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 1.98 2017/11/02 20:25:39 christos Exp $")
39 #endif /* lint */
40
41 #include "magic.h"
42 #include <string.h>
43 #include <memory.h>
44 #include <ctype.h>
45 #include <stdlib.h>
46 #ifdef HAVE_UNISTD_H
47 #include <unistd.h>
48 #endif
49
50 #define MAXLINELEN 300 /* longest sane line length */
51 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \
52 || (x) == 0x85 || (x) == '\f')
53
54 private unsigned char *encode_utf8(unsigned char *, size_t, unichar *, 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 unichar *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(b->fbuf, b->flen);
84
85 /* If file doesn't look like any sort of text, give up. */
86 if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime,
87 &type) == 0)
88 rv = 0;
89 else
90 rv = file_ascmagic_with_encoding(ms, &bb,
91 ubuf, ulen, code, type, text);
92
93 efree(ubuf);
94
95 return rv;
96 }
97
98 protected int
file_ascmagic_with_encoding(struct magic_set * ms,const struct buffer * b,unichar * ubuf,size_t ulen,const char * code,const char * type,int text)99 file_ascmagic_with_encoding(struct magic_set *ms,
100 const struct buffer *b, unichar *ubuf, size_t ulen, const char *code,
101 const char *type, int text)
102 {
103 struct buffer bb;
104 const unsigned char *buf = b->fbuf;
105 size_t nbytes = b->flen;
106 unsigned char *utf8_buf = NULL, *utf8_end;
107 size_t mlen, i;
108 int rv = -1;
109 int mime = ms->flags & MAGIC_MIME;
110
111 const char *subtype = NULL;
112 const char *subtype_mime = NULL;
113
114 int has_escapes = 0;
115 int has_backspace = 0;
116 int seen_cr = 0;
117
118 int n_crlf = 0;
119 int n_lf = 0;
120 int n_cr = 0;
121 int n_nel = 0;
122 int executable = 0;
123
124 size_t last_line_end = (size_t)-1;
125 int has_long_lines = 0;
126
127 nbytes = trim_nuls(buf, nbytes);
128
129 /* If we have fewer than 2 bytes, give up. */
130 if (nbytes <= 1) {
131 rv = 0;
132 goto done;
133 }
134
135 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) {
136 /* Convert ubuf to UTF-8 and try text soft magic */
137 /* malloc size is a conservative overestimate; could be
138 improved, or at least realloced after conversion. */
139 mlen = ulen * 6;
140 if ((utf8_buf = CAST(unsigned char *, emalloc(mlen))) == NULL) {
141 file_oomem(ms, mlen);
142 goto done;
143 }
144 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen))
145 == NULL)
146 goto done;
147 buffer_init(&bb, b->fd, utf8_buf,
148 (size_t)(utf8_end - utf8_buf));
149
150 if ((rv = file_softmagic(ms, &bb, NULL, NULL,
151 TEXTTEST, text)) == 0)
152 rv = -1;
153 buffer_fini(&bb);
154 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) {
155 rv = rv == -1 ? 0 : 1;
156 goto done;
157 }
158 }
159 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)))
160 return 0;
161
162 /* Now try to discover other details about the file. */
163 for (i = 0; i < ulen; i++) {
164 if (ubuf[i] == '\n') {
165 if (seen_cr)
166 n_crlf++;
167 else
168 n_lf++;
169 last_line_end = i;
170 } else if (seen_cr)
171 n_cr++;
172
173 seen_cr = (ubuf[i] == '\r');
174 if (seen_cr)
175 last_line_end = i;
176
177 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
178 n_nel++;
179 last_line_end = i;
180 }
181
182 /* If this line is _longer_ than MAXLINELEN, remember it. */
183 if (i > last_line_end + MAXLINELEN)
184 has_long_lines = 1;
185
186 if (ubuf[i] == '\033')
187 has_escapes = 1;
188 if (ubuf[i] == '\b')
189 has_backspace = 1;
190 }
191
192 /* Beware, if the data has been truncated, the final CR could have
193 been followed by a LF. If we have ms->bytes_max bytes, it indicates
194 that the data might have been truncated, probably even before
195 this function was called. */
196 if (seen_cr && nbytes < ms->bytes_max)
197 n_cr++;
198
199 if (strcmp(type, "binary") == 0) {
200 rv = 0;
201 goto done;
202 }
203 if (mime) {
204 if (!file_printedlen(ms) && (mime & MAGIC_MIME_TYPE) != 0) {
205 if (subtype_mime) {
206 if (file_printf(ms, "%s", subtype_mime) == -1)
207 goto done;
208 } else {
209 if (file_printf(ms, "text/plain") == -1)
210 goto done;
211 }
212 }
213 } else {
214 if (file_printedlen(ms)) {
215 switch (file_replace(ms, " text$", ", ")) {
216 case 0:
217 switch (file_replace(ms, " text executable$",
218 ", ")) {
219 case 0:
220 if (file_printf(ms, ", ") == -1)
221 goto done;
222 break;
223 case -1:
224 goto done;
225 default:
226 executable = 1;
227 break;
228 }
229 break;
230 case -1:
231 goto done;
232 default:
233 break;
234 }
235 }
236
237 if (file_printf(ms, "%s", code) == -1)
238 goto done;
239
240 if (subtype) {
241 if (file_printf(ms, " %s", subtype) == -1)
242 goto done;
243 }
244
245 if (file_printf(ms, " %s", type) == -1)
246 goto done;
247
248 if (executable)
249 if (file_printf(ms, " executable") == -1)
250 goto done;
251
252 if (has_long_lines)
253 if (file_printf(ms, ", with very long lines") == -1)
254 goto done;
255
256 /*
257 * Only report line terminators if we find one other than LF,
258 * or if we find none at all.
259 */
260 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
261 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
262 if (file_printf(ms, ", with") == -1)
263 goto done;
264
265 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
266 if (file_printf(ms, " no") == -1)
267 goto done;
268 } else {
269 if (n_crlf) {
270 if (file_printf(ms, " CRLF") == -1)
271 goto done;
272 if (n_cr || n_lf || n_nel)
273 if (file_printf(ms, ",") == -1)
274 goto done;
275 }
276 if (n_cr) {
277 if (file_printf(ms, " CR") == -1)
278 goto done;
279 if (n_lf || n_nel)
280 if (file_printf(ms, ",") == -1)
281 goto done;
282 }
283 if (n_lf) {
284 if (file_printf(ms, " LF") == -1)
285 goto done;
286 if (n_nel)
287 if (file_printf(ms, ",") == -1)
288 goto done;
289 }
290 if (n_nel)
291 if (file_printf(ms, " NEL") == -1)
292 goto done;
293 }
294
295 if (file_printf(ms, " line terminators") == -1)
296 goto done;
297 }
298
299 if (has_escapes)
300 if (file_printf(ms, ", with escape sequences") == -1)
301 goto done;
302 if (has_backspace)
303 if (file_printf(ms, ", with overstriking") == -1)
304 goto done;
305 }
306 rv = 1;
307 done:
308 if (utf8_buf)
309 efree(utf8_buf);
310
311 return rv;
312 }
313
314 /*
315 * Encode Unicode string as UTF-8, returning pointer to character
316 * after end of string, or NULL if an invalid character is found.
317 */
318 private unsigned char *
encode_utf8(unsigned char * buf,size_t len,unichar * ubuf,size_t ulen)319 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen)
320 {
321 size_t i;
322 unsigned char *end = buf + len;
323
324 for (i = 0; i < ulen; i++) {
325 if (ubuf[i] <= 0x7f) {
326 if (end - buf < 1)
327 return NULL;
328 *buf++ = (unsigned char)ubuf[i];
329 } else if (ubuf[i] <= 0x7ff) {
330 if (end - buf < 2)
331 return NULL;
332 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0);
333 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
334 } else if (ubuf[i] <= 0xffff) {
335 if (end - buf < 3)
336 return NULL;
337 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0);
338 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
339 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
340 } else if (ubuf[i] <= 0x1fffff) {
341 if (end - buf < 4)
342 return NULL;
343 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0);
344 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
345 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
346 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
347 } else if (ubuf[i] <= 0x3ffffff) {
348 if (end - buf < 5)
349 return NULL;
350 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8);
351 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
352 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
353 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
354 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
355 } else if (ubuf[i] <= 0x7fffffff) {
356 if (end - buf < 6)
357 return NULL;
358 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc);
359 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80);
360 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
361 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
362 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
363 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
364 } else /* Invalid character */
365 return NULL;
366 }
367
368 return buf;
369 }
370
