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fstatvfs(), fstatvfs64()

Get filesystem information, given a file descriptor


#include <sys/statvfs.h>

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

int fstatvfs64( int fildes,
                struct statvfs64 *buf );


The descriptor for a file that resides on the filesystem that you want to get information about.
A pointer to a buffer where the function can store information about the filesystem; see below.



Use the -l c option to qcc to link against this library. This library is usually included automatically.


The fstatvfs() function returns a “generic superblock” describing a filesystem; you can use it to get information about mounted filesystems. The fstatvfs64() function is a 64-bit version of fstatvfs().

The fildes argument is an open file descriptor, obtained from a successful call to open(), creat(), dup(), fcntl(), or pipe(), for a file that resides on that filesystem. The filesystem type is known to the operating system. Read, write, or execute permission for the named file isn't required.

The buf argument is a pointer to a statvfs or statvfs64 structure that's filled by the function. It contains at least:

unsigned long f_bsize
The preferred filesystem blocksize.
unsigned long f_frsize
The fundamental filesystem blocksize (if supported)
fsblkcnt_t f_blocks
The total number of blocks on the filesystem, in units of f_frsize.
fsblkcnt_t f_bfree
The total number of free blocks.
fsblkcnt_t f_bavail
The number of free blocks available to a nonsuperuser.
fsfilcnt_t f_files
The total number of file nodes (inodes).
fsfilcnt_t f_ffree
The total number of free file nodes.
fsfilcnt_t f_favail
The number of inodes available to a nonsuperuser.
unsigned long f_fsid
The filesystem ID (dev for now).
char f_basetype[16]
The type of the target filesystem, as a null-terminated string.
unsigned long f_flag
A bitmask of flags; the function can set these flags:
unsigned long f_namemax
The maximum filename length.


An error occurred (errno is set).


The fildes argument isn't an open file descriptor.
The buf argument points to an illegal address.
A signal was caught during execution.
An I/O error occurred while reading the filesystem.
One of the values to be returned can't be represented correctly in the structure pointed to by buf.


fstatvfs() is POSIX 1003.1 XSI; fstatvfs64() is Large-file support

Cancellation point No
Interrupt handler No
Signal handler Yes
Thread Yes


The values returned for f_files, f_ffree, and f_favail might not be valid for NFS-mounted filesystems.

See also:

chmod(), chown(), creat(), dup(), fcntl(), link(), mknod(), open(), pipe(), read(), statvfs(), statvfs64(), time(), unlink(), utime(), write()