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 1.107 2020/06/08 19:58:36 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; 118 119 int has_escapes = 0; 120 int has_backspace = 0; 121 int seen_cr = 0; 122 123 int n_crlf = 0; 124 int n_lf = 0; 125 int n_cr = 0; 126 int n_nel = 0; 127 int executable = 0; 128 129 size_t last_line_end = CAST(size_t, -1); 130 int has_long_lines = 0; 131 132 nbytes = trim_nuls(buf, nbytes); 133 134 /* If we have fewer than 2 bytes, give up. */ 135 if (nbytes <= 1) { 136 rv = 0; 137 goto done; 138 } 139 140 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { 141 /* Convert ubuf to UTF-8 and try text soft magic */ 142 /* malloc size is a conservative overestimate; could be 143 improved, or at least realloced after conversion. */ 144 mlen = ulen * 6; 145 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { 146 file_oomem(ms, mlen); 147 goto done; 148 } 149 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) 150 == NULL) 151 goto done; 152 buffer_init(&bb, b->fd, &b->st, utf8_buf, 153 CAST(size_t, utf8_end - utf8_buf)); 154 155 if ((rv = file_softmagic(ms, &bb, NULL, NULL, 156 TEXTTEST, text)) == 0) 157 rv = -1; 158 else 159 need_separator = 1; 160 buffer_fini(&bb); 161 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { 162 rv = rv == -1 ? 0 : 1; 163 goto done; 164 } 165 } 166 167 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { 168 rv = 0; 169 goto done; 170 } 171 172 /* Now try to discover other details about the file. */ 173 for (i = 0; i < ulen; i++) { 174 if (ubuf[i] == '\n') { 175 if (seen_cr) 176 n_crlf++; 177 else 178 n_lf++; 179 last_line_end = i; 180 } else if (seen_cr) 181 n_cr++; 182 183 seen_cr = (ubuf[i] == '\r'); 184 if (seen_cr) 185 last_line_end = i; 186 187 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ 188 n_nel++; 189 last_line_end = i; 190 } 191 192 /* If this line is _longer_ than MAXLINELEN, remember it. */ 193 if (i > last_line_end + MAXLINELEN) 194 has_long_lines = 1; 195 196 if (ubuf[i] == '\033') 197 has_escapes = 1; 198 if (ubuf[i] == '\b') 199 has_backspace = 1; 200 } 201 202 /* Beware, if the data has been truncated, the final CR could have 203 been followed by a LF. If we have ms->bytes_max bytes, it indicates 204 that the data might have been truncated, probably even before 205 this function was called. */ 206 if (seen_cr && nbytes < ms->bytes_max) 207 n_cr++; 208 209 if (strcmp(type, "binary") == 0) { 210 rv = 0; 211 goto done; 212 } 213 len = file_printedlen(ms); 214 if (mime) { 215 if ((mime & MAGIC_MIME_TYPE) != 0) { 216 if (len) { 217 /* 218 * Softmagic printed something, we 219 * are either done, or we need a separator 220 */ 221 if ((ms->flags & MAGIC_CONTINUE) == 0) { 222 rv = 1; 223 goto done; 224 } 225 if (need_separator && file_separator(ms) == -1) 226 goto done; 227 } else { 228 if (file_printf(ms, "text/plain") == -1) 229 goto done; 230 } 231 } 232 } else { 233 if (len) { 234 switch (file_replace(ms, " text$", ", ")) { 235 case 0: 236 switch (file_replace(ms, " text executable$", 237 ", ")) { 238 case 0: 239 if (file_printf(ms, ", ") == -1) 240 goto done; 241 break; 242 case -1: 243 goto done; 244 default: 245 executable = 1; 246 break; 247 } 248 break; 249 case -1: 250 goto done; 251 default: 252 break; 253 } 254 } 255 256 if (file_printf(ms, "%s", code) == -1) 257 goto done; 258 259 if (subtype) { 260 if (file_printf(ms, " %s", subtype) == -1) 261 goto done; 262 } 263 264 if (file_printf(ms, " %s", type) == -1) 265 goto done; 266 267 if (executable) 268 if (file_printf(ms, " executable") == -1) 269 goto done; 270 271 if (has_long_lines) 272 if (file_printf(ms, ", with very long lines") == -1) 273 goto done; 274 275 /* 276 * Only report line terminators if we find one other than LF, 277 * or if we find none at all. 278 */ 279 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || 280 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { 281 if (file_printf(ms, ", with") == -1) 282 goto done; 283 284 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { 285 if (file_printf(ms, " no") == -1) 286 goto done; 287 } else { 288 if (n_crlf) { 289 if (file_printf(ms, " CRLF") == -1) 290 goto done; 291 if (n_cr || n_lf || n_nel) 292 if (file_printf(ms, ",") == -1) 293 goto done; 294 } 295 if (n_cr) { 296 if (file_printf(ms, " CR") == -1) 297 goto done; 298 if (n_lf || n_nel) 299 if (file_printf(ms, ",") == -1) 300 goto done; 301 } 302 if (n_lf) { 303 if (file_printf(ms, " LF") == -1) 304 goto done; 305 if (n_nel) 306 if (file_printf(ms, ",") == -1) 307 goto done; 308 } 309 if (n_nel) 310 if (file_printf(ms, " NEL") == -1) 311 goto done; 312 } 313 314 if (file_printf(ms, " line terminators") == -1) 315 goto done; 316 } 317 318 if (has_escapes) 319 if (file_printf(ms, ", with escape sequences") == -1) 320 goto done; 321 if (has_backspace) 322 if (file_printf(ms, ", with overstriking") == -1) 323 goto done; 324 } 325 rv = 1; 326 done: 327 free(utf8_buf); 328 329 return rv; 330 } 331 332 /* 333 * Encode Unicode string as UTF-8, returning pointer to character 334 * after end of string, or NULL if an invalid character is found. 335 */ 336 private unsigned char * 337 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen) 338 { 339 size_t i; 340 unsigned char *end = buf + len; 341 342 for (i = 0; i < ulen; i++) { 343 if (ubuf[i] <= 0x7f) { 344 if (end - buf < 1) 345 return NULL; 346 *buf++ = CAST(unsigned char, ubuf[i]); 347 } else if (ubuf[i] <= 0x7ff) { 348 if (end - buf < 2) 349 return NULL; 350 *buf++ = CAST(unsigned char, (ubuf[i] >> 6) + 0xc0); 351 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 352 } else if (ubuf[i] <= 0xffff) { 353 if (end - buf < 3) 354 return NULL; 355 *buf++ = CAST(unsigned char, (ubuf[i] >> 12) + 0xe0); 356 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 357 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 358 } else if (ubuf[i] <= 0x1fffff) { 359 if (end - buf < 4) 360 return NULL; 361 *buf++ = CAST(unsigned char, (ubuf[i] >> 18) + 0xf0); 362 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 363 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 364 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 365 } else if (ubuf[i] <= 0x3ffffff) { 366 if (end - buf < 5) 367 return NULL; 368 *buf++ = CAST(unsigned char, (ubuf[i] >> 24) + 0xf8); 369 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); 370 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 371 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 372 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 373 } else if (ubuf[i] <= 0x7fffffff) { 374 if (end - buf < 6) 375 return NULL; 376 *buf++ = CAST(unsigned char, (ubuf[i] >> 30) + 0xfc); 377 *buf++ = CAST(unsigned char, ((ubuf[i] >> 24) & 0x3f) + 0x80); 378 *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); 379 *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); 380 *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); 381 *buf++ = CAST(unsigned char, (ubuf[i] & 0x3f) + 0x80); 382 } else /* Invalid character */ 383 return NULL; 384 } 385 386 return buf; 387 } 388