1 /* $NetBSD: ascmagic.c,v 1.1.1.8 2017/02/10 17:42:57 christos Exp $ */ 2 3 /* 4 * Copyright (c) Ian F. Darwin 1986-1995. 5 * Software written by Ian F. Darwin and others; 6 * maintained 1995-present by Christos Zoulas and others. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice immediately at the beginning of the file, without modification, 13 * this list of conditions, and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR 22 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 /* 31 * ASCII magic -- try to detect text encoding. 32 * 33 * Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000, 34 * to handle character codes other than ASCII on a unified basis. 35 */ 36 37 #include "file.h" 38 39 #ifndef lint 40 #if 0 41 FILE_RCSID("@(#)$File: ascmagic.c,v 1.97 2016/06/27 20:56:25 christos Exp $") 42 #else 43 __RCSID("$NetBSD: ascmagic.c,v 1.1.1.8 2017/02/10 17:42:57 christos Exp $"); 44 #endif 45 #endif /* lint */ 46 47 #include "magic.h" 48 #include <string.h> 49 #include <memory.h> 50 #include <ctype.h> 51 #include <stdlib.h> 52 #ifdef HAVE_UNISTD_H 53 #include <unistd.h> 54 #endif 55 56 #define MAXLINELEN 300 /* longest sane line length */ 57 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \ 58 || (x) == 0x85 || (x) == '\f') 59 60 private unsigned char *encode_utf8(unsigned char *, size_t, unichar *, size_t); 61 private size_t trim_nuls(const unsigned char *, size_t); 62 63 /* 64 * Undo the NUL-termination kindly provided by process() 65 * but leave at least one byte to look at 66 */ 67 private size_t 68 trim_nuls(const unsigned char *buf, size_t nbytes) 69 { 70 while (nbytes > 1 && buf[nbytes - 1] == '\0') 71 nbytes--; 72 73 return nbytes; 74 } 75 76 protected int 77 file_ascmagic(struct magic_set *ms, const unsigned char *buf, size_t nbytes, 78 int text) 79 { 80 unichar *ubuf = NULL; 81 size_t ulen = 0; 82 int rv = 1; 83 84 const char *code = NULL; 85 const char *code_mime = NULL; 86 const char *type = NULL; 87 88 nbytes = trim_nuls(buf, nbytes); 89 90 /* If file doesn't look like any sort of text, give up. */ 91 if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime, 92 &type) == 0) 93 rv = 0; 94 else 95 rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code, 96 type, text); 97 98 free(ubuf); 99 100 return rv; 101 } 102 103 protected int 104 file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf, 105 size_t nbytes, unichar *ubuf, size_t ulen, const char *code, 106 const char *type, int text) 107 { 108 unsigned char *utf8_buf = NULL, *utf8_end; 109 size_t mlen, i; 110 int rv = -1; 111 int mime = ms->flags & MAGIC_MIME; 112 113 const char *subtype = NULL; 114 const char *subtype_mime = NULL; 115 116 int has_escapes = 0; 117 int has_backspace = 0; 118 int seen_cr = 0; 119 120 int n_crlf = 0; 121 int n_lf = 0; 122 int n_cr = 0; 123 int n_nel = 0; 124 int executable = 0; 125 126 size_t last_line_end = (size_t)-1; 127 int has_long_lines = 0; 128 129 nbytes = trim_nuls(buf, nbytes); 130 131 /* If we have fewer than 2 bytes, give up. */ 132 if (nbytes <= 1) { 133 rv = 0; 134 goto done; 135 } 136 137 if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { 138 /* Convert ubuf to UTF-8 and try text soft magic */ 139 /* malloc size is a conservative overestimate; could be 140 improved, or at least realloced after conversion. */ 141 mlen = ulen * 6; 142 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { 143 file_oomem(ms, mlen); 144 goto done; 145 } 146 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) 147 == NULL) 148 goto done; 149 if ((rv = file_softmagic(ms, utf8_buf, 150 (size_t)(utf8_end - utf8_buf), NULL, NULL, 151 TEXTTEST, text)) == 0) 152 rv = -1; 153 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { 154 rv = rv == -1 ? 0 : 1; 155 goto done; 156 } 157 } 158 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) 159 return 0; 160 161 /* Now try to discover other details about the file. */ 162 for (i = 0; i < ulen; i++) { 163 if (ubuf[i] == '\n') { 164 if (seen_cr) 165 n_crlf++; 166 else 167 n_lf++; 168 last_line_end = i; 169 } else if (seen_cr) 170 n_cr++; 171 172 seen_cr = (ubuf[i] == '\r'); 173 if (seen_cr) 174 last_line_end = i; 175 176 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ 177 n_nel++; 178 last_line_end = i; 179 } 180 181 /* If this line is _longer_ than MAXLINELEN, remember it. */ 182 if (i > last_line_end + MAXLINELEN) 183 has_long_lines = 1; 184 185 if (ubuf[i] == '\033') 186 has_escapes = 1; 187 if (ubuf[i] == '\b') 188 has_backspace = 1; 189 } 190 191 /* Beware, if the data has been truncated, the final CR could have 192 been followed by a LF. If we have ms->bytes_max bytes, it indicates 193 that the data might have been truncated, probably even before 194 this function was called. */ 195 if (seen_cr && nbytes < ms->bytes_max) 196 n_cr++; 197 198 if (strcmp(type, "binary") == 0) { 199 rv = 0; 200 goto done; 201 } 202 if (mime) { 203 if (!file_printedlen(ms) && (mime & MAGIC_MIME_TYPE) != 0) { 204 if (subtype_mime) { 205 if (file_printf(ms, "%s", subtype_mime) == -1) 206 goto done; 207 } else { 208 if (file_printf(ms, "text/plain") == -1) 209 goto done; 210 } 211 } 212 } else { 213 if (file_printedlen(ms)) { 214 switch (file_replace(ms, " text$", ", ")) { 215 case 0: 216 switch (file_replace(ms, " text executable$", 217 ", ")) { 218 case 0: 219 if (file_printf(ms, ", ") == -1) 220 goto done; 221 break; 222 case -1: 223 goto done; 224 default: 225 executable = 1; 226 break; 227 } 228 break; 229 case -1: 230 goto done; 231 default: 232 break; 233 } 234 } 235 236 if (file_printf(ms, "%s", code) == -1) 237 goto done; 238 239 if (subtype) { 240 if (file_printf(ms, " %s", subtype) == -1) 241 goto done; 242 } 243 244 if (file_printf(ms, " %s", type) == -1) 245 goto done; 246 247 if (executable) 248 if (file_printf(ms, " executable") == -1) 249 goto done; 250 251 if (has_long_lines) 252 if (file_printf(ms, ", with very long lines") == -1) 253 goto done; 254 255 /* 256 * Only report line terminators if we find one other than LF, 257 * or if we find none at all. 258 */ 259 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || 260 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { 261 if (file_printf(ms, ", with") == -1) 262 goto done; 263 264 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { 265 if (file_printf(ms, " no") == -1) 266 goto done; 267 } else { 268 if (n_crlf) { 269 if (file_printf(ms, " CRLF") == -1) 270 goto done; 271 if (n_cr || n_lf || n_nel) 272 if (file_printf(ms, ",") == -1) 273 goto done; 274 } 275 if (n_cr) { 276 if (file_printf(ms, " CR") == -1) 277 goto done; 278 if (n_lf || n_nel) 279 if (file_printf(ms, ",") == -1) 280 goto done; 281 } 282 if (n_lf) { 283 if (file_printf(ms, " LF") == -1) 284 goto done; 285 if (n_nel) 286 if (file_printf(ms, ",") == -1) 287 goto done; 288 } 289 if (n_nel) 290 if (file_printf(ms, " NEL") == -1) 291 goto done; 292 } 293 294 if (file_printf(ms, " line terminators") == -1) 295 goto done; 296 } 297 298 if (has_escapes) 299 if (file_printf(ms, ", with escape sequences") == -1) 300 goto done; 301 if (has_backspace) 302 if (file_printf(ms, ", with overstriking") == -1) 303 goto done; 304 } 305 rv = 1; 306 done: 307 free(utf8_buf); 308 309 return rv; 310 } 311 312 /* 313 * Encode Unicode string as UTF-8, returning pointer to character 314 * after end of string, or NULL if an invalid character is found. 315 */ 316 private unsigned char * 317 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen) 318 { 319 size_t i; 320 unsigned char *end = buf + len; 321 322 for (i = 0; i < ulen; i++) { 323 if (ubuf[i] <= 0x7f) { 324 if (end - buf < 1) 325 return NULL; 326 *buf++ = (unsigned char)ubuf[i]; 327 } else if (ubuf[i] <= 0x7ff) { 328 if (end - buf < 2) 329 return NULL; 330 *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0); 331 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 332 } else if (ubuf[i] <= 0xffff) { 333 if (end - buf < 3) 334 return NULL; 335 *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0); 336 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 337 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 338 } else if (ubuf[i] <= 0x1fffff) { 339 if (end - buf < 4) 340 return NULL; 341 *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0); 342 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 343 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 344 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 345 } else if (ubuf[i] <= 0x3ffffff) { 346 if (end - buf < 5) 347 return NULL; 348 *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8); 349 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80); 350 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 351 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 352 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 353 } else if (ubuf[i] <= 0x7fffffff) { 354 if (end - buf < 6) 355 return NULL; 356 *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc); 357 *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80); 358 *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80); 359 *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80); 360 *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80); 361 *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80); 362 } else /* Invalid character */ 363 return NULL; 364 } 365 366 return buf; 367 } 368