From 1c13f9634cd5910f4c5f70cb137ae780d2a5e742 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 4 Dec 2019 23:03:34 +0530
Subject: [PATCH] Restore reporting of unhandled exceptions during GUI
 application startup on windows

Not as nice as it was previously since errors importing the site module
will not be reported, but the python API provides no hooks for this in
Py_RunMain
---
 bypy/run-python.h    |  6 ++++++
 bypy/windows/site.py | 11 ++++++++++-
 bypy/windows/util.c  | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/bypy/run-python.h b/bypy/run-python.h
index fcf2dd4db5..a1f5bc21ef 100644
--- a/bypy/run-python.h
+++ b/bypy/run-python.h
@@ -170,6 +170,7 @@ typedef struct {
 #endif
 	const wchar_t *basename, *module, *function;
 	int argc;
+    PyObject* (*calibre_os_module)(void);
 #ifdef _WIN32
 	wchar_t* const *argv;
 #else
@@ -237,6 +238,11 @@ run_interpreter() {
     status = PyConfig_SetBytesArgv(&config, interpreter_data.argc, interpreter_data.argv);
 #endif
     CHECK_STATUS;
+    if (interpreter_data.calibre_os_module) {
+        if (PyImport_AppendInittab("calibre_os_module", interpreter_data.calibre_os_module) == -1) {
+            fatal("Failed to add calibre_os_module to the init table");
+        }
+    }
     status = Py_InitializeFromConfig(&config);
     CHECK_STATUS;
 
diff --git a/bypy/windows/site.py b/bypy/windows/site.py
index 2ec48e0754..ef9b55634f 100644
--- a/bypy/windows/site.py
+++ b/bypy/windows/site.py
@@ -85,4 +85,13 @@ def main():
 
 
 if __name__ == '__main__':
-    main()
+    try:
+        main()
+    except Exception:
+        if sys.gui_app:
+            import traceback
+            import calibre_os_module
+            calibre_os_module.gui_error_message(
+                f"Unhandled exception running {sys.calibre_basename}",
+                traceback.format_exc())
+        raise
diff --git a/bypy/windows/util.c b/bypy/windows/util.c
index b079123c61..a9296f1f07 100644
--- a/bypy/windows/util.c
+++ b/bypy/windows/util.c
@@ -115,6 +115,42 @@ redirect_out_stream(FILE *stream) {
     }
 }
 
+static PyObject*
+gui_error_message(PyObject *self, PyObject *args) {
+    PyObject *pt, *pm;
+    if (!PyArg_ParseTuple(args, "UU", &pt, &pm)) return NULL;
+    wchar_t title[256] = {0}, text[4096] = {0};
+    PyUnicode_AsWideChar(pt, title, arraysz(title)-1);
+    PyUnicode_AsWideChar(pm, text, arraysz(text)-1);
+    MessageBoxW(NULL, text, title, MB_ICONERROR|MB_OK);
+    return PyBool_FromLong(1);
+}
+
+static PyMethodDef methods[] = {
+    {"gui_error_message", (PyCFunction)gui_error_message, METH_VARARGS,
+     "gui_error_message(title, msg) -> Show a GUI based error message."
+    },
+    {NULL}  /* Sentinel */
+};
+
+
+static struct PyModuleDef module = {
+    /* m_base     */ PyModuleDef_HEAD_INIT,
+    /* m_name     */ "calibre_os_module",
+    /* m_doc      */ "Integration with OS facilities during startup",
+    /* m_size     */ -1,
+    /* m_methods  */ methods,
+    /* m_slots    */ 0,
+    /* m_traverse */ 0,
+    /* m_clear    */ 0,
+    /* m_free     */ 0,
+};
+
+PyObject*
+calibre_os_module(void) {
+    return PyModule_Create(&module);
+}
+
 static void
 null_invalid_parameter_handler(
    const wchar_t * expression,
@@ -151,6 +187,7 @@ execute_python_entrypoint(const wchar_t *basename, const wchar_t *module, const
     interpreter_data.argv = CommandLineToArgvW(GetCommandLineW(), &interpreter_data.argc);
     if (interpreter_data.argv == NULL) ExitProcess(show_last_error(L"Failed to get command line"));
     interpreter_data.basename = basename; interpreter_data.module = module; interpreter_data.function = function;
+    interpreter_data.calibre_os_module = calibre_os_module;
     load_python_dll();
     pre_initialize_interpreter(is_gui_app);
 	run_interpreter();