#include <sys/types.h>
#include <sys/statvfs.h> 

int statvfs(const char *restrict path, struct statvfs *restrict buf);

int fstatvfs(int fildes, struct statvfs *buf);

The statvfs() function returns a "generic superblock" describing a file system; it can be used to acquire information about mounted file systems. The buf argument is a pointer to a structure (described below) that is filled by the function.

The path argument should name a file that resides on that file system. The file system type is known to the operating system. Read, write, or execute permission for the named file is not required, but all directories listed in the path name leading to the file must be searchable.

The statvfs structure pointed to by buf includes the following members:

u_long f_bsize; /* preferred file system block size */
u_long f_frsize; /* fundamental filesystem block
 (size if supported) */
fsblkcnt_t f_blocks; /* total # of blocks on file system
 in units of f_frsize */
fsblkcnt_t f_bfree; /* total # of free blocks */
fsblkcnt_t f_bavail; /* # of free blocks avail to
 non-privileged user */
fsfilcnt_t f_files; /* total # of file nodes (inodes) */
fsfilcnt_t f_ffree; /* total # of free file nodes */
fsfilcnt_t f_favail; /* # of inodes avail to
 non-privileged user*/
u_long f_fsid; /* file system id (dev for now) */
char f_basetype[FSTYPSZ]; /* target fs type name, 
 null-terminated */
u_long f_flag; /* bit mask of flags */
u_long f_namemax; /* maximum file name length */
char f_fstr[32]; /* file system specific string */
u_long f_filler[16]; /* reserved for future expansion */

The f_basetype member contains a null-terminated FSType name of the mounted target.

The following values can be returned in the f_flag field:

ST_RDONLY 0x01 /* read-only file system */
ST_NOSUID 0x02 /* does not support setuid/setgid semantics */
ST_NOTRUNC 0x04 /* does not truncate file names longer than
 NAME_MAX */

The fstatvfs() function is similar to statvfs(), except that the file named by path in statvfs() is instead identified by an open file descriptor fildes obtained from a successful open(2), creat(2), dup(2), fcntl(2), or pipe(2) function call.

Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

The statvfs() and fstatvfs() functions will fail if:

EOVERFLOW

The statvfs() function will fail if:

EACCES

EFAULT

EINTR

EIO

ELOOP

ENAMETOOLONG

ENOENT

ENOLINK

ENOTDIR

The fstatvfs() function will fail if:

EBADF

EFAULT

EINTR

EIO

The statvfs() and fstatvfs() functions have transitional interfaces for 64-bit file offsets. See lf64(5).

See attributes(5) for descriptions of the following attributes:

chmod(2), chown(2), creat(2), dup(2), fcntl(2), link(2), mknod(2), open(2), pipe(2), read(2), time(2), unlink(2), utime(2), write(2), attributes(5), lf64(5), standards(5)

The values returned for f_files, f_ffree, and f_favail may not be valid for NFS mounted file systems.