Logo Search packages:      
Sourcecode: yaboot version File versions  Download package

ismounted.c

/*
 * ismounted.c --- Check to see if the filesystem was mounted
 * 
 * Copyright (C) 1995,1996,1997,1998,1999,2000 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#include <fcntl.h>
#ifdef HAVE_LINUX_FD_H
#include <linux/fd.h>
#endif
#ifdef HAVE_MNTENT_H
#include <mntent.h>
#endif
#ifdef HAVE_GETMNTINFO
#include <paths.h>
#include <sys/param.h>
#include <sys/mount.h>
#endif /* HAVE_GETMNTINFO */
#include <string.h>
#include <sys/stat.h>

#include "ext2_fs.h"
#include "ext2fs.h"

#ifdef HAVE_MNTENT_H
/*
 * Helper function which checks a file in /etc/mtab format to see if a
 * filesystem is mounted.  Returns an error if the file doesn't exist
 * or can't be opened.  
 */
static errcode_t check_mntent_file(const char *mtab_file, const char *file, 
                           int *mount_flags, char *mtpt, int mtlen)
{
      struct mntent     *mnt;
      struct stat st_buf;
      errcode_t   retval = 0;
      dev_t       file_dev;
      FILE        *f;
      int         fd;

      *mount_flags = 0;
      if ((f = setmntent (mtab_file, "r")) == NULL)
            return errno;
      file_dev = 0;
#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
      if (stat(file, &st_buf) == 0)
            file_dev = st_buf.st_rdev;
#endif      
      while ((mnt = getmntent (f)) != NULL) {
            if (strcmp(file, mnt->mnt_fsname) == 0)
                  break;
#ifndef __GNU__
            if (file_dev && (stat(mnt->mnt_fsname, &st_buf) == 0) &&
                file_dev == st_buf.st_rdev)
                  break;
#endif
      }

      if (mnt == 0) {
#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
            /*
             * Do an extra check to see if this is the root device.  We
             * can't trust /etc/mtab, and /proc/mounts will only list
             * /dev/root for the root filesystem.  Argh.  Instead we
             * check if the given device has the same major/minor number
             * as the device that the root directory is on.
             */
            if (file_dev && stat("/", &st_buf) == 0) {
                  if (st_buf.st_dev == file_dev) {
                        *mount_flags = EXT2_MF_MOUNTED;
                        if (mtpt)
                              strncpy(mtpt, "/", mtlen);
                        goto is_root;
                  }
            }
#endif
            goto exit;
      }
#ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
      /* Validate the entry in case /etc/mtab is out of date */
      /* 
       * We need to be paranoid, because some broken distributions
       * (read: Slackware) don't initialize /etc/mtab before checking
       * all of the non-root filesystems on the disk.
       */
      if (stat(mnt->mnt_dir, &st_buf) < 0) {
            retval = errno;
            if (retval == ENOENT) {
#ifdef DEBUG
                  printf("Bogus entry in %s!  (%s does not exist)\n",
                         mtab_file, mnt->mnt_dir);
#endif
                  retval = 0;
            }
            goto exit;
      }
      if (file_dev && (st_buf.st_dev != file_dev)) {
#ifdef DEBUG
            printf("Bogus entry in %s!  (%s not mounted on %s)\n",
                   mtab_file, file, mnt->mnt_dir);
#endif
            goto exit;
      }
#endif
      *mount_flags = EXT2_MF_MOUNTED;
      
      /* Check to see if the ro option is set */
      if (hasmntopt(mnt, MNTOPT_RO))
            *mount_flags |= EXT2_MF_READONLY;

      if (mtpt)
            strncpy(mtpt, mnt->mnt_dir, mtlen);
      /*
       * Check to see if we're referring to the root filesystem.
       * If so, do a manual check to see if we can open /etc/mtab
       * read/write, since if the root is mounted read/only, the
       * contents of /etc/mtab may not be accurate.
       */
      if (!strcmp(mnt->mnt_dir, "/")) {
is_root:
#define TEST_FILE "/.ismount-test-file"         
            *mount_flags |= EXT2_MF_ISROOT;
            fd = open(TEST_FILE, O_RDWR|O_CREAT);
            if (fd < 0) {
                  if (errno == EROFS)
                        *mount_flags |= EXT2_MF_READONLY;
            } else
                  close(fd);
            (void) unlink(TEST_FILE);
      }
      retval = 0;
exit:
      endmntent (f);
      return retval;
}

/*
 * Check to see if we're dealing with the swap device.
 */
static int is_swap_device(const char *file)
{
      FILE        *f;
      char        buf[1024], *cp;
      dev_t       file_dev;
      struct stat st_buf;
      int         ret = 0;

      file_dev = 0;
#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
      if (stat(file, &st_buf) == 0)
            file_dev = st_buf.st_rdev;
#endif      

      if (!(f = fopen("/proc/swaps", "r")))
            return 0;
      /* Skip the first line */
      fgets(buf, sizeof(buf), f);
      while (!feof(f)) {
            if (!fgets(buf, sizeof(buf), f))
                  break;
            if ((cp = strchr(buf, ' ')) != NULL)
                  *cp = 0;
            if ((cp = strchr(buf, '\t')) != NULL)
                  *cp = 0;
            if (strcmp(buf, file) == 0) {
                  ret++;
                  break;
            }
#ifndef __GNU__
            if (file_dev && (stat(buf, &st_buf) == 0) &&
                file_dev == st_buf.st_rdev) {
                  ret++;
                  break;
            }
#endif
      }
      fclose(f);
      return ret;
}

static errcode_t check_mntent(const char *file, int *mount_flags,
                        char *mtpt, int mtlen)
{
      errcode_t   retval;

#ifdef DEBUG
      retval = check_mntent_file("/tmp/mtab", file, mount_flags,
                           mtpt, mtlen);
      if (retval == 0)
            return 0;
#endif
#ifdef __linux__
      retval = check_mntent_file("/proc/mounts", file, mount_flags,
                           mtpt, mtlen);
      if (retval == 0)
            return 0;
#endif
      retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
      return retval;
}

#elif defined(HAVE_GETMNTINFO)

static errcode_t check_getmntinfo(const char *file, int *mount_flags,
                          char *mtpt, int mtlen)
{
      struct statfs *mp;
        int    len, n;
        const  char   *s1;
      char  *s2;

        n = getmntinfo(&mp, MNT_NOWAIT);
        if (n == 0)
            return errno;

        len = sizeof(_PATH_DEV) - 1;
        s1 = file;
        if (strncmp(_PATH_DEV, s1, len) == 0)
                s1 += len;
 
      *mount_flags = 0;
        while (--n >= 0) {
                s2 = mp->f_mntfromname;
                if (strncmp(_PATH_DEV, s2, len) == 0) {
                        s2 += len - 1;
                        *s2 = 'r';
                }
                if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
                  *mount_flags = EXT2_MF_MOUNTED;
                  break;
            }
                ++mp;
      }
      if (mtpt)
            strncpy(mtpt, mp->f_mntonname, mtlen);
      return 0;
}
#endif /* HAVE_GETMNTINFO */

/*
 * ext2fs_check_mount_point() returns 1 if the device is mounted, 0
 * otherwise.  If mtpt is non-NULL, the directory where the device is
 * mounted is copied to where mtpt is pointing, up to mtlen
 * characters.
 */
#ifdef __TURBOC__
 #pragma argsused
#endif
errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
                          char *mtpt, int mtlen)
{
      if (is_swap_device(device)) {
            *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
            strncpy(mtpt, "<swap>", mtlen);
            return 0;
      }
#ifdef HAVE_MNTENT_H
      return check_mntent(device, mount_flags, mtpt, mtlen);
#else 
#ifdef HAVE_GETMNTINFO
      return check_getmntinfo(device, mount_flags, mtpt, mtlen);
#else
#warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
      *mount_flags = 0;
      return 0;
#endif /* HAVE_GETMNTINFO */
#endif /* HAVE_MNTENT_H */
}

/*
 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
 * EXT2_MF_READONLY, and EXT2_MF_ROOT
 * 
 */
errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
{
      return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
}

#ifdef DEBUG
int main(int argc, char **argv)
{
      int   retval, mount_flags;
      char  mntpt[80];
      
      if (argc < 2) {
            fprintf(stderr, "Usage: %s device\n", argv[0]);
            exit(1);
      }

      mntpt[0] = 0;
      retval = ext2fs_check_mount_point(argv[1], &mount_flags,
                                mntpt, sizeof(mntpt));
      if (retval) {
            com_err(argv[0], retval,
                  "while calling ext2fs_check_if_mounted");
            exit(1);
      }
      printf("Device %s reports flags %02x\n", argv[1], mount_flags);
      if (mount_flags & EXT2_MF_MOUNTED)
            printf("\t%s is mounted.\n", argv[1]);

      if (mount_flags & EXT2_MF_SWAP)
            printf("\t%s is a swap device.\n", argv[1]);

      if (mount_flags & EXT2_MF_READONLY)
            printf("\t%s is read-only.\n", argv[1]);
      
      if (mount_flags & EXT2_MF_ISROOT)
            printf("\t%s is the root filesystem.\n", argv[1]);
      if (mntpt[0])
            printf("\t%s is mounted on %s.\n", argv[1], mntpt);
      
      exit(0);
}
#endif

Generated by  Doxygen 1.6.0   Back to index