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 1.97 2016/06/27 20:56:25 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 unsigned char * buf,size_t nbytes,int text)71 file_ascmagic(struct magic_set *ms, const unsigned char *buf, size_t nbytes,
72 int text)
73 {
74 unichar *ubuf = NULL;
75 size_t ulen = 0;
76 int rv = 1;
77
78 const char *code = NULL;
79 const char *code_mime = NULL;
80 const char *type = NULL;
81
82 nbytes = trim_nuls(buf, nbytes);
83
84 /* If file doesn't look like any sort of text, give up. */
85 if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime,
86 &type) == 0)
87 rv = 0;
88 else
89 rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code,
90 type, text);
91
92 free(ubuf);
93
94 return rv;
95 }
96
97 protected int
file_ascmagic_with_encoding(struct magic_set * ms,const unsigned char * buf,size_t nbytes,unichar * ubuf,size_t ulen,const char * code,const char * type,int text)98 file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf,
99 size_t nbytes, unichar *ubuf, size_t ulen, const char *code,
100 const char *type, int text)
101 {
102 unsigned char *utf8_buf = NULL, *utf8_end;
103 size_t mlen, i;
104 int rv = -1;
105 int mime = ms->flags & MAGIC_MIME;
106
107 const char *subtype = NULL;
108 const char *subtype_mime = NULL;
109
110 int has_escapes = 0;
111 int has_backspace = 0;
112 int seen_cr = 0;
113
114 int n_crlf = 0;
115 int n_lf = 0;
116 int n_cr = 0;
117 int n_nel = 0;
118 int executable = 0;
119
120 size_t last_line_end = (size_t)-1;
121 int has_long_lines = 0;
122
123 nbytes = trim_nuls(buf, nbytes);
124
125 /* If we have fewer than 2 bytes, give up. */
126 if (nbytes <= 1) {
127 rv = 0;
128 goto done;
129 }
130
131 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) {
132 /* Convert ubuf to UTF-8 and try text soft magic */
133 /* malloc size is a conservative overestimate; could be
134 improved, or at least realloced after conversion. */
135 mlen = ulen * 6;
136 if ((utf8_buf = CAST(unsigned char *, emalloc(mlen))) == NULL) {
137 file_oomem(ms, mlen);
138 goto done;
139 }
140 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen))
141 == NULL)
142 goto done;
143 if ((rv = file_softmagic(ms, utf8_buf,
144 (size_t)(utf8_end - utf8_buf), NULL, NULL,
145 TEXTTEST, text)) == 0)
146 rv = -1;
147 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) {
148 rv = rv == -1 ? 0 : 1;
149 goto done;
150 }
151 }
152 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)))
153 return 0;
154
155 /* Now try to discover other details about the file. */
156 for (i = 0; i < ulen; i++) {
157 if (ubuf[i] == '\n') {
158 if (seen_cr)
159 n_crlf++;
160 else
161 n_lf++;
162 last_line_end = i;
163 } else if (seen_cr)
164 n_cr++;
165
166 seen_cr = (ubuf[i] == '\r');
167 if (seen_cr)
168 last_line_end = i;
169
170 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
171 n_nel++;
172 last_line_end = i;
173 }
174
175 /* If this line is _longer_ than MAXLINELEN, remember it. */
176 if (i > last_line_end + MAXLINELEN)
177 has_long_lines = 1;
178
179 if (ubuf[i] == '\033')
180 has_escapes = 1;
181 if (ubuf[i] == '\b')
182 has_backspace = 1;
183 }
184
185 /* Beware, if the data has been truncated, the final CR could have
186 been followed by a LF. If we have ms->bytes_max bytes, it indicates
187 that the data might have been truncated, probably even before
188 this function was called. */
189 if (seen_cr && nbytes < ms->bytes_max)
190 n_cr++;
191
192 if (strcmp(type, "binary") == 0) {
193 rv = 0;
194 goto done;
195 }
196 if (mime) {
197 if (!file_printedlen(ms) && (mime & MAGIC_MIME_TYPE) != 0) {
198 if (subtype_mime) {
199 if (file_printf(ms, "%s", subtype_mime) == -1)
200 goto done;
201 } else {
202 if (file_printf(ms, "text/plain") == -1)
203 goto done;
204 }
205 }
206 } else {
207 if (file_printedlen(ms)) {
208 switch (file_replace(ms, " text$", ", ")) {
209 case 0:
210 switch (file_replace(ms, " text executable$",
211 ", ")) {
212 case 0:
213 if (file_printf(ms, ", ") == -1)
214 goto done;
215 break;
216 case -1:
217 goto done;
218 default:
219 executable = 1;
220 break;
221 }
222 break;
223 case -1:
224 goto done;
225 default:
226 break;
227 }
228 }
229
230 if (file_printf(ms, "%s", code) == -1)
231 goto done;
232
233 if (subtype) {
234 if (file_printf(ms, " %s", subtype) == -1)
235 goto done;
236 }
237
238 if (file_printf(ms, " %s", type) == -1)
239 goto done;
240
241 if (executable)
242 if (file_printf(ms, " executable") == -1)
243 goto done;
244
245 if (has_long_lines)
246 if (file_printf(ms, ", with very long lines") == -1)
247 goto done;
248
249 /*
250 * Only report line terminators if we find one other than LF,
251 * or if we find none at all.
252 */
253 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
254 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
255 if (file_printf(ms, ", with") == -1)
256 goto done;
257
258 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
259 if (file_printf(ms, " no") == -1)
260 goto done;
261 } else {
262 if (n_crlf) {
263 if (file_printf(ms, " CRLF") == -1)
264 goto done;
265 if (n_cr || n_lf || n_nel)
266 if (file_printf(ms, ",") == -1)
267 goto done;
268 }
269 if (n_cr) {
270 if (file_printf(ms, " CR") == -1)
271 goto done;
272 if (n_lf || n_nel)
273 if (file_printf(ms, ",") == -1)
274 goto done;
275 }
276 if (n_lf) {
277 if (file_printf(ms, " LF") == -1)
278 goto done;
279 if (n_nel)
280 if (file_printf(ms, ",") == -1)
281 goto done;
282 }
283 if (n_nel)
284 if (file_printf(ms, " NEL") == -1)
285 goto done;
286 }
287
288 if (file_printf(ms, " line terminators") == -1)
289 goto done;
290 }
291
292 if (has_escapes)
293 if (file_printf(ms, ", with escape sequences") == -1)
294 goto done;
295 if (has_backspace)
296 if (file_printf(ms, ", with overstriking") == -1)
297 goto done;
298 }
299 rv = 1;
300 done:
301 if (utf8_buf)
302 efree(utf8_buf);
303
304 return rv;
305 }
306
307 /*
308 * Encode Unicode string as UTF-8, returning pointer to character
309 * after end of string, or NULL if an invalid character is found.
310 */
311 private unsigned char *
encode_utf8(unsigned char * buf,size_t len,unichar * ubuf,size_t ulen)312 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen)
313 {
314 size_t i;
315 unsigned char *end = buf + len;
316
317 for (i = 0; i < ulen; i++) {
318 if (ubuf[i] <= 0x7f) {
319 if (end - buf < 1)
320 return NULL;
321 *buf++ = (unsigned char)ubuf[i];
322 } else if (ubuf[i] <= 0x7ff) {
323 if (end - buf < 2)
324 return NULL;
325 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0);
326 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
327 } else if (ubuf[i] <= 0xffff) {
328 if (end - buf < 3)
329 return NULL;
330 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0);
331 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
332 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
333 } else if (ubuf[i] <= 0x1fffff) {
334 if (end - buf < 4)
335 return NULL;
336 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0);
337 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
338 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
339 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
340 } else if (ubuf[i] <= 0x3ffffff) {
341 if (end - buf < 5)
342 return NULL;
343 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8);
344 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
345 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
346 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
347 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
348 } else if (ubuf[i] <= 0x7fffffff) {
349 if (end - buf < 6)
350 return NULL;
351 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc);
352 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80);
353 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
354 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
355 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
356 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
357 } else /* Invalid character */
358 return NULL;
359 }
360
361 return buf;
362 }
363
