fstatvfs(2)
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
The statvfs() function returns a "generic superblock"
describing a file system; it can be used to acquire informa-
tion 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 follow-
ing 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.
RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is
returned and errno is set to indicate the error.
ERRORS
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 translat-
ing path.
ENAMETOOLONG
The length of a path component exceeds NAME_MAX char-
acters, 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 direc-
tory.
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.
USAGE
The statvfs() and fstatvfs() functions have transitional
interfaces for 64-bit file offsets. See lf64(5).
When a UFS file system is mounted with logging enabled, file
system transactions that free blocks from files might not
actually add those freed blocks to the file system's free
list until some unspecified time in the future. In particu-
lar, the value of the f_bfree, f_bavail, f_ffree, and
f_favail members of the statvfs structure returned by these
calls might not reflect blocks recently freed on the under-
lying file system. This behavior improves file system per-
formance but does not conform to the POSIX, Single UNIX
Specification, SPARC Conformance Definition, System V Appli-
cation Binary Interface, System V Interface Definition, and
X/Open Portability Guide Standards, which require that freed
space be available immediately. To enable standards confor-
mance regarding file deletions or to address the problem of
not being able to grow files on a relatively full UFS file
system even after files have been deleted, disable UFS log-
ging (see mount_ufs(1M).
SEE ALSO
mount_ufs(1M), 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)
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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