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 1.104 2019/05/07 02:27:11 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 struct buffer *b, int text) 72 { 73 unichar *ubuf = NULL; 74 size_t ulen = 0; 75 int rv = 1; 76 struct buffer bb; 77 78 const char *code = NULL; 79 const char *code_mime = NULL; 80 const char *type = NULL; 81 82 bb = *b; 83 bb.flen = trim_nuls(CAST(const unsigned char *, b->fbuf), b->flen); 84 /* 85 * Avoid trimming at an odd byte if the original buffer was evenly 86 * sized; this avoids losing the last character on UTF-16 LE text 87 */ 88 if ((bb.flen & 1) && !(b->flen & 1)) 89 bb.flen++; 90 91 /* If file doesn't look like any sort of text, give up. */ 92 if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime, 93 &type) == 0) 94 rv = 0; 95 else 96 rv = file_ascmagic_with_encoding(ms, &bb, 97 ubuf, ulen, code, type, text); 98 99 free(ubuf); 100 101 return rv; 102 } 103 104 protected int 105 file_ascmagic_with_encoding(struct magic_set *ms, 106 const struct buffer *b, unichar *ubuf, size_t ulen, const char *code, 107 const char *type, int text) 108 { 109 struct buffer bb; 110 const unsigned char *buf = CAST(const unsigned char *, b->fbuf); 111 size_t nbytes = b->flen; 112 unsigned char *utf8_buf = NULL, *utf8_end; 113 size_t mlen, i, len; 114 int rv = -1; 115 int mime = ms->flags & MAGIC_MIME; 116 int need_separator = 0; 117 118 const char *subtype = NULL; 119 const char *subtype_mime = NULL; 120 121 int has_escapes = 0; 122 int has_backspace = 0; 123 int seen_cr = 0; 124 125 int n_crlf = 0; 126 int n_lf = 0; 127 int n_cr = 0; 128 int n_nel = 0; 129 int executable = 0; 130 131 size_t last_line_end = CAST(size_t, -1); 132 int has_long_lines = 0; 133 134 nbytes = trim_nuls(buf, nbytes); 135 136 /* If we have fewer than 2 bytes, give up. */ 137 if (nbytes <= 1) { 138 rv = 0; 139 goto done; 140 } 141 142 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { 143 /* Convert ubuf to UTF-8 and try text soft magic */ 144 /* malloc size is a conservative overestimate; could be 145 improved, or at least realloced after conversion. */ 146 mlen = ulen * 6; 147 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { 148 file_oomem(ms, mlen); 149 goto done; 150 } 151 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) 152 == NULL) 153 goto done; 154 buffer_init(&bb, b->fd, &b->st, utf8_buf, 155 CAST(size_t, utf8_end - utf8_buf)); 156 157 if ((rv = file_softmagic(ms, &bb, NULL, NULL, 158 TEXTTEST, text)) == 0) 159 rv = -1; 160 else 161 need_separator = 1; 162 buffer_fini(&bb); 163 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { 164 rv = rv == -1 ? 0 : 1; 165 goto done; 166 } 167 } 168 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) 169 return 0; 170 171 /* Now try to discover other details about the file. */ 172 for (i = 0; i < ulen; i++) { 173 if (ubuf[i] == '\n') { 174 if (seen_cr) 175 n_crlf++; 176 else 177 n_lf++; 178 last_line_end = i; 179 } else if (seen_cr) 180 n_cr++; 181 182 seen_cr = (ubuf[i] == '\r'); 183 if (seen_cr) 184 last_line_end = i; 185 186 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ 187 n_nel++; 188 last_line_end = i; 189 } 190 191 /* If this line is _longer_ than MAXLINELEN, remember it. */ 192 if (i > last_line_end + MAXLINELEN) 193 has_long_lines = 1; 194 195 if (ubuf[i] == '\033') 196 has_escapes = 1; 197 if (ubuf[i] == '\b') 198 has_backspace = 1; 199 } 200 201 /* Beware, if the data has been truncated, the final CR could have 202 been followed by a LF. If we have ms->bytes_max bytes, it indicates 203 that the data might have been truncated, probably even before 204 this function was called. */ 205 if (seen_cr && nbytes < ms->bytes_max) 206 n_cr++; 207 208 if (strcmp(type, "binary") == 0) { 209 rv = 0; 210 goto done; 211 } 212 len = file_printedlen(ms); 213 if (mime) { 214 if ((mime & MAGIC_MIME_TYPE) != 0) { 215 if (len) { 216 /* 217 * Softmagic printed something, we 218 * are either done, or we need a separator 219 */ 220 if ((ms->flags & MAGIC_CONTINUE) == 0) { 221 rv = 1; 222 goto done; 223 } 224 if (need_separator && file_separator(ms) == -1) 225 goto done; 226 } 227 if (subtype_mime) { 228 if (file_printf(ms, "%s", subtype_mime) == -1) 229 goto done; 230 } else { 231 if (file_printf(ms, "text/plain") == -1) 232 goto done; 233 } 234 } 235 } else { 236 if (len) { 237 switch (file_replace(ms, " text$", ", ")) { 238 case 0: 239 switch (file_replace(ms, " text executable$", 240 ", ")) { 241 case 0: 242 if (file_printf(ms, ", ") == -1) 243 goto done; 244 break; 245 case -1: 246 goto done; 247 default: 248 executable = 1; 249 break; 250 } 251 break; 252 case -1: 253 goto done; 254 default: 255 break; 256 } 257 } 258 259 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 (executable) 271 if (file_printf(ms, " executable") == -1) 272 goto done; 273 274 if (has_long_lines) 275 if (file_printf(ms, ", with very long lines") == -1) 276 goto done; 277 278 /* 279 * Only report line terminators if we find one other than LF, 280 * or if we find none at all. 281 */ 282 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || 283 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { 284 if (file_printf(ms, ", with") == -1) 285 goto done; 286 287 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { 288 if (file_printf(ms, " no") == -1) 289 goto done; 290 } else { 291 if (n_crlf) { 292 if (file_printf(ms, " CRLF") == -1) 293 goto done; 294 if (n_cr || n_lf || n_nel) 295 if (file_printf(ms, ",") == -1) 296 goto done; 297 } 298 if (n_cr) { 299 if (file_printf(ms, " CR") == -1) 300 goto done; 301 if (n_lf || n_nel) 302 if (file_printf(ms, ",") == -1) 303 goto done; 304 } 305 if (n_lf) { 306 if (file_printf(ms, " LF") == -1) 307 goto done; 308 if (n_nel) 309 if (file_printf(ms, ",") == -1) 310 goto done; 311 } 312 if (n_nel) 313 if (file_printf(ms, " NEL") == -1) 314 goto done; 315 } 316 317 if (file_printf(ms, " line terminators") == -1) 318 goto done; 319 } 320 321 if (has_escapes) 322 if (file_printf(ms, ", with escape sequences") == -1) 323 goto done; 324 if (has_backspace) 325 if (file_printf(ms, ", with overstriking") == -1) 326 goto done; 327 } 328 rv = 1; 329 done: 330 free(utf8_buf); 331 332 return rv; 333 } 334 335 /* 336 * Encode Unicode string as UTF-8, returning pointer to character 337 * after end of string, or NULL if an invalid character is found. 338 */ 339 private unsigned char * 340 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen) 341 { 342 size_t i; 343 unsigned char *end = buf + len; 344 345 for (i = 0; i < ulen; i++) { 346 if (ubuf[i] <= 0x7f) { 347 if (end - buf < 1) 348 return NULL; 349 *buf++ = CAST(unsigned char, ubuf[i]); 350 } else if (ubuf[i] <= 0x7ff) { 351 if (end - buf < 2) 352 return NULL; 353 *buf++ = CAST(unsigned char, (ubuf[i] >> 6) + 0xc0); 354 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 355 } else if (ubuf[i] <= 0xffff) { 356 if (end - buf < 3) 357 return NULL; 358 *buf++ = CAST(unsigned char, (ubuf[i] >> 12) + 0xe0); 359 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 360 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 361 } else if (ubuf[i] <= 0x1fffff) { 362 if (end - buf < 4) 363 return NULL; 364 *buf++ = CAST(unsigned char, (ubuf[i] >> 18) + 0xf0); 365 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 366 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 367 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 368 } else if (ubuf[i] <= 0x3ffffff) { 369 if (end - buf < 5) 370 return NULL; 371 *buf++ = CAST(unsigned char, (ubuf[i] >> 24) + 0xf8); 372 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); 373 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 374 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 375 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 376 } else if (ubuf[i] <= 0x7fffffff) { 377 if (end - buf < 6) 378 return NULL; 379 *buf++ = CAST(unsigned char, (ubuf[i] >> 30) + 0xfc); 380 *buf++ = CAST(unsigned char, ((ubuf[i] >> 24) & 0x3f) + 0x80); 381 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); 382 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 383 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 384 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 385 } else /* Invalid character */ 386 return NULL; 387 } 388 389 return buf; 390 } 391