misc/ios: support go run in go_darwin_arm_exec

The -lldb flag makes it easy to use go run and end up in a debugging
session on darwin/arm.

Change-Id: I556f93e950086a7dff4839f301b9c55f7579f87b
Reviewed-on: https://go-review.googlesource.com/8024
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

diff --git a/misc/ios/go_darwin_arm_exec.go b/misc/ios/go_darwin_arm_exec.go
index 4495f52c90d344f75d1286bb5963c3bf58b28446..5b044f2a931e0349d65dfa28558927b0304663a2 100644 (file)
--- a/misc/ios/go_darwin_arm_exec.go
+++ b/misc/ios/go_darwin_arm_exec.go
@@ -5,6 +5,12 @@
 // This program can be used as go_darwin_arm_exec by the Go tool.
 // It executes binaries on an iOS device using the XCode toolchain
 // and the ios-deploy program: https://github.com/phonegap/ios-deploy
+//
+// This script supports an extra flag, -lldb, that pauses execution
+// just before the main program begins and allows the user to control
+// the remote lldb session. This flag is appended to the end of the
+// script's arguments and is not passed through to the underlying
+// binary.
 package main
 
 import (
@@ -13,6 +19,7 @@ import (
        "flag"
        "fmt"
        "go/build"
+       "io"
        "io/ioutil"
        "log"
        "os"
@@ -139,6 +146,9 @@ func run(bin string, args []string) (err error) {
 
        exec.Command("killall", "ios-deploy").Run()
 
+       var opts options
+       opts, args = parseArgs(args)
+
        // ios-deploy invokes lldb to give us a shell session with the app.
        cmd = exec.Command(
                // lldb tries to be clever with terminals.
@@ -165,8 +175,14 @@ func run(bin string, args []string) (err error) {
                return err
        }
        w := new(bufWriter)
-       cmd.Stdout = w
-       cmd.Stderr = w // everything of interest is on stderr
+       if opts.lldb {
+               mw := io.MultiWriter(w, os.Stderr)
+               cmd.Stdout = mw
+               cmd.Stderr = mw
+       } else {
+               cmd.Stdout = w
+               cmd.Stderr = w // everything of interest is on stderr
+       }
        cmd.Stdin = lldbr
 
        if err := cmd.Start(); err != nil {
@@ -177,9 +193,9 @@ func run(bin string, args []string) (err error) {
        // of moving parts in an iOS test harness (notably lldb) that can
        // swallow useful stdio or cause its own ruckus.
        var timedout chan struct{}
-       if t := parseTimeout(args); t > 1*time.Second {
+       if opts.timeout > 1*time.Second {
                timedout = make(chan struct{})
-               time.AfterFunc(t-1*time.Second, func() {
+               time.AfterFunc(opts.timeout-1*time.Second, func() {
                        close(timedout)
                })
        }
@@ -232,6 +248,14 @@ func run(bin string, args []string) (err error) {
        do(`process handle SIGSEGV --stop false --pass true --notify false`) // does not work
        do(`process handle SIGBUS  --stop false --pass true --notify false`) // does not work
 
+       if opts.lldb {
+               _, err := io.Copy(lldb, os.Stdin)
+               if err != io.EOF {
+                       return err
+               }
+               return nil
+       }
+
        do(`breakpoint set -n getwd`) // in runtime/cgo/gcc_darwin_arm.go
 
        fmt.Fprintln(lldb, `run`)
@@ -257,11 +281,13 @@ func run(bin string, args []string) (err error) {
        }
 
        // Move the current working directory into the faux gopath.
-       do(`breakpoint delete 1`)
-       do(`expr char* $mem = (char*)malloc(512)`)
-       do(`expr $mem = (char*)getwd($mem, 512)`)
-       do(`expr $mem = (char*)strcat($mem, "/` + pkgpath + `")`)
-       do(`call (void)chdir($mem)`)
+       if pkgpath != "src" {
+               do(`breakpoint delete 1`)
+               do(`expr char* $mem = (char*)malloc(512)`)
+               do(`expr $mem = (char*)getwd($mem, 512)`)
+               do(`expr $mem = (char*)strcat($mem, "/` + pkgpath + `")`)
+               do(`call (void)chdir($mem)`)
+       }
 
        // Watch for SIGSEGV. Ideally lldb would never break on SIGSEGV.
        // http://golang.org/issue/10043
@@ -408,20 +434,29 @@ func (w *bufWriter) isPass() bool {
        return bytes.Contains(w.buf, []byte("\nPASS\n")) || bytes.Contains(w.buf, []byte("\nPASS\r"))
 }
 
-func parseTimeout(testArgs []string) (timeout time.Duration) {
-       var args []string
-       for _, arg := range testArgs {
-               if strings.Contains(arg, "test.timeout") {
-                       args = append(args, arg)
+type options struct {
+       timeout time.Duration
+       lldb    bool
+}
+
+func parseArgs(binArgs []string) (opts options, remainingArgs []string) {
+       var flagArgs []string
+       for _, arg := range binArgs {
+               if strings.Contains(arg, "-test.timeout") {
+                       flagArgs = append(flagArgs, arg)
+               }
+               if strings.Contains(arg, "-lldb") {
+                       flagArgs = append(flagArgs, arg)
+                       continue
                }
+               remainingArgs = append(remainingArgs, arg)
        }
        f := flag.NewFlagSet("", flag.ContinueOnError)
-       f.DurationVar(&timeout, "test.timeout", 0, "")
-       f.Parse(args)
-       if debug {
-               log.Printf("parseTimeout of %s, got %s", args, timeout)
-       }
-       return timeout
+       f.DurationVar(&opts.timeout, "test.timeout", 0, "")
+       f.BoolVar(&opts.lldb, "lldb", false, "")
+       f.Parse(flagArgs)
+       return opts, remainingArgs
+
 }
 
 func copyLocalDir(dst, src string) error {