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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package autocert
import (
"context"
"errors"
"io/ioutil"
"os"
"path/filepath"
)
// ErrCacheMiss is returned when a certificate is not found in cache.
var ErrCacheMiss = errors.New("acme/autocert: certificate cache miss")
// Cache is used by Manager to store and retrieve previously obtained certificates
// and other account data as opaque blobs.
//
// Cache implementations should not rely on the key naming pattern. Keys can
// include any printable ASCII characters, except the following: \/:*?"<>|
type Cache interface {
// Get returns a certificate data for the specified key.
// If there's no such key, Get returns ErrCacheMiss.
Get(ctx context.Context, key string) ([]byte, error)
// Put stores the data in the cache under the specified key.
// Underlying implementations may use any data storage format,
// as long as the reverse operation, Get, results in the original data.
Put(ctx context.Context, key string, data []byte) error
// Delete removes a certificate data from the cache under the specified key.
// If there's no such key in the cache, Delete returns nil.
Delete(ctx context.Context, key string) error
}
// DirCache implements Cache using a directory on the local filesystem.
// If the directory does not exist, it will be created with 0700 permissions.
type DirCache string
// Get reads a certificate data from the specified file name.
func (d DirCache) Get(ctx context.Context, name string) ([]byte, error) {
name = filepath.Join(string(d), name)
var (
data []byte
err error
done = make(chan struct{})
)
go func() {
data, err = ioutil.ReadFile(name)
close(done)
}()
select {
case <-ctx.Done():
return nil, ctx.Err()
case <-done:
}
if os.IsNotExist(err) {
return nil, ErrCacheMiss
}
return data, err
}
// Put writes the certificate data to the specified file name.
// The file will be created with 0600 permissions.
func (d DirCache) Put(ctx context.Context, name string, data []byte) error {
if err := os.MkdirAll(string(d), 0700); err != nil {
return err
}
done := make(chan struct{})
var err error
go func() {
defer close(done)
var tmp string
if tmp, err = d.writeTempFile(name, data); err != nil {
return
}
select {
case <-ctx.Done():
// Don't overwrite the file if the context was canceled.
default:
newName := filepath.Join(string(d), name)
err = os.Rename(tmp, newName)
}
}()
select {
case <-ctx.Done():
return ctx.Err()
case <-done:
}
return err
}
// Delete removes the specified file name.
func (d DirCache) Delete(ctx context.Context, name string) error {
name = filepath.Join(string(d), name)
var (
err error
done = make(chan struct{})
)
go func() {
err = os.Remove(name)
close(done)
}()
select {
case <-ctx.Done():
return ctx.Err()
case <-done:
}
if err != nil && !os.IsNotExist(err) {
return err
}
return nil
}
// writeTempFile writes b to a temporary file, closes the file and returns its path.
func (d DirCache) writeTempFile(prefix string, b []byte) (string, error) {
// TempFile uses 0600 permissions
f, err := ioutil.TempFile(string(d), prefix)
if err != nil {
return "", err
}
if _, err := f.Write(b); err != nil {
f.Close()
return "", err
}
return f.Name(), f.Close()
}