117 lines
3.1 KiB
Go
117 lines
3.1 KiB
Go
/*
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Copyright 2014 CoreOS, Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package system
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import (
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"bytes"
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"fmt"
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"io/ioutil"
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"os"
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"path"
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"regexp"
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"sort"
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)
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type EnvFile struct {
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Vars map[string]string
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// mask File.Content, it shouldn't be used.
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Content interface{} `json:"-" yaml:"-"`
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*File
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}
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// only allow sh compatible identifiers
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var validKey = regexp.MustCompile(`^[a-zA-Z0-9_]+$`)
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// match each line, optionally capturing valid identifiers, discarding dos line endings
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var lineLexer = regexp.MustCompile(`(?m)^((?:([a-zA-Z0-9_]+)=)?.*?)\r?\n`)
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// mergeEnvContents: Update the existing file contents with new values,
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// preserving variable ordering and all content this code doesn't understand.
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// All new values are appended to the bottom of the old, sorted by key.
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func mergeEnvContents(old []byte, pending map[string]string) []byte {
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var buf bytes.Buffer
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var match [][]byte
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// it is awkward for the regex to handle a missing newline gracefully
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if len(old) != 0 && !bytes.HasSuffix(old, []byte{'\n'}) {
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old = append(old, byte('\n'))
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}
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for _, match = range lineLexer.FindAllSubmatch(old, -1) {
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key := string(match[2])
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if value, ok := pending[key]; ok {
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fmt.Fprintf(&buf, "%s=%s\n", key, value)
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delete(pending, key)
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} else {
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fmt.Fprintf(&buf, "%s\n", match[1])
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}
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}
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for _, key := range keys(pending) {
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value := pending[key]
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fmt.Fprintf(&buf, "%s=%s\n", key, value)
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}
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return buf.Bytes()
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}
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// WriteEnvFile updates an existing env `KEY=value` formated file with
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// new values provided in EnvFile.Vars; File.Content is ignored.
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// Existing ordering and any unknown formatting such as comments are
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// preserved. If no changes are required the file is untouched.
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func WriteEnvFile(ef *EnvFile, root string) error {
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// validate new keys, mergeEnvContents uses pending to track writes
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pending := make(map[string]string, len(ef.Vars))
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for key, value := range ef.Vars {
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if !validKey.MatchString(key) {
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return fmt.Errorf("Invalid name %q for %s", key, ef.Path)
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}
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pending[key] = value
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}
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if len(pending) == 0 {
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return nil
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}
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oldContent, err := ioutil.ReadFile(path.Join(root, ef.Path))
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if err != nil {
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if os.IsNotExist(err) {
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oldContent = []byte{}
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} else {
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return err
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}
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}
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newContent := mergeEnvContents(oldContent, pending)
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if bytes.Equal(oldContent, newContent) {
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return nil
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}
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ef.File.Content = string(newContent)
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_, err = WriteFile(ef.File, root)
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return err
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}
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// keys returns the keys of a map in sorted order
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func keys(m map[string]string) (s []string) {
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for k, _ := range m {
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s = append(s, k)
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}
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sort.Strings(s)
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return
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}
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