Merge pull request #907 from stevvooe/digest-tool

Add generic content digest tool
This commit is contained in:
Stephen Day 2015-08-21 11:11:40 -07:00
commit 8c3fc2619c
4 changed files with 165 additions and 9 deletions

View file

@ -28,6 +28,10 @@ ${PREFIX}/bin/registry: version/version.go $(shell find . -type f -name '*.go')
@echo "+ $@"
@go build -tags "${DOCKER_BUILDTAGS}" -o $@ ${GO_LDFLAGS} ${GO_GCFLAGS} ./cmd/registry
${PREFIX}/bin/digest: version/version.go $(shell find . -type f -name '*.go')
@echo "+ $@"
@go build -tags "${DOCKER_BUILDTAGS}" -o $@ ${GO_LDFLAGS} ${GO_GCFLAGS} ./cmd/digest
${PREFIX}/bin/registry-api-descriptor-template: version/version.go $(shell find . -type f -name '*.go')
@echo "+ $@"
@go build -o $@ ${GO_LDFLAGS} ${GO_GCFLAGS} ./cmd/registry-api-descriptor-template
@ -62,7 +66,7 @@ test-full:
@echo "+ $@"
@go test ./...
binaries: ${PREFIX}/bin/registry ${PREFIX}/bin/registry-api-descriptor-template
binaries: ${PREFIX}/bin/registry ${PREFIX}/bin/digest ${PREFIX}/bin/registry-api-descriptor-template
@echo "+ $@"
clean:

129
cmd/digest/main.go Normal file
View file

@ -0,0 +1,129 @@
package main
import (
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"strings"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/version"
"github.com/docker/docker/pkg/tarsum"
)
var (
algorithm = digest.Canonical
showVersion bool
)
type job struct {
name string
reader io.Reader
}
func init() {
flag.Var(&algorithm, "a", "select the digest algorithm (shorthand)")
flag.Var(&algorithm, "algorithm", "select the digest algorithm")
flag.BoolVar(&showVersion, "version", false, "show the version and exit")
log.SetFlags(0)
log.SetPrefix(os.Args[0] + ": ")
}
func usage() {
fmt.Fprintf(os.Stderr, "usage: %s [files...]\n", os.Args[0])
fmt.Fprintf(os.Stderr, `
Calculate the digest of one or more input files, emitting the result
to standard out. If no files are provided, the digest of stdin will
be calculated.
`)
flag.PrintDefaults()
}
func unsupported() {
log.Fatalf("unsupported digest algorithm: %v", algorithm)
}
func main() {
var jobs []job
flag.Usage = usage
flag.Parse()
if showVersion {
version.PrintVersion()
return
}
var fail bool // if we fail on one item, foul the exit code
if flag.NArg() > 0 {
for _, path := range flag.Args() {
fp, err := os.Open(path)
if err != nil {
log.Printf("%s: %v", path, err)
fail = true
continue
}
defer fp.Close()
jobs = append(jobs, job{name: path, reader: fp})
}
} else {
// just read stdin
jobs = append(jobs, job{name: "-", reader: os.Stdin})
}
digestFn := algorithm.FromReader
if !algorithm.Available() {
// we cannot digest if is not available. An exception is made for
// tarsum.
if !strings.HasPrefix(algorithm.String(), "tarsum") {
unsupported()
}
var version tarsum.Version
if algorithm == "tarsum" {
// small hack: if we just have tarsum, use latest
version = tarsum.Version1
} else {
var err error
version, err = tarsum.GetVersionFromTarsum(algorithm.String())
if err != nil {
unsupported()
}
}
digestFn = func(rd io.Reader) (digest.Digest, error) {
ts, err := tarsum.NewTarSum(rd, true, version)
if err != nil {
return "", err
}
if _, err := io.Copy(ioutil.Discard, ts); err != nil {
return "", err
}
return digest.Digest(ts.Sum(nil)), nil
}
}
for _, job := range jobs {
dgst, err := digestFn(job.reader)
if err != nil {
log.Printf("%s: %v", job.name, err)
fail = true
continue
}
fmt.Printf("%v\t%s\n", dgst, job.name)
}
if fail {
os.Exit(1)
}
}

View file

@ -70,15 +70,10 @@ func ParseDigest(s string) (Digest, error) {
return d, d.Validate()
}
// FromReader returns the most valid digest for the underlying content.
// FromReader returns the most valid digest for the underlying content using
// the canonical digest algorithm.
func FromReader(rd io.Reader) (Digest, error) {
digester := Canonical.New()
if _, err := io.Copy(digester.Hash(), rd); err != nil {
return "", err
}
return digester.Digest(), nil
return Canonical.FromReader(rd)
}
// FromTarArchive produces a tarsum digest from reader rd.

View file

@ -3,6 +3,7 @@ package digest
import (
"crypto"
"hash"
"io"
)
// Algorithm identifies and implementation of a digester by an identifier.
@ -49,6 +50,22 @@ func (a Algorithm) Available() bool {
return h.Available()
}
func (a Algorithm) String() string {
return string(a)
}
// Set implemented to allow use of Algorithm as a command line flag.
func (a *Algorithm) Set(value string) error {
if value == "" {
*a = Canonical
} else {
// just do a type conversion, support is queried with Available.
*a = Algorithm(value)
}
return nil
}
// New returns a new digester for the specified algorithm. If the algorithm
// does not have a digester implementation, nil will be returned. This can be
// checked by calling Available before calling New.
@ -69,6 +86,17 @@ func (a Algorithm) Hash() hash.Hash {
return algorithms[a].New()
}
// FromReader returns the digest of the reader using the algorithm.
func (a Algorithm) FromReader(rd io.Reader) (Digest, error) {
digester := a.New()
if _, err := io.Copy(digester.Hash(), rd); err != nil {
return "", err
}
return digester.Digest(), nil
}
// TODO(stevvooe): Allow resolution of verifiers using the digest type and
// this registration system.