github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/store/nbs/test/manifest_clobber.go (about)

     1  // Copyright 2019 Dolthub, 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  // This file incorporates work covered by the following copyright and
    16  // permission notice:
    17  //
    18  // Copyright 2016 Attic Labs, Inc. All rights reserved.
    19  // Licensed under the Apache License, version 2.0:
    20  // http://www.apache.org/licenses/LICENSE-2.0
    21  
    22  package main
    23  
    24  import (
    25  	"flag"
    26  	"log"
    27  	"os"
    28  
    29  	"github.com/dolthub/fslock"
    30  )
    31  
    32  func main() {
    33  	flag.Parse()
    34  
    35  	if flag.NArg() < 3 {
    36  		log.Fatalln("Not enough arguments")
    37  	}
    38  
    39  	// Clobber manifest file at flag.Arg(1) with contents at flag.Arg(2) after taking lock of file flag.Arg(0)
    40  	lockFile := flag.Arg(0)
    41  	manifestFile := flag.Arg(1)
    42  	manifestContents := flag.Arg(2)
    43  
    44  	// lock released by closing l.
    45  	lck := fslock.New(lockFile)
    46  	err := lck.TryLock()
    47  	if err == fslock.ErrLocked {
    48  		return
    49  	}
    50  	if err != nil {
    51  		log.Fatalln(err)
    52  	}
    53  
    54  	defer lck.Unlock()
    55  
    56  	m, err := os.Create(manifestFile)
    57  	if err != nil {
    58  		log.Fatalln(err)
    59  	}
    60  	defer m.Close()
    61  
    62  	if _, err = m.WriteString(manifestContents); err != nil {
    63  		log.Fatalln(err)
    64  	}
    65  }