From cf893f2c67461c8931b97ae70a2228948bd0272f Mon Sep 17 00:00:00 2001
From: Jim Schmidt <jimschmidt@nabancard.com>
Date: Wed, 7 Feb 2024 10:57:31 -0500
Subject: [PATCH] Fix https://github.com/spf13/afero/issues/415

---
 memmap.go      |  2 +-
 memmap_test.go | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/memmap.go b/memmap.go
index d6c744e8..0797f9b8 100644
--- a/memmap.go
+++ b/memmap.go
@@ -245,7 +245,7 @@ func (m *MemMapFs) OpenFile(name string, flag int, perm os.FileMode) (File, erro
 	perm &= chmodBits
 	chmod := false
 	file, err := m.openWrite(name)
-	if err == nil && (flag&os.O_EXCL > 0) {
+	if err == nil && (flag&(os.O_CREATE|os.O_EXCL)) == (os.O_CREATE|os.O_EXCL) {
 		return nil, &os.PathError{Op: "open", Path: name, Err: ErrFileExists}
 	}
 	if os.IsNotExist(err) && (flag&os.O_CREATE > 0) {
diff --git a/memmap_test.go b/memmap_test.go
index c47fadc8..1e93ddf6 100644
--- a/memmap_test.go
+++ b/memmap_test.go
@@ -918,3 +918,25 @@ func TestMemMapFsRename(t *testing.T) {
 		}
 	}
 }
+
+func TestMemMapCreateThenOpen(t *testing.T) {
+	fs := NewMemMapFs()
+	filePath := "/test/data.txt"
+	err := fs.MkdirAll("/test", 0744)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f1, err := fs.OpenFile(filePath, os.O_CREATE|os.O_RDWR|os.O_EXCL, 0644)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = f1.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+	f2, err := fs.OpenFile(filePath, os.O_RDWR|os.O_EXCL, 0644)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f2.Close()
+}