maker/copy.go

// Copyright (C) 2015 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package maker

import (
	"fmt"
	"io"
	"log"
	"os"
)

// CopyFile builds a new Step that copies the file from src to dst, and returns
// the dst entity.
// The step will depend on the src, and the existance of the directory dst is
// inside.
func CopyFile(dst, src Entity) {
	NewStep(copyFile).Creates(dst).DependsOn(src, DirOf(dst))
}

func copyFile(s *Step) error {
	if len(s.inputs) <= 1 {
		return fmt.Errorf("copy needs inputs")
	}
	src := s.inputs[0]
	if !IsFile(src) {
		return fmt.Errorf("cannot copy from %s, not a file", src.Name())
	}
	if len(s.outputs) != 1 {
		return fmt.Errorf("copy expects 1 output, got %d", len(s.outputs))
	}
	dst := s.outputs[0]
	if !IsFile(dst) {
		return fmt.Errorf("cannot copy to %s, not a file", dst.Name())
	}
	if Config.Verbose > 0 {
		log.Printf("-> cp %v to %v", src, dst)
	}
	in, err := os.Open(src.Name())
	if err != nil {
		return err
	}
	defer in.Close()
	out, err := os.Create(dst.Name())
	if err != nil {
		return err
	}
	defer out.Close()
	_, err = io.Copy(out, in)
	if err != nil {
		return err
	}
	return nil
}