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 1.97 2016/06/27 20:56:25 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 nbytes = trim_nuls(buf, nbytes); 83 84 /* If file doesn't look like any sort of text, give up. */ 85 if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime, 86 &type) == 0) 87 rv = 0; 88 else 89 rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code, 90 type, text); 91 92 free(ubuf); 93 94 return rv; 95 } 96 97 protected int 98 file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf, 99 size_t nbytes, unichar *ubuf, size_t ulen, const char *code, 100 const char *type, int text) 101 { 102 unsigned char *utf8_buf = NULL, *utf8_end; 103 size_t mlen, i; 104 int rv = -1; 105 int mime = ms->flags & MAGIC_MIME; 106 107 const char *subtype = NULL; 108 const char *subtype_mime = NULL; 109 110 int has_escapes = 0; 111 int has_backspace = 0; 112 int seen_cr = 0; 113 114 int n_crlf = 0; 115 int n_lf = 0; 116 int n_cr = 0; 117 int n_nel = 0; 118 int executable = 0; 119 120 size_t last_line_end = (size_t)-1; 121 int has_long_lines = 0; 122 123 nbytes = trim_nuls(buf, nbytes); 124 125 /* If we have fewer than 2 bytes, give up. */ 126 if (nbytes <= 1) { 127 rv = 0; 128 goto done; 129 } 130 131 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { 132 /* Convert ubuf to UTF-8 and try text soft magic */ 133 /* malloc size is a conservative overestimate; could be 134 improved, or at least realloced after conversion. */ 135 mlen = ulen * 6; 136 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { 137 file_oomem(ms, mlen); 138 goto done; 139 } 140 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) 141 == NULL) 142 goto done; 143 if ((rv = file_softmagic(ms, utf8_buf, 144 (size_t)(utf8_end - utf8_buf), NULL, NULL, 145 TEXTTEST, text)) == 0) 146 rv = -1; 147 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { 148 rv = rv == -1 ? 0 : 1; 149 goto done; 150 } 151 } 152 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) 153 return 0; 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 ms->bytes_max bytes, it indicates 187 that the data might have been truncated, probably even before 188 this function was called. */ 189 if (seen_cr && nbytes < ms->bytes_max) 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 free(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 } 362