GETFSSTAT(2)

NAME
getfsstat - get list of all mounted file systems

SYNOPSIS
#include <sys/param.h>
#include <sys/ucred.h>
#include <sys/mount.h>
int
getfsstat(struct statfs *buf, long bufsize, int flags);

DESCRIPTION
Getfsstat() returns information about all mounted file systems. Buf is a pointer to an array of statfs structures defined as follows:

    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 {
        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 (super-user only) */
        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 */
    };

Fields that are undefined for a particular file system are set to -1. The buffer is filled with an array of statfs structures, one for each mounted file system up to the size specified by bufsize.

If buf is given as NULL, getfsstat() returns just the number of mounted file systems.

Normally flags should be specified as MNT_WAIT. If flags is set to MNT_NOWAIT, getfsstat() will return the information it has available without requesting an update from each file system. Thus, some of the information will be out of date, but getfsstat() will not block waiting for information from a file system that is unable to respond.

RETURN VALUES
Upon successful completion, the number of statfs structures is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error.

ERRORS
Getfsstat() fails if one or more of the following are true:

[EFAULT]
    Buf points to an invalid address.

[EIO]
    An I/O error occurred while reading from or writing to the file system.

SEE ALSO
statfs(2), fstab(5), mount(8)

HISTORY
The getfsstat() function first appeared in 4.4BSD.