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copy.go
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copy.go
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package utils
import (
"fmt"
"io"
"os"
"path"
"path/filepath"
)
// CopyFile copies a file from src to dst. If src and dst files exist, and are
// the same, then return success. Otherise, attempt to create a hard link
// between the two files. If that fail, copy the file contents from src to dst.
func CopyFile(src, dst string) (err error) {
absSrc, err := filepath.Abs(src)
if err != nil {
return fmt.Errorf("failed to get absolute path of source file %q: %w", src, err)
}
sfi, err := os.Stat(src)
if err != nil {
err = fmt.Errorf("couldn't stat source file %q: %w", absSrc, err)
return
}
if !sfi.Mode().IsRegular() {
// Cannot copy non-regular files (e.g., directories, symlinks, devices, etc.)
return fmt.Errorf("non-regular source file %s (%q)", absSrc, sfi.Mode().String())
}
dpath := filepath.Dir(dst)
exists, err := Exists(dpath)
if err != nil {
return err
}
if !exists {
err = fmt.Errorf("destination directory doesn't exist: %q", dpath)
return
}
var dfi os.FileInfo
dfi, err = os.Stat(dst)
if err != nil {
if !os.IsNotExist(err) {
return
}
} else {
if !(dfi.Mode().IsRegular()) {
return fmt.Errorf("non-regular destination file %s (%q)", dfi.Name(), dfi.Mode().String())
}
if os.SameFile(sfi, dfi) {
return
}
}
if err = os.Link(src, dst); err == nil {
return
}
err = copyFileContents(src, dst)
return err
}
// copyFileContents copies the contents of the file named src to the file named
// by dst. The file will be created if it does not already exist. If the
// destination file exists, all it's contents will be replaced by the contents
// of the source file.
func copyFileContents(src, dst string) (err error) {
in, err := os.Open(src)
if err != nil {
return
}
defer in.Close()
out, err := os.Create(dst)
if err != nil {
return
}
defer func() {
if cerr := out.Close(); err == nil {
err = cerr
}
}()
if _, err = io.Copy(out, in); err != nil {
return
}
err = out.Sync()
return
}
// CopyRecursive copies files and directories recursively.
func CopyRecursive(src, dst string) error {
sfi, err := os.Stat(src)
if err != nil {
return err
}
if !sfi.Mode().IsDir() {
return CopyFile(src, dst)
}
if _, err := os.Stat(dst); os.IsNotExist(err) {
if err := os.MkdirAll(dst, sfi.Mode()); err != nil {
return fmt.Errorf("failed to create directory %q: %s", dst, err)
}
}
entries, err := os.ReadDir(src)
if err != nil {
return err
}
for _, entry := range entries {
srcPath := path.Join(src, entry.Name())
dstPath := path.Join(dst, entry.Name())
srcFi, err := os.Stat(srcPath)
if err != nil {
return err
}
switch srcFi.Mode() & os.ModeType {
case os.ModeDir:
if err := CopyRecursive(srcPath, dstPath); err != nil {
return err
}
case os.ModeSymlink:
link, err := os.Readlink(srcPath)
if err != nil {
return err
}
if err := os.Symlink(link, dstPath); err != nil {
return err
}
default:
if err := CopyFile(srcPath, dstPath); err != nil {
return err
}
}
if srcFi.Mode()&os.ModeSymlink != 0 {
if err := os.Chmod(dstPath, srcFi.Mode()); err != nil {
return err
}
}
}
return nil
}