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Copy pathreader.go
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220 lines (196 loc) · 6.06 KB
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/*
* MinIO Cloud Storage, (C) 2017 MinIO, Inc.
*
* 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 hash
import (
"bytes"
"encoding/base64"
"encoding/hex"
"errors"
"hash"
"io"
"github.com/minio/minio/pkg/etag"
)
// A Reader wraps an io.Reader and computes the MD5 checksum
// of the read content as ETag. Optionally, it also computes
// the SHA256 checksum of the content.
//
// If the reference values for the ETag and content SHA26
// are not empty then it will check whether the computed
// match the reference values.
type Reader struct {
src io.Reader
bytesRead int64
size int64
actualSize int64
checksum etag.ETag
contentSHA256 []byte
sha256 hash.Hash
}
// NewReader returns a new Reader that wraps src and computes
// MD5 checksum of everything it reads as ETag.
//
// It also computes the SHA256 checksum of everything it reads
// if sha256Hex is not the empty string.
//
// If size resp. actualSize is unknown at the time of calling
// NewReader then it should be set to -1.
//
// NewReader may try merge the given size, MD5 and SHA256 values
// into src - if src is a Reader - to avoid computing the same
// checksums multiple times.
func NewReader(src io.Reader, size int64, md5Hex, sha256Hex string, actualSize int64) (*Reader, error) {
MD5, err := hex.DecodeString(md5Hex)
if err != nil {
return nil, BadDigest{ // TODO(aead): Return an error that indicates that an invalid ETag has been specified
ExpectedMD5: md5Hex,
CalculatedMD5: "",
}
}
SHA256, err := hex.DecodeString(sha256Hex)
if err != nil {
return nil, SHA256Mismatch{ // TODO(aead): Return an error that indicates that an invalid Content-SHA256 has been specified
ExpectedSHA256: sha256Hex,
CalculatedSHA256: "",
}
}
// Merge the size, MD5 and SHA256 values if src is a Reader.
// The size may be set to -1 by callers if unknown.
if r, ok := src.(*Reader); ok {
if r.bytesRead > 0 {
return nil, errors.New("hash: already read from hash reader")
}
if len(r.checksum) != 0 && len(MD5) != 0 && !etag.Equal(r.checksum, etag.ETag(MD5)) {
return nil, BadDigest{
ExpectedMD5: r.checksum.String(),
CalculatedMD5: md5Hex,
}
}
if len(r.contentSHA256) != 0 && len(SHA256) != 0 && !bytes.Equal(r.contentSHA256, SHA256) {
return nil, SHA256Mismatch{
ExpectedSHA256: hex.EncodeToString(r.contentSHA256),
CalculatedSHA256: sha256Hex,
}
}
if r.size >= 0 && size >= 0 && r.size != size {
return nil, ErrSizeMismatch{Want: r.size, Got: size}
}
r.checksum = etag.ETag(MD5)
r.contentSHA256 = SHA256
if r.size < 0 && size >= 0 {
r.src = etag.Wrap(io.LimitReader(r.src, size), r.src)
r.size = size
}
if r.actualSize <= 0 && actualSize >= 0 {
r.actualSize = actualSize
}
return r, nil
}
var hash hash.Hash
if size >= 0 {
src = io.LimitReader(src, size)
}
if len(SHA256) != 0 {
hash = newSHA256()
}
return &Reader{
src: etag.NewReader(src, etag.ETag(MD5)),
size: size,
actualSize: actualSize,
checksum: etag.ETag(MD5),
contentSHA256: SHA256,
sha256: hash,
}, nil
}
func (r *Reader) Read(p []byte) (int, error) {
n, err := r.src.Read(p)
r.bytesRead += int64(n)
if r.sha256 != nil {
r.sha256.Write(p[:n])
}
if err == io.EOF { // Verify content SHA256, if set.
if r.sha256 != nil {
if sum := r.sha256.Sum(nil); !bytes.Equal(r.contentSHA256, sum) {
return n, SHA256Mismatch{
ExpectedSHA256: hex.EncodeToString(r.contentSHA256),
CalculatedSHA256: hex.EncodeToString(sum),
}
}
}
}
if err != nil && err != io.EOF {
if v, ok := err.(etag.VerifyError); ok {
return n, BadDigest{
ExpectedMD5: v.Expected.String(),
CalculatedMD5: v.Computed.String(),
}
}
}
return n, err
}
// Size returns the absolute number of bytes the Reader
// will return during reading. It returns -1 for unlimited
// data.
func (r *Reader) Size() int64 { return r.size }
// ActualSize returns the pre-modified size of the object.
// DecompressedSize - For compressed objects.
func (r *Reader) ActualSize() int64 { return r.actualSize }
// ETag returns the ETag computed by an underlying etag.Tagger.
// If the underlying io.Reader does not implement etag.Tagger
// it returns nil.
func (r *Reader) ETag() etag.ETag {
if t, ok := r.src.(etag.Tagger); ok {
return t.ETag()
}
return nil
}
// MD5 returns the MD5 checksum set as reference value.
//
// It corresponds to the checksum that is expected and
// not the actual MD5 checksum of the content.
// Therefore, refer to MD5Current.
func (r *Reader) MD5() []byte {
return r.checksum
}
// MD5Current returns the MD5 checksum of the content
// that has been read so far.
//
// Calling MD5Current again after reading more data may
// result in a different checksum.
func (r *Reader) MD5Current() []byte {
return r.ETag()[:]
}
// SHA256 returns the SHA256 checksum set as reference value.
//
// It corresponds to the checksum that is expected and
// not the actual SHA256 checksum of the content.
func (r *Reader) SHA256() []byte {
return r.contentSHA256
}
// MD5HexString returns a hex representation of the MD5.
func (r *Reader) MD5HexString() string {
return hex.EncodeToString(r.checksum)
}
// MD5Base64String returns a hex representation of the MD5.
func (r *Reader) MD5Base64String() string {
return base64.StdEncoding.EncodeToString(r.checksum)
}
// SHA256HexString returns a hex representation of the SHA256.
func (r *Reader) SHA256HexString() string {
return hex.EncodeToString(r.contentSHA256)
}
var _ io.Closer = (*Reader)(nil) // compiler check
// Close and release resources.
func (r *Reader) Close() error { return nil }