lib/support/plausible.c

   1 /*
   2  * plausible.c --- Figure out if a pathname is ext* or something else.
   3  *
   4  * Copyright 2014, Oracle, Inc.
   5  *
   6  * Some parts are:
   7  * Copyright 1995, 1996, 1997, 1998, 1999, 2000 by Theodore Ts'o.
   8  *
   9  * %Begin-Header%
  10  * This file may be redistributed under the terms of the GNU Public
  11  * License.
  12  * %End-Header%
  13  */
  14
  15 #ifndef _LARGEFILE_SOURCE
  16 #define _LARGEFILE_SOURCE
  17 #endif
  18 #ifndef _LARGEFILE64_SOURCE
  19 #define _LARGEFILE64_SOURCE
  20 #endif
  21
  22 #include "config.h"
  23 #include <fcntl.h>
  24 #include <time.h>
  25 #include <sys/types.h>
  26 #ifdef HAVE_SYS_STAT_H
  27 #include <sys/stat.h>
  28 #endif
  29 #ifdef HAVE_UNISTD_H
  30 #include <unistd.h>
  31 #endif
  32 #ifdef HAVE_MAGIC_H
  33 #include <magic.h>
  34 #endif
  35 #include "plausible.h"
  36 #include "ext2fs/ext2fs.h"
  37 #include "nls-enable.h"
  38 #include "blkid/blkid.h"
  39
  40 #ifdef HAVE_MAGIC_H
  41 static magic_t (*dl_magic_open)(int);
  42 static const char *(*dl_magic_file)(magic_t, const char *);
  43 static int (*dl_magic_load)(magic_t, const char *);
  44 static void (*dl_magic_close)(magic_t);
  45
  46 #ifdef HAVE_DLOPEN
  47 #include <dlfcn.h>
  48
  49 static void *magic_handle;
  50
  51 static int magic_library_available(void)
  52 {
  53         if (!magic_handle) {
  54                 magic_handle = dlopen("libmagic.so.1", RTLD_NOW);
  55                 if (!magic_handle)
  56                         return 0;
  57
  58                 dl_magic_open = dlsym(magic_handle, "magic_open");
  59                 dl_magic_file = dlsym(magic_handle, "magic_file");
  60                 dl_magic_load = dlsym(magic_handle, "magic_load");
  61                 dl_magic_close = dlsym(magic_handle, "magic_close");
  62         }
  63
  64         if (!dl_magic_open || !dl_magic_file ||
  65             !dl_magic_load || !dl_magic_close)
  66                 return 0;
  67         return 1;
  68 }
  69 #else
  70 static int magic_library_available(void)
  71 {
  72         dl_magic_open = magic_open;
  73         dl_magic_file = magic_file;
  74         dl_magic_load = magic_load;
  75         dl_magic_close = magic_close;
  76
  77         return 1;
  78 }
  79 #endif
  80 #endif
  81
  82 static void print_ext2_info(const char *device)
  83
  84 {
  85         struct ext2_super_block *sb;
  86         ext2_filsys             fs;
  87         errcode_t               retval;
  88         time_t                  tm;
  89         char                    buf[80];
  90
  91         retval = ext2fs_open2(device, 0, EXT2_FLAG_64BITS, 0, 0,
  92                               unix_io_manager, &fs);
  93         if (retval)
  94                 return;
  95         sb = fs->super;
  96
  97         if (sb->s_mtime) {
  98                 tm = sb->s_mtime;
  99                 if (sb->s_last_mounted[0]) {
 100                         memset(buf, 0, sizeof(buf));
 101                         strncpy(buf, sb->s_last_mounted,
 102                                 sizeof(sb->s_last_mounted));
 103                         printf(_("\tlast mounted on %s on %s"), buf,
 104                                ctime(&tm));
 105                 } else
 106                         printf(_("\tlast mounted on %s"), ctime(&tm));
 107         } else if (sb->s_mkfs_time) {
 108                 tm = sb->s_mkfs_time;
 109                 printf(_("\tcreated on %s"), ctime(&tm));
 110         } else if (sb->s_wtime) {
 111                 tm = sb->s_wtime;
 112                 printf(_("\tlast modified on %s"), ctime(&tm));
 113         }
 114         ext2fs_close_free(&fs);
 115 }
 116
 117 /*
 118  * return 1 if there is no partition table, 0 if a partition table is
 119  * detected, and -1 on an error.
 120  */
 121 #ifdef HAVE_BLKID_PROBE_ENABLE_PARTITIONS
 122 static int check_partition_table(const char *device)
 123 {
 124         blkid_probe pr;
 125         const char *value;
 126         int ret;
 127
 128         pr = blkid_new_probe_from_filename(device);
 129         if (!pr)
 130                 return -1;
 131
 132         ret = blkid_probe_enable_partitions(pr, 1);
 133         if (ret < 0)
 134                 goto errout;
 135
 136         ret = blkid_probe_enable_superblocks(pr, 0);
 137         if (ret < 0)
 138                 goto errout;
 139
 140         ret = blkid_do_fullprobe(pr);
 141         if (ret < 0)
 142                 goto errout;
 143
 144         ret = blkid_probe_lookup_value(pr, "PTTYPE", &value, NULL);
 145         if (ret == 0)
 146                 fprintf(stderr, _("Found a %s partition table in %s\n"),
 147                         value, device);
 148         else
 149                 ret = 1;
 150
 151 errout:
 152         blkid_free_probe(pr);
 153         return ret;
 154 }
 155 #else
 156 static int check_partition_table(const char *device EXT2FS_ATTR((unused)))
 157 {
 158         return -1;
 159 }
 160 #endif
 161
 162 /*
 163  * return 1 if the device looks plausible, creating the file if necessary
 164  */
 165 int check_plausibility(const char *device, int flags, int *ret_is_dev)
 166 {
 167         int fd, ret, is_dev = 0;
 168         ext2fs_struct_stat s;
 169         int fl = O_RDONLY;
 170         blkid_cache cache = NULL;
 171         char *fs_type = NULL;
 172         char *fs_label = NULL;
 173
 174         fd = ext2fs_open_file(device, fl, 0666);
 175         if ((fd < 0) && (errno == ENOENT) && (flags & NO_SIZE)) {
 176                 fprintf(stderr, _("The file %s does not exist and no "
 177                                   "size was specified.\n"), device);
 178                 exit(1);
 179         }
 180         if ((fd < 0) && (errno == ENOENT) && (flags & CREATE_FILE)) {
 181                 fl |= O_CREAT;
 182                 fd = ext2fs_open_file(device, fl, 0666);
 183                 if (fd >= 0 && (flags & VERBOSE_CREATE))
 184                         printf(_("Creating regular file %s\n"), device);
 185         }
 186         if (fd < 0) {
 187                 fprintf(stderr, _("Could not open %s: %s\n"),
 188                         device, error_message(errno));
 189                 if (errno == ENOENT)
 190                         fputs(_("\nThe device apparently does not exist; "
 191                                 "did you specify it correctly?\n"), stderr);
 192                 exit(1);
 193         }
 194
 195         if (ext2fs_fstat(fd, &s) < 0) {
 196                 perror("stat");
 197                 exit(1);
 198         }
 199         close(fd);
 200
 201         if (S_ISBLK(s.st_mode))
 202                 is_dev = 1;
 203 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 204         /* On FreeBSD, all disk devices are character specials */
 205         if (S_ISCHR(s.st_mode))
 206                 is_dev = 1;
 207 #endif
 208         if (ret_is_dev)
 209                 *ret_is_dev = is_dev;
 210
 211         if ((flags & CHECK_BLOCK_DEV) && !is_dev) {
 212                 printf(_("%s is not a block special device.\n"), device);
 213                 return 0;
 214         }
 215
 216         /*
 217          * Note: we use the older-style blkid API's here because we
 218          * want as much functionality to be available when using the
 219          * internal blkid library, when e2fsprogs is compiled for
 220          * non-Linux systems that will probably not have the libraries
 221          * from util-linux available.  We only use the newer
 222          * blkid-probe interfaces to access functionality not
 223          * available in the original blkid library.
 224          */
 225         if ((flags & CHECK_FS_EXIST) && blkid_get_cache(&cache, NULL) >= 0) {
 226                 fs_type = blkid_get_tag_value(cache, "TYPE", device);
 227                 if (fs_type)
 228                         fs_label = blkid_get_tag_value(cache, "LABEL", device);
 229                 blkid_put_cache(cache);
 230         }
 231
 232         if (fs_type) {
 233                 if (fs_label)
 234                         printf(_("%s contains a %s file system "
 235                                  "labelled '%s'\n"), device, fs_type, fs_label);
 236                 else
 237                         printf(_("%s contains a %s file system\n"), device,
 238                                fs_type);
 239                 if (strncmp(fs_type, "ext", 3) == 0)
 240                         print_ext2_info(device);
 241                 free(fs_type);
 242                 free(fs_label);
 243                 return 0;
 244         }
 245
 246 #ifdef HAVE_MAGIC_H
 247         if ((flags & CHECK_FS_EXIST) && magic_library_available()) {
 248                 const char *msg;
 249                 magic_t mag;
 250                 int has_magic = 0;
 251
 252                 mag = dl_magic_open(MAGIC_RAW | MAGIC_SYMLINK | MAGIC_DEVICES |
 253                                     MAGIC_ERROR | MAGIC_NO_CHECK_ELF |
 254                                     MAGIC_NO_CHECK_COMPRESS);
 255                 dl_magic_load(mag, NULL);
 256
 257                 msg = dl_magic_file(mag, device);
 258                 if (msg && strcmp(msg, "data") && strcmp(msg, "empty")) {
 259                         printf(_("%s contains `%s' data\n"), device, msg);
 260                         has_magic = 1;
 261                 }
 262
 263                 dl_magic_close(mag);
 264                 return !has_magic;
 265         }
 266 #endif
 267
 268         ret = check_partition_table(device);
 269         if (ret >= 0)
 270                 return ret;
 271
 272         return 1;
 273 }
 274