unix: fix MmapPtr test failing on OpenBSD

ncruces · gopherbot · commit c892bb7ec2a2 · 2024-06-26T17:48:03.000Z
OpenBSD apparently doesn't allow unmapping address space if part of the region is already unmapped. This tweaks the test so that munmapping twice no longer happens. Fixes golang/go#68181 Change-Id: I588255f5e10ec015dbb7188eac79cee6be570680 GitHub-Last-Rev: 2535abd GitHub-Pull-Request: #199 Cq-Include-Trybots: luci.golang.try:go1.22-openbsd-amd64 Reviewed-on: https://go-review.googlesource.com/c/sys/+/595095 TryBot-Bypass: Ian Lance Taylor <iant@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> Auto-Submit: Ian Lance Taylor <iant@golang.org>
diff --git a/unix/mmap_unix_test.go b/unix/mmap_unix_test.go
@@ -9,7 +9,6 @@ package unix_test
 import (
 	"runtime"
 	"testing"
-	"unsafe"
 
 	"golang.org/x/sys/unix"
 )
@@ -52,23 +51,20 @@ func TestMmap(t *testing.T) {
 }
 
 func TestMmapPtr(t *testing.T) {
-	mmapProt := unix.PROT_NONE
-	mmapPtrProt := unix.PROT_READ | unix.PROT_WRITE
-	b, err := unix.Mmap(-1, 0, 2*unix.Getpagesize(), mmapProt, unix.MAP_ANON|unix.MAP_PRIVATE)
+	p, err := unix.MmapPtr(-1, 0, nil, uintptr(2*unix.Getpagesize()),
+		unix.PROT_NONE, unix.MAP_ANON|unix.MAP_PRIVATE)
 	if err != nil {
-		t.Fatalf("Mmap: %v", err)
+		t.Fatalf("MmapPtr: %v", err)
 	}
-	if _, err := unix.MmapPtr(-1, 0, unsafe.Pointer(&b[0]), uintptr(unix.Getpagesize()),
-		mmapPtrProt, unix.MAP_ANON|unix.MAP_PRIVATE|unix.MAP_FIXED); err != nil {
+
+	if _, err := unix.MmapPtr(-1, 0, p, uintptr(unix.Getpagesize()),
+		unix.PROT_READ|unix.PROT_WRITE, unix.MAP_ANON|unix.MAP_PRIVATE|unix.MAP_FIXED); err != nil {
 		t.Fatalf("MmapPtr: %v", err)
 	}
 
-	b[0] = 42
+	*(*byte)(p) = 42
 
-	if err := unix.MunmapPtr(unsafe.Pointer(&b[0]), uintptr(unix.Getpagesize())); err != nil {
+	if err := unix.MunmapPtr(p, uintptr(2*unix.Getpagesize())); err != nil {
 		t.Fatalf("MunmapPtr: %v", err)
 	}
-	if err := unix.Munmap(b); err != nil {
-		t.Fatalf("Munmap: %v", err)
-	}
 }
