Initial commit

vendor/github.com/cockroachdb/redact/builder.go

@@ -0,0 +1,149 @@
+// Copyright 2020 The Cockroach Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied. See the License for the specific language governing
+// permissions and limitations under the License.
+
+package redact
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"unicode/utf8"
+)
+
+// StringBuilder accumulates strings with optional redaction markers.
+//
+// It implements io.Writer but marks direct writes as redactable.
+// To distinguish safe and unsafe bits, it also implements the SafeWriter
+// interface.
+type StringBuilder struct {
+	// we use bytes.Buffer internally to simplify the implementation of
+	// the SafeWriter interface.
+	buf bytes.Buffer
+}
+
+// String returns the accumulated string, with redaction markers stripped out.
+// To obtain the redactable string, call RedactableString().
+func (b StringBuilder) String() string { return b.RedactableString().StripMarkers() }
+
+var _ fmt.Stringer = StringBuilder{}
+var _ fmt.Stringer = (*StringBuilder)(nil)
+
+// RedactableString returns the accumulated string, including redaction markers.
+func (b StringBuilder) RedactableString() RedactableString { return RedactableString(b.buf.String()) }
+
+// RedactableBytes returns the accumulated bytes, including redaction markers.
+func (b StringBuilder) RedactableBytes() RedactableBytes { return RedactableBytes(b.buf.Bytes()) }
+
+// SafeFormat implements SafeFormatter.
+func (b StringBuilder) SafeFormat(p SafePrinter, _ rune) {
+	// We only support the %v / %s natural print here.
+	// Go supports other formatting verbs for strings: %x/%X/%q.
+	//
+	// We don't do this here, keeping in mind that the output
+	// of a SafeFormat must remain a redactable string.
+	//
+	// %x/%X cannot be implemented because they would turn redaction
+	//       markers into hex codes, and the entire result string would
+	//       appear safe for reporting, which would break the semantics
+	//       of this package.
+	//
+	// %q    cannot be implemented because it replaces non-ASCII characters
+	//       with numeric unicode escapes, which breaks redaction
+	//       markers too.
+	p.Print(b.RedactableString())
+}
+
+var _ SafeFormatter = StringBuilder{}
+var _ SafeFormatter = (*StringBuilder)(nil)
+
+// Len returns the number of accumulated bytes, including redaction
+// markers; b.Len() == len(b.RedactableString()).
+func (b *StringBuilder) Len() int { return b.buf.Len() }
+
+// Cap returns the capacity of the builder's underlying byte slice. It is the
+// total space allocated for the string being built and includes any bytes
+// already written.
+func (b *StringBuilder) Cap() int { return b.buf.Cap() }
+
+// Reset resets the Builder to be empty.
+func (b *StringBuilder) Reset() { b.buf.Reset() }
+
+// StringBuilder implements io.Writer.
+// Direct Write() calls are considered unsafe.
+var _ io.Writer = (*StringBuilder)(nil)
+
+// Write implements the io.Writer interface.
+func (b *StringBuilder) Write(s []byte) (int, error) {
+	b.UnsafeBytes(s)
+	return len(s), nil
+}
+
+// StringBuilder implements SafeWriter.
+var _ SafeWriter = (*StringBuilder)(nil)
+
+// Print is part of the SafeWriter interface.
+func (b *StringBuilder) Print(args ...interface{}) {
+	_, _ = Fprint(&b.buf, args...)
+}
+
+// Printf is part of the SafeWriter interface.
+func (b *StringBuilder) Printf(format string, args ...interface{}) {
+	_, _ = Fprintf(&b.buf, format, args...)
+}
+
+// SafeString is part of the SafeWriter interface.
+func (b *StringBuilder) SafeString(s SafeString) {
+	w := escapeWriter{w: &b.buf, enclose: false}
+	_, _ = w.Write([]byte(s))
+}
+
+// SafeRune is part of the SafeWriter interface.
+func (b *StringBuilder) SafeRune(s SafeRune) {
+	if s == startRedactable || s == endRedactable {
+		s = escapeMark
+	}
+	_, _ = b.buf.WriteRune(rune(s))
+}
+
+// UnsafeString is part of the SafeWriter interface.
+func (b *StringBuilder) UnsafeString(s string) {
+	w := escapeWriter{w: &b.buf, enclose: true, strip: true}
+	_, _ = w.Write([]byte(s))
+}
+
+// UnsafeRune is part of the SafeWriter interface.
+func (b *StringBuilder) UnsafeRune(s rune) {
+	_, _ = b.buf.WriteRune(startRedactable)
+	b.SafeRune(SafeRune(s))
+	_, _ = b.buf.WriteRune(endRedactable)
+}
+
+// UnsafeByte is part of the SafeWriter interface.
+func (b *StringBuilder) UnsafeByte(s byte) {
+	_, _ = b.buf.WriteRune(startRedactable)
+	if s >= utf8.RuneSelf ||
+		s == startRedactableBytes[0] || s == endRedactableBytes[0] {
+		// Unsafe byte. Escape it.
+		_, _ = b.buf.Write(escapeBytes)
+	} else {
+		_ = b.buf.WriteByte(s)
+	}
+	_, _ = b.buf.WriteRune(endRedactable)
+}
+
+// UnsafeBytes is part of the SafeWriter interface.
+func (b *StringBuilder) UnsafeBytes(s []byte) {
+	w := escapeWriter{w: &b.buf, enclose: true, strip: true}
+	_, _ = w.Write(s)
+}