terraform/internal/copy/copy_dir.go

147 lines
3.7 KiB
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package copy
import (
"io"
"os"
"path/filepath"
"strings"
)
// CopyDir recursively copies all of the files within the directory given in
// src to the directory given in dst.
//
// Both directories should already exist. If the destination directory is
// non-empty then the new files will merge in with the old, overwriting any
// files that have a relative path in common between source and destination.
//
// Recursive copying of directories is inevitably a rather opinionated sort of
// operation, so this function won't be appropriate for all use-cases. Some
// of the "opinions" it has are described in the following paragraphs:
//
// Symlinks in the source directory are recreated with the same target in the
// destination directory. If the symlink is to a directory itself, that
// directory is not recursively visited for further copying.
//
// File and directory modes are not preserved exactly, but the executable
// flag is preserved for files on operating systems where it is significant.
//
// Any "dot files" it encounters along the way are skipped, even on platforms
// that do not normally ascribe special meaning to files with names starting
// with dots.
//
// Callers may rely on the above details and other undocumented details of
// this function, so if you intend to change it be sure to review the callers
// first and make sure they are compatible with the change you intend to make.
func CopyDir(dst, src string) error {
src, err := filepath.EvalSymlinks(src)
if err != nil {
return err
}
walkFn := func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
if path == src {
return nil
}
if strings.HasPrefix(filepath.Base(path), ".") {
// Skip any dot files
if info.IsDir() {
return filepath.SkipDir
} else {
return nil
}
}
// The "path" has the src prefixed to it. We need to join our
// destination with the path without the src on it.
dstPath := filepath.Join(dst, path[len(src):])
// we don't want to try and copy the same file over itself.
if eq, err := SameFile(path, dstPath); eq {
return nil
} else if err != nil {
return err
}
// If we have a directory, make that subdirectory, then continue
// the walk.
if info.IsDir() {
if path == filepath.Join(src, dst) {
// dst is in src; don't walk it.
return nil
}
if err := os.MkdirAll(dstPath, 0755); err != nil {
return err
}
return nil
}
// If the current path is a symlink, recreate the symlink relative to
// the dst directory
if info.Mode()&os.ModeSymlink == os.ModeSymlink {
target, err := os.Readlink(path)
if err != nil {
return err
}
return os.Symlink(target, dstPath)
}
// If we have a file, copy the contents.
srcF, err := os.Open(path)
if err != nil {
return err
}
defer srcF.Close()
dstF, err := os.Create(dstPath)
if err != nil {
return err
}
defer dstF.Close()
if _, err := io.Copy(dstF, srcF); err != nil {
return err
}
// Chmod it
return os.Chmod(dstPath, info.Mode())
}
return filepath.Walk(src, walkFn)
}
// SameFile returns true if the two given paths refer to the same physical
// file on disk, using the unique file identifiers from the underlying
// operating system. For example, on Unix systems this checks whether the
// two files are on the same device and have the same inode.
func SameFile(a, b string) (bool, error) {
if a == b {
return true, nil
}
aInfo, err := os.Lstat(a)
if err != nil {
if os.IsNotExist(err) {
return false, nil
}
return false, err
}
bInfo, err := os.Lstat(b)
if err != nil {
if os.IsNotExist(err) {
return false, nil
}
return false, err
}
return os.SameFile(aInfo, bInfo), nil
}