Extract files from a zip that was zipped without directories but just files even if files are inside directories

unzip.go

// Iterate through all the zip files in multi-part form-data (memory or disk)
// For each file, extract it to destDir and change permissions of the file to the user one
// If the zip file is a directory , empty subdirectories are ignored
func extractFilesWithUserRights(files []*zip.File, filePath string, username string) error {

	uid, gid, err := getIdentifier(username)
	if err != nil {
		return err
	}

	for _, f := range files {

		// Get relative path because if zip archive is a directory: f.Name is prefixed this dir name
		// relpath is the path of the file inside the zip (by removing prefix)
		// See api/client/http_client.go:112
		relpath := strings.Join(strings.SplitAfter(f.Name, "/")[1:], "")

		// If empty, f.Name is at the root of the zip archive
		// we just have to write it in experiment basepath
		if relpath == "" {

			fpath := filepath.Join(filePath, f.Name)
			extractFile(f, fpath)
			if err != nil {
				return err
			}

			err = os.Chown(fpath, uid, gid)
			if err != nil {
				return err
			}
			continue

		}

		// If not, f.Name contains at least one dir in its filename
		// filepath.Split split relpath in dir(s)+file
		// dPath is the directory part we need to create inside experiment basepth
		dir, _ := filepath.Split(relpath)
		dPath := filepath.Join(filePath, dir)
		fpath := filepath.Join(filePath, relpath)

		if dPath != "" {
			if err := os.MkdirAll(dPath, f.Mode()|0700); err != nil {
				return err
			}

			if err := os.Chown(dPath, uid, gid); err != nil {
				return err
			}
		}

		// Then we copy the file at experiment basepath/relativepath
		extractFile(f, fpath)
		if err != nil {
			return err
		}

		err = os.Chown(fpath, uid, gid)
		if err != nil {
			return err
		}
	}

	return nil
}