freebsd-skq/lib/libc/sys/getfsstat.2

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.\"	@(#)getfsstat.2	8.1 (Berkeley) 6/9/93
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.Dd June 9, 1993
.Dt GETFSSTAT 2
.Os
.Sh NAME
.Nm getfsstat
.Nd get list of all mounted filesystems
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/ucred.h>
.Fd #include <sys/mount.h>
.Ft int
.Fn getfsstat "struct statfs *buf" "long bufsize" "int flags"
.Sh DESCRIPTION
.Fn Getfsstat
returns information about all mounted filesystems.
.Fa Buf
is a pointer to
.Xr statfs
structures defined as follows:
.Bd -literal
typedef struct fsid { int32_t val[2]; } fsid_t;	/* file system id type */

/*
 * file system statistics
 */

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

struct statfs {
    long    f_spare2;		/* placeholder */
    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 filesystem */
    int     f_type;		/* type of filesystem (see below) */
    int     f_flags;		/* copy of mount flags */
    long    f_spare[2];		/* spare for later */
    char    f_fstypename[MFSNAMELEN];/* fs type name */
    char    f_mntonname[MNAMELEN];/* directory on which mounted */
    char    f_mntfromname[MNAMELEN];/* mounted filesystem */
};

/*
 * File system types.
 */
#define	MOUNT_NONE	0
#define	MOUNT_UFS	1	/* Fast Filesystem */
#define	MOUNT_NFS	2	/* Sun-compatible Network Filesystem */
#define	MOUNT_MFS	3	/* Memory-based Filesystem */
#define	MOUNT_MSDOS	4	/* MS/DOS Filesystem */
#define	MOUNT_LFS	5	/* Log-based Filesystem */
#define	MOUNT_LOFS	6	/* Loopback Filesystem */
#define	MOUNT_FDESC	7	/* File Descriptor Filesystem */
#define	MOUNT_PORTAL	8	/* Portal Filesystem */
#define MOUNT_NULL	9	/* Minimal Filesystem Layer */
#define MOUNT_UMAP	10	/* User/Group Identifier Remapping Filesystem */
#define MOUNT_KERNFS	11	/* Kernel Information Filesystem */
#define MOUNT_PROCFS	12	/* /proc Filesystem */
#define MOUNT_AFS	13	/* Andrew Filesystem */
#define MOUNT_CD9660	14	/* ISO9660 (aka CDROM) Filesystem */
#define MOUNT_UNION	15	/* Union (translucent) Filesystem */
#define MOUNT_DEVFS	16	/* existing device Filesystem */
#define	MOUNT_EXT2FS	17	/* Linux EXT2FS */
#define MOUNT_TFS	18	/* Netcon Novell filesystem */
#define	MOUNT_MAXTYPE	18
.Ed
.Pp
Fields that are undefined for a particular filesystem are set to -1.
The buffer is filled with an array of
.Fa fsstat
structures, one for each mounted filesystem
up to the size specified by
.Fa bufsize .
.Pp
If
.Fa buf
is given as NULL,
.Fn getfsstat
returns just the number of mounted filesystems.
.Pp
Normally
.Fa flags
should be specified as
.Dv MNT_WAIT .
If
.Fa flags
is set to
.Dv MNT_NOWAIT ,
.Fn getfsstat
will return the information it has available without requesting
an update from each filesystem.
Thus, some of the information will be out of date, but
.Fn getfsstat
will not block waiting for information from a filesystem that is
unable to respond.
.Sh RETURN VALUES
Upon successful completion, the number of 
.Fa fsstat
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 EFAULT
.Fa Buf
points to an invalid address.
.It EIO
An
.Tn I/O
error occurred while reading from or writing to the filesystem.
.El
.Sh SEE ALSO
.Xr statfs 2 ,
.Xr fstab 5 ,
.Xr mount 8
.Sh HISTORY
The
.Fn getfsstat
function first appeared in
.Bx 4.4 .