text: /*
   * 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=0, file_rdev=0;
  	ino_t		file_ino=0;
  	FILE 		*f;
  	int		fd;
  
  	*mount_flags = 0;
  	if ((f = setmntent (mtab_file, "r")) == NULL)
  		return (errno == ENOENT ? EXT2_NO_MTAB_FILE : errno);
  	if (stat(file, &st_buf) == 0) {
  		if (S_ISBLK(st_buf.st_mode)) {
  #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
  			file_rdev = st_buf.st_rdev;
  #endif	/* __GNU__ */
  		} else {
  			file_dev = st_buf.st_dev;
  			file_ino = st_buf.st_ino;
  		}
  	}
  	while ((mnt = getmntent (f)) != NULL) {
  		if (mnt->mnt_fsname[0] != '/')
  			continue;
  		if (strcmp(file, mnt->mnt_fsname) == 0)
  			break;
  		if (stat(mnt->mnt_fsname, &st_buf) == 0) {
  			if (S_ISBLK(st_buf.st_mode)) {
  #ifndef __GNU__
  				if (file_rdev && (file_rdev == st_buf.st_rdev))
  					break;
  #endif	/* __GNU__ */
  			} else {
  				if (file_dev && ((file_dev == st_buf.st_dev) &&
  						 (file_ino == st_buf.st_ino)))
  					break;
  			}
  		}
  	}
  
  	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_rdev && stat("/", &st_buf) == 0) {
  			if (st_buf.st_dev == file_rdev) {
  				*mount_flags = EXT2_MF_MOUNTED;
  				if (mtpt)
  					strncpy(mtpt, "/", mtlen);
  				goto is_root;
  			}
  		}
  #endif	/* __GNU__ */
  		goto errout;
  	}
  #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 /* DEBUG */
  			retval = 0;
  		}
  		goto errout;
  	}
  	if (file_rdev && (st_buf.st_dev != file_rdev)) {
  #ifdef DEBUG
  		printf("Bogus entry in %s!  (%s not mounted on %s)\n",
  		       mtab_file, file, mnt->mnt_dir);
  #endif /* DEBUG */
  		goto errout;
  	}
  #endif /* __GNU__ */
  	*mount_flags = EXT2_MF_MOUNTED;
  
  #ifdef MNTOPT_RO
  	/* Check to see if the ro option is set */
  	if (hasmntopt(mnt, MNTOPT_RO))
  		*mount_flags |= EXT2_MF_READONLY;
  #endif
  
  	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, 0600);
  		if (fd < 0) {
  			if (errno == EROFS)
  				*mount_flags |= EXT2_MF_READONLY;
  		} else
  			close(fd);
  		(void) unlink(TEST_FILE);
  	}
  	retval = 0;
  errout:
  	endmntent (f);
  	return retval;
  }
  
  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 /* DEBUG */
  #ifdef __linux__
  	retval = check_mntent_file("/proc/mounts", file, mount_flags,
  				   mtpt, mtlen);
  	if (retval == 0 && (*mount_flags != 0))
  		return 0;
  #endif /* __linux__ */
  #if defined(MOUNTED) || defined(_PATH_MOUNTED)
  #ifndef MOUNTED
  #define MOUNTED _PATH_MOUNTED
  #endif /* MOUNTED */
  	retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
  	return retval;
  #else
  	*mount_flags = 0;
  	return 0;
  #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
  }
  
  #else
  #if 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 */
  #endif /* HAVE_MNTENT_H */
  
  /*
   * 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) &&
  	    S_ISBLK(st_buf.st_mode))
  		file_dev = st_buf.st_rdev;
  #endif	/* __GNU__ */
  
  	if (!(f = fopen("/proc/swaps", "r")))
  		return 0;
  	/* Skip the first line */
  	if (fgets(buf, sizeof(buf), f))
  	while (fgets(buf, sizeof(buf), f)) {
  		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) &&
  		    S_ISBLK(st_buf.st_mode) &&
  		    file_dev == st_buf.st_rdev) {
  			ret++;
  			break;
  		}
  #endif 	/* __GNU__ */
  	}
  	fclose(f);
  	return ret;
  }
  
  
  /*
   * ext2fs_check_mount_point() fills determines if the device is
   * mounted or otherwise busy, and fills in mount_flags with one or
   * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
   * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY.  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)
  {
  	struct stat	st_buf;
  	errcode_t	retval = 0;
  	int		fd;
  
  	if (is_swap_device(device)) {
  		*mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
  		strncpy(mtpt, "<swap>", mtlen);
  	} else {
  #ifdef HAVE_MNTENT_H
  		retval = check_mntent(device, mount_flags, mtpt, mtlen);
  #else
  #ifdef HAVE_GETMNTINFO
  		retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
  #else
  #ifdef __GNUC__
   #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
  #endif
  		*mount_flags = 0;
  #endif /* HAVE_GETMNTINFO */
  #endif /* HAVE_MNTENT_H */
  	}
  	if (retval)
  		return retval;
  
  #ifdef __linux__ /* This only works on Linux 2.6+ systems */
  	if ((stat(device, &st_buf) != 0) ||
  	    !S_ISBLK(st_buf.st_mode))
  		return 0;
  	fd = open(device, O_RDONLY | O_EXCL);
  	if (fd < 0) {
  		if (errno == EBUSY)
  			*mount_flags |= EXT2_MF_BUSY;
  	} else
  		close(fd);
  #endif
  
  	return 0;
  }
  
  /*
   * 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_BUSY)
  		printf("\t%s is apparently in use.\n", argv[1]);
  	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 /* DEBUG */
  