@node unlock64, io
@findex unlock64
@subheading Syntax

@example
#include <io.h>

int unlock64(int fd, long long offset, long long length);
@end example

@subheading Description
Unlocks a region previously locked by @code{lock64}.

Arguments @var{offset} and @var{length} must be of type @code{long
long}, thus enabling you to unlock with offsets and lengths as large as
~@math{2^63} (FAT16 limits this to ~@math{2^31}; FAT32 limits this to
@math{2^32-2}).

@xref{lock64}.

@subheading Return Value
Zero if successful, nonzero if not.


@subheading Portability

@portability !ansi, !posix