MOUNT(2)

NAME
mount - mount file system

SYNOPSIS
#include <sys/mount.h>

int mount(type, dir, M_NEWTYPE|flags, data)
char *type;
char *dir;
int flags;
caddr_t data;

DESCRIPTION
mount() attaches a file system to a directory. After a successful return, references to directory dir will refer to the root directory on the newly mounted file system. dir is a pointer to a null-terminated string containing a path name. dir must exist already, and must be a directory. Its old contents are inaccessible while the file system is mounted.

mount() may be invoked only by the super-user.

The flags argument is constructed by the logical OR of the following bits (defined in <sys/mount.h>):

    M_RDONLY
        mount filesystem read-only.

    M_NOSUID
        ignore set-uid bit on execution.

    M_NEWTYPE
        this flag must always be set.

    M_GRPID
        use BSD file-creation semantics (see open(2)).

    M_REMOUNT
        change options on an existing mount.

    M_NOSUB
        disallow mounts beneath this filesystem.

Physically write-protected and magnetic tape file systems must be mounted read-only or errors will occur when access times are updated, whether or not any explicit write is attempted.

The type string indicates the type of the filesystem. data is a pointer to a structure which contains the type specific arguments to mount. Below is a list of the filesystem types supported and the type specific arguments to each:

"4.3"
    struct ufs_args {
    	char	*fspec;	/* Block special file to mount */
    };

"nfs"
    #include	<nfs/nfs.h>
    #include	<netinet/in.h>
    struct nfs_args {
    	struct sockaddr_in  *addr; /* file server address */
    	fhandle_t	*fh;	/* File handle to be mounted */
    	int	flags;		/* flags */
    	int	wsize;		/* write size in bytes */
    	int	rsize;		/* read size in bytes */
    	int	timeo;		/* initial timeout in .1 secs */
    	int	retrans;	/* times to retry send */
    	char	*hostname;	/* server's hostname */
    	int	acregmin;	/* attr cache file min secs */
    	int	acregmax;	/* attr cache file max secs */
    	int	acdirmin;	/* attr cache dir min secs */
    	int	acdirmax;	/* attr cache dir max secs */
    	char	*netname;	/* server's netname */
    };

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

ERRORS
mount() fails when one of the following occurs:

EPERM
    The caller is not the super-user.

ENODEV
    The file system type specified by type is not valid or is not configured into the system.

ENAMETOOLONG
    The length of a component of the path name of dir exceeds 255 characters, or the length of the entire path name of dir exceeds 1023 characters.

ENOENT
    A component of dir does not exist.

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

ENOTDIR
    The file named by dir is not a directory.

EBUSY
    Another process currently holds a reference to dir.

EFAULT
    dir points outside the process's allocated address space.

ELOOP
    Too many symbolic links were encountered in translating the path name of dir.

For a 4.2 file system, mount() fails when one of the following occurs:

ENOTBLK
    fspec is not a block device.

ENXIO
    The major device number of fspec is out of range (this indicates no device driver exists for the associated hardware).

EMFILE
    No space remains in the mount table.

EINVAL
    The super block for the file system had a bad magic number or an out of range block size.

ENOMEM
    Not enough memory was available to read the cylinder group information for the file system.

ENOTDIR
    A component of the path prefix of fspec is not a directory.

ENAMETOOLONG
    The length of a component of the path name of fspec exceeds 255 characters, or the length of the entire path name of fspec exceeds 1023 characters.

ENOENT
    A component of fspec does not exist.

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

EFAULT
    fspec points outside the process's allocated address space.

ELOOP
    Too many symbolic links were encountered in translating the path name of fspec.

EIO An I/O error occurred while reading from or writing to the file system.

SEE ALSO
unmount(2), open(2), mount(8)

BUGS
Some of the error codes need translation to more obvious messages.