exec: add Command.ExtraFiles

Allows passing extra fds to the child process.

Fixes #2329

R=rsc, dsymonds
CC=golang-dev
https://golang.org/cl/5162050

diff --git a/src/pkg/exec/exec.go b/src/pkg/exec/exec.go
index 3b20f2008cae0ccdf4905b486cccb76f0c9c0406..aaad50846ea7d88b4a67b52eab185c682fa38643 100644 (file)
--- a/src/pkg/exec/exec.go
+++ b/src/pkg/exec/exec.go
@@ -63,6 +63,11 @@ type Cmd struct {
        Stdout io.Writer
        Stderr io.Writer
 
+       // ExtraFiles specifies additional open files to be inherited by the
+       // new process. It does not include standard input, standard output, or
+       // standard error. If non-nil, entry i becomes file descriptor 3+i.
+       ExtraFiles []*os.File
+
        // SysProcAttr holds optional, operating system-specific attributes.
        // Run passes it to os.StartProcess as the os.ProcAttr's Sys field.
        SysProcAttr *syscall.SysProcAttr
@@ -224,6 +229,7 @@ func (c *Cmd) Start() os.Error {
                }
                c.childFiles = append(c.childFiles, fd)
        }
+       c.childFiles = append(c.childFiles, c.ExtraFiles...)
 
        var err os.Error
        c.Process, err = os.StartProcess(c.Path, c.argv(), &os.ProcAttr{

diff --git a/src/pkg/exec/exec_test.go b/src/pkg/exec/exec_test.go
index 242120faab544fa9af8a7ce9a2e3920dc07669c4..2b36e2535a4def27c788d6664ccf4b58aa3d5431 100644 (file)
--- a/src/pkg/exec/exec_test.go
+++ b/src/pkg/exec/exec_test.go
@@ -9,8 +9,10 @@ import (
        "bytes"
        "fmt"
        "io"
+       "io/ioutil"
        "testing"
        "os"
+       "runtime"
        "strconv"
        "strings"
 )
@@ -139,6 +141,39 @@ func TestPipes(t *testing.T) {
        check("Wait", err)
 }
 
+func TestExtraFiles(t *testing.T) {
+       if runtime.GOOS == "windows" {
+               t.Logf("no operating system support; skipping")
+               return
+       }
+       tf, err := ioutil.TempFile("", "")
+       if err != nil {
+               t.Fatalf("TempFile: %v", err)
+       }
+       defer os.Remove(tf.Name())
+       defer tf.Close()
+
+       const text = "Hello, fd 3!"
+       _, err = tf.Write([]byte(text))
+       if err != nil {
+               t.Fatalf("Write: %v", err)
+       }
+       _, err = tf.Seek(0, os.SEEK_SET)
+       if err != nil {
+               t.Fatalf("Seek: %v", err)
+       }
+
+       c := helperCommand("read3")
+       c.ExtraFiles = []*os.File{tf}
+       bs, err := c.CombinedOutput()
+       if err != nil {
+               t.Fatalf("CombinedOutput: %v", err)
+       }
+       if string(bs) != text {
+               t.Errorf("got %q; want %q", string(bs), text)
+       }
+}
+
 // TestHelperProcess isn't a real test. It's used as a helper process
 // for TestParameterRun.
 func TestHelperProcess(*testing.T) {
@@ -204,6 +239,14 @@ func TestHelperProcess(*testing.T) {
                                os.Exit(1)
                        }
                }
+       case "read3": // read fd 3
+               fd3 := os.NewFile(3, "fd3")
+               bs, err := ioutil.ReadAll(fd3)
+               if err != nil {
+                       fmt.Printf("ReadAll from fd 3: %v", err)
+                       os.Exit(1)
+               }
+               os.Stderr.Write(bs)
        case "exit":
                n, _ := strconv.Atoi(args[0])
                os.Exit(n)