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 1.88 2014/02/12 23:20:53 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
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
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 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
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 (ulen > 0 && (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 if ((utf8_buf = CAST(unsigned char *, emalloc(mlen))) == NULL) {
143 file_oomem(ms, mlen);
144 goto done;
145 }
146 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen))
147 == NULL)
148 goto done;
149 if ((rv = file_softmagic(ms, utf8_buf,
150 (size_t)(utf8_end - utf8_buf), 0, TEXTTEST, text)) == 0)
151 rv = -1;
152 }
153
154 /* Now try to discover other details about the file. */
155 for (i = 0; i < ulen; i++) {
156 if (ubuf[i] == '\n') {
157 if (seen_cr)
158 n_crlf++;
159 else
160 n_lf++;
161 last_line_end = i;
162 } else if (seen_cr)
163 n_cr++;
164
165 seen_cr = (ubuf[i] == '\r');
166 if (seen_cr)
167 last_line_end = i;
168
169 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
170 n_nel++;
171 last_line_end = i;
172 }
173
174 /* If this line is _longer_ than MAXLINELEN, remember it. */
175 if (i > last_line_end + MAXLINELEN)
176 has_long_lines = 1;
177
178 if (ubuf[i] == '\033')
179 has_escapes = 1;
180 if (ubuf[i] == '\b')
181 has_backspace = 1;
182 }
183
184 /* Beware, if the data has been truncated, the final CR could have
185 been followed by a LF. If we have HOWMANY bytes, it indicates
186 that the data might have been truncated, probably even before
187 this function was called. */
188 if (seen_cr && nbytes < HOWMANY)
189 n_cr++;
190
191 if (strcmp(type, "binary") == 0) {
192 rv = 0;
193 goto done;
194 }
195 if (mime) {
196 if (!file_printedlen(ms) && (mime & MAGIC_MIME_TYPE) != 0) {
197 if (subtype_mime) {
198 if (file_printf(ms, "%s", subtype_mime) == -1)
199 goto done;
200 } else {
201 if (file_printf(ms, "text/plain") == -1)
202 goto done;
203 }
204 }
205 } else {
206 if (file_printedlen(ms)) {
207 switch (file_replace(ms, " text$", ", ")) {
208 case 0:
209 switch (file_replace(ms, " text executable$",
210 ", ")) {
211 case 0:
212 if (file_printf(ms, ", ") == -1)
213 goto done;
214 break;
215 case -1:
216 goto done;
217 default:
218 executable = 1;
219 break;
220 }
221 break;
222 case -1:
223 goto done;
224 default:
225 break;
226 }
227 }
228
229 if (file_printf(ms, "%s", code) == -1)
230 goto done;
231
232 if (subtype) {
233 if (file_printf(ms, " %s", subtype) == -1)
234 goto done;
235 }
236
237 if (file_printf(ms, " %s", type) == -1)
238 goto done;
239
240 if (executable)
241 if (file_printf(ms, " executable") == -1)
242 goto done;
243
244 if (has_long_lines)
245 if (file_printf(ms, ", with very long lines") == -1)
246 goto done;
247
248 /*
249 * Only report line terminators if we find one other than LF,
250 * or if we find none at all.
251 */
252 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
253 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
254 if (file_printf(ms, ", with") == -1)
255 goto done;
256
257 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
258 if (file_printf(ms, " no") == -1)
259 goto done;
260 } else {
261 if (n_crlf) {
262 if (file_printf(ms, " CRLF") == -1)
263 goto done;
264 if (n_cr || n_lf || n_nel)
265 if (file_printf(ms, ",") == -1)
266 goto done;
267 }
268 if (n_cr) {
269 if (file_printf(ms, " CR") == -1)
270 goto done;
271 if (n_lf || n_nel)
272 if (file_printf(ms, ",") == -1)
273 goto done;
274 }
275 if (n_lf) {
276 if (file_printf(ms, " LF") == -1)
277 goto done;
278 if (n_nel)
279 if (file_printf(ms, ",") == -1)
280 goto done;
281 }
282 if (n_nel)
283 if (file_printf(ms, " NEL") == -1)
284 goto done;
285 }
286
287 if (file_printf(ms, " line terminators") == -1)
288 goto done;
289 }
290
291 if (has_escapes)
292 if (file_printf(ms, ", with escape sequences") == -1)
293 goto done;
294 if (has_backspace)
295 if (file_printf(ms, ", with overstriking") == -1)
296 goto done;
297 }
298 rv = 1;
299 done:
300 if (utf8_buf)
301 efree(utf8_buf);
302
303 return rv;
304 }
305
306 /*
307 * Encode Unicode string as UTF-8, returning pointer to character
308 * after end of string, or NULL if an invalid character is found.
309 */
310 private unsigned char *
311 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen)
312 {
313 size_t i;
314 unsigned char *end = buf + len;
315
316 for (i = 0; i < ulen; i++) {
317 if (ubuf[i] <= 0x7f) {
318 if (end - buf < 1)
319 return NULL;
320 *buf++ = (unsigned char)ubuf[i];
321 } else if (ubuf[i] <= 0x7ff) {
322 if (end - buf < 2)
323 return NULL;
324 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0);
325 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
326 } else if (ubuf[i] <= 0xffff) {
327 if (end - buf < 3)
328 return NULL;
329 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0);
330 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
331 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
332 } else if (ubuf[i] <= 0x1fffff) {
333 if (end - buf < 4)
334 return NULL;
335 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0);
336 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
337 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
338 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
339 } else if (ubuf[i] <= 0x3ffffff) {
340 if (end - buf < 5)
341 return NULL;
342 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8);
343 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
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] <= 0x7fffffff) {
348 if (end - buf < 6)
349 return NULL;
350 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc);
351 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80);
352 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
353 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
354 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
355 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
356 } else /* Invalid character */
357 return NULL;
358 }
359
360 return buf;
361 }