63 lines
1.7 KiB
Go
63 lines
1.7 KiB
Go
// Copyright 2019 the u-root Authors. All rights reserved
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package rand implements cancelable reads from a cryptographically safe
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// random number source.
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package rand
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import (
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"context"
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)
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// Reader is a cryptographically safe random number source.
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var Reader = DefaultReaderWithContext(context.Background())
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// Read blockingly reads from a random number source.
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func Read(b []byte) (int, error) {
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return Reader.Read(b)
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}
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// ReadContext is a context-aware reader for random numbers.
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func ReadContext(ctx context.Context, b []byte) (int, error) {
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return Reader.ReadContext(ctx, b)
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}
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// ContextReader is a cancelable io.Reader.
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type ContextReader interface {
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// Read behaves like a blocking io.Reader.Read.
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//
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// Read wraps ReadContext with a background context.
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Read(b []byte) (n int, err error)
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// ReadContext is an io.Reader that blocks until data is available or
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// until ctx is done.
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ReadContext(ctx context.Context, b []byte) (n int, err error)
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}
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// contextReader is a cancelable io.Reader.
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type contextReader interface {
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ReadContext(context.Context, []byte) (int, error)
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}
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// ctxReader takes a contextReader and turns it into a ContextReader.
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type ctxReader struct {
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contextReader
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ctx context.Context //nolint:containedctx
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}
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func (cr ctxReader) Read(b []byte) (int, error) {
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return cr.contextReader.ReadContext(cr.ctx, b)
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}
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// DefaultReaderWithContext returns a context-aware io.Reader.
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//
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// Because this stores the context, only use this in situations where an
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// io.Reader is unavoidable.
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func DefaultReaderWithContext(ctx context.Context) ContextReader {
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return ctxReader{
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ctx: ctx,
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contextReader: defaultContextReader,
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}
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}
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