xref: /PHP-7.1/ext/fileinfo/libmagic/ascmagic.c (revision 2181ed2e)
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 1.90 2014/11/28 02:35:05 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 	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, NULL,
151 		    TEXTTEST, text)) == 0)
152 			rv = -1;
153 	}
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 HOWMANY bytes, it indicates
187 	   that the data might have been truncated, probably even before
188 	   this function was called. */
189 	if (seen_cr && nbytes < HOWMANY)
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