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// Copyright 2017 Northern.tech AS
//
// 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 artifact
import (
"bytes"
"crypto/sha256"
"encoding/hex"
"fmt"
"hash"
"io"
"os"
"strings"
"syscall"
"github.com/pkg/errors"
)
type Checksum struct {
w io.Writer // underlying writer
h hash.Hash // writer calculated hash
r io.Reader
c []byte // reader pre-loaded checksum
}
func NewWriterChecksum(w io.Writer) *Checksum {
if w == nil {
return new(Checksum)
}
h := sha256.New()
return &Checksum{
w: io.MultiWriter(h, w),
h: h,
}
}
func NewReaderChecksum(r io.Reader, sum []byte) *Checksum {
if r == nil {
return new(Checksum)
}
h := sha256.New()
return &Checksum{
r: io.TeeReader(r, h),
c: sum,
h: h,
}
}
func (c *Checksum) Write(p []byte) (int, error) {
if c.w == nil {
return 0, syscall.EBADF
}
return c.w.Write(p)
}
// Do not call Read directly; use io.Copy instead as we are
// calculating checksum only after receiving io.EOF.
func (c *Checksum) Read(p []byte) (int, error) {
if c.r == nil {
return 0, syscall.EBADF
}
n, err := c.r.Read(p)
if err == io.EOF {
// verify checksum
if verErr := c.Verify(); verErr != nil {
return 0, verErr
}
}
return n, err
}
func (c *Checksum) Checksum() []byte {
if c.h == nil {
return nil
}
sum := c.h.Sum(nil)
checksum := make([]byte, hex.EncodedLen(len(sum)))
hex.Encode(checksum, sum)
return checksum
}
func (c *Checksum) Verify() error {
sum := c.Checksum()
if !bytes.Equal(c.c, sum) {
return errors.Errorf("invalid checksum; expected: [%s]; actual: [%s]",
c.c, sum)
}
return nil
}
type ChecksumStore struct {
// raw is storing raw data that is read from manifest file;
// we need to keep raw data as iterating over sums map may produce
// different result each time map is traversed
raw *bytes.Buffer
// sums is a map of all files and its checksums;
// key is the name of the file and value is the checksum
sums map[string]([]byte)
}
func NewChecksumStore() *ChecksumStore {
return &ChecksumStore{
sums: make(map[string]([]byte), 1),
raw: bytes.NewBuffer(nil),
}
}
func (c *ChecksumStore) Add(file string, sum []byte) error {
if _, ok := c.sums[file]; ok {
return os.ErrExist
}
c.sums[file] = sum
_, err := c.raw.WriteString(fmt.Sprintf("%s %s\n", sum, file))
return err
}
func (c *ChecksumStore) Get(file string) ([]byte, error) {
sum, ok := c.sums[file]
if !ok {
return nil, errors.Errorf("checksum: checksum missing for file: '%s'", file)
}
return sum, nil
}
func (c *ChecksumStore) GetRaw() []byte {
return c.raw.Bytes()
}
func (c *ChecksumStore) ReadRaw(data []byte) error {
raw := bytes.NewBuffer(data)
for {
line, err := raw.ReadString('\n')
if err == io.EOF {
break
} else if err != nil {
return errors.Wrap(err, "checksum: can not read raw")
}
if err = c.readChecksums(line); err != nil {
return err
}
}
return nil
}
func (c *ChecksumStore) readChecksums(line string) error {
chunks := strings.Split(strings.TrimSpace(line), " ")
if len(chunks) != 2 {
return errors.Errorf("checksum: malformed checksum line: '%s'", line)
}
// add element to map
return c.Add(chunks[1], []byte(chunks[0]))
}
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