wintun: load wintun.dll from RCDATA resource

Signed-off-by: Simon Rozman <simon@rozman.si>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

tun/wintun/resource/zsyscall_windows.go

@@ -0,0 +1,112 @@
+// Code generated by 'go generate'; DO NOT EDIT.
+
+package resource
+
+import (
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var _ unsafe.Pointer
+
+// Do the interface allocations only once for common
+// Errno values.
+const (
+	errnoERROR_IO_PENDING = 997
+)
+
+var (
+	errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return nil
+	case errnoERROR_IO_PENDING:
+		return errERROR_IO_PENDING
+	}
+	// TODO: add more here, after collecting data on the common
+	// error values see on Windows. (perhaps when running
+	// all.bat?)
+	return e
+}
+
+var (
+	modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
+	modversion  = windows.NewLazySystemDLL("version.dll")
+
+	procFindResourceW  = modkernel32.NewProc("FindResourceW")
+	procSizeofResource = modkernel32.NewProc("SizeofResource")
+	procLoadResource   = modkernel32.NewProc("LoadResource")
+	procLockResource   = modkernel32.NewProc("LockResource")
+	procVerQueryValueW = modversion.NewProc("VerQueryValueW")
+)
+
+func findResource(module windows.Handle, name *uint16, resType *uint16) (resInfo windows.Handle, err error) {
+	r0, _, e1 := syscall.Syscall(procFindResourceW.Addr(), 3, uintptr(module), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(resType)))
+	resInfo = windows.Handle(r0)
+	if resInfo == 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func sizeofResource(module windows.Handle, resInfo windows.Handle) (size uint32, err error) {
+	r0, _, e1 := syscall.Syscall(procSizeofResource.Addr(), 2, uintptr(module), uintptr(resInfo), 0)
+	size = uint32(r0)
+	if size == 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func loadResource(module windows.Handle, resInfo windows.Handle) (resData windows.Handle, err error) {
+	r0, _, e1 := syscall.Syscall(procLoadResource.Addr(), 2, uintptr(module), uintptr(resInfo), 0)
+	resData = windows.Handle(r0)
+	if resData == 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func lockResource(resData windows.Handle) (addr uintptr, err error) {
+	r0, _, e1 := syscall.Syscall(procLockResource.Addr(), 1, uintptr(resData), 0, 0)
+	addr = uintptr(r0)
+	if addr == 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func verQueryValue(block *byte, section *uint16, value **byte, size *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procVerQueryValueW.Addr(), 4, uintptr(unsafe.Pointer(block)), uintptr(unsafe.Pointer(section)), uintptr(unsafe.Pointer(value)), uintptr(unsafe.Pointer(size)), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}