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.Dd August 14, 2008
.Dt STATFS 2
.Os
.Sh NAME
.Nm statfs,
.Nm statfs64,
.Nm fstatfs,
.Nm fstatfs64
.Nd get file system statistics
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/mount.h>
.Ft int
.Fn statfs "const char *path" "struct statfs *buf"
.Ft int
.Fn fstatfs "int fd" "struct statfs *buf"
.Sh TRANSITIONAL SYNOPSIS (NOW DEPRECATED)
.Ft int
.br
.Fn statfs64 "const char *path" "struct statfs64 *buf" ;
.sp
.Ft int
.br
.Fn fstatfs64 "int fd" "struct statfs64 *buf" ;
.Sh DESCRIPTION
The
.Fn statfs
routine returns information about a mounted file system.
The
.Fa path
argument is the path name of any file or directory within the mounted file system.
The
.Fa buf
argument is a pointer to a 
.Fa statfs
structure.
When the macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is not defined (see
.Xr stat 2
for more information on this macro), the
.Fa statfs
structure is defined as:
.Bd -literal
typedef struct { int32_t val[2]; } fsid_t;

#define MFSNAMELEN      15 /* length of fs type name, not inc. nul */
#define MNAMELEN        90 /* length of buffer for returned name */

struct statfs { /* when _DARWIN_FEATURE_64_BIT_INODE is NOT defined */
    short   f_otype;	/* type of file system (reserved: zero) */
    short   f_oflags;	/* copy of mount flags (reserved: zero) */
    long    f_bsize;	/* fundamental file system block size */
    long    f_iosize;	/* optimal transfer block size */
    long    f_blocks;	/* total data blocks in file system */
    long    f_bfree;	/* free blocks in fs */
    long    f_bavail;	/* free blocks avail to non-superuser */
    long    f_files;	/* total file nodes in file system */
    long    f_ffree;	/* free file nodes in fs */
    fsid_t  f_fsid;	/* file system id */
    uid_t   f_owner;	/* user that mounted the file system */
    short   f_reserved1;	/* reserved for future use */
    short   f_type;	/* type of file system (reserved) */
    long    f_flags;	/* copy of mount flags (reserved) */
    long    f_reserved2[2];	/* reserved for future use */
    char    f_fstypename[MFSNAMELEN]; /* fs type name */
    char    f_mntonname[MNAMELEN];    /* directory on which mounted */
    char    f_mntfromname[MNAMELEN];  /* mounted file system */
    char    f_reserved3;	/* reserved for future use */
    long    f_reserved4[4];	/* reserved for future use */
};
.Ed
.Pp
However, when the macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is defined, the
.Fa statfs
structure is defined as:
.Bd -literal
#define MFSTYPENAMELEN  16 /* length of fs type name including null */
#define MAXPATHLEN      1024	
#define MNAMELEN        MAXPATHLEN

struct statfs { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */
    uint32_t    f_bsize;        /* fundamental file system block size */ 
    int32_t     f_iosize;       /* optimal transfer block size */ 
    uint64_t    f_blocks;       /* total data blocks in file system */ 
    uint64_t    f_bfree;        /* free blocks in fs */ 
    uint64_t    f_bavail;       /* free blocks avail to non-superuser */ 
    uint64_t    f_files;        /* total file nodes in file system */ 
    uint64_t    f_ffree;        /* free file nodes in fs */ 
    fsid_t      f_fsid;         /* file system id */ 
    uid_t       f_owner;        /* user that mounted the filesystem */ 
    uint32_t    f_type;         /* type of filesystem */ 
    uint32_t    f_flags;        /* copy of mount exported flags */ 
    uint32_t    f_fssubtype;    /* fs sub-type (flavor) */ 
    char        f_fstypename[MFSTYPENAMELEN];   /* fs type name */ 
    char        f_mntonname[MAXPATHLEN];        /* directory on which mounted */ 
    char        f_mntfromname[MAXPATHLEN];      /* mounted filesystem */ 
    uint32_t    f_reserved[8];  /* For future use */ 
};
.Ed
.Pp
Note that the
.Fa f_fstypename ,
.Fa f_mntonname ,
and
.Fa f_mntfromname
fields are also wider in this variant.
.Pp
Fields that are undefined for a particular file system are set to -1.
The
.Fn fstatfs
routine returns the same information about an open file referenced by descriptor
.Fa fd .
.Sh FLAGS
.Bl -tag -width MNT_UNKNOWNPERMISSIONS
These are some of the flags that may be present in the f_flags field. 
.It Dv MNT_RDONLY
A read-only filesystem
.It Dv MNT_SYNCHRONOUS
File system is written to synchronously
.It Dv MNT_NOEXEC
Can't exec from filesystem
.It Dv MNT_NOSUID
Setuid bits are not honored on this filesystem
.It Dv MNT_NODEV
Don't interpret special files
.It Dv MNT_UNION
Union with underlying filesysten
.It Dv MNT_ASYNC
File system written to asynchronously
.It Dv MNT_EXPORTED
File system is exported
.It Dv MNT_LOCAL
File system is stored locally
.It Dv MNT_QUOTA
Quotas are enabled on this file system
.It Dv MNT_ROOTFS
This file system is the root of the file system
.It Dv MNT_DOVOLFS
File system supports volfs
.It Dv MNT_DONTBROWSE
File system is not appropriate path to user data
.It Dv MNT_UNKNOWNPERMISSIONS
VFS will ignore ownership information on filesystem objects
.It Dv MNT_AUTOMOUNTED
File system was mounted by automounter
.It Dv MNT_JOURNALED
File system is journaled
.It Dv MNT_DEFWRITE
File system should defer writes
.It Dv MNT_MULTILABEL
MAC support for individual labels
.It Dv MNT_CPROTECT
File system supports per-file encrypted data protection
.El
.Sh CAVEATS
In Mac OS X versions before 10.4, f_iosize is 4096. On these older
systems, use MAXBSIZE instead.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, -1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn statfs
routine fails if one or more of the following are true:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix of
.Fa Path
is not a directory.
.It Bq Er ENAMETOOLONG
The length of a component of
.Fa path
exceeds 
.Dv {NAME_MAX}
characters, or the length of
.Fa path
exceeds 
.Dv {PATH_MAX}
characters.
.It Bq Er ENOENT
The file or directory referred to by
.Fa path
does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix of
.Fa path .
.It Bq Er ELOOP
Too many symbolic links were encountered in translating
.Fa path .
.It Bq Er EFAULT
.Fa Buf
or
.Fa path
points to an invalid address.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Pp
The
.Fn fstatfs
routine fails if one or more of the following are true:
.Bl -tag -width Er
.It Bq Er EBADF
.Fa fd
is not a valid open file descriptor.
.It Bq Er EFAULT
.Fa Buf
points to an invalid address.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Sh TRANSITIONAL DESCRIPTION (NOW DEPRECATED)
The
.Fa statfs64
and
.Fa fstatfs64
routines are equivalent to their corresponding non-64-suffixed routine,
when 64-bit inodes are in effect.
They were added before there was support for the symbol variants, and so are
now deprecated.
Instead of using these, set the
.Dv _DARWIN_USE_64_BIT_INODE
macro before including header files to force 64-bit inode support.
.Pp
The
.Fa statfs64
structure used by these deprecated routines is the same as the
.Fa statfs
structure when 64-bit inodes are in effect (see above).
.Sh HISTORY
The
.Fn statfs
function first appeared in 4.4BSD. The
.Fn statfs64
and 
.Fn fstatfs64
first appeared in Max OS X 10.5 (Leopard) and are now deprecated
in favor of the corresponding symbol variants.