Flag to set working directory (#650)

* proc: Add `wd` to Launch

This change adds the `wd` arg which specify working directory of the
program.

Fixes #295

* service/debugger: Add `Wd` field to debugger.Config

This change adds the `Wd` field which specify working directory of the
program launched by debugger.

Fixes #295

* service: Add `Wd` to service.Config

This change adds the `Wd` field which specify working directory of the
program debugger will launch.

Fixes #295

* cmd/dlv: Add `Wd` flag

This change adds `Wd` flag which specify working directory of the
program which launched by debugger.

Fixes #295

* only set the Linux working directory if it is set,
stub out param in darwin and windows

* set working directory for Windows
https://godoc.org/golang.org/x/sys/windows#CreateProcess
https://msdn.microsoft.com/en-us/library/windows/desktop/ms682425(v=vs.85).aspx

* Windows workingDir must be an *uint16

* attempt to chdir on darwin via @yuntan

* proc/exec_darwin.c: fix working directory for darwin

* Add tests to check if working directory works.
* Fix darwin implementation of fork/exec, which paniced if
  child fork returned.

* cmd, service: rename Wd to WorkingDir

_fixtures/workdir.go

+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	pwd, err := os.Getwd()
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	fmt.Println(pwd)
+}

cmd/dlv/cmds/commands.go

@@ -39,6 +39,8 @@ var (
 	InitFile string
 	// BuildFlags is the flags passed during compiler invocation.
 	BuildFlags string
+	// WorkingDir is the working directory for running the program.
+	WorkingDir string
 
 	// RootCommand is the root of the command tree.
 	RootCommand *cobra.Command
@@ -86,6 +88,7 @@ func New() *cobra.Command {
 	RootCommand.PersistentFlags().IntVar(&APIVersion, "api-version", 1, "Selects API version when headless.")
 	RootCommand.PersistentFlags().StringVar(&InitFile, "init", "", "Init file, executed by the terminal client.")
 	RootCommand.PersistentFlags().StringVar(&BuildFlags, "build-flags", buildFlagsDefault, "Build flags, to be passed to the compiler.")
+	RootCommand.PersistentFlags().StringVar(&WorkingDir, "wd", ".", "Working directory for running the program.")
 
 	// 'attach' subcommand.
 	attachCommand := &cobra.Command{
@@ -231,8 +234,12 @@ func debugCmd(cmd *cobra.Command, args []string) {
 			return 1
 		}
 		defer os.Remove(fp)
-
-		processArgs := append([]string{"./" + debugname}, targetArgs...)
+		abs, err := filepath.Abs(debugname)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "%v\n", err)
+			return 1
+		}
+		processArgs := append([]string{abs}, targetArgs...)
 		return execute(0, processArgs, conf, executingGeneratedFile)
 	}()
 	os.Exit(status)
@@ -275,6 +282,7 @@ func traceCmd(cmd *cobra.Command, args []string) {
 			ProcessArgs: processArgs,
 			AttachPid:   traceAttachPid,
 			APIVersion:  2,
+			WorkingDir:  WorkingDir,
 		}, Log)
 		if err := server.Run(); err != nil {
 			fmt.Fprintln(os.Stderr, err)
@@ -398,6 +406,7 @@ func execute(attachPid int, processArgs []string, conf *config.Config, kind exec
 			AttachPid:   attachPid,
 			AcceptMulti: AcceptMulti,
 			APIVersion:  APIVersion,
+			WorkingDir:  WorkingDir,
 		}, Log)
 	default:
 		fmt.Println("Unknown API version %d", APIVersion)

proc/exec_darwin.c

 #include "exec_darwin.h"
+#include "stdio.h"
 
 extern char** environ;
 
@@ -12,6 +13,7 @@ close_exec_pipe(int fd[2]) {
 
 int
 fork_exec(char *argv0, char **argv, int size,
+		char *wd,
 		task_t *task,
 		mach_port_t *port_set,
 		mach_port_t *exception_port,
@@ -53,7 +55,7 @@ fork_exec(char *argv0, char **argv, int size,
 	}
 
 	// Fork succeeded, we are in the child.
-	int pret;
+	int pret, cret;
 	char sig;
 
 	close(fd[1]);
@@ -62,7 +64,8 @@ fork_exec(char *argv0, char **argv, int size,
 
 	// Create a new process group.
 	if (setpgid(0, 0) < 0) {
-		return -1;
+		perror("setpgid");
+		exit(1);
 	}
 
 	// Set errno to zero before a call to ptrace.
@@ -70,11 +73,29 @@ fork_exec(char *argv0, char **argv, int size,
 	// for successful calls.
 	errno = 0;
 	pret = ptrace(PT_TRACE_ME, 0, 0, 0);
-	if (pret != 0 && errno != 0) return -errno;
+	if (pret != 0 && errno != 0) {
+		perror("ptrace");
+		exit(1);
+	}
+
+	// Change working directory if wd is not empty.
+	if (wd && wd[0]) {
+		errno = 0;
+		cret = chdir(wd);
+		if (cret != 0 && errno != 0) {
+			char *error_msg;
+			asprintf(&error_msg, "%s '%s'", "chdir", wd);
+			perror(error_msg);
+			exit(1);
+		}
+	}
 
 	errno = 0;
 	pret = ptrace(PT_SIGEXC, 0, 0, 0);
-	if (pret != 0 && errno != 0) return -errno;
+	if (pret != 0 && errno != 0) {
+		perror("ptrace");
+		exit(1);
+	}
 
 	// Create the child process.
 	execve(argv0, argv, environ);

proc/exec_darwin.h

@@ -7,4 +7,4 @@
 #include <fcntl.h>
 
 int
-fork_exec(char *, char **, int, task_t*, mach_port_t*, mach_port_t*, mach_port_t*);
+fork_exec(char *, char **, int, char *, task_t*, mach_port_t*, mach_port_t*, mach_port_t*);

proc/proc_darwin.go

@@ -37,12 +37,11 @@ type OSProcessDetails struct {
 // custom fork/exec process in order to take advantage of
 // PT_SIGEXC on Darwin which will turn Unix signals into
 // Mach exceptions.
-func Launch(cmd []string) (*Process, error) {
+func Launch(cmd []string, wd string) (*Process, error) {
 	// check that the argument to Launch is an executable file
 	if fi, staterr := os.Stat(cmd[0]); staterr == nil && (fi.Mode()&0111) == 0 {
 		return nil, NotExecutableErr
 	}
-
 	argv0Go, err := filepath.Abs(cmd[0])
 	if err != nil {
 		return nil, err
@@ -69,6 +68,7 @@ func Launch(cmd []string) (*Process, error) {
 	var pid int
 	dbp.execPtraceFunc(func() {
 		ret := C.fork_exec(argv0, &argvSlice[0], C.int(len(argvSlice)),
+			C.CString(wd),
 			&dbp.os.task, &dbp.os.portSet, &dbp.os.exceptionPort,
 			&dbp.os.notificationPort)
 		pid = int(ret)

proc/proc_linux.go

@@ -45,8 +45,8 @@ type OSProcessDetails struct {
 
 // Launch creates and begins debugging a new process. First entry in
 // `cmd` is the program to run, and then rest are the arguments
-// to be supplied to that process.
-func Launch(cmd []string) (*Process, error) {
+// to be supplied to that process. `wd` is working directory of the program.
+func Launch(cmd []string, wd string) (*Process, error) {
 	var (
 		proc *exec.Cmd
 		err  error
@@ -62,6 +62,9 @@ func Launch(cmd []string) (*Process, error) {
 		proc.Stdout = os.Stdout
 		proc.Stderr = os.Stderr
 		proc.SysProcAttr = &syscall.SysProcAttr{Ptrace: true, Setpgid: true}
+		if wd != "" {
+			proc.Dir = wd
+		}
 		err = proc.Start()
 	})
 	if err != nil {

proc/proc_test.go

@@ -33,7 +33,7 @@ func TestMain(m *testing.M) {
 
 func withTestProcess(name string, t testing.TB, fn func(p *Process, fixture protest.Fixture)) {
 	fixture := protest.BuildFixture(name)
-	p, err := Launch([]string{fixture.Path})
+	p, err := Launch([]string{fixture.Path}, ".")
 	if err != nil {
 		t.Fatal("Launch():", err)
 	}
@@ -46,9 +46,9 @@ func withTestProcess(name string, t testing.TB, fn func(p *Process, fixture prot
 	fn(p, fixture)
 }
 
-func withTestProcessArgs(name string, t testing.TB, fn func(p *Process, fixture protest.Fixture), args []string) {
+func withTestProcessArgs(name string, t testing.TB, wd string, fn func(p *Process, fixture protest.Fixture), args []string) {
 	fixture := protest.BuildFixture(name)
-	p, err := Launch(append([]string{fixture.Path}, args...))
+	p, err := Launch(append([]string{fixture.Path}, args...), wd)
 	if err != nil {
 		t.Fatal("Launch():", err)
 	}
@@ -1739,17 +1739,17 @@ func TestCmdLineArgs(t *testing.T) {
 	}
 
 	// make sure multiple arguments (including one with spaces) are passed to the binary correctly
-	withTestProcessArgs("testargs", t, expectSuccess, []string{"test"})
-	withTestProcessArgs("testargs", t, expectSuccess, []string{"test", "pass flag"})
+	withTestProcessArgs("testargs", t, ".", expectSuccess, []string{"test"})
+	withTestProcessArgs("testargs", t, ".", expectSuccess, []string{"test", "pass flag"})
 	// check that arguments with spaces are *only* passed correctly when correctly called
-	withTestProcessArgs("testargs", t, expectPanic, []string{"test pass", "flag"})
-	withTestProcessArgs("testargs", t, expectPanic, []string{"test", "pass", "flag"})
-	withTestProcessArgs("testargs", t, expectPanic, []string{"test pass flag"})
+	withTestProcessArgs("testargs", t, ".", expectPanic, []string{"test pass", "flag"})
+	withTestProcessArgs("testargs", t, ".", expectPanic, []string{"test", "pass", "flag"})
+	withTestProcessArgs("testargs", t, ".", expectPanic, []string{"test pass flag"})
 	// and that invalid cases (wrong arguments or no arguments) panic
 	withTestProcess("testargs", t, expectPanic)
-	withTestProcessArgs("testargs", t, expectPanic, []string{"invalid"})
-	withTestProcessArgs("testargs", t, expectPanic, []string{"test", "invalid"})
-	withTestProcessArgs("testargs", t, expectPanic, []string{"invalid", "pass flag"})
+	withTestProcessArgs("testargs", t, ".", expectPanic, []string{"invalid"})
+	withTestProcessArgs("testargs", t, ".", expectPanic, []string{"test", "invalid"})
+	withTestProcessArgs("testargs", t, ".", expectPanic, []string{"invalid", "pass flag"})
 }
 
 func TestIssue462(t *testing.T) {
@@ -1872,7 +1872,7 @@ func TestIssue509(t *testing.T) {
 	cmd.Dir = nomaindir
 	assertNoError(cmd.Run(), t, "go build")
 	exepath := filepath.Join(nomaindir, "debug")
-	_, err := Launch([]string{exepath})
+	_, err := Launch([]string{exepath}, ".")
 	if err == nil {
 		t.Fatalf("expected error but none was generated")
 	}
@@ -1906,7 +1906,7 @@ func TestUnsupportedArch(t *testing.T) {
 	}
 	defer os.Remove(outfile)
 
-	p, err := Launch([]string{outfile})
+	p, err := Launch([]string{outfile}, ".")
 	switch err {
 	case UnsupportedArchErr:
 		// all good
@@ -2306,3 +2306,23 @@ func TestStepOutPanicAndDirectCall(t *testing.T) {
 		}
 	})
 }
+
+func TestWorkDir(t *testing.T) {
+	wd := os.TempDir()
+	// For Darwin `os.TempDir()` returns `/tmp` which is symlink to `/private/tmp`.
+	if runtime.GOOS == "darwin" {
+		wd = "/private/tmp"
+	}
+	withTestProcessArgs("workdir", t, wd, func(p *Process, fixture protest.Fixture) {
+		addr, _, err := p.goSymTable.LineToPC(fixture.Source, 14)
+		assertNoError(err, t, "LineToPC")
+		p.SetBreakpoint(addr, UserBreakpoint, nil)
+		p.Continue()
+		v, err := evalVariable(p, "pwd")
+		assertNoError(err, t, "EvalVariable")
+		str := constant.StringVal(v.Value)
+		if wd != str {
+			t.Fatalf("Expected %s got %s\n", wd, str)
+		}
+	}, []string{})
+}

proc/proc_windows.go

@@ -26,7 +26,7 @@ type OSProcessDetails struct {
 }
 
 // Launch creates and begins debugging a new process.
-func Launch(cmd []string) (*Process, error) {
+func Launch(cmd []string, wd string) (*Process, error) {
 	argv0Go, err := filepath.Abs(cmd[0])
 	if err != nil {
 		return nil, err
@@ -82,6 +82,13 @@ func Launch(cmd []string) (*Process, error) {
 			return nil, err
 		}
 	}
+	
+	var workingDir *uint16
+	if wd != "" {
+		if workingDir, err = syscall.UTF16PtrFromString(wd); err != nil {
+			return nil, err
+		}
+	}
 
 	// Initialize the startup info and create process
 	si := new(sys.StartupInfo)
@@ -94,7 +101,11 @@ func Launch(cmd []string) (*Process, error) {
 
 	dbp := New(0)
 	dbp.execPtraceFunc(func() {
-		err = sys.CreateProcess(argv0, cmdLine, nil, nil, true, _DEBUG_ONLY_THIS_PROCESS, nil, nil, si, pi)
+		if wd == "" {
+			err = sys.CreateProcess(argv0, cmdLine, nil, nil, true, _DEBUG_ONLY_THIS_PROCESS, nil, nil, si, pi)
+		} else {
+			err = sys.CreateProcess(argv0, cmdLine, nil, nil, true, _DEBUG_ONLY_THIS_PROCESS, nil, workingDir, si, pi)
+		}
 	})
 	if err != nil {
 		return nil, err

service/config.go

@@ -13,6 +13,10 @@ type Config struct {
 	Listener net.Listener
 	// ProcessArgs are the arguments to launch a new process.
 	ProcessArgs []string
+	// WorkingDir is working directory of the new process. This field is used
+	// only when launching a new process.
+	WorkingDir string
+
 	// AttachPid is the PID of an existing process to which the debugger should
 	// attach.
 	AttachPid int

service/debugger/debugger.go

@@ -38,6 +38,10 @@ type Debugger struct {
 type Config struct {
 	// ProcessArgs are the arguments to launch a new process.
 	ProcessArgs []string
+	// WorkingDir is working directory of the new process. This field is used
+	// only when launching a new process.
+	WorkingDir string
+
 	// AttachPid is the PID of an existing process to which the debugger should
 	// attach.
 	AttachPid int
@@ -59,7 +63,7 @@ func New(config *Config) (*Debugger, error) {
 		d.process = p
 	} else {
 		log.Printf("launching process with args: %v", d.config.ProcessArgs)
-		p, err := proc.Launch(d.config.ProcessArgs)
+		p, err := proc.Launch(d.config.ProcessArgs, d.config.WorkingDir)
 		if err != nil {
 			if err != proc.NotExecutableErr && err != proc.UnsupportedArchErr {
 				err = fmt.Errorf("could not launch process: %s", err)
@@ -112,7 +116,7 @@ func (d *Debugger) Restart() error {
 			return err
 		}
 	}
-	p, err := proc.Launch(d.config.ProcessArgs)
+	p, err := proc.Launch(d.config.ProcessArgs, d.config.WorkingDir)
 	if err != nil {
 		return fmt.Errorf("could not launch process: %s", err)
 	}

service/rpccommon/server.go

@@ -111,6 +111,7 @@ func (s *ServerImpl) Run() error {
 	if s.debugger, err = debugger.New(&debugger.Config{
 		ProcessArgs: s.config.ProcessArgs,
 		AttachPid:   s.config.AttachPid,
+		WorkingDir:  s.config.WorkingDir,
 	}); err != nil {
 		return err
 	}

service/test/variables_test.go

@@ -79,7 +79,7 @@ const varTestBreakpointLineNumber = 59
 
 func withTestProcess(name string, t *testing.T, fn func(p *proc.Process, fixture protest.Fixture)) {
 	fixture := protest.BuildFixture(name)
-	p, err := proc.Launch([]string{fixture.Path})
+	p, err := proc.Launch([]string{fixture.Path}, ".")
 	if err != nil {
 		t.Fatal("Launch():", err)
 	}