forked from juju/juju
/
utils.go
54 lines (45 loc) · 1.54 KB
/
utils.go
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// Copyright 2016 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.
package context
import (
"io"
"os"
"github.com/juju/errors"
charmresource "gopkg.in/juju/charm.v6-unstable/resource"
)
// TODO(ericsnow) Move FingerprintMatcher to charm/resource (or even utils/hash)?
// FingerprintMatcher supports verifying a file's fingerprint.
type FingerprintMatcher struct {
// Open opens the identified file. It defaults to os.Open.
Open func(filename string) (io.ReadCloser, error)
// GenerateFingerprint produces the fingerprint that corresponds
// to the content of the provided reader. It defaults to
// charmresource.GenerateFingerprint.
GenerateFingerprint func(io.Reader) (charmresource.Fingerprint, error)
}
// FingerprintMatches determines whether or not the identified file's
// fingerprint matches the expected fingerprint.
func (fpm FingerprintMatcher) FingerprintMatches(filename string, expected charmresource.Fingerprint) (bool, error) {
open := fpm.Open
if open == nil {
open = func(filename string) (io.ReadCloser, error) { return os.Open(filename) }
}
generateFingerprint := fpm.GenerateFingerprint
if generateFingerprint == nil {
generateFingerprint = charmresource.GenerateFingerprint
}
file, err := open(filename)
if os.IsNotExist(errors.Cause(err)) {
return false, nil
}
if err != nil {
return false, errors.Trace(err)
}
defer file.Close()
fp, err := generateFingerprint(file)
if err != nil {
return false, errors.Trace(err)
}
matches := (fp.String() == expected.String())
return matches, nil
}