contrib/file-4/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("@(#)$Id: fsmagic.c,v 1.45 2004/11/13 10:19:48 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 #ifdef  S_IFLNK
  68         char buf[BUFSIZ+4];
  69         int nch;
  70         struct stat tstatbuf;
  71 #endif
  72
  73         if (fn == NULL)
  74                 return 0;
  75
  76         /*
  77          * Fstat is cheaper but fails for files you don't have read perms on.
  78          * On 4.2BSD and similar systems, use lstat() to identify symlinks.
  79          */
  80 #ifdef  S_IFLNK
  81         if ((ms->flags & MAGIC_SYMLINK) == 0)
  82                 ret = lstat(fn, sb);
  83         else
  84 #endif
  85         ret = stat(fn, sb);     /* don't merge into if; see "ret =" above */
  86
  87         if (ret) {
  88                 if (ms->flags & MAGIC_ERROR) {
  89                         file_error(ms, errno, "cannot stat `%s'", fn);
  90                         return -1;
  91                 }
  92                 if (file_printf(ms, "cannot open `%s' (%s)",
  93                     fn, strerror(errno)) == -1)
  94                         return -1;
  95                 return 1;
  96         }
  97
  98         if ((ms->flags & MAGIC_MIME) != 0) {
  99                 if ((sb->st_mode & S_IFMT) != S_IFREG) {
 100                         if (file_printf(ms, "application/x-not-regular-file")
 101                             == -1)
 102                                 return -1;
 103                         return 1;
 104                 }
 105         }
 106         else {
 107 #ifdef S_ISUID
 108                 if (sb->st_mode & S_ISUID)
 109                         if (file_printf(ms, "setuid ") == -1)
 110                                 return -1;
 111 #endif
 112 #ifdef S_ISGID
 113                 if (sb->st_mode & S_ISGID)
 114                         if (file_printf(ms, "setgid ") == -1)
 115                                 return -1;
 116 #endif
 117 #ifdef S_ISVTX
 118                 if (sb->st_mode & S_ISVTX)
 119                         if (file_printf(ms, "sticky ") == -1)
 120                                 return -1;
 121 #endif
 122         }
 123
 124         switch (sb->st_mode & S_IFMT) {
 125         case S_IFDIR:
 126                 if (file_printf(ms, "directory") == -1)
 127                         return -1;
 128                 return 1;
 129 #ifdef S_IFCHR
 130         case S_IFCHR:
 131                 /*
 132                  * If -s has been specified, treat character special files
 133                  * like ordinary files.  Otherwise, just report that they
 134                  * are block special files and go on to the next file.
 135                  */
 136                 if ((ms->flags & MAGIC_DEVICES) != 0)
 137                         break;
 138 #ifdef HAVE_ST_RDEV
 139 # ifdef dv_unit
 140                 if (file_printf(ms, "character special (%d/%d/%d)",
 141                     major(sb->st_rdev), dv_unit(sb->st_rdev),
 142                     dv_subunit(sb->st_rdev)) == -1)
 143                         return -1;
 144 # else
 145                 if (file_printf(ms, "character special (%ld/%ld)",
 146                     (long) major(sb->st_rdev), (long) minor(sb->st_rdev)) == -1)
 147                         return -1;
 148 # endif
 149 #else
 150                 if (file_printf(ms, "character special") == -1)
 151                         return -1;
 152 #endif
 153                 return 1;
 154 #endif
 155 #ifdef S_IFBLK
 156         case S_IFBLK:
 157                 /*
 158                  * If -s has been specified, treat block special files
 159                  * like ordinary files.  Otherwise, just report that they
 160                  * are block special files and go on to the next file.
 161                  */
 162                 if ((ms->flags & MAGIC_DEVICES) != 0)
 163                         break;
 164 #ifdef HAVE_ST_RDEV
 165 # ifdef dv_unit
 166                 if (file_printf(ms, "block special (%d/%d/%d)",
 167                     major(sb->st_rdev), dv_unit(sb->st_rdev),
 168                     dv_subunit(sb->st_rdev)) == -1)
 169                         return -1;
 170 # else
 171                 if (file_printf(ms, "block special (%ld/%ld)",
 172                     (long)major(sb->st_rdev), (long)minor(sb->st_rdev)) == -1)
 173                         return -1;
 174 # endif
 175 #else
 176                 if (file_printf(ms, "block special") == -1)
 177                         return -1;
 178 #endif
 179                 return 1;
 180 #endif
 181         /* TODO add code to handle V7 MUX and Blit MUX files */
 182 #ifdef  S_IFIFO
 183         case S_IFIFO:
 184                 if (file_printf(ms, "fifo (named pipe)") == -1)
 185                         return -1;
 186                 return 1;
 187 #endif
 188 #ifdef  S_IFDOOR
 189         case S_IFDOOR:
 190                 if (file_printf(ms, "door") == -1)
 191                         return -1;
 192                 return 1;
 193 #endif
 194 #ifdef  S_IFLNK
 195         case S_IFLNK:
 196                 if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) {
 197                         if (ms->flags & MAGIC_ERROR) {
 198                             file_error(ms, errno, "unreadable symlink `%s'",
 199                                 fn);
 200                             return -1;
 201                         }
 202                         if (file_printf(ms,
 203                             "unreadable symlink `%s' (%s)", fn,
 204                             strerror(errno)) == -1)
 205                                 return -1;
 206                         return 1;
 207                 }
 208                 buf[nch] = '\0';        /* readlink(2) forgets this */
 209
 210                 /* If broken symlink, say so and quit early. */
 211                 if (*buf == '/') {
 212                     if (stat(buf, &tstatbuf) < 0) {
 213                             if (ms->flags & MAGIC_ERROR) {
 214                                     file_error(ms, errno,
 215                                         "broken symbolic link to `%s'", buf);
 216                                     return -1;
 217                             }
 218                             if (file_printf(ms, "broken symbolic link to `%s'",
 219                                 buf) == -1)
 220                                     return -1;
 221                             return 1;
 222                     }
 223                 }
 224                 else {
 225                         char *tmp;
 226                         char buf2[BUFSIZ+BUFSIZ+4];
 227
 228                         if ((tmp = strrchr(fn,  '/')) == NULL) {
 229                                 tmp = buf; /* in current directory anyway */
 230                         } else {
 231                                 if (tmp - fn + 1 > BUFSIZ) {
 232                                         if (ms->flags & MAGIC_ERROR) {
 233                                                 file_error(ms, 0,
 234                                                     "path too long: `%s'", buf);
 235                                                 return -1;
 236                                         }
 237                                         if (file_printf(ms,
 238                                             "path too long: `%s'", fn) == -1)
 239                                                 return -1;
 240                                         return 1;
 241                                 }
 242                                 (void)strcpy(buf2, fn);  /* take dir part */
 243                                 buf2[tmp - fn + 1] = '\0';
 244                                 (void)strcat(buf2, buf); /* plus (rel) link */
 245                                 tmp = buf2;
 246                         }
 247                         if (stat(tmp, &tstatbuf) < 0) {
 248                                 if (ms->flags & MAGIC_ERROR) {
 249                                         file_error(ms, errno,
 250                                             "broken symbolic link to `%s'",
 251                                             buf);
 252                                         return -1;
 253                                 }
 254                                 if (file_printf(ms,
 255                                     "broken symbolic link to `%s'", buf) == -1)
 256                                         return -1;
 257                                 return 1;
 258                         }
 259                 }
 260
 261                 /* Otherwise, handle it. */
 262                 if ((ms->flags & MAGIC_SYMLINK) != 0) {
 263                         const char *p;
 264                         ms->flags &= MAGIC_SYMLINK;
 265                         p = magic_file(ms, buf);
 266                         ms->flags |= MAGIC_SYMLINK;
 267                         return p != NULL ? 1 : -1;
 268                 } else { /* just print what it points to */
 269                         if (file_printf(ms, "symbolic link to `%s'",
 270                             buf) == -1)
 271                                 return -1;
 272                 }
 273         return 1;
 274 #endif
 275 #ifdef  S_IFSOCK
 276 #ifndef __COHERENT__
 277         case S_IFSOCK:
 278                 if (file_printf(ms, "socket") == -1)
 279                         return -1;
 280                 return 1;
 281 #endif
 282 #endif
 283         case S_IFREG:
 284                 break;
 285         default:
 286                 file_error(ms, 0, "invalid mode 0%o", sb->st_mode);
 287                 return -1;
 288                 /*NOTREACHED*/
 289         }
 290
 291         /*
 292          * regular file, check next possibility
 293          *
 294          * If stat() tells us the file has zero length, report here that
 295          * the file is empty, so we can skip all the work of opening and
 296          * reading the file.
 297          * But if the -s option has been given, we skip this optimization,
 298          * since on some systems, stat() reports zero size for raw disk
 299          * partitions.  (If the block special device really has zero length,
 300          * the fact that it is empty will be detected and reported correctly
 301          * when we read the file.)
 302          */
 303         if ((ms->flags & MAGIC_DEVICES) == 0 && sb->st_size == 0) {
 304                 if (file_printf(ms, (ms->flags & MAGIC_MIME) ?
 305                     "application/x-empty" : "empty") == -1)
 306                         return -1;
 307                 return 1;
 308         }
 309         return 0;
 310 }