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Improve freeing objects on errors in PyImaging_GrabScreenWin32() #10094

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Merged
radarhere merged 2 commits into from
Oct 3, 2026
Merged

Improve freeing objects on errors in PyImaging_GrabScreenWin32() #10094

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b13e74a
Improve freeing objects on errors in PyImaging_GrabScreenWin32()
radarhere Oct 2, 2026
2e4e7d8
Rearranged code
radarhere Oct 2, 2026
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17 changes: 12 additions & 5 deletions src/display.c
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Original file line number Diff line number Diff line change
Expand Up @@ -311,12 +311,12 @@ PyObject *
PyImaging_GrabScreenWin32(PyObject *self, PyObject *args) {
int x = 0, y = 0, width = -1, height;
int includeLayeredWindows = 0, screens = 0;
HBITMAP bitmap;
HBITMAP bitmap = NULL;
BITMAPCOREHEADER core;
HDC screen, screen_copy;
HWND wnd;
DWORD rop;
PyObject *buffer;
PyObject *buffer = NULL;
HANDLE dpiAwareness = NULL;
HMODULE user32;
Func_GetWindowDpiAwarenessContext GetWindowDpiAwarenessContext_function;
Expand Down Expand Up @@ -382,15 +382,18 @@ PyImaging_GrabScreenWin32(PyObject *self, PyObject *args) {
FreeLibrary(user32);

if (width == -1) {
PyErr_SetString(PyExc_OSError, "screen grab failed");
goto error;
}

bitmap = CreateCompatibleBitmap(screen, width, height);
if (!bitmap) {
PyErr_SetString(PyExc_OSError, "screen grab failed");
goto error;
}

if (!SelectObject(screen_copy, bitmap)) {
PyErr_SetString(PyExc_OSError, "screen grab failed");
goto error;
}

Expand All @@ -401,14 +404,15 @@ PyImaging_GrabScreenWin32(PyObject *self, PyObject *args) {
rop |= CAPTUREBLT;
}
if (!BitBlt(screen_copy, 0, 0, width, height, screen, x, y, rop)) {
PyErr_SetString(PyExc_OSError, "screen grab failed");
goto error;
}

/* step 3: extract bits from bitmap */

buffer = PyBytes_FromStringAndSize(NULL, height * ((width * 3 + 3) & -4));
if (!buffer) {
return NULL;
goto error;
Comment on lines -411 to +415

@akx akx Oct 2, 2026

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Right, the idea with the repeated PyErr_SetStrings is that this branch will retain the error from PyBytes_FromStringAndSize 👍

}

core.bcSize = sizeof(core);
Expand All @@ -425,6 +429,7 @@ PyImaging_GrabScreenWin32(PyObject *self, PyObject *args) {
(BITMAPINFO *)&core,
DIB_RGB_COLORS
)) {
PyErr_SetString(PyExc_OSError, "screen grab failed");
goto error;
}

Expand All @@ -439,8 +444,10 @@ PyImaging_GrabScreenWin32(PyObject *self, PyObject *args) {
return Py_BuildValue("(ii)(ii)N", x, y, width, height, buffer);

error:
PyErr_SetString(PyExc_OSError, "screen grab failed");

Py_XDECREF(buffer);
if (bitmap != NULL) {
DeleteObject(bitmap);
}
DeleteDC(screen_copy);
if (screens == -1) {
ReleaseDC(wnd, screen);
Expand Down
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