int fsync(int fildes);
Declared, not implemented
IEEE Std 1003.1-2017
fsync() function shall request that all data for the open file descriptor named by fildes is to be transferred
to the storage device associated with the file described by fildes. The nature of the transfer is implementation-defined.
fsync() function shall not return until the system has completed that action or until an error is detected.
_POSIX_SYNCHRONIZED_IO is defined, the
fsync() function shall force all currently queued I/O operations associated with
the file indicated by file descriptor fildes to the synchronized I/O completion state. All I/O operations shall be completed
as defined for synchronized I/O file integrity completion.
Upon successful completion,
fsync() shall return
-1 shall be returned and
errno set to indicate the error. If the
fsync() function fails, outstanding I/O operations are not guaranteed to have been completed.
fsync() function shall fail if:
EBADF- The fildes argument is not a valid descriptor.
fsync()function was interrupted by a signal.
EINVAL- The fildes argument does not refer to a file on which this operation is possible.
EIO- An I/O error occurred while reading from or writing to the file system.
In the event that any of the queued I/O operations fail,
fsync() shall return the error conditions defined for