contrib/file/src/fsmagic.c

   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  * fsmagic - magic based on filesystem info - directory, special files, etc.
  30  */
  31
  32 #include "file.h"
  33 #include "magic.h"
  34 #include <string.h>
  35 #ifdef HAVE_UNISTD_H
  36 #include <unistd.h>
  37 #endif
  38 #include <stdlib.h>
  39 #include <sys/stat.h>
  40 /* Since major is a function on SVR4, we cannot use `ifndef major'.  */
  41 #ifdef MAJOR_IN_MKDEV
  42 # include <sys/mkdev.h>
  43 # define HAVE_MAJOR
  44 #endif
  45 #ifdef MAJOR_IN_SYSMACROS
  46 # include <sys/sysmacros.h>
  47 # define HAVE_MAJOR
  48 #endif
  49 #ifdef major                    /* Might be defined in sys/types.h.  */
  50 # define HAVE_MAJOR
  51 #endif
  52
  53 #ifndef HAVE_MAJOR
  54 # define major(dev)  (((dev) >> 8) & 0xff)
  55 # define minor(dev)  ((dev) & 0xff)
  56 #endif
  57 #undef HAVE_MAJOR
  58
  59 #ifndef lint
  60 FILE_RCSID("@(#)$File: fsmagic.c,v 1.48 2007/10/17 19:33:31 christos Exp $")
  61 #endif  /* lint */
  62
  63 protected int
  64 file_fsmagic(struct magic_set *ms, const char *fn, struct stat *sb)
  65 {
  66         int ret = 0;
  67         int mime = ms->flags & MAGIC_MIME;
  68 #ifdef  S_IFLNK
  69         char buf[BUFSIZ+4];
  70         int nch;
  71         struct stat tstatbuf;
  72 #endif
  73
  74         if (fn == NULL)
  75                 return 0;
  76
  77         /*
  78          * Fstat is cheaper but fails for files you don't have read perms on.
  79          * On 4.2BSD and similar systems, use lstat() to identify symlinks.
  80          */
  81 #ifdef  S_IFLNK
  82         if ((ms->flags & MAGIC_SYMLINK) == 0)
  83                 ret = lstat(fn, sb);
  84         else
  85 #endif
  86         ret = stat(fn, sb);     /* don't merge into if; see "ret =" above */
  87
  88         if (ret) {
  89                 if (ms->flags & MAGIC_ERROR) {
  90                         file_error(ms, errno, "cannot stat `%s'", fn);
  91                         return -1;
  92                 }
  93                 if (file_printf(ms, "cannot open `%s' (%s)",
  94                     fn, strerror(errno)) == -1)
  95                         return -1;
  96                 return 1;
  97         }
  98
  99         if (mime) {
 100                 if ((sb->st_mode & S_IFMT) != S_IFREG) {
 101                         if ((mime & MAGIC_MIME_TYPE) &&
 102                             file_printf(ms, "application/x-not-regular-file")
 103                             == -1)
 104                                     return -1;
 105                         return 1;
 106                 }
 107         }
 108         else {
 109 #ifdef S_ISUID
 110                 if (sb->st_mode & S_ISUID)
 111                         if (file_printf(ms, "setuid ") == -1)
 112                                 return -1;
 113 #endif
 114 #ifdef S_ISGID
 115                 if (sb->st_mode & S_ISGID)
 116                         if (file_printf(ms, "setgid ") == -1)
 117                                 return -1;
 118 #endif
 119 #ifdef S_ISVTX
 120                 if (sb->st_mode & S_ISVTX)
 121                         if (file_printf(ms, "sticky ") == -1)
 122                                 return -1;
 123 #endif
 124         }
 125
 126         switch (sb->st_mode & S_IFMT) {
 127         case S_IFDIR:
 128                 if (file_printf(ms, "directory") == -1)
 129                         return -1;
 130                 return 1;
 131 #ifdef S_IFCHR
 132         case S_IFCHR:
 133                 /*
 134                  * If -s has been specified, treat character special files
 135                  * like ordinary files.  Otherwise, just report that they
 136                  * are block special files and go on to the next file.
 137                  */
 138                 if ((ms->flags & MAGIC_DEVICES) != 0)
 139                         break;
 140 #ifdef HAVE_ST_RDEV
 141 # ifdef dv_unit
 142                 if (file_printf(ms, "character special (%d/%d/%d)",
 143                     major(sb->st_rdev), dv_unit(sb->st_rdev),
 144                     dv_subunit(sb->st_rdev)) == -1)
 145                         return -1;
 146 # else
 147                 if (file_printf(ms, "character special (%ld/%ld)",
 148                     (long) major(sb->st_rdev), (long) minor(sb->st_rdev)) == -1)
 149                         return -1;
 150 # endif
 151 #else
 152                 if (file_printf(ms, "character special") == -1)
 153                         return -1;
 154 #endif
 155                 return 1;
 156 #endif
 157 #ifdef S_IFBLK
 158         case S_IFBLK:
 159                 /*
 160                  * If -s has been specified, treat block special files
 161                  * like ordinary files.  Otherwise, just report that they
 162                  * are block special files and go on to the next file.
 163                  */
 164                 if ((ms->flags & MAGIC_DEVICES) != 0)
 165                         break;
 166 #ifdef HAVE_ST_RDEV
 167 # ifdef dv_unit
 168                 if (file_printf(ms, "block special (%d/%d/%d)",
 169                     major(sb->st_rdev), dv_unit(sb->st_rdev),
 170                     dv_subunit(sb->st_rdev)) == -1)
 171                         return -1;
 172 # else
 173                 if (file_printf(ms, "block special (%ld/%ld)",
 174                     (long)major(sb->st_rdev), (long)minor(sb->st_rdev)) == -1)
 175                         return -1;
 176 # endif
 177 #else
 178                 if (file_printf(ms, "block special") == -1)
 179                         return -1;
 180 #endif
 181                 return 1;
 182 #endif
 183         /* TODO add code to handle V7 MUX and Blit MUX files */
 184 #ifdef  S_IFIFO
 185         case S_IFIFO:
 186                 if((ms->flags & MAGIC_DEVICES) != 0)
 187                         break;
 188                 if (file_printf(ms, "fifo (named pipe)") == -1)
 189                         return -1;
 190                 return 1;
 191 #endif
 192 #ifdef  S_IFDOOR
 193         case S_IFDOOR:
 194                 if (file_printf(ms, "door") == -1)
 195                         return -1;
 196                 return 1;
 197 #endif
 198 #ifdef  S_IFLNK
 199         case S_IFLNK:
 200                 if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) {
 201                         if (ms->flags & MAGIC_ERROR) {
 202                             file_error(ms, errno, "unreadable symlink `%s'",
 203                                 fn);
 204                             return -1;
 205                         }
 206                         if (file_printf(ms,
 207                             "unreadable symlink `%s' (%s)", fn,
 208                             strerror(errno)) == -1)
 209                                 return -1;
 210                         return 1;
 211                 }
 212                 buf[nch] = '\0';        /* readlink(2) forgets this */
 213
 214                 /* If broken symlink, say so and quit early. */
 215                 if (*buf == '/') {
 216                     if (stat(buf, &tstatbuf) < 0) {
 217                             if (ms->flags & MAGIC_ERROR) {
 218                                     file_error(ms, errno,
 219                                         "broken symbolic link to `%s'", buf);
 220                                     return -1;
 221                             }
 222                             if (file_printf(ms, "broken symbolic link to `%s'",
 223                                 buf) == -1)
 224                                     return -1;
 225                             return 1;
 226                     }
 227                 }
 228                 else {
 229                         char *tmp;
 230                         char buf2[BUFSIZ+BUFSIZ+4];
 231
 232                         if ((tmp = strrchr(fn,  '/')) == NULL) {
 233                                 tmp = buf; /* in current directory anyway */
 234                         } else {
 235                                 if (tmp - fn + 1 > BUFSIZ) {
 236                                         if (ms->flags & MAGIC_ERROR) {
 237                                                 file_error(ms, 0,
 238                                                     "path too long: `%s'", buf);
 239                                                 return -1;
 240                                         }
 241                                         if (file_printf(ms,
 242                                             "path too long: `%s'", fn) == -1)
 243                                                 return -1;
 244                                         return 1;
 245                                 }
 246                                 (void)strcpy(buf2, fn);  /* take dir part */
 247                                 buf2[tmp - fn + 1] = '\0';
 248                                 (void)strcat(buf2, buf); /* plus (rel) link */
 249                                 tmp = buf2;
 250                         }
 251                         if (stat(tmp, &tstatbuf) < 0) {
 252                                 if (ms->flags & MAGIC_ERROR) {
 253                                         file_error(ms, errno,
 254                                             "broken symbolic link to `%s'",
 255                                             buf);
 256                                         return -1;
 257                                 }
 258                                 if (file_printf(ms,
 259                                     "broken symbolic link to `%s'", buf) == -1)
 260                                         return -1;
 261                                 return 1;
 262                         }
 263                 }
 264
 265                 /* Otherwise, handle it. */
 266                 if ((ms->flags & MAGIC_SYMLINK) != 0) {
 267                         const char *p;
 268                         ms->flags &= MAGIC_SYMLINK;
 269                         p = magic_file(ms, buf);
 270                         ms->flags |= MAGIC_SYMLINK;
 271                         return p != NULL ? 1 : -1;
 272                 } else { /* just print what it points to */
 273                         if (file_printf(ms, "symbolic link to `%s'",
 274                             buf) == -1)
 275                                 return -1;
 276                 }
 277         return 1;
 278 #endif
 279 #ifdef  S_IFSOCK
 280 #ifndef __COHERENT__
 281         case S_IFSOCK:
 282                 if (file_printf(ms, "socket") == -1)
 283                         return -1;
 284                 return 1;
 285 #endif
 286 #endif
 287         case S_IFREG:
 288                 break;
 289         default:
 290                 file_error(ms, 0, "invalid mode 0%o", sb->st_mode);
 291                 return -1;
 292                 /*NOTREACHED*/
 293         }
 294
 295         /*
 296          * regular file, check next possibility
 297          *
 298          * If stat() tells us the file has zero length, report here that
 299          * the file is empty, so we can skip all the work of opening and
 300          * reading the file.
 301          * But if the -s option has been given, we skip this optimization,
 302          * since on some systems, stat() reports zero size for raw disk
 303          * partitions.  (If the block special device really has zero length,
 304          * the fact that it is empty will be detected and reported correctly
 305          * when we read the file.)
 306          */
 307         if ((ms->flags & MAGIC_DEVICES) == 0 && sb->st_size == 0) {
 308                 if ((!mime || (mime & MAGIC_MIME_TYPE)) &&
 309                     file_printf(ms, mime ? "application/x-empty" :
 310                     "empty") == -1)
 311                         return -1;
 312                 return 1;
 313         }
 314         return 0;
 315 }