migrate from go-ipfs

extractor.go

@@ -0,0 +1,109 @@
+package tar
+
+import (
+	"archive/tar"
+	"io"
+	"os"
+	gopath "path"
+	fp "path/filepath"
+	"strings"
+)
+
+type Extractor struct {
+	Path string
+}
+
+func (te *Extractor) Extract(reader io.Reader) error {
+	tarReader := tar.NewReader(reader)
+
+	// Check if the output path already exists, so we know whether we should
+	// create our output with that name, or if we should put the output inside
+	// a preexisting directory
+	rootExists := true
+	rootIsDir := false
+	if stat, err := os.Stat(te.Path); err != nil && os.IsNotExist(err) {
+		rootExists = false
+	} else if err != nil {
+		return err
+	} else if stat.IsDir() {
+		rootIsDir = true
+	}
+
+	// files come recursively in order (i == 0 is root directory)
+	for i := 0; ; i++ {
+		header, err := tarReader.Next()
+		if err != nil && err != io.EOF {
+			return err
+		}
+		if header == nil || err == io.EOF {
+			break
+		}
+
+		if header.Typeflag == tar.TypeDir {
+			if err := te.extractDir(header, i); err != nil {
+				return err
+			}
+			continue
+		}
+
+		if err := te.extractFile(header, tarReader, i, rootExists, rootIsDir); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// outputPath returns the path at whicht o place tarPath
+func (te *Extractor) outputPath(tarPath string) string {
+	elems := strings.Split(tarPath, "/") // break into elems
+	elems = elems[1:]                    // remove original root
+
+	path := fp.Join(elems...)     // join elems
+	path = fp.Join(te.Path, path) // rebase on extractor root
+	return path
+}
+
+func (te *Extractor) extractDir(h *tar.Header, depth int) error {
+	path := te.outputPath(h.Name)
+
+	if depth == 0 {
+		// if this is the root root directory, use it as the output path for remaining files
+		te.Path = path
+	}
+
+	err := os.MkdirAll(path, 0755)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (te *Extractor) extractFile(h *tar.Header, r *tar.Reader, depth int, rootExists bool, rootIsDir bool) error {
+	path := te.outputPath(h.Name)
+
+	if depth == 0 { // if depth is 0, this is the only file (we aren't 'ipfs get'ing a directory)
+		if rootExists && rootIsDir {
+			// putting file inside of a root dir.
+			fnameo := gopath.Base(h.Name)
+			fnamen := fp.Base(path)
+			// add back original name if lost.
+			if fnameo != fnamen {
+				path = fp.Join(path, fnameo)
+			}
+		} // else if old file exists, just overwrite it.
+	}
+
+	file, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	_, err = io.Copy(file, r)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}