github.com/spinnaker/spin@v1.30.0/util/args_reader.go (about)

     1  // Copyright (c) 2019, Google, Inc.
     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 util
    16  
    17  import (
    18  	"bufio"
    19  	"errors"
    20  	"os"
    21  )
    22  
    23  func ReadArgsOrStdin(args []string) (string, error) {
    24  	if len(args) > 0 {
    25  		return args[0], nil
    26  	}
    27  
    28  	stdin := os.Stdin
    29  	fi, err := stdin.Stat()
    30  	if err != nil {
    31  		return "", err
    32  	}
    33  
    34  	pipedStdin := (fi.Mode() & os.ModeCharDevice) == 0
    35  	if fi.Size() <= 0 && !pipedStdin {
    36  		return "", errors.New("no args or STDIN provided")
    37  	}
    38  
    39  	scanner := bufio.NewScanner(os.Stdin)
    40  	input := ""
    41  	for scanner.Scan() {
    42  		input = scanner.Text()
    43  	}
    44  	return input, nil
    45  }