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 1.105 2019/06/08 20:49:14 christos Exp $") 39 #endif /* lint */ 40 41 #include "magic.h" 42 #include <string.h> 43 #include <ctype.h> 44 #include <stdlib.h> 45 #ifdef HAVE_UNISTD_H 46 #include <unistd.h> 47 #endif 48 49 #define MAXLINELEN 300 /* longest sane line length */ 50 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \ 51 || (x) == 0x85 || (x) == '\f') 52 53 private unsigned char *encode_utf8(unsigned char *, size_t, unichar *, size_t); 54 private size_t trim_nuls(const unsigned char *, size_t); 55 56 /* 57 * Undo the NUL-termination kindly provided by process() 58 * but leave at least one byte to look at 59 */ 60 private size_t 61 trim_nuls(const unsigned char *buf, size_t nbytes) 62 { 63 while (nbytes > 1 && buf[nbytes - 1] == '\0') 64 nbytes--; 65 66 return nbytes; 67 } 68 69 protected int 70 file_ascmagic(struct magic_set *ms, const struct buffer *b, int text) 71 { 72 unichar *ubuf = NULL; 73 size_t ulen = 0; 74 int rv = 1; 75 struct buffer bb; 76 77 const char *code = NULL; 78 const char *code_mime = NULL; 79 const char *type = NULL; 80 81 bb = *b; 82 bb.flen = trim_nuls(CAST(const unsigned char *, b->fbuf), b->flen); 83 /* 84 * Avoid trimming at an odd byte if the original buffer was evenly 85 * sized; this avoids losing the last character on UTF-16 LE text 86 */ 87 if ((bb.flen & 1) && !(b->flen & 1)) 88 bb.flen++; 89 90 /* If file doesn't look like any sort of text, give up. */ 91 if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime, 92 &type) == 0) 93 rv = 0; 94 else 95 rv = file_ascmagic_with_encoding(ms, &bb, 96 ubuf, ulen, code, type, text); 97 98 free(ubuf); 99 100 return rv; 101 } 102 103 protected int 104 file_ascmagic_with_encoding(struct magic_set *ms, 105 const struct buffer *b, unichar *ubuf, size_t ulen, const char *code, 106 const char *type, int text) 107 { 108 struct buffer bb; 109 const unsigned char *buf = CAST(const unsigned char *, b->fbuf); 110 size_t nbytes = b->flen; 111 unsigned char *utf8_buf = NULL, *utf8_end; 112 size_t mlen, i, len; 113 int rv = -1; 114 int mime = ms->flags & MAGIC_MIME; 115 int need_separator = 0; 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 executable = 0; 129 130 size_t last_line_end = CAST(size_t, -1); 131 int has_long_lines = 0; 132 133 nbytes = trim_nuls(buf, nbytes); 134 135 /* If we have fewer than 2 bytes, give up. */ 136 if (nbytes <= 1) { 137 rv = 0; 138 goto done; 139 } 140 141 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { 142 /* Convert ubuf to UTF-8 and try text soft magic */ 143 /* malloc size is a conservative overestimate; could be 144 improved, or at least realloced after conversion. */ 145 mlen = ulen * 6; 146 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { 147 file_oomem(ms, mlen); 148 goto done; 149 } 150 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) 151 == NULL) 152 goto done; 153 buffer_init(&bb, b->fd, &b->st, utf8_buf, 154 CAST(size_t, utf8_end - utf8_buf)); 155 156 if ((rv = file_softmagic(ms, &bb, NULL, NULL, 157 TEXTTEST, text)) == 0) 158 rv = -1; 159 else 160 need_separator = 1; 161 buffer_fini(&bb); 162 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { 163 rv = rv == -1 ? 0 : 1; 164 goto done; 165 } 166 } 167 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) 168 return 0; 169 170 /* Now try to discover other details about the file. */ 171 for (i = 0; i < ulen; i++) { 172 if (ubuf[i] == '\n') { 173 if (seen_cr) 174 n_crlf++; 175 else 176 n_lf++; 177 last_line_end = i; 178 } else if (seen_cr) 179 n_cr++; 180 181 seen_cr = (ubuf[i] == '\r'); 182 if (seen_cr) 183 last_line_end = i; 184 185 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ 186 n_nel++; 187 last_line_end = i; 188 } 189 190 /* If this line is _longer_ than MAXLINELEN, remember it. */ 191 if (i > last_line_end + MAXLINELEN) 192 has_long_lines = 1; 193 194 if (ubuf[i] == '\033') 195 has_escapes = 1; 196 if (ubuf[i] == '\b') 197 has_backspace = 1; 198 } 199 200 /* Beware, if the data has been truncated, the final CR could have 201 been followed by a LF. If we have ms->bytes_max bytes, it indicates 202 that the data might have been truncated, probably even before 203 this function was called. */ 204 if (seen_cr && nbytes < ms->bytes_max) 205 n_cr++; 206 207 if (strcmp(type, "binary") == 0) { 208 rv = 0; 209 goto done; 210 } 211 len = file_printedlen(ms); 212 if (mime) { 213 if ((mime & MAGIC_MIME_TYPE) != 0) { 214 if (len) { 215 /* 216 * Softmagic printed something, we 217 * are either done, or we need a separator 218 */ 219 if ((ms->flags & MAGIC_CONTINUE) == 0) { 220 rv = 1; 221 goto done; 222 } 223 if (need_separator && file_separator(ms) == -1) 224 goto done; 225 } 226 if (subtype_mime) { 227 if (file_printf(ms, "%s", subtype_mime) == -1) 228 goto done; 229 } else { 230 if (file_printf(ms, "text/plain") == -1) 231 goto done; 232 } 233 } 234 } else { 235 if (len) { 236 switch (file_replace(ms, " text$", ", ")) { 237 case 0: 238 switch (file_replace(ms, " text executable$", 239 ", ")) { 240 case 0: 241 if (file_printf(ms, ", ") == -1) 242 goto done; 243 break; 244 case -1: 245 goto done; 246 default: 247 executable = 1; 248 break; 249 } 250 break; 251 case -1: 252 goto done; 253 default: 254 break; 255 } 256 } 257 258 if (file_printf(ms, "%s", code) == -1) 259 goto done; 260 261 if (subtype) { 262 if (file_printf(ms, " %s", subtype) == -1) 263 goto done; 264 } 265 266 if (file_printf(ms, " %s", type) == -1) 267 goto done; 268 269 if (executable) 270 if (file_printf(ms, " executable") == -1) 271 goto done; 272 273 if (has_long_lines) 274 if (file_printf(ms, ", with very long lines") == -1) 275 goto done; 276 277 /* 278 * Only report line terminators if we find one other than LF, 279 * or if we find none at all. 280 */ 281 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || 282 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { 283 if (file_printf(ms, ", with") == -1) 284 goto done; 285 286 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { 287 if (file_printf(ms, " no") == -1) 288 goto done; 289 } else { 290 if (n_crlf) { 291 if (file_printf(ms, " CRLF") == -1) 292 goto done; 293 if (n_cr || n_lf || n_nel) 294 if (file_printf(ms, ",") == -1) 295 goto done; 296 } 297 if (n_cr) { 298 if (file_printf(ms, " CR") == -1) 299 goto done; 300 if (n_lf || n_nel) 301 if (file_printf(ms, ",") == -1) 302 goto done; 303 } 304 if (n_lf) { 305 if (file_printf(ms, " LF") == -1) 306 goto done; 307 if (n_nel) 308 if (file_printf(ms, ",") == -1) 309 goto done; 310 } 311 if (n_nel) 312 if (file_printf(ms, " NEL") == -1) 313 goto done; 314 } 315 316 if (file_printf(ms, " line terminators") == -1) 317 goto done; 318 } 319 320 if (has_escapes) 321 if (file_printf(ms, ", with escape sequences") == -1) 322 goto done; 323 if (has_backspace) 324 if (file_printf(ms, ", with overstriking") == -1) 325 goto done; 326 } 327 rv = 1; 328 done: 329 free(utf8_buf); 330 331 return rv; 332 } 333 334 /* 335 * Encode Unicode string as UTF-8, returning pointer to character 336 * after end of string, or NULL if an invalid character is found. 337 */ 338 private unsigned char * 339 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen) 340 { 341 size_t i; 342 unsigned char *end = buf + len; 343 344 for (i = 0; i < ulen; i++) { 345 if (ubuf[i] <= 0x7f) { 346 if (end - buf < 1) 347 return NULL; 348 *buf++ = CAST(unsigned char, ubuf[i]); 349 } else if (ubuf[i] <= 0x7ff) { 350 if (end - buf < 2) 351 return NULL; 352 *buf++ = CAST(unsigned char, (ubuf[i] >> 6) + 0xc0); 353 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 354 } else if (ubuf[i] <= 0xffff) { 355 if (end - buf < 3) 356 return NULL; 357 *buf++ = CAST(unsigned char, (ubuf[i] >> 12) + 0xe0); 358 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 359 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 360 } else if (ubuf[i] <= 0x1fffff) { 361 if (end - buf < 4) 362 return NULL; 363 *buf++ = CAST(unsigned char, (ubuf[i] >> 18) + 0xf0); 364 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 365 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 366 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 367 } else if (ubuf[i] <= 0x3ffffff) { 368 if (end - buf < 5) 369 return NULL; 370 *buf++ = CAST(unsigned char, (ubuf[i] >> 24) + 0xf8); 371 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); 372 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 373 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 374 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 375 } else if (ubuf[i] <= 0x7fffffff) { 376 if (end - buf < 6) 377 return NULL; 378 *buf++ = CAST(unsigned char, (ubuf[i] >> 30) + 0xfc); 379 *buf++ = CAST(unsigned char, ((ubuf[i] >> 24) & 0x3f) + 0x80); 380 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); 381 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 382 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 383 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 384 } else /* Invalid character */ 385 return NULL; 386 } 387 388 return buf; 389 } 390