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.\" $FreeBSD: src/lib/libc/gen/statvfs.3,v 1.7 2003/06/08 10:01:51 charnier Exp $
.\"
.Dd July 13, 2002
.Dt STATVFS 3
.Os
.Sh NAME
.Nm statvfs ,
.Nm fstatvfs
.Nd retrieve file system information
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/statvfs.h
.Ft int
.Fn statvfs "const char * restrict path" "struct statvfs * restrict buf"
.Ft int
.Fn fstatvfs "int fd" "struct statvfs *buf"
.Sh DESCRIPTION
The
.Fn statvfs
and
.Fn fstatvfs
functions attempt to fill the structure pointed to by
.Fa buf
with file system
statistics, but portable applications must not depend on this.
Applications must pass a pathname or file descriptor which refers to a
file on the file system in which they are interested.
.Pp
The
.Vt statvfs
structure contains the following members:
.Bl -tag -offset indent -width ".Va f_namemax"
.It Va f_namemax
The maximum length in bytes of a file name on this file system.
Applications should use
.Xr pathconf 2
instead.
.It Va f_fsid
Not meaningful in this implementation.
.It Va f_frsize
The size in bytes of the minimum unit of allocation on this
file system.
(This corresponds to the
.Va f_bsize
member of
.Vt "struct statfs" . )
.It Va f_bsize
The preferred length of I/O requests for files on this file system.
(Corresponds to the
.Va f_iosize
member of
.Vt "struct statfs" . )
.It Va f_flag
Flags describing mount options for this file system; see below.
.El
.Pp
In addition, there are three members of type
.Vt fsfilcnt_t ,
which represent counts of file serial numbers
.Em ( i.e. ,
inodes); these are named
.Va f_files , f_favail ,
and
.Va f_ffree ,
and represent the number of file serial numbers which exist in total,
are available to unprivileged processes, and are available to
privileged processes, respectively.
Likewise, the members
.Va f_blocks , f_bavail ,
and
.Va f_bfree
(all of type
.Vt fsblkcnt_t )
represent the respective allocation-block counts.
.Pp
There are two flags defined for the
.Va f_flag
member:
.Bl -tag -offset indent -width ".Dv ST_NOSUID"
.It Dv ST_RDONLY
The file system is mounted read-only.
.It Dv ST_NOSUID
The semantics of the
.Dv S_ISUID
and
.Dv S_ISGID
file mode bits
are not supported by, or are disabled on, this file system.
.El
.Sh IMPLEMENTATION NOTES
The
.Fn statvfs
and
.Fn fstatvfs
functions are implemented as wrappers around the
.Fn statfs
and
.Fn fstatfs
functions, respectively.
Not all the information provided by those functions is made available
through this interface.
.Sh RETURN VALUES
.Rv -std statvfs fstatvfs
.Sh ERRORS
The
.Fn statvfs
function 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
The
.Fn fstatvfs
functions 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 statfs 2
.Sh STANDARDS
The
.Fn statvfs
and
.Fn fstatvfs
functions conform to
.St -p1003.1-2001 .
As standardized, portable applications cannot depend on these functions
returning any valid information at all.
This implementation attempts to provide as much useful information as
is provided by the underlying file system, subject to the limitations
of the specified data types.
.Sh AUTHORS
The
.Fn statvfs
and
.Fn fstatvfs
manual page was originally written by
.An Garrett Wollman Aq wollman@FreeBSD.org .