From 10e2ffdf2ca657567fc1708f6387fef69a8445b6 Mon Sep 17 00:00:00 2001
From: Andrew Gerrand <adg@golang.org>
Date: Thu, 29 Aug 2013 14:41:44 +1000
Subject: os/exec: return idempotent Closer from StdinPipe

Before this fix, it was always an error to use the Close method on the
io.WriteCloser obtained from Cmd.StdinPipe, as it would race with the
Close performed by Cmd.Wait.

Fixes #6270.

R=golang-dev, r, remyoudompheng, bradfitz, dsymonds
CC=golang-dev
https://golang.org/cl/13329043
---
 src/pkg/os/exec/exec_test.go | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

(limited to 'src/pkg/os/exec/exec_test.go')

diff --git a/src/pkg/os/exec/exec_test.go b/src/pkg/os/exec/exec_test.go
index d7e8573a08..c380d6506c 100644
--- a/src/pkg/os/exec/exec_test.go
+++ b/src/pkg/os/exec/exec_test.go
@@ -152,6 +152,34 @@ func TestPipes(t *testing.T) {
 	check("Wait", err)
 }
 
+const stdinCloseTestString = "Some test string."
+
+// Issue 6270.
+func TestStdinClose(t *testing.T) {
+	check := func(what string, err error) {
+		if err != nil {
+			t.Fatalf("%s: %v", what, err)
+		}
+	}
+	cmd := helperCommand("stdinClose")
+	stdin, err := cmd.StdinPipe()
+	check("StdinPipe", err)
+	// Check that we can access methods of the underlying os.File.`
+	if _, ok := stdin.(interface {
+		Fd() uintptr
+	}); !ok {
+		t.Error("can't access methods of underlying *os.File")
+	}
+	check("Start", cmd.Start())
+	go func() {
+		_, err := io.Copy(stdin, strings.NewReader(stdinCloseTestString))
+		check("Copy", err)
+		// Before the fix, this next line would race with cmd.Wait.
+		check("Close", stdin.Close())
+	}()
+	check("Wait", cmd.Wait())
+}
+
 // Issue 5071
 func TestPipeLookPathLeak(t *testing.T) {
 	fd0 := numOpenFDS(t)
@@ -507,6 +535,17 @@ func TestHelperProcess(*testing.T) {
 				os.Exit(1)
 			}
 		}
+	case "stdinClose":
+		b, err := ioutil.ReadAll(os.Stdin)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+			os.Exit(1)
+		}
+		if s := string(b); s != stdinCloseTestString {
+			fmt.Fprintf(os.Stderr, "Error: Read %q, want %q", s, stdinCloseTestString)
+			os.Exit(1)
+		}
+		os.Exit(0)
 	case "read3": // read fd 3
 		fd3 := os.NewFile(3, "fd3")
 		bs, err := ioutil.ReadAll(fd3)
-- 
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