statfs(S)

statfs, fstatfs -- get file system information

Syntax

cc . . . -lc

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

int statfs (path, buf, len, fstyp)
char *path;
struct statfs *buf;
int len, fstyp;

int fstatfs (fildes, buf, len, fstyp)
int fildes;
struct statfs *buf;
int len, fstyp;

Description

statfs- get file system information

fstatfs- get file system information

The statfs system call returns a ``generic superblock'' describing a file system. It can be used to acquire information about mounted as well as unmounted file systems, and usage is slightly different in the two cases. In all cases, buf is a pointer to a structure (described below) which is filled by the system call, and len is the number of bytes of information which the system should return in the structure. len must be no greater than sizeof (struct statfs) and ordinarily it contains exactly that value; if it holds a smaller value, the system fills the structure with that number of bytes. (This allows future versions of the system to grow the structure without invalidating older binary programs.)

If the file system of interest is currently mounted, path should name a file which resides on that file system. In this case the file system type is known to the operating system and the fstyp argument must be zero. For an unmounted file system path must name the block special file containing it and fstyp must contain the (non-zero) file system type. In both cases read, write, or execute permission of the named file is not required, but all directories listed in the path name leading to the file must be searchable.

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

   short   f_fstyp;        /* File system type */
   long    f_bsize;        /* Block size */
   long    f_frsize;       /* Fragment size */
   long    f_blocks;       /* Total number of 512-byte blocks */
   long    f_bfree;        /* Count of free blocks */
   long    f_files;        /* Total number of file nodes */
   long    f_ffree;        /* Count of free file nodes */
   char    f_fname[6];     /* Volume name */
   char    f_fpack[6];     /* Pack name */

The fstatfs system call is similar, except that the file named by path in statfs is instead identified by an open file descriptor fildes obtained from a successful open(S), creat(S), dup(S), fcntl(S), or pipe(S) system call.

The statfs system call obsoletes ustat(S) and should be used in preference to it in new programs.

Return value

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

Diagnostics

The statfs and fstatfs system calls fails if one or more of the following is true:

[EACCES]: Search permission is denied for a component of the path prefix.
[EBADF]: fildes is not a valid open file descriptor.
[EFAULT]: buf or path points to an invalid address.
[EINVAL]: fstyp is an invalid file system type; path is not a block special file and fstyp is nonzero; len is negative or is greater than sizeof (struct statfs).
[EMULTIHOP]: Components of path require hopping to multiple remote machines.
[ENOENT]: The named file does not exist.
[ENOLINK]: path points to a remote machine, and the link to that machine is no longer active.
[ENOTDIR]: A component of the path prefix is not a directory.

Standards conformance