Fix mmap closing

Author: BCSharp

Src/IronPython.Modules/mmap.cs

@@ -812,6 +812,10 @@ public void resize(long newsize) {
                             if (_handle.IsInvalid) {
                                 throw PythonNT.GetOsError(PythonErrno.EBADF);
                             }
+                            if (_view.Capacity == newsize) {
+                                // resizing to the same size
+                                return;
+                            }
                             if (newsize == 0) {
                                 // resizing to an empty mapped region is not allowed
                                 throw PythonNT.GetOsError(PythonErrno.EINVAL);
@@ -844,14 +848,6 @@ public void resize(long newsize) {
                         throw WindowsError(PythonExceptions._OSError.ERROR_INVALID_PARAMETER);
                     }
 
-                    if (newsize == 0) {
-                        // resizing to an empty mapped region is not allowed
-                        throw WindowsError(_offset != 0 && RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
-                            ? PythonExceptions._OSError.ERROR_ACCESS_DENIED
-                            : PythonExceptions._OSError.ERROR_FILE_INVALID
-                        );
-                    }
-
                     if (_view.Capacity == newsize) {
                         // resizing to the same size
                         return;
@@ -860,6 +856,14 @@ public void resize(long newsize) {
                     long capacity = checked(_offset + newsize);
 
                     try {
+                        if (newsize == 0) {
+                            // resizing to an empty mapped region is not allowed
+                            throw WindowsError(_offset != 0 && RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
+                                ? PythonExceptions._OSError.ERROR_ACCESS_DENIED
+                                : PythonExceptions._OSError.ERROR_FILE_INVALID
+                            );
+                        }
+
                         _view.Flush();
                         _view.Dispose();
                         _file.Dispose();
@@ -1143,13 +1147,13 @@ private void EnsureOpen() {
                 }
             }
 
-            private struct MmapLocker : IDisposable {
+            private readonly struct MmapLocker : IDisposable {
                 private readonly MmapDefault _mmap;
 
                 public MmapLocker(MmapDefault mmap) {
                     _mmap = mmap;
-                    Interlocked.Increment(ref _mmap._refCount);
                     _mmap.EnsureOpen();
+                    Interlocked.Increment(ref _mmap._refCount);
                 }
 
                 #region IDisposable Members

Tests/modules/io_related/test_mmap.py

@@ -18,7 +18,7 @@ class MmapTest(IronPythonTestCase):
     def setUp(self):
         super(MmapTest, self).setUp()
 
-        self.temp_file = os.path.join(self.temporary_dir, "temp_%d.dat" % os.getpid())
+        self.temp_file = os.path.join(self.temporary_dir, "temp_mmap_%d.dat" % os.getpid())
 
     def tearDown(self):
         self.delete_files(self.temp_file)
@@ -60,6 +60,8 @@ def test_resize_errors(self):
             else:
                 self.assertEqual(cm.exception.strerror, "Invalid argument")
 
+            self.assertTrue(m.closed)
+
 
     def test_resize_errors_negative(self):
         with open(self.temp_file, "wb+") as f:
@@ -69,8 +71,10 @@ def test_resize_errors_negative(self):
             m = mmap.mmap(f.fileno(), 0, offset=0)
             if is_cli or sys.version_info >= (3, 5):
                 self.assertRaises(ValueError, m.resize, -1)
+                self.assertFalse(m.closed)
             else:
                 self.assertRaises(OSError, m.resize, -1)
+                self.assertTrue(m.closed)
 
             m.close()
 
@@ -93,7 +97,8 @@ def test_resize_errors_offset(self):
                     m.resize(0)
                 self.assertEqual(cm.exception.errno, errno.EINVAL)  # 22
                 self.assertEqual(cm.exception.strerror, "Invalid argument")
-            m.close()
+
+            self.assertTrue(m.closed)
 
 
 run_test(__name__)