forked from prometheus/promu
/
checksum.go
95 lines (83 loc) · 2.4 KB
/
checksum.go
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// Copyright © 2017 Prometheus Team
//
// 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 cmd
import (
"crypto/sha256"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"github.com/pkg/errors"
)
const (
checksumsFilename = "sha256sums.txt"
)
var (
checksumcmd = app.Command("checksum", "Calculate the SHA256 checksum for each file in the given location")
checksumLocation = checksumcmd.Arg("location", "Location to checksum").Default(".").Strings()
)
func runChecksum(path string) {
checksums, err := calculateSHA256s(path)
if err != nil {
fatal(errors.Wrap(err, "Failed to calculate checksums"))
}
file, err := os.Create(filepath.Join(path, checksumsFilename))
if err != nil {
fatal(errors.Wrap(err, "Failed to create checksums file"))
}
defer file.Close()
for _, c := range checksums {
if _, err := fmt.Fprintf(file, "%x %s\n", c.checksum, c.filename); err != nil {
fatal(errors.Wrap(err, "Failed to write to checksums file"))
}
}
}
type checksumSHA256 struct {
filename string
checksum []byte
}
// calculateSHA256s calculates the sha256 checksum for each file in the given
// path and returns a checksumSHA256 type in the order returned of
// filepath.Walk.
func calculateSHA256s(path string) ([]checksumSHA256, error) {
var checksums []checksumSHA256
path = fmt.Sprintf("%s%c", filepath.Clean(path), filepath.Separator)
calculateSHA256 := func(filepath string, f os.FileInfo, err error) error {
if err != nil {
return err
}
if f.IsDir() {
return nil
}
file, err := os.Open(filepath)
if err != nil {
return err
}
defer file.Close()
hash := sha256.New()
if _, err = io.Copy(hash, file); err != nil {
return err
}
checksums = append(checksums, checksumSHA256{
filename: strings.TrimPrefix(filepath, path),
checksum: hash.Sum(nil),
})
return nil
}
if err := filepath.Walk(path, calculateSHA256); err != nil {
return nil, err
}
return checksums, nil
}