72 lines
1.9 KiB
Go
72 lines
1.9 KiB
Go
package fileutils // import "github.com/docker/docker/pkg/fileutils"
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import (
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"fmt"
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"io"
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"os"
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"path/filepath"
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)
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// CopyFile copies from src to dst until either EOF is reached
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// on src or an error occurs. It verifies src exists and removes
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// the dst if it exists.
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func CopyFile(src, dst string) (int64, error) {
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cleanSrc := filepath.Clean(src)
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cleanDst := filepath.Clean(dst)
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if cleanSrc == cleanDst {
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return 0, nil
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}
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sf, err := os.Open(cleanSrc)
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if err != nil {
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return 0, err
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}
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defer sf.Close()
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if err := os.Remove(cleanDst); err != nil && !os.IsNotExist(err) {
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return 0, err
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}
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df, err := os.Create(cleanDst)
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if err != nil {
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return 0, err
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}
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defer df.Close()
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return io.Copy(df, sf)
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}
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// ReadSymlinkedDirectory returns the target directory of a symlink.
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// The target of the symbolic link may not be a file.
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func ReadSymlinkedDirectory(path string) (realPath string, err error) {
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if realPath, err = filepath.Abs(path); err != nil {
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return "", fmt.Errorf("unable to get absolute path for %s: %w", path, err)
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}
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if realPath, err = filepath.EvalSymlinks(realPath); err != nil {
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return "", fmt.Errorf("failed to canonicalise path for %s: %w", path, err)
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}
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realPathInfo, err := os.Stat(realPath)
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if err != nil {
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return "", fmt.Errorf("failed to stat target '%s' of '%s': %w", realPath, path, err)
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}
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if !realPathInfo.Mode().IsDir() {
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return "", fmt.Errorf("canonical path points to a file '%s'", realPath)
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}
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return realPath, nil
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}
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// CreateIfNotExists creates a file or a directory only if it does not already exist.
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func CreateIfNotExists(path string, isDir bool) error {
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if _, err := os.Stat(path); err != nil {
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if os.IsNotExist(err) {
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if isDir {
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return os.MkdirAll(path, 0o755)
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}
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if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
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return err
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}
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f, err := os.OpenFile(path, os.O_CREATE, 0o755)
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if err != nil {
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return err
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}
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f.Close()
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}
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}
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return nil
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}
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