syscall: add Flock_t.Lock method
Fixes #7059
R=golang-codereviews, iant, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/53470043
diff --git a/src/pkg/syscall/flock.go b/src/pkg/syscall/flock.go
new file mode 100644
index 0000000..5e5f8b5
--- /dev/null
+++ b/src/pkg/syscall/flock.go
@@ -0,0 +1,22 @@
+// +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.
+
+package syscall
+
+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
+
+// Lock performs a fcntl syscall for F_GETLK, F_SETLK or F_SETLKW commands.
+func (lk *Flock_t) Lock(fd uintptr, cmd int) error {
+ _, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
+ if errno == 0 {
+ return nil
+ }
+ return errno
+}
