STATFS(2)

NAME
statfs, fstatfs - get file system statistics

SYNOPSIS
#include <sys/param.h>
#include <sys/mount.h>
int
statfs(const char *path, struct statfs *buf);
int
fstatfs(int fd, struct statfs *buf);

DESCRIPTION
statfs() returns information about a mounted file system. path is the path name of any file within the mounted file system. buf is a pointer to a statfs structure defined as follows:

    typedef struct { int32_t val[2]; } fsid_t;
    #define MFSNAMELEN   16 /* length of fs type name, including nul */
    #define MNAMELEN     32	/* length of buffer for returned name */
    struct statfs {
        short   f_type;	/* type of file system (unused; zero) */
        u_short f_flags;	/* copy of mount flags */
        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 file system */
        long    f_spare[4];	/* spare for later */
        char    f_fstypename[MFSNAMELEN]; /* fs type name */
        char    f_mntonname[MNAMELEN];    /* directory on which mounted */
        char    f_mntfromname[MNAMELEN];  /* mounted file system */
    };

The flags that may be returned include:

MNT_RDONLY
    The filesystem is mounted read-only; Even the super-user may not write on it.

MNT_NOEXEC
    Files may not be executed from the filesystem.

MNT_NOSUID
    Setuid and setgid bits on files are not honored when they are executed.

MNT_NODEV
    Special files in the filesystem may not be opened.

MNT_SYNCHRONOUS
    All I/O to the filesystem is done synchronously.

MNT_ASYNCHRONOUS
    No filesystem I/O is done synchronously.

MNT_LOCAL
    The filesystem resides locally.

MNT_QUOTA
    The filesystem has quotas enabled on it.

MNT_ROOTFS
    Identifies the root filesystem.

MNT_EXRDONLY
    The filesystem is exported read-only.

MNT_EXPORTED
    The filesystem is exported for both reading and writing.

MNT_DEFEXPORTED
    The filesystem is exported for both reading and writing to any Internet host.

MNT_EXPORTANON
    The filesystem maps all remote accesses to the anonymous user.

MNT_EXKERB
    The filesystem is exported with Kerberos uid mapping.

Fields that are undefined for a particular file system are set to -1. fstatfs() returns the same information about an open file referenced by descriptor fd.

RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error.

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

[ENOTDIR]
    A component of the path prefix of path is not a directory.

[ENAMETOOLONG]
    The length of a component of path exceeds {NAME_MAX} characters, or the length of path exceeds {PATH_MAX} characters.

[ENOENT]
    The file referred to by path does not exist.

[EACCES]
    Search permission is denied for a component of the path prefix of path.

[ELOOP]
    Too many symbolic links were encountered in translating path.

[EFAULT]
    buf or path points to an invalid address.

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

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

[EBADF]
    fd is not a valid open file descriptor.

[EFAULT]
    buf points to an invalid address.

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

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