xref: /PHP-5.4/ext/fileinfo/libmagic/ascmagic.c (revision 89f864c5)
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 1.85 2012/08/09 16:33:15 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;
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 (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 *
encode_utf8(unsigned char * buf,size_t len,unichar * ubuf,size_t ulen)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 }
362