*: Implement collector interface for registry perfdata (#1670)

internal/perfdata/v1/utf16.go

@@ -0,0 +1,49 @@
+package v1
+
+import (
+	"encoding/binary"
+	"io"
+
+	"golang.org/x/sys/windows"
+)
+
+// readUTF16StringAtPos Read an unterminated UTF16 string at a given position, specifying its length.
+func readUTF16StringAtPos(r io.ReadSeeker, absPos int64, length uint32) (string, error) {
+	value := make([]uint16, length/2)
+
+	_, err := r.Seek(absPos, io.SeekStart)
+	if err != nil {
+		return "", err
+	}
+
+	err = binary.Read(r, bo, value)
+	if err != nil {
+		return "", err
+	}
+
+	return windows.UTF16ToString(value), nil
+}
+
+// readUTF16String Reads a null-terminated UTF16 string at the current offset.
+func readUTF16String(r io.Reader) (string, error) {
+	var err error
+
+	b := make([]byte, 2)
+	out := make([]uint16, 0, 100)
+
+	for i := 0; err == nil; i += 2 {
+		_, err = r.Read(b)
+
+		if b[0] == 0 && b[1] == 0 {
+			break
+		}
+
+		out = append(out, bo.Uint16(b))
+	}
+
+	if err != nil {
+		return "", err
+	}
+
+	return windows.UTF16ToString(out), nil
+}