noble (3) statvfs.3.gz

NAME

       statvfs, fstatvfs - get filesystem statistics

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <sys/statvfs.h>

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

DESCRIPTION

       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.

RETURN VALUE

       On success, zero is returned.  On error, -1 is returned, and errno is set to indicate the error.

ERRORS

       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.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                                     │ Attribute     │ Value   │
       ├──────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │statvfs(), fstatvfs()                                                         │ Thread safety │ MT-Safe │
       └──────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

VERSIONS

       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.

NOTES

       The Linux kernel has system calls statfs(2) and fstatfs(2) to support this library call.

       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.

       Under  Linux,  f_favail  is  always  the  same  as f_ffree, and there's no way for a filesystem to report
       otherwise.  This is not an issue, since no filesystems with an inode root reservation exist.

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001.

       Before glibc 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  2.13,  the  statvfs()  function  will  use
       information from that field rather than scanning /proc/mounts.

SEE ALSO

       statfs(2)