os/exec: ignore some pipe write errors on windows

This change is windows version of CL 12152.
It also extends test to cover scenarios reported on issue #20445.
Some source files copied and renamed to make code clearer.

Fixes #20445

Change-Id: Idd2f636f27c6bd5cfe98017ba2df911358263382
Reviewed-on: https://go-review.googlesource.com/43910
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 27 insertions, 11 deletions

diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go
index 95af597f15..0132906933 100644
--- a/src/os/exec/exec_test.go
+++ b/src/os/exec/exec_test.go
@@ -877,25 +877,41 @@ func TestHelperProcess(*testing.T) {
 	}
 }
 
+type delayedInfiniteReader struct{}
+
+func (delayedInfiniteReader) Read(b []byte) (int, error) {
+	time.Sleep(100 * time.Millisecond)
+	for i := range b {
+		b[i] = 'x'
+	}
+	return len(b), nil
+}
+
 // Issue 9173: ignore stdin pipe writes if the program completes successfully.
 func TestIgnorePipeErrorOnSuccess(t *testing.T) {
 	testenv.MustHaveExec(t)
 
-	// We really only care about testing this on Unixy things.
-	if runtime.GOOS == "windows" || runtime.GOOS == "plan9" {
+	// We really only care about testing this on Unixy and Windowsy things.
+	if runtime.GOOS == "plan9" {
 		t.Skipf("skipping test on %q", runtime.GOOS)
 	}
 
-	cmd := helperCommand(t, "echo", "foo")
-	var out bytes.Buffer
-	cmd.Stdin = strings.NewReader(strings.Repeat("x", 10<<20))
-	cmd.Stdout = &out
-	if err := cmd.Run(); err != nil {
-		t.Fatal(err)
-	}
-	if got, want := out.String(), "foo\n"; got != want {
-		t.Errorf("output = %q; want %q", got, want)
+	testWith := func(r io.Reader) func(*testing.T) {
+		return func(t *testing.T) {
+			cmd := helperCommand(t, "echo", "foo")
+			var out bytes.Buffer
+			cmd.Stdin = r
+			cmd.Stdout = &out
+			if err := cmd.Run(); err != nil {
+				t.Fatal(err)
+			}
+			if got, want := out.String(), "foo\n"; got != want {
+				t.Errorf("output = %q; want %q", got, want)
+			}
+		}
 	}
+	t.Run("10MB", testWith(strings.NewReader(strings.Repeat("x", 10<<20))))
+	t.Run("Infinite", testWith(delayedInfiniteReader{}))
 }
 
 type badWriter struct{}