github.com/joomcode/cue@v0.4.4-0.20221111115225-539fe3512047/internal/ci/updatetxtar/main.go (about)

     1  // Copyright 2021 The CUE Authors
     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 main
    16  
    17  import (
    18  	"flag"
    19  	"io"
    20  	"io/ioutil"
    21  	"log"
    22  	"os"
    23  
    24  	"github.com/rogpeppe/go-internal/txtar"
    25  )
    26  
    27  // Usage:
    28  //    updateTxtar source target filename
    29  //
    30  // updateTxtar writes the contents of source (could be - for stdin) to a file
    31  // (identified by filename) within the txtar archive at target.
    32  
    33  func main() {
    34  	log.SetFlags(0)
    35  	flag.Parse()
    36  	if flag.NArg() != 3 {
    37  		log.Fatal("Usage:\n\tupdateTxtar source target filename")
    38  	}
    39  	source := flag.Arg(0)
    40  	target := flag.Arg(1)
    41  	fn := flag.Arg(2)
    42  	a, err := txtar.ParseFile(target)
    43  	if err != nil {
    44  		log.Fatal(err)
    45  	}
    46  	var file *txtar.File
    47  	for i, f := range a.Files {
    48  		if f.Name == fn {
    49  			file = &a.Files[i]
    50  			break
    51  		}
    52  	}
    53  	if file == nil {
    54  		a.Files = append(a.Files, txtar.File{Name: fn})
    55  		file = &a.Files[len(a.Files)-1]
    56  	}
    57  	var sourceReader io.Reader
    58  	if source == "-" {
    59  		sourceReader = os.Stdin
    60  	} else {
    61  		sourceReader, err = os.Open(source)
    62  		if err != nil {
    63  			log.Fatal(err)
    64  		}
    65  	}
    66  	contents, err := ioutil.ReadAll(sourceReader)
    67  	if err != nil {
    68  		log.Fatal(err)
    69  	}
    70  	file.Data = contents
    71  	if err := ioutil.WriteFile(target, txtar.Format(a), 0666); err != nil {
    72  		log.Fatal(err)
    73  	}
    74  }