TUN-528: Move cloudflared into a separate repo

vendor/zombiezen.com/go/capnproto2/internal/strquote/strquote.go

@@ -0,0 +1,52 @@
+// Package strquote provides a function for formatting a string as a
+// Cap'n Proto string literal.
+package strquote
+
+// Append appends a Cap'n Proto string literal of s to buf.
+func Append(buf []byte, s []byte) []byte {
+	buf = append(buf, '"')
+	last := 0
+	for i, b := range s {
+		if !needsEscape(b) {
+			continue
+		}
+		buf = append(buf, s[last:i]...)
+		switch b {
+		case '\a':
+			buf = append(buf, '\\', 'a')
+		case '\b':
+			buf = append(buf, '\\', 'b')
+		case '\f':
+			buf = append(buf, '\\', 'f')
+		case '\n':
+			buf = append(buf, '\\', 'n')
+		case '\r':
+			buf = append(buf, '\\', 'r')
+		case '\t':
+			buf = append(buf, '\\', 't')
+		case '\v':
+			buf = append(buf, '\\', 'v')
+		case '\'':
+			buf = append(buf, '\\', '\'')
+		case '"':
+			buf = append(buf, '\\', '"')
+		case '\\':
+			buf = append(buf, '\\', '\\')
+		default:
+			buf = append(buf, '\\', 'x', hexDigit(b/16), hexDigit(b%16))
+		}
+		last = i + 1
+	}
+	buf = append(buf, s[last:]...)
+	buf = append(buf, '"')
+	return buf
+}
+
+func needsEscape(b byte) bool {
+	return b < 0x20 || b >= 0x7f
+}
+
+func hexDigit(b byte) byte {
+	const digits = "0123456789abcdef"
+	return digits[b]
+}