maker/command.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 (
	"bytes"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

var (
	// EnvVars holds the environment overrides used when spawning external commands.
	EnvVars = map[string][]string{}
)

// Command builds and returns a new Step that runs the specified external binary
// with the supplied arguments. The newly created Step will be made to depend on
// the binary.
func Command(binary Entity, args ...string) *Step {
	wd := Paths.Root
	return NewStep(func(step *Step) error {
		cmd := exec.Command(binary.Name(), args...)
		var output bytes.Buffer
		if Config.Verbose > 1 {
			cmd.Stdout = &output
			cmd.Stderr = &output
		} else {
			cmd.Stdout = os.Stdout
			cmd.Stderr = os.Stderr
		}

		cmd.Env = getEnvVars()
		cmd.Dir = wd
		if Config.Verbose > 0 {
			log.Printf("-> %s", strings.Join(cmd.Args, " "))
		}
		if Config.Verbose > 1 {
			log.Printf("Working directory: %v", cmd.Dir)
			log.Printf("Environment:")
			for _, v := range cmd.Env {
				log.Printf("• %s", v)
			}
		}
		return cmd.Run()
	}).DependsOn(binary)
}

type envVar struct {
	key, value string
}

func getEnvVars() []string {
	env := map[string]envVar{}
	for _, pair := range os.Environ() {
		v := strings.LastIndex(pair, "=")
		key, value := pair[:v], pair[v+1:]
		env[strings.ToUpper(key)] = envVar{key, value}
	}

	sep := fmt.Sprintf("%c", filepath.ListSeparator)

	for key, values := range EnvVars {
		keyUpper := strings.ToUpper(key)
		if existing, found := env[keyUpper]; found {
			values = append(values, existing.value)
			env[keyUpper] = envVar{existing.key, strings.Join(values, sep)}
		} else {
			env[keyUpper] = envVar{key, strings.Join(values, sep)}
		}
	}

	vars := []string{}
	for _, v := range env {
		vars = append(vars, v.key+"="+v.value)
	}
	return vars
}