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 -- file types that we know based on keywords 30 * that can appear anywhere in the file. 31 * 32 * Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000, 33 * to handle character codes other than ASCII on a unified basis. 34 */ 35 36 #include "file.h" 37 38 #ifndef lint 39 FILE_RCSID("@(#)$File: ascmagic.c,v 1.77 2010/11/30 14:58:53 rrt Exp $") 40 #endif /* lint */ 41 42 #include "magic.h" 43 #include <string.h> 44 #include <memory.h> 45 #include <ctype.h> 46 #include <stdlib.h> 47 #ifdef HAVE_UNISTD_H 48 #include <unistd.h> 49 #endif 50 #include "names.h" 51 52 #define MAXLINELEN 300 /* longest sane line length */ 53 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \ 54 || (x) == 0x85 || (x) == '\f') 55 56 private int ascmatch(const unsigned char *, const unichar *, size_t); 57 private unsigned char *encode_utf8(unsigned char *, size_t, unichar *, size_t); 58 private size_t trim_nuls(const unsigned char *, size_t); 59 60 /* 61 * Undo the NUL-termination kindly provided by process() 62 * but leave at least one byte to look at 63 */ 64 private size_t 65 trim_nuls(const unsigned char *buf, size_t nbytes) 66 { 67 while (nbytes > 1 && buf[nbytes - 1] == '\0') 68 nbytes--; 69 70 return nbytes; 71 } 72 73 protected int 74 file_ascmagic(struct magic_set *ms, const unsigned char *buf, size_t nbytes) 75 { 76 unichar *ubuf = NULL; 77 size_t ulen; 78 int rv = 1; 79 80 const char *code = NULL; 81 const char *code_mime = NULL; 82 const char *type = NULL; 83 84 if (ms->flags & MAGIC_APPLE) 85 return 0; 86 87 nbytes = trim_nuls(buf, nbytes); 88 89 /* If file doesn't look like any sort of text, give up. */ 90 if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime, 91 &type) == 0) { 92 rv = 0; 93 goto done; 94 } 95 96 rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code, 97 type); 98 99 done: 100 if (ubuf) 101 free(ubuf); 102 103 return rv; 104 } 105 106 protected int 107 file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf, 108 size_t nbytes, unichar *ubuf, size_t ulen, const char *code, 109 const char *type) 110 { 111 unsigned char *utf8_buf = NULL, *utf8_end; 112 size_t mlen, i; 113 const struct names *p; 114 int rv = -1; 115 int mime = ms->flags & MAGIC_MIME; 116 117 const char *subtype = NULL; 118 const char *subtype_mime = NULL; 119 120 int has_escapes = 0; 121 int has_backspace = 0; 122 int seen_cr = 0; 123 124 int n_crlf = 0; 125 int n_lf = 0; 126 int n_cr = 0; 127 int n_nel = 0; 128 int score, curtype; 129 130 size_t last_line_end = (size_t)-1; 131 int has_long_lines = 0; 132 133 if (ms->flags & MAGIC_APPLE) 134 return 0; 135 136 nbytes = trim_nuls(buf, nbytes); 137 138 /* If we have fewer than 2 bytes, give up. */ 139 if (nbytes <= 1) { 140 rv = 0; 141 goto done; 142 } 143 144 if ((ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { 145 /* Convert ubuf to UTF-8 and try text soft magic */ 146 /* malloc size is a conservative overestimate; could be 147 improved, or at least realloced after conversion. */ 148 mlen = ulen * 6; 149 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { 150 file_oomem(ms, mlen); 151 goto done; 152 } 153 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) == NULL) 154 goto done; 155 if ((rv = file_softmagic(ms, utf8_buf, (size_t)(utf8_end - utf8_buf), 156 TEXTTEST)) != 0) 157 goto done; 158 else 159 rv = -1; 160 } 161 162 /* look for tokens from names.h - this is expensive! */ 163 if ((ms->flags & MAGIC_NO_CHECK_TOKENS) != 0) 164 goto subtype_identified; 165 166 i = 0; 167 score = 0; 168 curtype = -1; 169 while (i < ulen) { 170 size_t end; 171 172 /* skip past any leading space */ 173 while (i < ulen && ISSPC(ubuf[i])) 174 i++; 175 if (i >= ulen) 176 break; 177 178 /* find the next whitespace */ 179 for (end = i + 1; end < nbytes; end++) 180 if (ISSPC(ubuf[end])) 181 break; 182 183 /* compare the word thus isolated against the token list */ 184 for (p = names; p < names + NNAMES; p++) { 185 if (ascmatch((const unsigned char *)p->name, ubuf + i, 186 end - i)) { 187 if (curtype == -1) 188 curtype = p->type; 189 else if (curtype != p->type) { 190 score = p->score; 191 curtype = p->type; 192 } else 193 score += p->score; 194 if (score > 1) { 195 subtype = types[p->type].human; 196 subtype_mime = types[p->type].mime; 197 goto subtype_identified; 198 } 199 } 200 } 201 202 i = end; 203 } 204 205 subtype_identified: 206 207 /* Now try to discover other details about the file. */ 208 for (i = 0; i < ulen; i++) { 209 if (ubuf[i] == '\n') { 210 if (seen_cr) 211 n_crlf++; 212 else 213 n_lf++; 214 last_line_end = i; 215 } else if (seen_cr) 216 n_cr++; 217 218 seen_cr = (ubuf[i] == '\r'); 219 if (seen_cr) 220 last_line_end = i; 221 222 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ 223 n_nel++; 224 last_line_end = i; 225 } 226 227 /* If this line is _longer_ than MAXLINELEN, remember it. */ 228 if (i > last_line_end + MAXLINELEN) 229 has_long_lines = 1; 230 231 if (ubuf[i] == '\033') 232 has_escapes = 1; 233 if (ubuf[i] == '\b') 234 has_backspace = 1; 235 } 236 237 /* Beware, if the data has been truncated, the final CR could have 238 been followed by a LF. If we have HOWMANY bytes, it indicates 239 that the data might have been truncated, probably even before 240 this function was called. */ 241 if (seen_cr && nbytes < HOWMANY) 242 n_cr++; 243 244 if (strcmp(type, "binary") == 0) { 245 rv = 0; 246 goto done; 247 } 248 if (mime) { 249 if ((mime & MAGIC_MIME_TYPE) != 0) { 250 if (subtype_mime) { 251 if (file_printf(ms, "%s", subtype_mime) == -1) 252 goto done; 253 } else { 254 if (file_printf(ms, "text/plain") == -1) 255 goto done; 256 } 257 } 258 } else { 259 if (file_printf(ms, "%s", code) == -1) 260 goto done; 261 262 if (subtype) { 263 if (file_printf(ms, " %s", subtype) == -1) 264 goto done; 265 } 266 267 if (file_printf(ms, " %s", type) == -1) 268 goto done; 269 270 if (has_long_lines) 271 if (file_printf(ms, ", with very long lines") == -1) 272 goto done; 273 274 /* 275 * Only report line terminators if we find one other than LF, 276 * or if we find none at all. 277 */ 278 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || 279 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { 280 if (file_printf(ms, ", with") == -1) 281 goto done; 282 283 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { 284 if (file_printf(ms, " no") == -1) 285 goto done; 286 } else { 287 if (n_crlf) { 288 if (file_printf(ms, " CRLF") == -1) 289 goto done; 290 if (n_cr || n_lf || n_nel) 291 if (file_printf(ms, ",") == -1) 292 goto done; 293 } 294 if (n_cr) { 295 if (file_printf(ms, " CR") == -1) 296 goto done; 297 if (n_lf || n_nel) 298 if (file_printf(ms, ",") == -1) 299 goto done; 300 } 301 if (n_lf) { 302 if (file_printf(ms, " LF") == -1) 303 goto done; 304 if (n_nel) 305 if (file_printf(ms, ",") == -1) 306 goto done; 307 } 308 if (n_nel) 309 if (file_printf(ms, " NEL") == -1) 310 goto done; 311 } 312 313 if (file_printf(ms, " line terminators") == -1) 314 goto done; 315 } 316 317 if (has_escapes) 318 if (file_printf(ms, ", with escape sequences") == -1) 319 goto done; 320 if (has_backspace) 321 if (file_printf(ms, ", with overstriking") == -1) 322 goto done; 323 } 324 rv = 1; 325 done: 326 if (utf8_buf) 327 free(utf8_buf); 328 329 return rv; 330 } 331 332 private int 333 ascmatch(const unsigned char *s, const unichar *us, size_t ulen) 334 { 335 size_t i; 336 337 for (i = 0; i < ulen; i++) { 338 if (s[i] != us[i]) 339 return 0; 340 } 341 342 if (s[i]) 343 return 0; 344 else 345 return 1; 346 } 347 348 /* 349 * Encode Unicode string as UTF-8, returning pointer to character 350 * after end of string, or NULL if an invalid character is found. 351 */ 352 private unsigned char * 353 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen) 354 { 355 size_t i; 356 unsigned char *end = buf + len; 357 358 for (i = 0; i < ulen; i++) { 359 if (ubuf[i] <= 0x7f) { 360 if (end - buf < 1) 361 return NULL; 362 *buf++ = (unsigned char)ubuf[i]; 363 } else if (ubuf[i] <= 0x7ff) { 364 if (end - buf < 2) 365 return NULL; 366 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0); 367 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 368 } else if (ubuf[i] <= 0xffff) { 369 if (end - buf < 3) 370 return NULL; 371 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0); 372 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 373 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 374 } else if (ubuf[i] <= 0x1fffff) { 375 if (end - buf < 4) 376 return NULL; 377 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0); 378 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 379 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 380 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 381 } else if (ubuf[i] <= 0x3ffffff) { 382 if (end - buf < 5) 383 return NULL; 384 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8); 385 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80); 386 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 387 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 388 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 389 } else if (ubuf[i] <= 0x7fffffff) { 390 if (end - buf < 6) 391 return NULL; 392 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc); 393 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80); 394 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80); 395 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 396 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 397 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 398 } else /* Invalid character */ 399 return NULL; 400 } 401 402 return buf; 403 } 404