registry/cmd/digest/main.go
zhouhaibing089 d66208108d cmd/digest: import crypto algorithms
the digest cli does not work if we do not import this two packages,
tested in go1.9. basically, we have to make several algorithms to
be available by calling crypto.RegisterHash in init functions.

Signed-off-by: zhouhaibing089 <zhouhaibing089@gmail.com>
2017-10-14 12:36:55 +08:00

100 lines
1.7 KiB
Go

package main
import (
"flag"
"fmt"
"io"
"log"
"os"
"github.com/docker/distribution/version"
"github.com/opencontainers/go-digest"
_ "crypto/sha256"
_ "crypto/sha512"
)
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.Fprint(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() {
unsupported()
}
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)
}
}