From b66a064ddfb8f613c876e7bafddcbe0dce280730 Mon Sep 17 00:00:00 2001
From: Nicola Murino <nicola.murino@gmail.com>
Date: Wed, 29 Oct 2025 21:24:06 +0100
Subject: [PATCH] don't panic on double close

---
 pipeat.go      | 14 ++++++++++----
 pipeat_test.go | 17 +++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/pipeat.go b/pipeat.go
index 549a8a7..a092a29 100644
--- a/pipeat.go
+++ b/pipeat.go
@@ -102,8 +102,11 @@ func (f *pipeFile) readerror() error {
 func (f *pipeFile) setReaderror(err error) {
 	f.dataLock.Lock()
 	defer f.dataLock.Unlock()
-	f.rerr = err
-	close(f.eor)
+
+	if f.rerr == nil {
+		f.rerr = err
+		close(f.eor)
+	}
 	f.rCond.Broadcast()
 	f.wCond.Broadcast()
 }
@@ -148,8 +151,11 @@ func (f *pipeFile) writeerror() error {
 func (f *pipeFile) setWriteerror(err error) {
 	f.dataLock.Lock()
 	defer f.dataLock.Unlock()
-	f.werr = err
-	close(f.eow)
+
+	if f.werr == nil {
+		f.werr = err
+		close(f.eow)
+	}
 	f.rCond.Broadcast()
 	f.wCond.Broadcast()
 }
diff --git a/pipeat_test.go b/pipeat_test.go
index a7cff4a..f909671 100644
--- a/pipeat_test.go
+++ b/pipeat_test.go
@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"errors"
 	"io"
+	"io/fs"
 	"math/rand"
 	"strings"
 	"sync"
@@ -534,3 +535,19 @@ func TestUnlockWriteOnWriterClose(t *testing.T) {
 	assert.Equal(t, errTest, err)
 	r.Close()
 }
+
+func TestDoubleClose(t *testing.T) {
+	r, w, err := Pipe()
+	if err != nil {
+		panic(err)
+	}
+	err = r.Close()
+	assert.NoError(t, err)
+	err = w.Close()
+	assert.NoError(t, err)
+
+	err = r.Close()
+	assert.ErrorIs(t, err, fs.ErrClosed)
+	err = w.Close()
+	assert.NoError(t, err)
+}