unicode_string.go

package ntdll

import (
	"reflect"
	"unicode/utf16"
	"unsafe"
)

//go:generate -command mkcode go run mkcode.go --
//go:generate mkcode $GOFILE

/*
type:
typedef struct _UNICODE_STRING {
  USHORT Length;
  USHORT MaximumLength;
  PWSTR  Buffer;
} UNICODE_STRING, *PUNICODE_STRING;
*/

// String converts the UTF-16-encoded string stored in a UnicodeString
// to UTF-8 and returns that as a Go string.
func (u UnicodeString) String() string {
	var s []uint16
	hdr := (*reflect.SliceHeader)(unsafe.Pointer(&s))
	hdr.Data = uintptr(unsafe.Pointer(u.Buffer))
	hdr.Len = int(u.Length / 2)
	hdr.Cap = int(u.MaximumLength / 2)
	return string(utf16.Decode(s))
}

// NewUnicodeString converts its argument to UTF-16 and returns a
// pointer to a UnicodeString that can be used with various Windows
// Native API functions.
func NewUnicodeString(s string) *UnicodeString {
	buf := utf16.Encode([]rune(s))
	return &UnicodeString{
		Length:        uint16(2 * len(buf)),
		MaximumLength: uint16(2 * len(buf)),
		Buffer:        &buf[0],
	}
}

// NewEmptyUnicodeString initializes a UnicodeString for length UTF-16
// characters and returns it.
func NewEmptyUnicodeString(length int) *UnicodeString {
	buf := make([]uint16, length, length)
	return &UnicodeString{
		Length:        0,
		MaximumLength: uint16(2 * length),
		Buffer:        &buf[0],
	}
}

// NewUnicodeStringFromBuffer initializes a UnicodeString from a
// pointer and a length value as returned by many NTDLL API calls.
func NewUnicodeStringFromBuffer(buffer *uint16, length int) *UnicodeString {
	return &UnicodeString{
		Length:        uint16(length),
		MaximumLength: uint16(length),
		Buffer:        buffer,
	}
}