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