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 1.98 2017/11/02 20:25:39 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(b->fbuf, b->flen); 84 85 /* If file doesn't look like any sort of text, give up. */ 86 if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime, 87 &type) == 0) 88 rv = 0; 89 else 90 rv = file_ascmagic_with_encoding(ms, &bb, 91 ubuf, ulen, code, type, text); 92 93 free(ubuf); 94 95 return rv; 96 } 97 98 protected int 99 file_ascmagic_with_encoding(struct magic_set *ms, 100 const struct buffer *b, unichar *ubuf, size_t ulen, const char *code, 101 const char *type, int text) 102 { 103 struct buffer bb; 104 const unsigned char *buf = b->fbuf; 105 size_t nbytes = b->flen; 106 unsigned char *utf8_buf = NULL, *utf8_end; 107 size_t mlen, i; 108 int rv = -1; 109 int mime = ms->flags & MAGIC_MIME; 110 111 const char *subtype = NULL; 112 const char *subtype_mime = NULL; 113 114 int has_escapes = 0; 115 int has_backspace = 0; 116 int seen_cr = 0; 117 118 int n_crlf = 0; 119 int n_lf = 0; 120 int n_cr = 0; 121 int n_nel = 0; 122 int executable = 0; 123 124 size_t last_line_end = (size_t)-1; 125 int has_long_lines = 0; 126 127 nbytes = trim_nuls(buf, nbytes); 128 129 /* If we have fewer than 2 bytes, give up. */ 130 if (nbytes <= 1) { 131 rv = 0; 132 goto done; 133 } 134 135 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { 136 /* Convert ubuf to UTF-8 and try text soft magic */ 137 /* malloc size is a conservative overestimate; could be 138 improved, or at least realloced after conversion. */ 139 mlen = ulen * 6; 140 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { 141 file_oomem(ms, mlen); 142 goto done; 143 } 144 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) 145 == NULL) 146 goto done; 147 buffer_init(&bb, b->fd, utf8_buf, 148 (size_t)(utf8_end - utf8_buf)); 149 150 if ((rv = file_softmagic(ms, &bb, NULL, NULL, 151 TEXTTEST, text)) == 0) 152 rv = -1; 153 buffer_fini(&bb); 154 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { 155 rv = rv == -1 ? 0 : 1; 156 goto done; 157 } 158 } 159 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) 160 return 0; 161 162 /* Now try to discover other details about the file. */ 163 for (i = 0; i < ulen; i++) { 164 if (ubuf[i] == '\n') { 165 if (seen_cr) 166 n_crlf++; 167 else 168 n_lf++; 169 last_line_end = i; 170 } else if (seen_cr) 171 n_cr++; 172 173 seen_cr = (ubuf[i] == '\r'); 174 if (seen_cr) 175 last_line_end = i; 176 177 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ 178 n_nel++; 179 last_line_end = i; 180 } 181 182 /* If this line is _longer_ than MAXLINELEN, remember it. */ 183 if (i > last_line_end + MAXLINELEN) 184 has_long_lines = 1; 185 186 if (ubuf[i] == '\033') 187 has_escapes = 1; 188 if (ubuf[i] == '\b') 189 has_backspace = 1; 190 } 191 192 /* Beware, if the data has been truncated, the final CR could have 193 been followed by a LF. If we have ms->bytes_max bytes, it indicates 194 that the data might have been truncated, probably even before 195 this function was called. */ 196 if (seen_cr && nbytes < ms->bytes_max) 197 n_cr++; 198 199 if (strcmp(type, "binary") == 0) { 200 rv = 0; 201 goto done; 202 } 203 if (mime) { 204 if (!file_printedlen(ms) && (mime & MAGIC_MIME_TYPE) != 0) { 205 if (subtype_mime) { 206 if (file_printf(ms, "%s", subtype_mime) == -1) 207 goto done; 208 } else { 209 if (file_printf(ms, "text/plain") == -1) 210 goto done; 211 } 212 } 213 } else { 214 if (file_printedlen(ms)) { 215 switch (file_replace(ms, " text$", ", ")) { 216 case 0: 217 switch (file_replace(ms, " text executable$", 218 ", ")) { 219 case 0: 220 if (file_printf(ms, ", ") == -1) 221 goto done; 222 break; 223 case -1: 224 goto done; 225 default: 226 executable = 1; 227 break; 228 } 229 break; 230 case -1: 231 goto done; 232 default: 233 break; 234 } 235 } 236 237 if (file_printf(ms, "%s", code) == -1) 238 goto done; 239 240 if (subtype) { 241 if (file_printf(ms, " %s", subtype) == -1) 242 goto done; 243 } 244 245 if (file_printf(ms, " %s", type) == -1) 246 goto done; 247 248 if (executable) 249 if (file_printf(ms, " executable") == -1) 250 goto done; 251 252 if (has_long_lines) 253 if (file_printf(ms, ", with very long lines") == -1) 254 goto done; 255 256 /* 257 * Only report line terminators if we find one other than LF, 258 * or if we find none at all. 259 */ 260 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || 261 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { 262 if (file_printf(ms, ", with") == -1) 263 goto done; 264 265 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { 266 if (file_printf(ms, " no") == -1) 267 goto done; 268 } else { 269 if (n_crlf) { 270 if (file_printf(ms, " CRLF") == -1) 271 goto done; 272 if (n_cr || n_lf || n_nel) 273 if (file_printf(ms, ",") == -1) 274 goto done; 275 } 276 if (n_cr) { 277 if (file_printf(ms, " CR") == -1) 278 goto done; 279 if (n_lf || n_nel) 280 if (file_printf(ms, ",") == -1) 281 goto done; 282 } 283 if (n_lf) { 284 if (file_printf(ms, " LF") == -1) 285 goto done; 286 if (n_nel) 287 if (file_printf(ms, ",") == -1) 288 goto done; 289 } 290 if (n_nel) 291 if (file_printf(ms, " NEL") == -1) 292 goto done; 293 } 294 295 if (file_printf(ms, " line terminators") == -1) 296 goto done; 297 } 298 299 if (has_escapes) 300 if (file_printf(ms, ", with escape sequences") == -1) 301 goto done; 302 if (has_backspace) 303 if (file_printf(ms, ", with overstriking") == -1) 304 goto done; 305 } 306 rv = 1; 307 done: 308 free(utf8_buf); 309 310 return rv; 311 } 312 313 /* 314 * Encode Unicode string as UTF-8, returning pointer to character 315 * after end of string, or NULL if an invalid character is found. 316 */ 317 private unsigned char * 318 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen) 319 { 320 size_t i; 321 unsigned char *end = buf + len; 322 323 for (i = 0; i < ulen; i++) { 324 if (ubuf[i] <= 0x7f) { 325 if (end - buf < 1) 326 return NULL; 327 *buf++ = (unsigned char)ubuf[i]; 328 } else if (ubuf[i] <= 0x7ff) { 329 if (end - buf < 2) 330 return NULL; 331 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0); 332 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 333 } else if (ubuf[i] <= 0xffff) { 334 if (end - buf < 3) 335 return NULL; 336 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0); 337 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 338 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 339 } else if (ubuf[i] <= 0x1fffff) { 340 if (end - buf < 4) 341 return NULL; 342 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0); 343 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 344 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 345 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 346 } else if (ubuf[i] <= 0x3ffffff) { 347 if (end - buf < 5) 348 return NULL; 349 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8); 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 if (ubuf[i] <= 0x7fffffff) { 355 if (end - buf < 6) 356 return NULL; 357 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc); 358 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80); 359 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80); 360 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 361 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 362 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 363 } else /* Invalid character */ 364 return NULL; 365 } 366 367 return buf; 368 } 369