os/exec: fix plan9 build

Fixes build from https://golang.org/cl/12152

Plan 9 lacks syscall.EPIPE. I was misled by api/go1.txt and also
forgot to use the trybots. :(

Change-Id: I4982fe969ad4a8724090cb03009bfb21780d8aa7
Reviewed-on: https://go-review.googlesource.com/12153
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
index e3c6fb62b11f8af81fa983c1ddc68ab6879cb6e8..1f5fb6e39c912659b1bc04786f0211601e64d575 100644 (file)
--- a/src/os/exec/exec.go
+++ b/src/os/exec/exec.go
@@ -157,6 +157,11 @@ func (c *Cmd) argv() []string {
        return []string{c.Path}
 }
 
+// skipStdinCopyError optionally specifies a function which reports
+// whether the provided the stdin copy error should be ignored.
+// It is non-nil everywhere but Plan 9, which lacks EPIPE. See exec_posix.go.
+var skipStdinCopyError func(error) bool
+
 func (c *Cmd) stdin() (f *os.File, err error) {
        if c.Stdin == nil {
                f, err = os.Open(os.DevNull)
@@ -180,16 +185,9 @@ func (c *Cmd) stdin() (f *os.File, err error) {
        c.closeAfterWait = append(c.closeAfterWait, pw)
        c.goroutine = append(c.goroutine, func() error {
                _, err := io.Copy(pw, c.Stdin)
-
-               // Ignore EPIPE errors copying to stdin if the program
-               // completed successfully otherwise.
-               // See Issue 9173.
-               if pe, ok := err.(*os.PathError); ok &&
-                       pe.Op == "write" && pe.Path == "|1" &&
-                       pe.Err == syscall.EPIPE {
+               if skip := skipStdinCopyError; skip != nil && skip(err) {
                        err = nil
                }
-
                if err1 := pw.Close(); err == nil {
                        err = err1
                }

diff --git a/src/os/exec/exec_posix.go b/src/os/exec/exec_posix.go
new file mode 100644 (file)
index 0000000..5e11137
--- /dev/null
+++ b/src/os/exec/exec_posix.go
@@ -0,0 +1,24 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !plan9
+
+package exec
+
+import (
+       "os"
+       "syscall"
+)
+
+func init() {
+       skipStdinCopyError = func(err error) bool {
+               // Ignore EPIPE errors copying to stdin if the program
+               // completed successfully otherwise.
+               // See Issue 9173.
+               pe, ok := err.(*os.PathError)
+               return ok &&
+                       pe.Op == "write" && pe.Path == "|1" &&
+                       pe.Err == syscall.EPIPE
+       }
+}