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 1.84 2011/12/08 12:38:24 rrt 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;
76 int rv = 1;
77
78 const char *code = NULL;
79 const char *code_mime = NULL;
80 const char *type = NULL;
81
82 if (ms->flags & MAGIC_APPLE)
83 return 0;
84
85 nbytes = trim_nuls(buf, nbytes);
86
87 /* If file doesn't look like any sort of text, give up. */
88 if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime,
89 &type) == 0)
90 rv = 0;
91 else
92 rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code,
93 type, text);
94
95 free(ubuf);
96
97 return rv;
98 }
99
100 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)101 file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf,
102 size_t nbytes, unichar *ubuf, size_t ulen, const char *code,
103 const char *type, int text)
104 {
105 unsigned char *utf8_buf = NULL, *utf8_end;
106 size_t mlen, i;
107 int rv = -1;
108 int mime = ms->flags & MAGIC_MIME;
109
110 const char *subtype = NULL;
111 const char *subtype_mime = NULL;
112
113 int has_escapes = 0;
114 int has_backspace = 0;
115 int seen_cr = 0;
116
117 int n_crlf = 0;
118 int n_lf = 0;
119 int n_cr = 0;
120 int n_nel = 0;
121 int executable = 0;
122
123 size_t last_line_end = (size_t)-1;
124 int has_long_lines = 0;
125
126 if (ms->flags & MAGIC_APPLE)
127 return 0;
128
129 nbytes = trim_nuls(buf, nbytes);
130
131 /* If we have fewer than 2 bytes, give up. */
132 if (nbytes <= 1) {
133 rv = 0;
134 goto done;
135 }
136
137 if ((ms->flags & MAGIC_NO_CHECK_SOFT) == 0) {
138 /* Convert ubuf to UTF-8 and try text soft magic */
139 /* malloc size is a conservative overestimate; could be
140 improved, or at least realloced after conversion. */
141 mlen = ulen * 6;
142 utf8_buf = emalloc(mlen);
143
144 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen))
145 == NULL)
146 goto done;
147 if ((rv = file_softmagic(ms, utf8_buf,
148 (size_t)(utf8_end - utf8_buf), TEXTTEST, text)) == 0)
149 rv = -1;
150 }
151
152 /* Now try to discover other details about the file. */
153 for (i = 0; i < ulen; i++) {
154 if (ubuf[i] == '\n') {
155 if (seen_cr)
156 n_crlf++;
157 else
158 n_lf++;
159 last_line_end = i;
160 } else if (seen_cr)
161 n_cr++;
162
163 seen_cr = (ubuf[i] == '\r');
164 if (seen_cr)
165 last_line_end = i;
166
167 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
168 n_nel++;
169 last_line_end = i;
170 }
171
172 /* If this line is _longer_ than MAXLINELEN, remember it. */
173 if (i > last_line_end + MAXLINELEN)
174 has_long_lines = 1;
175
176 if (ubuf[i] == '\033')
177 has_escapes = 1;
178 if (ubuf[i] == '\b')
179 has_backspace = 1;
180 }
181
182 /* Beware, if the data has been truncated, the final CR could have
183 been followed by a LF. If we have HOWMANY bytes, it indicates
184 that the data might have been truncated, probably even before
185 this function was called. */
186 if (seen_cr && nbytes < HOWMANY)
187 n_cr++;
188
189 if (strcmp(type, "binary") == 0) {
190 rv = 0;
191 goto done;
192 }
193 if (mime) {
194 if (!file_printedlen(ms) && (mime & MAGIC_MIME_TYPE) != 0) {
195 if (subtype_mime) {
196 if (file_printf(ms, "%s", subtype_mime) == -1)
197 goto done;
198 } else {
199 if (file_printf(ms, "text/plain") == -1)
200 goto done;
201 }
202 }
203 } else {
204 if (file_printedlen(ms)) {
205 switch (file_replace(ms, " text$", ", ")) {
206 case 0:
207 switch (file_replace(ms, " text executable$",
208 ", ")) {
209 case 0:
210 if (file_printf(ms, ", ") == -1)
211 goto done;
212 case -1:
213 goto done;
214 default:
215 executable = 1;
216 break;
217 }
218 break;
219 case -1:
220 goto done;
221 default:
222 break;
223 }
224 }
225
226 if (file_printf(ms, "%s", code) == -1)
227 goto done;
228
229 if (subtype) {
230 if (file_printf(ms, " %s", subtype) == -1)
231 goto done;
232 }
233
234 if (file_printf(ms, " %s", type) == -1)
235 goto done;
236
237 if (executable)
238 if (file_printf(ms, " executable") == -1)
239 goto done;
240
241 if (has_long_lines)
242 if (file_printf(ms, ", with very long lines") == -1)
243 goto done;
244
245 /*
246 * Only report line terminators if we find one other than LF,
247 * or if we find none at all.
248 */
249 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
250 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
251 if (file_printf(ms, ", with") == -1)
252 goto done;
253
254 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
255 if (file_printf(ms, " no") == -1)
256 goto done;
257 } else {
258 if (n_crlf) {
259 if (file_printf(ms, " CRLF") == -1)
260 goto done;
261 if (n_cr || n_lf || n_nel)
262 if (file_printf(ms, ",") == -1)
263 goto done;
264 }
265 if (n_cr) {
266 if (file_printf(ms, " CR") == -1)
267 goto done;
268 if (n_lf || n_nel)
269 if (file_printf(ms, ",") == -1)
270 goto done;
271 }
272 if (n_lf) {
273 if (file_printf(ms, " LF") == -1)
274 goto done;
275 if (n_nel)
276 if (file_printf(ms, ",") == -1)
277 goto done;
278 }
279 if (n_nel)
280 if (file_printf(ms, " NEL") == -1)
281 goto done;
282 }
283
284 if (file_printf(ms, " line terminators") == -1)
285 goto done;
286 }
287
288 if (has_escapes)
289 if (file_printf(ms, ", with escape sequences") == -1)
290 goto done;
291 if (has_backspace)
292 if (file_printf(ms, ", with overstriking") == -1)
293 goto done;
294 }
295 rv = 1;
296 done:
297 if (utf8_buf)
298 efree(utf8_buf);
299
300 return rv;
301 }
302
303 /*
304 * Encode Unicode string as UTF-8, returning pointer to character
305 * after end of string, or NULL if an invalid character is found.
306 */
307 private unsigned char *
encode_utf8(unsigned char * buf,size_t len,unichar * ubuf,size_t ulen)308 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen)
309 {
310 size_t i;
311 unsigned char *end = buf + len;
312
313 for (i = 0; i < ulen; i++) {
314 if (ubuf[i] <= 0x7f) {
315 if (end - buf < 1)
316 return NULL;
317 *buf++ = (unsigned char)ubuf[i];
318 } else if (ubuf[i] <= 0x7ff) {
319 if (end - buf < 2)
320 return NULL;
321 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0);
322 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
323 } else if (ubuf[i] <= 0xffff) {
324 if (end - buf < 3)
325 return NULL;
326 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0);
327 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
328 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
329 } else if (ubuf[i] <= 0x1fffff) {
330 if (end - buf < 4)
331 return NULL;
332 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0);
333 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
334 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
335 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
336 } else if (ubuf[i] <= 0x3ffffff) {
337 if (end - buf < 5)
338 return NULL;
339 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8);
340 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
341 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
342 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
343 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
344 } else if (ubuf[i] <= 0x7fffffff) {
345 if (end - buf < 6)
346 return NULL;
347 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc);
348 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80);
349 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
350 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
351 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
352 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
353 } else /* Invalid character */
354 return NULL;
355 }
356
357 return buf;
358 }
359
