vendor: adding in golang.org/x/sys/unix package

This commit adds in the golang.org/x/sys/unix package. This package
provides a low-level interface to unix syscalls. We will uses this
package instead of the built-in "syscall" package because the syscall
package is locked down (https://golang.org/pkg/syscall) and is not
exposing any new kernel functionality.

In fact, this is actually a patched version of the x/sys/unix package
pending review (first part: https://go-review.googlesource.com/c/37943).
The version included in this commit exposes all of the filesystem
encryption kernel interfaces to Go code.

Change-Id: Ic5f9c98b858ccb00db97502c9a60e9249aa8ba38

1 files changed, 24 insertions, 0 deletions

diff --git a/vendor/golang.org/x/sys/unix/flock.go b/vendor/golang.org/x/sys/unix/flock.go
new file mode 100644
index 0000000..ce67a59
--- /dev/null
+++ b/vendor/golang.org/x/sys/unix/flock.go
@@ -0,0 +1,24 @@
+// +build linux darwin freebsd openbsd netbsd dragonfly
+
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd
+
+package unix
+
+import "unsafe"
+
+// fcntl64Syscall is usually SYS_FCNTL, but is overridden on 32-bit Linux
+// systems by flock_linux_32bit.go to be SYS_FCNTL64.
+var fcntl64Syscall uintptr = SYS_FCNTL
+
+// FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
+func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
+	_, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
+	if errno == 0 {
+		return nil
+	}
+	return errno
+}