Port from PR 91579 and PR 20684 in Python

Author: wjsi

shared_memory/shared_memory.py

@@ -1,4 +1,5 @@
 """Provides shared memory for direct access across processes.
+
 The API of this package is currently provisional. Refer to the
 documentation for details.
 """
@@ -22,6 +23,7 @@
     from . import _posixshmem
     _USE_POSIX = True
 
+from . import resource_tracker
 
 _O_CREX = os.O_CREAT | os.O_EXCL
 
@@ -113,8 +115,7 @@ def __init__(self, name=None, create=False, size=0):
                 self.unlink()
                 raise
 
-            from .resource_tracker import register
-            register(self._name, "shared_memory")
+            resource_tracker.register(self._name, "shared_memory")
 
         else:
 
@@ -170,7 +171,10 @@ def __init__(self, name=None, create=False, size=0):
                     )
                 finally:
                     _winapi.CloseHandle(h_map)
-                size = _winshmem.VirtualQuerySize(p_buf)
+                try:
+                    size = _winshmem.VirtualQuerySize(p_buf)
+                finally:
+                    _winshmem.UnmapViewOfFile(p_buf)
                 self._mmap = mmap.mmap(-1, size, tagname=name)
 
         self._size = size
@@ -233,9 +237,8 @@ def unlink(self):
         called once (and only once) across all processes which have access
         to the shared memory block."""
         if _USE_POSIX and self._name:
-            from .resource_tracker import unregister
             _posixshmem.shm_unlink(self._name)
-            unregister(self._name, "shared_memory")
+            resource_tracker.unregister(self._name, "shared_memory")
 
 
 _encoding = "utf8"

shared_memory/winshmem.c

@@ -241,13 +241,37 @@ _winshmem_VirtualQuerySize_impl(PyObject *module, LPCVOID address)
     return region_size;
 }
 
+/*[clinic input]
+_winshmem.UnmapViewOfFile
+    address: LPCVOID
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_winshmem_UnmapViewOfFile_impl(PyObject *module, LPCVOID address)
+/*[clinic end generated code: output=0c5e521bc21e44f6 input=094db9950e24bbbe]*/
+{
+    BOOL success;
+
+    Py_BEGIN_ALLOW_THREADS
+    success = UnmapViewOfFile(address);
+    Py_END_ALLOW_THREADS
+
+    if (!success) {
+        return PyErr_SetFromWindowsErr(0);
+    }
+
+    Py_RETURN_NONE;
+}
+
 #include "clinic/winshmem.c.h"
 
 static PyMethodDef module_methods[ ] = {
     _WINSHMEM_CREATEFILEMAPPING_METHODDEF
     _WINSHMEM_MAPVIEWOFFILE_METHODDEF
     _WINSHMEM_OPENFILEMAPPING_METHODDEF
     _WINSHMEM_VIRTUALQUERYSIZE_METHODDEF
+    _WINSHMEM_UNMAPVIEWOFFILE_METHODDEF
     {NULL} /* Sentinel */
 };