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 1.107 2020/06/08 19:58:36 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, unicodechar *, size_t);
54 private size_t trim_nuls(const unsigned char *, size_t);
55
56 /*
57 * Undo the NUL-termination kindly provided by process()
58 * but leave at least one byte to look at
59 */
60 private size_t
trim_nuls(const unsigned char * buf,size_t nbytes)61 trim_nuls(const unsigned char *buf, size_t nbytes)
62 {
63 while (nbytes > 1 && buf[nbytes - 1] == '\0')
64 nbytes--;
65
66 return nbytes;
67 }
68
69 protected int
file_ascmagic(struct magic_set * ms,const struct buffer * b,int text)70 file_ascmagic(struct magic_set *ms, const struct buffer *b, int text)
71 {
72 unicodechar *ubuf = NULL;
73 size_t ulen = 0;
74 int rv = 1;
75 struct buffer bb;
76
77 const char *code = NULL;
78 const char *code_mime = NULL;
79 const char *type = NULL;
80
81 bb = *b;
82 bb.flen = trim_nuls(CAST(const unsigned char *, b->fbuf), b->flen);
83 /*
84 * Avoid trimming at an odd byte if the original buffer was evenly
85 * sized; this avoids losing the last character on UTF-16 LE text
86 */
87 if ((bb.flen & 1) && !(b->flen & 1))
88 bb.flen++;
89
90 /* If file doesn't look like any sort of text, give up. */
91 if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime,
92 &type) == 0)
93 rv = 0;
94 else
95 rv = file_ascmagic_with_encoding(ms, &bb,
96 ubuf, ulen, code, type, text);
97
98 efree(ubuf);
99
100 return rv;
101 }
102
103 protected int
file_ascmagic_with_encoding(struct magic_set * ms,const struct buffer * b,unicodechar * ubuf,size_t ulen,const char * code,const char * type,int text)104 file_ascmagic_with_encoding(struct magic_set *ms,
105 const struct buffer *b, unicodechar *ubuf, size_t ulen, const char *code,
106 const char *type, int text)
107 {
108 struct buffer bb;
109 const unsigned char *buf = CAST(const unsigned char *, b->fbuf);
110 size_t nbytes = b->flen;
111 unsigned char *utf8_buf = NULL, *utf8_end;
112 size_t mlen, i, len;
113 int rv = -1;
114 int mime = ms->flags & MAGIC_MIME;
115 int need_separator = 0;
116
117 const char *subtype = NULL;
118
119 int has_escapes = 0;
120 int has_backspace = 0;
121 int seen_cr = 0;
122
123 int n_crlf = 0;
124 int n_lf = 0;
125 int n_cr = 0;
126 int n_nel = 0;
127 int executable = 0;
128
129 size_t last_line_end = CAST(size_t, -1);
130 int has_long_lines = 0;
131
132 nbytes = trim_nuls(buf, nbytes);
133
134 /* If we have fewer than 2 bytes, give up. */
135 if (nbytes <= 1) {
136 rv = 0;
137 goto done;
138 }
139
140 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) {
141 /* Convert ubuf to UTF-8 and try text soft magic */
142 /* malloc size is a conservative overestimate; could be
143 improved, or at least realloced after conversion. */
144 mlen = ulen * 6;
145 if ((utf8_buf = CAST(unsigned char *, emalloc(mlen))) == NULL) {
146 file_oomem(ms, mlen);
147 goto done;
148 }
149 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen))
150 == NULL)
151 goto done;
152 buffer_init(&bb, b->fd, &b->st, utf8_buf,
153 CAST(size_t, utf8_end - utf8_buf));
154
155 if ((rv = file_softmagic(ms, &bb, NULL, NULL,
156 TEXTTEST, text)) == 0)
157 rv = -1;
158 else
159 need_separator = 1;
160 buffer_fini(&bb);
161 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) {
162 rv = rv == -1 ? 0 : 1;
163 goto done;
164 }
165 }
166
167 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) {
168 rv = 0;
169 goto done;
170 }
171
172 /* Now try to discover other details about the file. */
173 for (i = 0; i < ulen; i++) {
174 if (ubuf[i] == '\n') {
175 if (seen_cr)
176 n_crlf++;
177 else
178 n_lf++;
179 last_line_end = i;
180 } else if (seen_cr)
181 n_cr++;
182
183 seen_cr = (ubuf[i] == '\r');
184 if (seen_cr)
185 last_line_end = i;
186
187 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
188 n_nel++;
189 last_line_end = i;
190 }
191
192 /* If this line is _longer_ than MAXLINELEN, remember it. */
193 if (i > last_line_end + MAXLINELEN)
194 has_long_lines = 1;
195
196 if (ubuf[i] == '\033')
197 has_escapes = 1;
198 if (ubuf[i] == '\b')
199 has_backspace = 1;
200 }
201
202 /* Beware, if the data has been truncated, the final CR could have
203 been followed by a LF. If we have ms->bytes_max bytes, it indicates
204 that the data might have been truncated, probably even before
205 this function was called. */
206 if (seen_cr && nbytes < ms->bytes_max)
207 n_cr++;
208
209 if (strcmp(type, "binary") == 0) {
210 rv = 0;
211 goto done;
212 }
213 len = file_printedlen(ms);
214 if (mime) {
215 if ((mime & MAGIC_MIME_TYPE) != 0) {
216 if (len) {
217 /*
218 * Softmagic printed something, we
219 * are either done, or we need a separator
220 */
221 if ((ms->flags & MAGIC_CONTINUE) == 0) {
222 rv = 1;
223 goto done;
224 }
225 if (need_separator && file_separator(ms) == -1)
226 goto done;
227 } else {
228 if (file_printf(ms, "text/plain") == -1)
229 goto done;
230 }
231 }
232 } else {
233 if (len) {
234 switch (file_replace(ms, " text$", ", ")) {
235 case 0:
236 switch (file_replace(ms, " text executable$",
237 ", ")) {
238 case 0:
239 if (file_printf(ms, ", ") == -1)
240 goto done;
241 break;
242 case -1:
243 goto done;
244 default:
245 executable = 1;
246 break;
247 }
248 break;
249 case -1:
250 goto done;
251 default:
252 break;
253 }
254 }
255
256 if (file_printf(ms, "%s", code) == -1)
257 goto done;
258
259 if (subtype) {
260 if (file_printf(ms, " %s", subtype) == -1)
261 goto done;
262 }
263
264 if (file_printf(ms, " %s", type) == -1)
265 goto done;
266
267 if (executable)
268 if (file_printf(ms, " executable") == -1)
269 goto done;
270
271 if (has_long_lines)
272 if (file_printf(ms, ", with very long lines") == -1)
273 goto done;
274
275 /*
276 * Only report line terminators if we find one other than LF,
277 * or if we find none at all.
278 */
279 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
280 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
281 if (file_printf(ms, ", with") == -1)
282 goto done;
283
284 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
285 if (file_printf(ms, " no") == -1)
286 goto done;
287 } else {
288 if (n_crlf) {
289 if (file_printf(ms, " CRLF") == -1)
290 goto done;
291 if (n_cr || n_lf || n_nel)
292 if (file_printf(ms, ",") == -1)
293 goto done;
294 }
295 if (n_cr) {
296 if (file_printf(ms, " CR") == -1)
297 goto done;
298 if (n_lf || n_nel)
299 if (file_printf(ms, ",") == -1)
300 goto done;
301 }
302 if (n_lf) {
303 if (file_printf(ms, " LF") == -1)
304 goto done;
305 if (n_nel)
306 if (file_printf(ms, ",") == -1)
307 goto done;
308 }
309 if (n_nel)
310 if (file_printf(ms, " NEL") == -1)
311 goto done;
312 }
313
314 if (file_printf(ms, " line terminators") == -1)
315 goto done;
316 }
317
318 if (has_escapes)
319 if (file_printf(ms, ", with escape sequences") == -1)
320 goto done;
321 if (has_backspace)
322 if (file_printf(ms, ", with overstriking") == -1)
323 goto done;
324 }
325 rv = 1;
326 done:
327 if (utf8_buf)
328 efree(utf8_buf);
329
330 return rv;
331 }
332
333 /*
334 * Encode Unicode string as UTF-8, returning pointer to character
335 * after end of string, or NULL if an invalid character is found.
336 */
337 private unsigned char *
encode_utf8(unsigned char * buf,size_t len,unicodechar * ubuf,size_t ulen)338 encode_utf8(unsigned char *buf, size_t len, unicodechar *ubuf, size_t ulen)
339 {
340 size_t i;
341 unsigned char *end = buf + len;
342
343 for (i = 0; i < ulen; i++) {
344 if (ubuf[i] <= 0x7f) {
345 if (end - buf < 1)
346 return NULL;
347 *buf++ = CAST(unsigned char, ubuf[i]);
348 } else if (ubuf[i] <= 0x7ff) {
349 if (end - buf < 2)
350 return NULL;
351 *buf++ = CAST(unsigned char, (ubuf[i] >> 6) + 0xc0);
352 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80);
353 } else if (ubuf[i] <= 0xffff) {
354 if (end - buf < 3)
355 return NULL;
356 *buf++ = CAST(unsigned char, (ubuf[i] >> 12) + 0xe0);
357 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80);
358 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80);
359 } else if (ubuf[i] <= 0x1fffff) {
360 if (end - buf < 4)
361 return NULL;
362 *buf++ = CAST(unsigned char, (ubuf[i] >> 18) + 0xf0);
363 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80);
364 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80);
365 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80);
366 } else if (ubuf[i] <= 0x3ffffff) {
367 if (end - buf < 5)
368 return NULL;
369 *buf++ = CAST(unsigned char, (ubuf[i] >> 24) + 0xf8);
370 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80);
371 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80);
372 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80);
373 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80);
374 } else if (ubuf[i] <= 0x7fffffff) {
375 if (end - buf < 6)
376 return NULL;
377 *buf++ = CAST(unsigned char, (ubuf[i] >> 30) + 0xfc);
378 *buf++ = CAST(unsigned char, ((ubuf[i] >> 24) & 0x3f) + 0x80);
379 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80);
380 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80);
381 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80);
382 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80);
383 } else /* Invalid character */
384 return NULL;
385 }
386
387 return buf;
388 }
389
