x/sys/windows: Add GetComputerNameEx

Provides access to the GetComputerNameEx syscall.

This mirrors the change golang.org/cl/5852 in the standard library, but
provides public access to all name types provided by windows.

Change-Id: I5fbad5abe721de70e9d2b5dda2fafb7a9c419220
Reviewed-on: https://go-review.googlesource.com/6320Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

windows/syscall_windows.go

@@ -104,6 +104,7 @@ func NewCallbackCDecl(fn interface{}) uintptr
 //sys	DeleteFile(path *uint16) (err error) = DeleteFileW
 //sys	MoveFile(from *uint16, to *uint16) (err error) = MoveFileW
 //sys	GetComputerName(buf *uint16, n *uint32) (err error) = GetComputerNameW
+//sys	GetComputerNameEx(nametype uint32, buf *uint16, n *uint32) (err error) = GetComputerNameExW
 //sys	SetEndOfFile(handle Handle) (err error)
 //sys	GetSystemTimeAsFileTime(time *Filetime)
 //sys	GetTimeZoneInformation(tzi *Timezoneinformation) (rc uint32, err error) [failretval==0xffffffff]

windows/zsyscall_windows.go

-// go build mksyscall_windows.go && ./mksyscall_windows syscall_windows.go security_windows.go
-// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+// MACHINE GENERATED BY 'go generate' COMMAND; DO NOT EDIT
 
 package windows
 
 import "unsafe"
 import "syscall"
 
+var _ unsafe.Pointer
+
 var (
 	modkernel32 = syscall.NewLazyDLL("kernel32.dll")
 	modadvapi32 = syscall.NewLazyDLL("advapi32.dll")
@@ -43,6 +44,7 @@ var (
 	procDeleteFileW                        = modkernel32.NewProc("DeleteFileW")
 	procMoveFileW                          = modkernel32.NewProc("MoveFileW")
 	procGetComputerNameW                   = modkernel32.NewProc("GetComputerNameW")
+	procGetComputerNameExW                 = modkernel32.NewProc("GetComputerNameExW")
 	procSetEndOfFile                       = modkernel32.NewProc("SetEndOfFile")
 	procGetSystemTimeAsFileTime            = modkernel32.NewProc("GetSystemTimeAsFileTime")
 	procGetTimeZoneInformation             = modkernel32.NewProc("GetTimeZoneInformation")
@@ -479,6 +481,18 @@ func GetComputerName(buf *uint16, n *uint32) (err error) {
 	return
 }
 
+func GetComputerNameEx(nametype uint32, buf *uint16, n *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall(procGetComputerNameExW.Addr(), 3, uintptr(nametype), uintptr(unsafe.Pointer(buf)), uintptr(unsafe.Pointer(n)))
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
 func SetEndOfFile(handle Handle) (err error) {
 	r1, _, e1 := syscall.Syscall(procSetEndOfFile.Addr(), 1, uintptr(handle), 0, 0)
 	if r1 == 0 {

windows/ztypes_windows.go

@@ -1108,3 +1108,15 @@ const (
 	IO_REPARSE_TAG_SYMLINK           = 0xA000000C
 	SYMBOLIC_LINK_FLAG_DIRECTORY     = 0x1
 )
+
+const (
+	ComputerNameNetBIOS                   = 0
+	ComputerNameDnsHostname               = 1
+	ComputerNameDnsDomain                 = 2
+	ComputerNameDnsFullyQualified         = 3
+	ComputerNamePhysicalNetBIOS           = 4
+	ComputerNamePhysicalDnsHostname       = 5
+	ComputerNamePhysicalDnsDomain         = 6
+	ComputerNamePhysicalDnsFullyQualified = 7
+	ComputerNameMax                       = 8
+)