From 275ee76c20ed3075b14ab77f64b17b9d685a0bc5 Mon Sep 17 00:00:00 2001
From: John Howard <jhoward@microsoft.com>
Date: Thu, 23 Aug 2018 15:00:38 -0700
Subject: [PATCH] Add DetachVhd entrypoint

Signed-off-by: John Howard <jhoward@microsoft.com>
---
 vhd/vhd.go  | 26 ++++++++++++++++++++++++++
 vhd/zvhd.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/vhd/vhd.go b/vhd/vhd.go
index fb9add41..8fa90e91 100644
--- a/vhd/vhd.go
+++ b/vhd/vhd.go
@@ -7,6 +7,8 @@ import "syscall"
 //go:generate go run mksyscall_windows.go -output zvhd.go vhd.go
 
 //sys createVirtualDisk(virtualStorageType *virtualStorageType, path string, virtualDiskAccessMask uint32, securityDescriptor *uintptr, flags uint32, providerSpecificFlags uint32, parameters *createVirtualDiskParameters, o *syscall.Overlapped, handle *syscall.Handle) (err error) [failretval != 0] = VirtDisk.CreateVirtualDisk
+//sys openVirtualDisk(virtualStorageType *virtualStorageType, path string, virtualDiskAccessMask uint32, flags uint32, parameters *uintptr, handle *syscall.Handle) (err error) [failretval != 0] = VirtDisk.OpenVirtualDisk
+//sys detachVirtualDisk(handle syscall.Handle, flags uint32, providerSpecificFlags uint32) (err error) [failretval != 0] = VirtDisk.DetachVirtualDisk
 
 type virtualStorageType struct {
 	DeviceID uint32
@@ -80,3 +82,27 @@ func CreateVhdx(path string, maxSizeInGb, blockSizeInMb uint32) error {
 
 	return nil
 }
+
+// DetachVhd detaches a VHD attached at the given path.
+func DetachVhd(path string) error {
+	var (
+		defaultType virtualStorageType
+		handle      syscall.Handle
+	)
+
+	if err := openVirtualDisk(
+		&defaultType,
+		path,
+		virtualDiskAccessDETACH,
+		0,
+		nil,
+		&handle); err != nil {
+		return err
+	}
+	defer syscall.CloseHandle(handle)
+
+	if err := detachVirtualDisk(handle, 0, 0); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/vhd/zvhd.go b/vhd/zvhd.go
index c450955a..73f52596 100644
--- a/vhd/zvhd.go
+++ b/vhd/zvhd.go
@@ -40,6 +40,8 @@ var (
 	modVirtDisk = windows.NewLazySystemDLL("VirtDisk.dll")
 
 	procCreateVirtualDisk = modVirtDisk.NewProc("CreateVirtualDisk")
+	procOpenVirtualDisk   = modVirtDisk.NewProc("OpenVirtualDisk")
+	procDetachVirtualDisk = modVirtDisk.NewProc("DetachVirtualDisk")
 )
 
 func createVirtualDisk(virtualStorageType *virtualStorageType, path string, virtualDiskAccessMask uint32, securityDescriptor *uintptr, flags uint32, providerSpecificFlags uint32, parameters *createVirtualDiskParameters, o *syscall.Overlapped, handle *syscall.Handle) (err error) {
@@ -62,3 +64,36 @@ func _createVirtualDisk(virtualStorageType *virtualStorageType, path *uint16, vi
 	}
 	return
 }
+
+func openVirtualDisk(virtualStorageType *virtualStorageType, path string, virtualDiskAccessMask uint32, flags uint32, parameters *uintptr, handle *syscall.Handle) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return
+	}
+	return _openVirtualDisk(virtualStorageType, _p0, virtualDiskAccessMask, flags, parameters, handle)
+}
+
+func _openVirtualDisk(virtualStorageType *virtualStorageType, path *uint16, virtualDiskAccessMask uint32, flags uint32, parameters *uintptr, handle *syscall.Handle) (err error) {
+	r1, _, e1 := syscall.Syscall6(procOpenVirtualDisk.Addr(), 6, uintptr(unsafe.Pointer(virtualStorageType)), uintptr(unsafe.Pointer(path)), uintptr(virtualDiskAccessMask), uintptr(flags), uintptr(unsafe.Pointer(parameters)), uintptr(unsafe.Pointer(handle)))
+	if r1 != 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func detachVirtualDisk(handle syscall.Handle, flags uint32, providerSpecificFlags uint32) (err error) {
+	r1, _, e1 := syscall.Syscall(procDetachVirtualDisk.Addr(), 3, uintptr(handle), uintptr(flags), uintptr(providerSpecificFlags))
+	if r1 != 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}