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