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 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; 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 ((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 *, malloc(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), 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 case -1: 215 goto done; 216 default: 217 executable = 1; 218 break; 219 } 220 break; 221 case -1: 222 goto done; 223 default: 224 break; 225 } 226 } 227 228 if (file_printf(ms, "%s", code) == -1) 229 goto done; 230 231 if (subtype) { 232 if (file_printf(ms, " %s", subtype) == -1) 233 goto done; 234 } 235 236 if (file_printf(ms, " %s", type) == -1) 237 goto done; 238 239 if (executable) 240 if (file_printf(ms, " executable") == -1) 241 goto done; 242 243 if (has_long_lines) 244 if (file_printf(ms, ", with very long lines") == -1) 245 goto done; 246 247 /* 248 * Only report line terminators if we find one other than LF, 249 * or if we find none at all. 250 */ 251 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || 252 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { 253 if (file_printf(ms, ", with") == -1) 254 goto done; 255 256 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { 257 if (file_printf(ms, " no") == -1) 258 goto done; 259 } else { 260 if (n_crlf) { 261 if (file_printf(ms, " CRLF") == -1) 262 goto done; 263 if (n_cr || n_lf || n_nel) 264 if (file_printf(ms, ",") == -1) 265 goto done; 266 } 267 if (n_cr) { 268 if (file_printf(ms, " CR") == -1) 269 goto done; 270 if (n_lf || n_nel) 271 if (file_printf(ms, ",") == -1) 272 goto done; 273 } 274 if (n_lf) { 275 if (file_printf(ms, " LF") == -1) 276 goto done; 277 if (n_nel) 278 if (file_printf(ms, ",") == -1) 279 goto done; 280 } 281 if (n_nel) 282 if (file_printf(ms, " NEL") == -1) 283 goto done; 284 } 285 286 if (file_printf(ms, " line terminators") == -1) 287 goto done; 288 } 289 290 if (has_escapes) 291 if (file_printf(ms, ", with escape sequences") == -1) 292 goto done; 293 if (has_backspace) 294 if (file_printf(ms, ", with overstriking") == -1) 295 goto done; 296 } 297 rv = 1; 298 done: 299 free(utf8_buf); 300 301 return rv; 302 } 303 304 /* 305 * Encode Unicode string as UTF-8, returning pointer to character 306 * after end of string, or NULL if an invalid character is found. 307 */ 308 private unsigned char * 309 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen) 310 { 311 size_t i; 312 unsigned char *end = buf + len; 313 314 for (i = 0; i < ulen; i++) { 315 if (ubuf[i] <= 0x7f) { 316 if (end - buf < 1) 317 return NULL; 318 *buf++ = (unsigned char)ubuf[i]; 319 } else if (ubuf[i] <= 0x7ff) { 320 if (end - buf < 2) 321 return NULL; 322 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0); 323 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 324 } else if (ubuf[i] <= 0xffff) { 325 if (end - buf < 3) 326 return NULL; 327 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0); 328 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 329 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 330 } else if (ubuf[i] <= 0x1fffff) { 331 if (end - buf < 4) 332 return NULL; 333 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0); 334 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 335 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 336 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 337 } else if (ubuf[i] <= 0x3ffffff) { 338 if (end - buf < 5) 339 return NULL; 340 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8); 341 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80); 342 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 343 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 344 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 345 } else if (ubuf[i] <= 0x7fffffff) { 346 if (end - buf < 6) 347 return NULL; 348 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc); 349 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80); 350 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80); 351 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 352 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 353 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 354 } else /* Invalid character */ 355 return NULL; 356 } 357 358 return buf; 359 } 360