os, net, internal/poll: return consistent error for closed socket

In the past we returned "use of closed network connection" when using
a closed network descriptor in some way. In CL 36799 that was changed
to return "use of closed file or network connection". Because programs
have no access to a value of this error type (see issue #4373) they
resort to doing direct string comparisons (see issue #19252). This CL
restores the old error string so that we don't break programs
unnecessarily with the 1.9 release.

This adds a test to the net package for the expected string.

For symmetry check that the os package returns the expected error,
which for os already exists as os.ErrClosed.

Updates #4373.
Fixed #19252.

Change-Id: I5b83fd12cfa03501a077cad9336499b819f4a38b
Reviewed-on: https://go-review.googlesource.com/39997
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 14 insertions, 14 deletions

diff --git a/src/internal/poll/fd_poll_runtime.go b/src/internal/poll/fd_poll_runtime.go
index b1e3a84fc2..08b40c2720 100644
--- a/src/internal/poll/fd_poll_runtime.go
+++ b/src/internal/poll/fd_poll_runtime.go
@@ -62,36 +62,36 @@ func (pd *pollDesc) evict() {
 	runtime_pollUnblock(pd.runtimeCtx)
 }
 
-func (pd *pollDesc) prepare(mode int) error {
+func (pd *pollDesc) prepare(mode int, isFile bool) error {
 	if pd.runtimeCtx == 0 {
 		return nil
 	}
 	res := runtime_pollReset(pd.runtimeCtx, mode)
-	return convertErr(res)
+	return convertErr(res, isFile)
 }
 
-func (pd *pollDesc) prepareRead() error {
-	return pd.prepare('r')
+func (pd *pollDesc) prepareRead(isFile bool) error {
+	return pd.prepare('r', isFile)
 }
 
-func (pd *pollDesc) prepareWrite() error {
-	return pd.prepare('w')
+func (pd *pollDesc) prepareWrite(isFile bool) error {
+	return pd.prepare('w', isFile)
 }
 
-func (pd *pollDesc) wait(mode int) error {
+func (pd *pollDesc) wait(mode int, isFile bool) error {
 	if pd.runtimeCtx == 0 {
 		return errors.New("waiting for unsupported file type")
 	}
 	res := runtime_pollWait(pd.runtimeCtx, mode)
-	return convertErr(res)
+	return convertErr(res, isFile)
 }
 
-func (pd *pollDesc) waitRead() error {
-	return pd.wait('r')
+func (pd *pollDesc) waitRead(isFile bool) error {
+	return pd.wait('r', isFile)
 }
 
-func (pd *pollDesc) waitWrite() error {
-	return pd.wait('w')
+func (pd *pollDesc) waitWrite(isFile bool) error {
+	return pd.wait('w', isFile)
 }
 
 func (pd *pollDesc) waitCanceled(mode int) {
@@ -101,12 +101,12 @@ func (pd *pollDesc) waitCanceled(mode int) {
 	runtime_pollWaitCanceled(pd.runtimeCtx, mode)
 }
 
-func convertErr(res int) error {
+func convertErr(res int, isFile bool) error {
 	switch res {
 	case 0:
 		return nil
 	case 1:
-		return ErrClosing
+		return errClosing(isFile)
 	case 2:
 		return ErrTimeout
 	}