github.com/mre-fog/trillianxx@v1.1.2-0.20180615153820-ae375a99d36a/cmd/flags.go (about) 1 // Copyright 2017 Google Inc. All Rights Reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package cmd 16 17 import ( 18 "errors" 19 "flag" 20 "io/ioutil" 21 "os" 22 23 "bitbucket.org/creachadair/shell" 24 ) 25 26 func parseFlags(file string) error { 27 args, valid := shell.Split(file) 28 if !valid { 29 return errors.New("flag file contains unclosed quotations") 30 } 31 // Expand any environment variables in the args 32 for i := range args { 33 args[i] = os.ExpandEnv(args[i]) 34 } 35 36 if err := flag.CommandLine.Parse(args); err != nil { 37 return err 38 } 39 40 // Call flag.Parse() again so that command line flags 41 // can override flags provided in the provided flag file. 42 flag.Parse() 43 return nil 44 } 45 46 // ParseFlagFile parses a set of flags from a file at the provided 47 // path. Re-calls flag.Parse() after parsing the flags in the file 48 // so that flags provided on the command line take precedence over 49 // flags provided in the file. 50 func ParseFlagFile(path string) error { 51 file, err := ioutil.ReadFile(path) 52 if err != nil { 53 return err 54 } 55 return parseFlags(string(file)) 56 }