github.com/searKing/golang/go@v1.2.117/io/copy.go (about)

     1  // Copyright 2020 The searKing Author. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package io
     6  
     7  import (
     8  	"errors"
     9  	"io"
    10  	"os"
    11  	"path/filepath"
    12  )
    13  
    14  var ErrNotImplemented = errors.New("not implemented")
    15  
    16  // Mode indicates whether to use hardlink or copy content
    17  type Mode int
    18  
    19  const (
    20  	// Content creates a new file, and copies the content of the file
    21  	Content Mode = iota
    22  	// Hardlink creates a new hardlink to the existing file
    23  	Hardlink
    24  )
    25  
    26  func CopyRegular(srcPath, dstPath string, fileInfo os.FileInfo) error {
    27  	srcFile, err := os.Open(srcPath)
    28  	if err != nil {
    29  		return err
    30  	}
    31  	defer srcFile.Close()
    32  
    33  	// If the destination file already exists, we shouldn't blow it away
    34  	dstFile, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, fileInfo.Mode())
    35  	if err != nil {
    36  		return err
    37  	}
    38  	defer dstFile.Close()
    39  
    40  	if err = doCopyFileClone(srcFile, dstFile); err == nil {
    41  		return nil
    42  	}
    43  
    44  	if err = doCopyWithFileRange(srcFile, dstFile, fileInfo); err == nil {
    45  		return nil
    46  	}
    47  
    48  	return legacyCopy(srcFile, dstFile)
    49  }
    50  
    51  func doCopyFileClone(srcFile, dstFile *os.File) error {
    52  	return copyFileClone(dstFile, srcFile)
    53  }
    54  
    55  func doCopyWithFileRange(srcFile, dstFile *os.File, fileInfo os.FileInfo) error {
    56  	amountLeftToCopy := fileInfo.Size()
    57  
    58  	for amountLeftToCopy > 0 {
    59  		n, err := copyFileRange(int(srcFile.Fd()), nil, int(dstFile.Fd()), nil, int(amountLeftToCopy), 0)
    60  		if err != nil {
    61  			return err
    62  		}
    63  
    64  		amountLeftToCopy = amountLeftToCopy - int64(n)
    65  	}
    66  
    67  	return nil
    68  }
    69  
    70  func legacyCopy(srcFile io.Reader, dstFile io.Writer) error {
    71  	_, err := io.Copy(dstFile, srcFile)
    72  	return err
    73  }
    74  
    75  // CopyDir copies or hardlinks the contents of one directory to another,
    76  // properly handling mods, and soft links
    77  func CopyDir(srcDir, dstDir string, copyMode Mode) error {
    78  	return filepath.Walk(srcDir, func(srcPath string, f os.FileInfo, err error) error {
    79  		if err != nil {
    80  			return err
    81  		}
    82  
    83  		// Rebase path
    84  		relPath, err := filepath.Rel(srcDir, srcPath)
    85  		if err != nil {
    86  			return err
    87  		}
    88  
    89  		dstPath := filepath.Join(dstDir, relPath)
    90  		return copyPath(srcPath, dstPath, f, copyMode)
    91  	})
    92  }