copy.go

Documentation: k8s.io/kubernetes/cmd/kubeadm/app/util

     1  /*
     2  Copyright 2023 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package util
    18  
    19  import (
    20  	"io"
    21  	"os"
    22  	"strings"
    23  
    24  	"github.com/pkg/errors"
    25  
    26  	"k8s.io/klog/v2"
    27  )
    28  
    29  // CopyFile copies a file from src to dest.
    30  func CopyFile(src, dest string) error {
    31  	sourceFileInfo, err := os.Stat(src)
    32  	if err != nil {
    33  		return err
    34  	}
    35  
    36  	sourceFile, err := os.Open(src)
    37  	if err != nil {
    38  		return err
    39  	}
    40  	defer func() {
    41  		_ = sourceFile.Close()
    42  	}()
    43  
    44  	destFile, err := os.OpenFile(dest, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, sourceFileInfo.Mode())
    45  	if err != nil {
    46  		return err
    47  	}
    48  	defer func() {
    49  		_ = destFile.Close()
    50  	}()
    51  
    52  	_, err = io.Copy(destFile, sourceFile)
    53  
    54  	return err
    55  }
    56  
    57  // MoveFile moves a file from src to dest.
    58  func MoveFile(src, dest string) error {
    59  	err := os.Rename(src, dest)
    60  	if err != nil && strings.Contains(err.Error(), "invalid cross-device link") {
    61  		// When calling os.Rename(), an "invalid cross-device link" error may occur
    62  		// if the source and destination files are on different file systems.
    63  		// In this case, the file is moved by copying and then deleting the source file,
    64  		// although it is less efficient than os.Rename().
    65  		klog.V(4).Infof("cannot rename %v to %v due to %v, attempting an alternative method", src, dest, err)
    66  		if err := CopyFile(src, dest); err != nil {
    67  			return errors.Wrapf(err, "failed to copy file %v to %v", src, dest)
    68  		}
    69  		return os.Remove(src)
    70  	}
    71  	return err
    72  }
    73
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