#include <sys/vfs.h> int fstatfs(int fd, struct statfs *buf);
fstatfs returns information about a mounted file system. fd is the open file descriptor of any file within the mounted filesystem. buf is a pointer to a statfs structure defined as follows:
long f_type; /* type of filesystem (see below) */
long f_bsize; /* optimal transfer block size */
long f_blocks; /* total data blocks in file system */
long f_bfree; /* free blocks in fs */
long f_bavail; /* free blocks avail to non-superuser */
long f_files; /* total file nodes in file system */
long f_ffree; /* free file nodes in fs */
fsid_t f_fsid; /* file system id */
long f_namelen; /* maximum length of filenames */
long f_spare; /* spare for later */
Fields that are undefined for a particular file system are set to 0.
fd is not a valid open file descriptor.
buf points to an invalid address.
An I/O error occurred while reading from or writing to the file system.
The filesystem fd is open on does not support statfs.