_line_end = i;
187
188 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
189 n_nel++;
190 last_line_end = i;
191 }
192
193 /* If this line is _longer_ than MAXLINELEN, remember it. */
194 if (i > last_line_end + MAXLINELEN) {
195 size_t ll = i - last_line_end;
196 if (ll > has_long_lines)
197 has_long_lines = ll;
198 }
199
200 if (ubuf[i] == '\033')
201 has_escapes = 1;
202 if (ubuf[i] == '\b')
203 has_backspace = 1;
204 }
205
206 /* Beware, if the data has been truncated, the final CR could have
207 been followed by a LF. If we have ms->bytes_max bytes, it indicates
208 that the data might have been truncated, probably even before
209 this function was called. */
210 if (seen_cr && nbytes < ms->bytes_max)
211 n_cr++;
212
213 if (strcmp(type, "binary") == 0) {
214 rv = 0;
215 goto done;
216 }
217 len = file_printedlen(ms);
218 if (mime) {
219 if ((mime & MAGIC_MIME_TYPE) != 0) {
220 if (len) {
221 /*
222 * Softmagic printed something, we
223 * are either done, or we need a separator
224 */
225 if ((ms->flags & MAGIC_CONTINUE) == 0) {
226 rv = 1;
227 goto done;
228 }
229 if (need_separator && file_separator(ms) == -1)
230 goto done;
231 } else {
232 if (file_printf(ms, "text/plain") == -1)
233 goto done;
234 }
235 }
236 } else {
237 if (len) {
238 switch (file_replace(ms, " text$", ", ")) {
239 case 0:
240 switch (file_replace(ms, " text executable$",
241 ", ")) {
242 case 0:
243 if (file_printf(ms, ", ") == -1)
244 goto done;
245 break;
246 case -1:
247 goto done;
248 default:
249 executable = 1;
250 break;
251 }
252 break;
253 case -1:
254 goto done;
255 default:
256 break;
257 }
258 }
259
260 if (file_printf(ms, "%s", code) == -1)
261 goto done;
262
263 if (subtype) {
264 if (file_printf(ms, " %s", subtype) == -1)
265 goto done;
266 }
267
268 if (file_printf(ms, " %s", type) == -1)
269 goto done;
270
271 if (executable)
272 if (file_printf(ms, " executable") == -1)
273 goto done;
274
275 if (has_long_lines)
276 if (file_printf(ms, ", with very long lines (%zu)",
277 has_long_lines) == -1)
278 goto done;
279
280 /*
281 * Only report line terminators if we find one other than LF,
282 * or if we find none at all.
283 */
284 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
285 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
286 if (file_printf(ms, ", with") == -1)
287 goto done;
288
289 if (n_crlf == 0 && n_cr == 0 &&
290 n_nel == 0 && n_lf == 0) {
291 if (file_printf(ms, " no") == -1)
292 goto done;
293 } else {
294 if (n_crlf) {
295 if (file_printf(ms, " CRLF") == -1)
296 goto done;
297 if (n_cr || n_lf || n_nel)
298 if (file_printf(ms, ",") == -1)
299 goto done;
300 }
301 if (n_cr) {
302 if (file_printf(ms, " CR") == -1)
303 goto done;
304 if (n_lf || n_nel)
305 if (file_printf(ms, ",") == -1)
306 goto done;
307 }
308 if (n_lf) {
309 if (file_printf(ms, " LF") == -1)
310 goto done;
311 if (n_nel)
312 if (file_printf(ms, ",") == -1)
313 goto done;
314 }
315 if (n_nel)
316 if (file_printf(ms, " NEL") == -1)
317 goto done;
318 }
319
320 if (file_printf(ms, " line terminators") == -1)
321 goto done;
322 }
323
324 if (has_escapes)
325 if (file_printf(ms, ", with escape sequences") == -1)
326 goto done;
327 if (has_backspace)
328 if (file_printf(ms, ", with overstriking") == -1)
329 goto done;
330 }
331 rv = 1;
332 done:
333 if (utf8_buf)
334 efree(utf8_buf);
335
336 return rv;
337 }
338
339 /*
340 * Encode Unicode string as UTF-8, returning pointer to character
341 * after end of string, or NULL if an invalid character is found.
342 */
343 private unsigned char *
encode_utf8(unsigned char * buf,size_t len,file_unichar_t * ubuf,size_t ulen)344 encode_utf8(unsigned char *buf, size_t len, file_unichar_t *ubuf, size_t ulen)
345 {
346 size_t i;
347 unsigned char *end = buf + len;
348
349 for (i = 0; i < ulen; i++) {
350 if (ubuf[i] <= 0x7f) {
351 if (end - buf < 1)
352 return NULL;
353 *buf++ = CAST(unsigned char, ubuf[i]);
354 continue;
355 }
356 if (ubuf[i] <= 0x7ff) {
357 if (end - buf < 2)
358 return NULL;
359 *buf++ = CAST(unsigned char, (ubuf[i] >> 6) + 0xc0);
360 goto out1;
361 }
362 if (ubuf[i] <= 0xffff) {
363 if (end - buf < 3)
364 return NULL;
365 *buf++ = CAST(unsigned char, (ubuf[i] >> 12) + 0xe0);
366 goto out2;
367 }
368 if (ubuf[i] <= 0x1fffff) {
369 if (end - buf < 4)
370 return NULL;
371 *buf++ = CAST(unsigned char, (ubuf[i] >> 18) + 0xf0);
372 goto out3;
373 }
374 if (ubuf[i] <= 0x3ffffff) {
375 if (end - buf < 5)
376 return NULL;
377 *buf++ = CAST(unsigned char, (ubuf[i] >> 24) + 0xf8);
378 goto out4;
379 }
380 if (ubuf[i] <= 0x7fffffff) {
381 if (end - buf < 6)
382 return NULL;
383 *buf++ = CAST(unsigned char, (ubuf[i] >> 30) + 0xfc);
384 goto out5;
385 }
386 /* Invalid character */
387 return NULL;
388 out5: *buf++ = CAST(unsigned char, ((ubuf[i] >> 24) & 0x3f) + 0x80);
389 out4: *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80);
390 out3: *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80);
391 out2: *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80);
392 out1: *buf++ = CAST(unsigned char, ((ubuf[i] >> 0) & 0x3f) + 0x80);
393 }
394
395 return buf;
396 }
397
