perkeep/dev/devcam/devcam.go

/*
Copyright 2013 The Camlistore Authors.

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 main

import (
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"os/signal"
	"path/filepath"
	"strings"
	"syscall"

	"camlistore.org/pkg/cmdmain"
)

// The path to the Camlistore source tree. Any devcam command
// should be run from there.
var camliSrcRoot string

// sysExec is set to syscall.Exec on platforms that support it.
var sysExec func(argv0 string, argv []string, envv []string) (err error)

// runExec execs bin. If the platform doesn't support exec, it runs it and waits
// for it to finish.
func runExec(bin string, args []string) error {
	if sysExec != nil {
		sysExec(bin, append([]string{filepath.Base(bin)}, args...), os.Environ())
	}

	cmd := exec.Command(bin, args...)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Start(); err != nil {
		return fmt.Errorf("Could not run camput: %v", err)
	}
	go handleSignals(cmd.Process)
	return cmd.Wait()
}

func setenv(key, value string) {
	err := os.Setenv(key, value)
	if err != nil {
		log.Fatalf("Could not set env var %v to %v: %v", key, value, err)
	}
}

// cpDir copies the contents of src dir into dst dir.
// filter is a list of file suffixes to skip. ex: ".go"
func cpDir(src, dst string, filter []string) error {
	return filepath.Walk(src, func(fullpath string, fi os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		for _, suffix := range filter {
			if strings.HasSuffix(fi.Name(), suffix) {
				return nil
			}
		}
		suffix, err := filepath.Rel(src, fullpath)
		if err != nil {
			return fmt.Errorf("Failed to find Rel(%q, %q): %v", src, fullpath, err)
		}
		if fi.IsDir() {
			return nil
		}
		return cpFile(fullpath, filepath.Join(dst, suffix))
	})
}

func cpFile(src, dst string) error {
	sfi, err := os.Stat(src)
	if err != nil {
		return err
	}
	if !sfi.Mode().IsRegular() {
		return fmt.Errorf("cpFile can't deal with non-regular file %s", src)
	}

	dstDir := filepath.Dir(dst)
	if err := os.MkdirAll(dstDir, 0755); err != nil {
		return err
	}

	df, err := os.Create(dst)
	if err != nil {
		return err
	}
	sf, err := os.Open(src)
	if err != nil {
		return err
	}
	defer sf.Close()

	n, err := io.Copy(df, sf)
	if err == nil && n != sfi.Size() {
		err = fmt.Errorf("copied wrong size for %s -> %s: copied %d; want %d", src, dst, n, sfi.Size())
	}
	cerr := df.Close()
	if err == nil {
		err = cerr
	}
	return err
}

func handleSignals(camliProc *os.Process) {
	c := make(chan os.Signal, 1)
	signal.Notify(c, syscall.SIGTERM, syscall.SIGINT, syscall.SIGQUIT)
	for {
		sig := <-c
		sysSig, ok := sig.(syscall.Signal)
		if !ok {
			log.Fatal("Not a unix signal")
		}
		switch sysSig {
		case syscall.SIGTERM, syscall.SIGINT, syscall.SIGQUIT:
			log.Printf("Received %v signal, terminating.", sig)
			err := camliProc.Kill()
			if err != nil {
				log.Fatalf("Failed to kill child: %v ", err)
			}
		default:
			log.Fatal("Received another signal, should not happen.")
		}
	}
}

func checkCamliSrcRoot() {
	if _, err := os.Stat("make.go"); err != nil {
		if !os.IsNotExist(err) {
			log.Fatalf("Could not stat make.go: %v", err)
		}
		log.Fatal("./make.go not found; devcam needs to be run from the Camlistore source tree root.")
	}
	cwd, err := os.Getwd()
	if err != nil {
		log.Fatal(err)
	}
	camliSrcRoot = cwd
}

func main() {
	checkCamliSrcRoot()
	// TODO(mpl): usage error is not really correct for devcam.
	// See if I can reimplement it while still using cmdmain.Main().
	cmdmain.Main()
}