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-super-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-super-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

One of the values to be returned cannot be represented correctly in the structure pointed to by buf.

The statvfs() function will fail if:

EACCES

Search permission is denied on a component of the path prefix.

EFAULT

The path or buf argument points to an illegal address.

EINTR

A signal was caught during the execution of the statvfs() function.

EIO

An I/O error occurred while reading the file system.

ELOOP

Too many symbolic links were encountered in translating path.

ENAMETOOLONG

The length of a path component exceeds NAME_MAX characters, or the length of path The exceeds PATH_MAX characters.

ENOENT

Either a component of the path prefix or the file referred to by path does not exist.

ENOLINK

The path argument points to a remote machine and the link to that machine is no longer active.

ENOTDIR

A component of the path prefix of path is not a directory.

The fstatvfs() function will fail if:

EBADF

The fildes argument is not an open file descriptor.

EFAULT

The buf argument points to an illegal address.

EINTR

A signal was caught during the execution of the fstatvfs() function.

EIO

An I/O error occurred while reading the file system.

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

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), lf64(5)

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