130 lines
2.5 KiB
Go
130 lines
2.5 KiB
Go
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package main
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import (
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"os"
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"strings"
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"github.com/docker/distribution/digest"
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"github.com/docker/distribution/version"
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"github.com/docker/docker/pkg/tarsum"
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)
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var (
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algorithm = digest.Canonical
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showVersion bool
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)
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type job struct {
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name string
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reader io.Reader
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}
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func init() {
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flag.Var(&algorithm, "a", "select the digest algorithm (shorthand)")
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flag.Var(&algorithm, "algorithm", "select the digest algorithm")
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flag.BoolVar(&showVersion, "version", false, "show the version and exit")
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log.SetFlags(0)
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log.SetPrefix(os.Args[0] + ": ")
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}
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func usage() {
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fmt.Fprintf(os.Stderr, "usage: %s [files...]\n", os.Args[0])
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fmt.Fprintf(os.Stderr, `
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Calculate the digest of one or more input files, emitting the result
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to standard out. If no files are provided, the digest of stdin will
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be calculated.
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`)
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flag.PrintDefaults()
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}
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func unsupported() {
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log.Fatalf("unsupported digest algorithm: %v", algorithm)
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}
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func main() {
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var jobs []job
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flag.Usage = usage
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flag.Parse()
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if showVersion {
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version.PrintVersion()
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return
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}
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var fail bool // if we fail on one item, foul the exit code
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if flag.NArg() > 0 {
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for _, path := range flag.Args() {
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fp, err := os.Open(path)
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if err != nil {
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log.Printf("%s: %v", path, err)
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fail = true
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continue
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}
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defer fp.Close()
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jobs = append(jobs, job{name: path, reader: fp})
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}
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} else {
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// just read stdin
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jobs = append(jobs, job{name: "-", reader: os.Stdin})
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}
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digestFn := algorithm.FromReader
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if !algorithm.Available() {
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// we cannot digest if is not available. An exception is made for
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// tarsum.
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if !strings.HasPrefix(algorithm.String(), "tarsum") {
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unsupported()
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}
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var version tarsum.Version
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if algorithm == "tarsum" {
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// small hack: if we just have tarsum, use latest
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version = tarsum.Version1
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} else {
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var err error
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version, err = tarsum.GetVersionFromTarsum(algorithm.String())
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if err != nil {
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unsupported()
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}
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}
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digestFn = func(rd io.Reader) (digest.Digest, error) {
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ts, err := tarsum.NewTarSum(rd, true, version)
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if err != nil {
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return "", err
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}
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if _, err := io.Copy(ioutil.Discard, ts); err != nil {
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return "", err
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}
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return digest.Digest(ts.Sum(nil)), nil
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}
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}
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for _, job := range jobs {
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dgst, err := digestFn(job.reader)
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if err != nil {
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log.Printf("%s: %v", job.name, err)
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fail = true
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continue
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}
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fmt.Printf("%v\t%s\n", dgst, job.name)
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}
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if fail {
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os.Exit(1)
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}
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}
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