external/bsd/file/dist/src/ascmagic.c

   1 /*      $NetBSD$        */
   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 -- file types that we know based on keywords
  32  * that can appear anywhere in the file.
  33  *
  34  * Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000,
  35  * to handle character codes other than ASCII on a unified basis.
  36  */
  37
  38 #include "file.h"
  39
  40 #ifndef lint
  41 #if 0
  42 FILE_RCSID("@(#)$File: ascmagic.c,v 1.75 2009/02/03 20:27:51 christos Exp $")
  43 #else
  44 __RCSID("$NetBSD$");
  45 #endif
  46 #endif  /* lint */
  47
  48 #include "magic.h"
  49 #include <string.h>
  50 #include <memory.h>
  51 #include <ctype.h>
  52 #include <stdlib.h>
  53 #ifdef HAVE_UNISTD_H
  54 #include <unistd.h>
  55 #endif
  56 #include "names.h"
  57
  58 #define MAXLINELEN 300  /* longest sane line length */
  59 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \
  60                   || (x) == 0x85 || (x) == '\f')
  61
  62 private int ascmatch(const unsigned char *, const unichar *, size_t);
  63 private unsigned char *encode_utf8(unsigned char *, size_t, unichar *, size_t);
  64 private size_t trim_nuls(const unsigned char *, size_t);
  65
  66 /*
  67  * Undo the NUL-termination kindly provided by process()
  68  * but leave at least one byte to look at
  69  */
  70 private size_t
  71 trim_nuls(const unsigned char *buf, size_t nbytes)
  72 {
  73         while (nbytes > 1 && buf[nbytes - 1] == '\0')
  74                 nbytes--;
  75
  76         return nbytes;
  77 }
  78
  79 protected int
  80 file_ascmagic(struct magic_set *ms, const unsigned char *buf, size_t nbytes)
  81 {
  82         unichar *ubuf = NULL;
  83         size_t ulen;
  84         int rv = 1;
  85
  86         const char *code = NULL;
  87         const char *code_mime = NULL;
  88         const char *type = NULL;
  89
  90         if (ms->flags & MAGIC_APPLE)
  91                 return 0;
  92
  93         nbytes = trim_nuls(buf, nbytes);
  94
  95         /* If file doesn't look like any sort of text, give up. */
  96         if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime,
  97             &type) == 0) {
  98                 rv = 0;
  99                 goto done;
 100         }
 101
 102         rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code,
 103             type);
 104
 105  done:
 106         if (ubuf)
 107                 free(ubuf);
 108
 109         return rv;
 110 }
 111
 112 protected int
 113 file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf,
 114     size_t nbytes, unichar *ubuf, size_t ulen, const char *code,
 115     const char *type)
 116 {
 117         unsigned char *utf8_buf = NULL, *utf8_end;
 118         size_t mlen, i;
 119         const struct names *p;
 120         int rv = -1;
 121         int mime = ms->flags & MAGIC_MIME;
 122
 123         const char *subtype = NULL;
 124         const char *subtype_mime = NULL;
 125
 126         int has_escapes = 0;
 127         int has_backspace = 0;
 128         int seen_cr = 0;
 129
 130         int n_crlf = 0;
 131         int n_lf = 0;
 132         int n_cr = 0;
 133         int n_nel = 0;
 134
 135         size_t last_line_end = (size_t)-1;
 136         int has_long_lines = 0;
 137
 138         if (ms->flags & MAGIC_APPLE)
 139                 return 0;
 140
 141         nbytes = trim_nuls(buf, nbytes);
 142
 143         /* If we have fewer than 2 bytes, give up. */
 144         if (nbytes <= 1) {
 145                 rv = 0;
 146                 goto done;
 147         }
 148
 149         /* Convert ubuf to UTF-8 and try text soft magic */
 150         /* malloc size is a conservative overestimate; could be
 151            improved, or at least realloced after conversion. */
 152         mlen = ulen * 6;
 153         if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) {
 154                 file_oomem(ms, mlen);
 155                 goto done;
 156         }
 157         if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) == NULL)
 158                 goto done;
 159         if ((rv = file_softmagic(ms, utf8_buf, (size_t)(utf8_end - utf8_buf),
 160             TEXTTEST)) != 0)
 161                 goto done;
 162         else
 163                 rv = -1;
 164
 165         /* look for tokens from names.h - this is expensive! */
 166         if ((ms->flags & MAGIC_NO_CHECK_TOKENS) != 0)
 167                 goto subtype_identified;
 168
 169         i = 0;
 170         while (i < ulen) {
 171                 size_t end;
 172
 173                 /* skip past any leading space */
 174                 while (i < ulen && ISSPC(ubuf[i]))
 175                         i++;
 176                 if (i >= ulen)
 177                         break;
 178
 179                 /* find the next whitespace */
 180                 for (end = i + 1; end < nbytes; end++)
 181                         if (ISSPC(ubuf[end]))
 182                                 break;
 183
 184                 /* compare the word thus isolated against the token list */
 185                 for (p = names; p < names + NNAMES; p++) {
 186                         if (ascmatch((const unsigned char *)p->name, ubuf + i,
 187                             end - i)) {
 188                                 subtype = types[p->type].human;
 189                                 subtype_mime = types[p->type].mime;
 190                                 goto subtype_identified;
 191                         }
 192                 }
 193
 194                 i = end;
 195         }
 196
 197 subtype_identified:
 198
 199         /* Now try to discover other details about the file. */
 200         for (i = 0; i < ulen; i++) {
 201                 if (ubuf[i] == '\n') {
 202                         if (seen_cr)
 203                                 n_crlf++;
 204                         else
 205                                 n_lf++;
 206                         last_line_end = i;
 207                 } else if (seen_cr)
 208                         n_cr++;
 209
 210                 seen_cr = (ubuf[i] == '\r');
 211                 if (seen_cr)
 212                         last_line_end = i;
 213
 214                 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
 215                         n_nel++;
 216                         last_line_end = i;
 217                 }
 218
 219                 /* If this line is _longer_ than MAXLINELEN, remember it. */
 220                 if (i > last_line_end + MAXLINELEN)
 221                         has_long_lines = 1;
 222
 223                 if (ubuf[i] == '\033')
 224                         has_escapes = 1;
 225                 if (ubuf[i] == '\b')
 226                         has_backspace = 1;
 227         }
 228
 229         /* Beware, if the data has been truncated, the final CR could have
 230            been followed by a LF.  If we have HOWMANY bytes, it indicates
 231            that the data might have been truncated, probably even before
 232            this function was called. */
 233         if (seen_cr && nbytes < HOWMANY)
 234                 n_cr++;
 235
 236         if (strcmp(type, "binary") == 0) {
 237                 rv = 0;
 238                 goto done;
 239         }
 240         if (mime) {
 241                 if ((mime & MAGIC_MIME_TYPE) != 0) {
 242                         if (subtype_mime) {
 243                                 if (file_printf(ms, "%s", subtype_mime) == -1)
 244                                         goto done;
 245                         } else {
 246                                 if (file_printf(ms, "text/plain") == -1)
 247                                         goto done;
 248                         }
 249                 }
 250         } else {
 251                 if (file_printf(ms, "%s", code) == -1)
 252                         goto done;
 253
 254                 if (subtype) {
 255                         if (file_printf(ms, " %s", subtype) == -1)
 256                                 goto done;
 257                 }
 258
 259                 if (file_printf(ms, " %s", type) == -1)
 260                         goto done;
 261
 262                 if (has_long_lines)
 263                         if (file_printf(ms, ", with very long lines") == -1)
 264                                 goto done;
 265
 266                 /*
 267                  * Only report line terminators if we find one other than LF,
 268                  * or if we find none at all.
 269                  */
 270                 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
 271                     (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
 272                         if (file_printf(ms, ", with") == -1)
 273                                 goto done;
 274
 275                         if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
 276                                 if (file_printf(ms, " no") == -1)
 277                                         goto done;
 278                         } else {
 279                                 if (n_crlf) {
 280                                         if (file_printf(ms, " CRLF") == -1)
 281                                                 goto done;
 282                                         if (n_cr || n_lf || n_nel)
 283                                                 if (file_printf(ms, ",") == -1)
 284                                                         goto done;
 285                                 }
 286                                 if (n_cr) {
 287                                         if (file_printf(ms, " CR") == -1)
 288                                                 goto done;
 289                                         if (n_lf || n_nel)
 290                                                 if (file_printf(ms, ",") == -1)
 291                                                         goto done;
 292                                 }
 293                                 if (n_lf) {
 294                                         if (file_printf(ms, " LF") == -1)
 295                                                 goto done;
 296                                         if (n_nel)
 297                                                 if (file_printf(ms, ",") == -1)
 298                                                         goto done;
 299                                 }
 300                                 if (n_nel)
 301                                         if (file_printf(ms, " NEL") == -1)
 302                                                 goto done;
 303                         }
 304
 305                         if (file_printf(ms, " line terminators") == -1)
 306                                 goto done;
 307                 }
 308
 309                 if (has_escapes)
 310                         if (file_printf(ms, ", with escape sequences") == -1)
 311                                 goto done;
 312                 if (has_backspace)
 313                         if (file_printf(ms, ", with overstriking") == -1)
 314                                 goto done;
 315         }
 316         rv = 1;
 317 done:
 318         if (utf8_buf)
 319                 free(utf8_buf);
 320
 321         return rv;
 322 }
 323
 324 private int
 325 ascmatch(const unsigned char *s, const unichar *us, size_t ulen)
 326 {
 327         size_t i;
 328
 329         for (i = 0; i < ulen; i++) {
 330                 if (s[i] != us[i])
 331                         return 0;
 332         }
 333
 334         if (s[i])
 335                 return 0;
 336         else
 337                 return 1;
 338 }
 339
 340 /*
 341  * Encode Unicode string as UTF-8, returning pointer to character
 342  * after end of string, or NULL if an invalid character is found.
 343  */
 344 private unsigned char *
 345 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen)
 346 {
 347         size_t i;
 348         unsigned char *end = buf + len;
 349
 350         for (i = 0; i < ulen; i++) {
 351                 if (ubuf[i] <= 0x7f) {
 352                         if (end - buf < 1)
 353                                 return NULL;
 354                         *buf++ = (unsigned char)ubuf[i];
 355                 } else if (ubuf[i] <= 0x7ff) {
 356                         if (end - buf < 2)
 357                                 return NULL;
 358                         *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0);
 359                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
 360                 } else if (ubuf[i] <= 0xffff) {
 361                         if (end - buf < 3)
 362                                 return NULL;
 363                         *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0);
 364                         *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
 365                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
 366                 } else if (ubuf[i] <= 0x1fffff) {
 367                         if (end - buf < 4)
 368                                 return NULL;
 369                         *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0);
 370                         *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
 371                         *buf++ = (unsigned char)(((ubuf[i] >>  6) & 0x3f) + 0x80);
 372                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
 373                 } else if (ubuf[i] <= 0x3ffffff) {
 374                         if (end - buf < 5)
 375                                 return NULL;
 376                         *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8);
 377                         *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
 378                         *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
 379                         *buf++ = (unsigned char)(((ubuf[i] >>  6) & 0x3f) + 0x80);
 380                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
 381                 } else if (ubuf[i] <= 0x7fffffff) {
 382                         if (end - buf < 6)
 383                                 return NULL;
 384                         *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc);
 385                         *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80);
 386                         *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
 387                         *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
 388                         *buf++ = (unsigned char)(((ubuf[i] >>  6) & 0x3f) + 0x80);
 389                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
 390                 } else /* Invalid character */
 391                         return NULL;
 392         }
 393
 394         return buf;
 395 }