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package main
import (
"fmt"
"log"
"os"
"os/exec"
"os/signal"
"github.com/codegangsta/cli"
"github.com/docker/libcontainer"
"github.com/docker/libcontainer/namespaces"
)
var execCommand = cli.Command{
Name: "exec",
Usage: "execute a new command inside a container",
Action: execAction,
}
func execAction(context *cli.Context) {
var nspid, exitCode int
container, err := loadContainer()
if err != nil {
log.Fatal(err)
}
if nspid, err = readPid(); err != nil && !os.IsNotExist(err) {
log.Fatalf("unable to read pid: %s", err)
}
if nspid > 0 {
err = namespaces.ExecIn(container, nspid, []string(context.Args()))
} else {
term := namespaces.NewTerminal(os.Stdin, os.Stdout, os.Stderr, container.Tty)
exitCode, err = startContainer(container, term, dataPath, []string(context.Args()))
}
if err != nil {
log.Fatalf("failed to exec: %s", err)
}
os.Exit(exitCode)
}
// startContainer starts the container. Returns the exit status or -1 and an
// error.
//
// Signals sent to the current process will be forwarded to container.
func startContainer(container *libcontainer.Container, term namespaces.Terminal, dataPath string, args []string) (int, error) {
var (
cmd *exec.Cmd
sigc = make(chan os.Signal, 10)
)
signal.Notify(sigc)
createCommand := func(container *libcontainer.Container, console, rootfs, dataPath, init string, pipe *os.File, args []string) *exec.Cmd {
cmd = namespaces.DefaultCreateCommand(container, console, rootfs, dataPath, init, pipe, args)
if logPath != "" {
cmd.Env = append(cmd.Env, fmt.Sprintf("log=%s", logPath))
}
return cmd
}
startCallback := func() {
go func() {
for sig := range sigc {
cmd.Process.Signal(sig)
}
}()
}
return namespaces.Exec(container, term, "", dataPath, args, createCommand, startCallback)
}
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