Refactor: move cli logic into cli client

First of a few refactors to allow multiple clients / frontends for
Delve. Current implementation now uses a cli client, but conceivably we
could have an http or socket based client as well.

client/cli/cli.go

@@ -0,0 +1,136 @@
+package cli
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+
+	"github.com/derekparker/delve/command"
+	"github.com/derekparker/delve/goreadline"
+	"github.com/derekparker/delve/proctl"
+)
+
+const historyFile string = ".dbg_history"
+
+func Run(run bool, pid int, args ...[]string) {
+	var (
+		dbp *proctl.DebuggedProcess
+		err error
+	)
+
+	switch {
+	case run:
+		const debugname = "debug"
+		cmd := exec.Command("go", "build", "-o", debugname, "-gcflags", "-N -l")
+		err := cmd.Run()
+		if err != nil {
+			die(1, "Could not compile program:", err)
+		}
+		defer os.Remove(debugname)
+
+		dbp, err = proctl.Launch(append([]string{"./" + debugname}, flag.Args()...))
+		if err != nil {
+			die(1, "Could not launch program:", err)
+		}
+	case pid != 0:
+		dbp, err = proctl.Attach(pid)
+		if err != nil {
+			die(1, "Could not attach to process:", err)
+		}
+	default:
+		dbp, err = proctl.Launch(flag.Args())
+		if err != nil {
+			die(1, "Could not launch program:", err)
+		}
+	}
+
+	cmds := command.DebugCommands()
+	goreadline.LoadHistoryFromFile(historyFile)
+	fmt.Println("Type 'help' for list of commands.")
+
+	for {
+		cmdstr, err := promptForInput()
+		if err != nil {
+			if err == io.EOF {
+				handleExit(dbp, 0)
+			}
+			die(1, "Prompt for input failed.\n")
+		}
+
+		cmdstr, args := parseCommand(cmdstr)
+
+		if cmdstr == "exit" {
+			handleExit(dbp, 0)
+		}
+
+		cmd := cmds.Find(cmdstr)
+		err = cmd(dbp, args...)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Command failed: %s\n", err)
+		}
+	}
+}
+
+func handleExit(dbp *proctl.DebuggedProcess, status int) {
+	errno := goreadline.WriteHistoryToFile(historyFile)
+	fmt.Println("readline:", errno)
+
+	prompt := "Would you like to kill the process? [y/n]"
+	answerp := goreadline.ReadLine(&prompt)
+	if answerp == nil {
+		die(2, io.EOF)
+	}
+	answer := strings.TrimSuffix(*answerp, "\n")
+
+	for pc := range dbp.BreakPoints {
+		if _, err := dbp.Clear(pc); err != nil {
+			fmt.Printf("Can't clear breakpoint @%x: %s\n", pc, err)
+		}
+	}
+
+	fmt.Println("Detaching from process...")
+	err := syscall.PtraceDetach(dbp.Process.Pid)
+	if err != nil {
+		die(2, "Could not detach", err)
+	}
+
+	if answer == "y" {
+		fmt.Println("Killing process", dbp.Process.Pid)
+
+		err := dbp.Process.Kill()
+		if err != nil {
+			fmt.Println("Could not kill process", err)
+		}
+	}
+
+	die(status, "Hope I was of service hunting your bug!")
+}
+
+func die(status int, args ...interface{}) {
+	fmt.Fprint(os.Stderr, args)
+	fmt.Fprint(os.Stderr, "\n")
+	os.Exit(status)
+}
+
+func parseCommand(cmdstr string) (string, []string) {
+	vals := strings.Split(cmdstr, " ")
+	return vals[0], vals[1:]
+}
+
+func promptForInput() (string, error) {
+	prompt := "(dlv) "
+	linep := goreadline.ReadLine(&prompt)
+	if linep == nil {
+		return "", io.EOF
+	}
+	line := strings.TrimSuffix(*linep, "\n")
+	if line != "" {
+		goreadline.AddHistory(line)
+	}
+
+	return line, nil
+}