-// Lightweight implementation of io.ReadCloser that checks the contents read
-// from the underlying io.Reader a against checksum hash. To avoid reading the
-// entire contents into a buffer up front, the hash is updated with each read,
-// and the actual checksum is not checked until the underlying reader returns
-// EOF.
+// Copyright (C) The Arvados Authors. All rights reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+
package keepclient
import (
var BadChecksum = errors.New("Reader failed checksum")
+// HashCheckingReader is an io.ReadCloser that checks the contents
+// read from the underlying io.Reader against the provided hash.
type HashCheckingReader struct {
// The underlying data source
io.Reader
- // The hashing function to use
+ // The hash function to use
hash.Hash
// The hash value to check against. Must be a hex-encoded lowercase string.
Check string
}
-// Read from the underlying reader, update the hashing function, and pass the
-// results through. Will return BadChecksum on the last read instead of EOF if
-// the checksum doesn't match.
-func (this HashCheckingReader) Read(p []byte) (n int, err error) {
- n, err = this.Reader.Read(p)
+// Reads from the underlying reader, update the hashing function, and
+// pass the results through. Returns BadChecksum (instead of EOF) on
+// the last read if the checksum doesn't match.
+func (hcr HashCheckingReader) Read(p []byte) (n int, err error) {
+ n, err = hcr.Reader.Read(p)
if n > 0 {
- this.Hash.Write(p[:n])
+ hcr.Hash.Write(p[:n])
}
if err == io.EOF {
- sum := this.Hash.Sum(make([]byte, 0, this.Hash.Size()))
- if fmt.Sprintf("%x", sum) != this.Check {
+ sum := hcr.Hash.Sum(nil)
+ if fmt.Sprintf("%x", sum) != hcr.Check {
err = BadChecksum
}
}
return n, err
}
-// Write entire contents of this.Reader to 'dest'. Returns BadChecksum if the
-// data written to 'dest' doesn't match the hash code of this.Check.
-func (this HashCheckingReader) WriteTo(dest io.Writer) (written int64, err error) {
- if writeto, ok := this.Reader.(io.WriterTo); ok {
- written, err = writeto.WriteTo(io.MultiWriter(dest, this.Hash))
+// WriteTo writes the entire contents of hcr.Reader to dest. Returns
+// BadChecksum if writing is successful but the checksum doesn't
+// match.
+func (hcr HashCheckingReader) WriteTo(dest io.Writer) (written int64, err error) {
+ if writeto, ok := hcr.Reader.(io.WriterTo); ok {
+ written, err = writeto.WriteTo(io.MultiWriter(dest, hcr.Hash))
} else {
- written, err = io.Copy(io.MultiWriter(dest, this.Hash), this.Reader)
+ written, err = io.Copy(io.MultiWriter(dest, hcr.Hash), hcr.Reader)
}
- sum := this.Hash.Sum(make([]byte, 0, this.Hash.Size()))
+ if err != nil {
+ return written, err
+ }
- if fmt.Sprintf("%x", sum) != this.Check {
- err = BadChecksum
+ sum := hcr.Hash.Sum(nil)
+ if fmt.Sprintf("%x", sum) != hcr.Check {
+ return written, BadChecksum
}
- return written, err
+ return written, nil
}
-// Close() the underlying Reader if it is castable to io.ReadCloser. This will
-// drain the underlying reader of any remaining data and check the checksum.
-func (this HashCheckingReader) Close() (err error) {
- _, err = io.Copy(this.Hash, this.Reader)
+// Close reads all remaining data from the underlying Reader and
+// returns BadChecksum if the checksum doesn't match. It also closes
+// the underlying Reader if it implements io.ReadCloser.
+func (hcr HashCheckingReader) Close() (err error) {
+ _, err = io.Copy(hcr.Hash, hcr.Reader)
- if closer, ok := this.Reader.(io.ReadCloser); ok {
- err = closer.Close()
+ if closer, ok := hcr.Reader.(io.Closer); ok {
+ closeErr := closer.Close()
+ if err == nil {
+ err = closeErr
+ }
}
-
- sum := this.Hash.Sum(make([]byte, 0, this.Hash.Size()))
- if fmt.Sprintf("%x", sum) != this.Check {
- err = BadChecksum
+ if err != nil {
+ return err
}
-
- return err
+ if fmt.Sprintf("%x", hcr.Hash.Sum(nil)) != hcr.Check {
+ return BadChecksum
+ }
+ return nil
}