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.\"	@(#)statfs.2	8.3 (Berkeley) 2/11/94
.\"
.Dd $Mdocdate: July 20 2013 $
.Dt STATFS 2
.Os
.Sh NAME
.Nm statfs ,
.Nm fstatfs
.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 DESCRIPTION
.Fn statfs
returns information about a mounted file system.
.Fa path
is the path name of any file within the mounted file system.
.Fa buf
is a pointer to a
.Nm statfs
structure defined as follows:
.Bd -literal
typedef struct { int32_t val[2]; } fsid_t;

#define MFSNAMELEN   16 /* length of fs type name, including nul */
#define MNAMELEN     90	/* length of buffer for returned name */

struct statfs {
   u_int32_t       f_flags;        /* copy of mount flags */
   u_int32_t       f_bsize;        /* file system block size */
   u_int32_t       f_iosize;       /* optimal transfer block size */

                                   /* unit is f_bsize */
   u_int64_t       f_blocks;       /* total data blocks in file system */
   u_int64_t       f_bfree;        /* free blocks in fs */
   int64_t         f_bavail;       /* free blocks avail to non-superuser */

   u_int64_t       f_files;        /* total file nodes in file system */
   u_int64_t       f_ffree;        /* free file nodes in fs */
   int64_t         f_favail;       /* free file nodes avail to non-root */

   u_int64_t       f_syncwrites;   /* count of sync writes since mount */
   u_int64_t       f_syncreads;    /* count of sync reads since mount */
   u_int64_t       f_asyncwrites;  /* count of async writes since mount */
   u_int64_t       f_asyncreads;   /* count of async reads since mount */

   fsid_t          f_fsid;         /* file system id */
   u_int32_t       f_namemax;      /* maximum filename length */
   uid_t           f_owner;        /* user that mounted the file system */
   u_int64_t       f_ctime;        /* last mount [-u] time */

   char f_fstypename[MFSNAMELEN];  /* fs type name */
   char f_mntonname[MNAMELEN];     /* directory on which mounted */
   char f_mntfromname[MNAMELEN];   /* mounted file system */
   char f_mntfromspec[MNAMELEN];   /* special for mount request */
   union mount_info mount_info;    /* per-filesystem mount options */
};
.Ed
.Pp
.Fn fstatfs
returns the same information about an open file referenced by descriptor
.Fa fd .
.Pp
Note that
.Fa f_fsid
will be empty unless the user is the superuser.
.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
.Fn statfs
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 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
.Fn fstatfs
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 SEE ALSO
.Xr df 1 ,
.Xr getfsstat 2 ,
.Xr mount 2 ,
.Xr stat 2
.Sh HISTORY
The
.Fn statfs
function first appeared in
.Bx 4.4 .