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verify.go
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verify.go
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// Copyright 2020 Google LLC All Rights Reserved.
//
// 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 verify
import (
"encoding/hex"
"fmt"
"hash"
"io"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/internal/and"
)
type verifyReader struct {
inner io.Reader
hasher hash.Hash
expected v1.Hash
}
// Read implements io.Reader
func (vc *verifyReader) Read(b []byte) (int, error) {
n, err := vc.inner.Read(b)
if err == io.EOF {
got := hex.EncodeToString(vc.hasher.Sum(make([]byte, 0, vc.hasher.Size())))
if want := vc.expected.Hex; got != want {
return n, fmt.Errorf("error verifying %s checksum; got %q, want %q",
vc.expected.Algorithm, got, want)
}
}
return n, err
}
// ReadCloser wraps the given io.ReadCloser to verify that its contents match
// the provided v1.Hash before io.EOF is returned.
func ReadCloser(r io.ReadCloser, h v1.Hash) (io.ReadCloser, error) {
w, err := v1.Hasher(h.Algorithm)
if err != nil {
return nil, err
}
r2 := io.TeeReader(r, w)
return &and.ReadCloser{
Reader: &verifyReader{
inner: r2,
hasher: w,
expected: h,
},
CloseFunc: r.Close,
}, nil
}