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Name

statvfs, fstatvfs - get file system information

Synopsis

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

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

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

Description

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

path 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) */
u_long    f_blocks;    /* total # of blocks on file system
        in units of f_frsize */
u_long    f_bfree;    /* total # of free blocks */
u_long    f_bavail;    /* # of free blocks avail to
        non-super-user */
u_long    f_files;    /* total # of file nodes (inodes) */
u_long    f_ffree;    /* total # of free file nodes */
u_long    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 */

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

The following flags 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}*/

fstatvfs() 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.

Return Values

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

Errors

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

EACCES
Search permission is denied on a component of the path prefix.
EFAULT
path or buf points to an illegal address.
EINTR
A signal was caught during statvfs() execution.
EIO
An I/O error occurred while reading the file system.
ELOOP
Too many symbolic links were encountered in translating path.
EMULTIHOP
Components of path require hopping to multiple remote machines and file system type does not allow it.
ENAMETOOLONG
The length of a path component exceeds {NAME_MAX} characters, or the length of path exceeds {PATH_MAX} characters.
ENOENT
Either a component of the path prefix or the file referred to by path 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 of path is not a directory.

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

EBADF
fildes is not an open file descriptor.
EFAULT
buf points to an illegal address.
EINTR
A signal was caught during fstatvfs() execution.
EIO
An I/O error occurred while reading the file system.

See Also

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)

Bugs

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

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