statvfs, fstatvfs - get filesystem statistics
#include <sys/statvfs.h>
int statvfs(const char *path, struct statvfs
*buf);
int fstatvfs(int fd, struct statvfs *buf);
The function
statvfs() returns information about a mounted filesystem.
path is the pathname of any file within the mounted filesystem.
buf is a pointer to a
statvfs structure defined approximately as
follows:
struct statvfs {
unsigned long f_bsize; /* Filesystem block size */
unsigned long f_frsize; /* Fragment size */
fsblkcnt_t f_blocks; /* Size of fs in f_frsize units */
fsblkcnt_t f_bfree; /* Number of free blocks */
fsblkcnt_t f_bavail; /* Number of free blocks for
unprivileged users */
fsfilcnt_t f_files; /* Number of inodes */
fsfilcnt_t f_ffree; /* Number of free inodes */
fsfilcnt_t f_favail; /* Number of free inodes for
unprivileged users */
unsigned long f_fsid; /* Filesystem ID */
unsigned long f_flag; /* Mount flags */
unsigned long f_namemax; /* Maximum filename length */
};
Here the types
fsblkcnt_t and
fsfilcnt_t are defined in
<sys/types.h>. Both used to be
unsigned long.
The field
f_flag is a bit mask indicating various options that were
employed when mounting this filesystem. It contains zero or more of the
following flags:
- ST_MANDLOCK
- Mandatory locking is permitted on the filesystem (see
fcntl(2)).
- ST_NOATIME
- Do not update access times; see mount(2).
- ST_NODEV
- Disallow access to device special files on this filesystem.
- ST_NODIRATIME
- Do not update directory access times; see mount(2).
- ST_NOEXEC
- Execution of programs is disallowed on this filesystem.
- ST_NOSUID
- The set-user-ID and set-group-ID bits are ignored by exec(3) for
executable files on this filesystem
- ST_RDONLY
- This filesystem is mounted read-only.
- ST_RELATIME
- Update atime relative to mtime/ctime; see mount(2).
- ST_SYNCHRONOUS
- Writes are synched to the filesystem immediately (see the description of
O_SYNC in open(2)).
It is unspecified whether all members of the returned struct have meaningful
values on all filesystems.
fstatvfs() returns the same information about an open file referenced by
descriptor
fd.
On success, zero is returned. On error, -1 is returned, and
errno is set
appropriately.
- EACCES
- (statvfs()) Search permission is denied for a component of the path
prefix of path. (See also path_resolution(7).)
- EBADF
- (fstatvfs()) fd is not a valid open file descriptor.
- EFAULT
- Buf or path points to an invalid address.
- EINTR
- This call was interrupted by a signal; see signal(7).
- EIO
- An I/O error occurred while reading from the filesystem.
- ELOOP
- (statvfs()) Too many symbolic links were encountered in translating
path.
- ENAMETOOLONG
- (statvfs()) path is too long.
- ENOENT
- (statvfs()) The file referred to by path does not
exist.
- ENOMEM
- Insufficient kernel memory was available.
- ENOSYS
- The filesystem does not support this call.
- ENOTDIR
- (statvfs()) A component of the path prefix of path is not a
directory.
- EOVERFLOW
- Some values were too large to be represented in the returned struct.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
statvfs (), fstatvfs () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008.
Only the
ST_NOSUID and
ST_RDONLY flags of the
f_flag field
are specified in POSIX.1. To obtain definitions of the remaining flags, one
must define
_GNU_SOURCE.
The Linux kernel has system calls
statfs(2) and
fstatfs(2) to
support this library call.
In glibc versions before 2.13,
statvfs() populated the bits of the
f_flag field by scanning the mount options shown in
/proc/mounts. However, starting with Linux 2.6.36, the underlying
statfs(2) system call provides the necessary information via the
f_flags field, and since glibc version 2.13, the
statvfs()
function will use information from that field rather than scanning
/proc/mounts.
The glibc implementations of
pathconf(path, _PC_REC_XFER_ALIGN);
pathconf(path, _PC_ALLOC_SIZE_MIN);
pathconf(path, _PC_REC_MIN_XFER_SIZE);
respectively use the
f_frsize,
f_frsize, and
f_bsize fields
returned by a call to
statvfs() with the argument
path.
statfs(2)