@node _dos_unlk64, dos
@findex _dos_unlk64
@subheading Syntax

@example
#include <io.h>

int _dos_unlk64(int fd, long long offset, long long length);
@end example

@subheading Description

Removes an advisory lock to the specified region of the file.

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{_dos_lk64}.

@subheading Return Value

Zero if the lock was removed, nonzero otherwise.

@subheading Portability

@portability !ansi, !posix