MREMAP_FIXED protection

Author: anton-kuklin

.idea/.gitignore

@@ -15,7 +15,7 @@ type mremapMmapper struct {
 }
 
 func (m *mremapMmapper) Mremap(oldData []byte, newLength int, flags int) (data []byte, err error) {
-	if newLength <= 0 || len(oldData) == 0 || len(oldData) != cap(oldData) {
+	if newLength <= 0 || len(oldData) == 0 || len(oldData) != cap(oldData) || flags&MREMAP_FIXED == 1 {
 		return nil, EINVAL
 	}
 

.idea/modules.xml

@@ -28,7 +28,7 @@ func TestMremap(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Mremap2: %v", err)
 	}
-	bNew[unix.Getpagesize()+1] = 84
+	bNew[unix.Getpagesize()+1] = 84 // checks
 
 	if bNew[0] != 42 {
 		t.Fatal("first element value was changed")
@@ -42,4 +42,9 @@ func TestMremap(t *testing.T) {
 	if cap(bNew) != unix.Getpagesize()*2 {
 		t.Fatal("new memory cap not equal to specified len")
 	}
+
+	_, err = unix.Mremap(b, unix.Getpagesize(), unix.MREMAP_FIXED)
+	if err != unix.EINVAL {
+		t.Fatalf("unix.MREMAP_FIXED should be forbidden")
+	}
 }