getmountid(2)

NAME
     getmountid - get filesystem mount identifier

SYNOPSIS
     #include <sys/mount.h>

     int getmountid (const char *path, mountid_t *buf);

DESCRIPTION
     getmountid returns an identifier for the filesystem containing the file
     named by path.  Read, write, or execute permission for the named file is
     not required, but all directories listed in the path name leading to the
     file must be searchable.  buf is a pointer to a mountid structure that is
     filled by the system call.

     The identifier returned is guaranteed to be unique for the mounted
     filesystem within the running system, except for autofs's lofs
     filesystems. The identifier is not guaranteed to be unique across
     systems, and it is not guaranteed to persist across reboots or even
     across mounts of the given filesystem. The identifier returned by lofs
     filesystems is that of the mounted filesystem that lofs is providing
     access to via a loopback mount. Therefore, for lofs filesystems the
     combination of getmountid and lstat's st_rdev must be used to identify
     uniqueness.

     getmountid fails if one or more of the following are true:

     EACCES         Search permission is denied on a component of the path
                    prefix.

     EFAULT         path or buf points outside the process's allocated address
                    space.

     EINTR          A signal was caught during getmountid execution.

     EIO            An I/O error occurred while reading the file system.

     ELOOP          Too many symbolic links were encountered in translating
                    path.

     ENAMETOOLONG   The length of a path component exceeds {NAME_MAX}
                    characters, or the length of path exceeds {PATH_MAX}
                    characters.

     ENOENT         Either a component of the path prefix or the file referred
                    to by path does not exist.

     ENOLINK        path points to a remote machine and the link to that
                    machine is no longer active.
     ENOTDIR        A component of the path prefix of path is not a directory.

DIAGNOSTICS
     Upon successful completion a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate the error.

SEE ALSO
     statvfs(2)