Adding VHD library with simple function, updating mksyscall

Adds the basic structs for VHD function calls and includes one simple wrapper for VHDX creation.
This includes the updated version of mksyscall_windows.go, which previously assumed any api that doesn't end in "W" must not be unicode, and encodes the strings incorrectly. This hard-codes for unicode support and generates the syscalls from there.

vhd/mksyscall_windows.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Hard-coding unicode mode for VHD library.
+
 // +build ignore
 
 /*
@@ -556,8 +558,7 @@ func (f *Fn) HelperCallParamList() string {
 // IsUTF16 is true, if f is W (utf16) function. It is false
 // for all A (ascii) functions.
 func (f *Fn) IsUTF16() bool {
-	s := f.DLLFuncName()
-	return s[len(s)-1] == 'W'
+	return true
 }
 
 // StrconvFunc returns name of Go string to OS string function for f.
@@ -897,4 +898,4 @@ func {{.HelperName}}({{.HelperParamList}}) {{template "results" .}}{
 {{define "printtrace"}}{{if .PrintTrace}}	print("SYSCALL: {{.Name}}(", {{.ParamPrintList}}") (", {{.Rets.PrintList}}")\n")
 {{end}}{{end}}
 
-`
+`

vhd/vhd.go

@@ -0,0 +1,82 @@
+// +build windows
+
+package vhd
+
+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
+
+type virtualStorageType struct {
+	DeviceID uint32
+	VendorID [16]byte
+}
+
+const virtualDiskAccessNONE uint32 = 0
+const virtualDiskAccessATTACHRO uint32 = 65536
+const virtualDiskAccessATTACHRW uint32 = 131072
+const virtualDiskAccessDETACH uint32 = 262144
+const virtualDiskAccessGETINFO uint32 = 524288
+const virtualDiskAccessCREATE uint32 = 1048576
+const virtualDiskAccessMETAOPS uint32 = 2097152
+const virtualDiskAccessREAD uint32 = 851968
+const virtualDiskAccessALL uint32 = 4128768
+const virtualDiskAccessWRITABLE uint32 = 3276800
+
+const createVirtualDiskFlagNone uint32 = 0
+const createVirtualDiskFlagFullPhysicalAllocation uint32 = 1
+const createVirtualDiskFlagPreventWritesToSourceDisk uint32 = 2
+const createVirtualDiskFlagDoNotCopyMetadataFromParent uint32 = 4
+
+type version2 struct {
+	UniqueID                 [16]byte // GUID
+	MaximumSize              uint64
+	BlockSizeInBytes         uint32
+	SectorSizeInBytes        uint32
+	ParentPath               *uint16 // string
+	SourcePath               *uint16 // string
+	OpenFlags                uint32
+	ParentVirtualStorageType virtualStorageType
+	SourceVirtualStorageType virtualStorageType
+	ResiliencyGUID           [16]byte // GUID
+}
+
+type createVirtualDiskParameters struct {
+	Version  uint32 // Must always be set to 2
+	Version2 version2
+}
+
+// CreateVhdx will create a simple vhdx file at the given path using default values.
+func CreateVhdx(path string, maxSizeInGb, blockSizeInMb uint32) error {
+	var defaultType virtualStorageType
+
+	parameters := createVirtualDiskParameters{
+		Version: 2,
+		Version2: version2{
+			MaximumSize:      uint64(maxSizeInGb) * 1024 * 1024 * 1024,
+			BlockSizeInBytes: blockSizeInMb * 1024 * 1024,
+		},
+	}
+
+	var handle syscall.Handle
+
+	if err := createVirtualDisk(
+		&defaultType,
+		path,
+		virtualDiskAccessNONE,
+		nil,
+		createVirtualDiskFlagNone,
+		0,
+		&parameters,
+		nil,
+		&handle); err != nil {
+		return err
+	}
+
+	if err := syscall.CloseHandle(handle); err != nil {
+		return err
+	}
+
+	return nil
+}

vhd/zvhd.go

@@ -0,0 +1,64 @@
+// MACHINE GENERATED BY 'go generate' COMMAND; DO NOT EDIT
+
+package vhd
+
+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 (
+	modVirtDisk = windows.NewLazySystemDLL("VirtDisk.dll")
+
+	procCreateVirtualDisk = modVirtDisk.NewProc("CreateVirtualDisk")
+)
+
+func createVirtualDisk(virtualStorageType *virtualStorageType, path string, virtualDiskAccessMask uint32, securityDescriptor *uintptr, flags uint32, providerSpecificFlags uint32, parameters *createVirtualDiskParameters, o *syscall.Overlapped, handle *syscall.Handle) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return
+	}
+	return _createVirtualDisk(virtualStorageType, _p0, virtualDiskAccessMask, securityDescriptor, flags, providerSpecificFlags, parameters, o, handle)
+}
+
+func _createVirtualDisk(virtualStorageType *virtualStorageType, path *uint16, virtualDiskAccessMask uint32, securityDescriptor *uintptr, flags uint32, providerSpecificFlags uint32, parameters *createVirtualDiskParameters, o *syscall.Overlapped, handle *syscall.Handle) (err error) {
+	r1, _, e1 := syscall.Syscall9(procCreateVirtualDisk.Addr(), 9, uintptr(unsafe.Pointer(virtualStorageType)), uintptr(unsafe.Pointer(path)), uintptr(virtualDiskAccessMask), uintptr(unsafe.Pointer(securityDescriptor)), uintptr(flags), uintptr(providerSpecificFlags), uintptr(unsafe.Pointer(parameters)), uintptr(unsafe.Pointer(o)), uintptr(unsafe.Pointer(handle)))
+	if r1 != 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}