.\"	$NetBSD: getfsstat.2,v 1.6 1995/06/29 11:40:44 cgd Exp $
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.\"	@(#)getfsstat.2	8.1 (Berkeley) 6/9/93
.\"
.Dd Oct 28, 2008
.Dt GETFSSTAT 2
.Os
.Sh NAME
.Nm getfsstat
.Nd get list of all mounted file systems
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/ucred.h>
.Fd #include <sys/mount.h>
.Ft int
.Fn getfsstat "struct statfs *buf" "int bufsize" "int flags"
.Sh TRANSITIIONAL SYNOPSIS (NOW DEPRECATED)
.Ft int
.br
.Fn getfsstat64 "struct statfs64 *buf" "int bufsize" "int flags" ;
.Sh DESCRIPTION
The
.Fn getfsstat
function returns information about all mounted file systems.
The
.Fa buf
argument is a pointer to an array of
.Fa statfs
structures (see 
.Xr statfs 2 ) .
As
.Xr statfs 2
indicates, the structure is defined differently depending on
whether the macro _DARWIN_FEATURE_64_BIT_INODE is defined (see
.Xr stat 2
for more information on this macro).
.Pp
Fields that are undefined for a particular file system are set to -1.
The buffer is filled with an array of
.Fa statfs
structures, one for each mounted file system
up to the size specified by
.Fa bufsize .
.Pp
If
.Fa buf
is given as NULL,
.Fn getfsstat
returns just the number of mounted file systems.
.Pp
If
.Fa flags
is set to
.Dv MNT_NOWAIT ,
.Fn getfsstat
will directly return the information retained in the kernel
to avoid delays caused by waiting for updated information from
a file system that is perhaps temporarily unable to respond.
Some of the information returned may be out of date, however; if
.Fa flags
is set to
.Dv MNT_WAIT
or
.Dv MNT_DWAIT
instead,
.Fn getfsstat
will request updated information from each mounted filesystem before
returning.
.Sh RETURN VALUES
Upon successful completion, the number of 
.Fa statfs
structures is returned.
Otherwise, -1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn getfsstat
fails if one or more of the following are true:
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa buf
argument 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
.Fn getfsstat64
routine is equivalent to the default
.Fn getfstat
(when
.Dv _DARWIN_FEATURE_64_BIT_INODE
is defined), so there is no longer any reason to use it (it will be removed
in the future).
.Sh SEE ALSO
.Xr stat 2 ,
.Xr statfs 2 ,
.Xr fstab 5 ,
.Xr mount 8
.Sh HISTORY
The
.Fn getfsstat
function first appeared in 4.4BSD.