Bootloader: Add showing traceback in debug windowed mode.

When running in Windows in windowed mode, the debug bootloader will now show
the Python traceback information. This help debuging errors during
pyiboot01_bootstrap. This will allow debugging errors like in Issue #4213.
For showing the source lines, the application needs to be frozen with ``--noarchive``.

Signed-off-by: Dan Yeaw <dyeaw@ford.com>

bootloader/src/pyi_launch.c

@@ -364,13 +364,18 @@ int
 pyi_launch_run_scripts(ARCHIVE_STATUS *status)
 {
     unsigned char *data;
+    const char *pvalue_cchar, *tb_cchar;
     char buf[PATH_MAX];
+    char *char_pvalue, *char_tb, *module_name;
     size_t namelen;
     TOC * ptoc = status->tocbuff;
     PyObject *__main__;
     PyObject *__file__;
     PyObject *main_dict;
     PyObject *code, *retval;
+    PyObject *ptype, *pvalue, *pvalue_str;
+    PyObject *ptraceback, *tb, *tb_str;
+    PyObject *module, *func;
 
     __main__ = PI_PyImport_AddModule("__main__");
 
@@ -417,14 +422,53 @@ pyi_launch_run_scripts(ARCHIVE_STATUS *status)
             /* Run it */
             retval = PI_PyEval_EvalCode(code, main_dict, main_dict);
 
-            /* If retval is NULL, an error occured. Otherwise, it is a Python object.
+            /* If retval is NULL, an error occurred. Otherwise, it is a Python object.
              * (Since we evaluate module-level code, which is not allowed to return an
              * object, the Python object returned is always None.) */
             if (!retval) {
-                PI_PyErr_Print();
-                /* If the error was SystemExit, PyErr_Print calls exit() without
-                 * returning. So don't print "Failed to execute" on SystemExit. */
                 FATALERROR("Failed to execute script %s\n", ptoc->name);
+
+                #if defined(WINDOWED) && defined(LAUNCH_DEBUG)
+                    /* If running in windowed mode, sys.stderr will be None
+                     * resp. NullWriter (see pyiboot01_bootstrap.py), thus
+                     * PyErr_Print() below will not show any traceback. With
+                     * debug, print the traceback to a message box. */
+
+                    /* First get the value of the error */
+                    PI_PyErr_Fetch(&ptype, &pvalue, &ptraceback);
+                    pvalue_str = PI_PyObject_Str(pvalue);
+                    pvalue_cchar = PI_PyUnicode_AsUTF8(pvalue_str);
+                    FATALERROR("Error: %s\n", pvalue_cchar);
+                    Py_DECREF(pvalue_str);
+
+                    /* Attempt to get a full traceback, source lines will only
+                     * be available with --noarchive option */
+                    module_name = "traceback";
+                    module = PI_PyImport_ImportModule(module_name);
+
+                    if (module != NULL) {
+                        func = PI_PyObject_GetAttrString(module, "format_exception");
+                        if (func) {
+                            tb = PI_PyObject_CallFunctionObjArgs(func, ptype, pvalue, ptraceback, NULL);
+                            tb_str = PI_PyObject_Str(tb);
+                            tb_cchar = PI_PyUnicode_AsUTF8(tb_str);
+                            FATALERROR("Traceback: %s\n", tb_cchar);
+                            Py_DECREF(tb);
+                            Py_DECREF(tb_str);
+                        }
+                        Py_DECREF(func);
+                    }
+                    Py_DECREF(ptype);
+                    Py_DECREF(pvalue);
+                    Py_DECREF(ptraceback);
+                    Py_DECREF(module);
+
+                #else /* if defined(WINDOWED) and defined(LAUNCH_DEBUG) */
+
+                    PI_PyErr_Print();
+
+                #endif /* if defined(WINDOWED) and defined(LAUNCH_DEBUG) */
+
                 return -1;
             }
             free(data);

bootloader/src/pyi_python.c

@@ -57,6 +57,7 @@ DECLPROC(PyDict_GetItemString);
 DECLPROC(PyErr_Clear);
 DECLPROC(PyErr_Occurred);
 DECLPROC(PyErr_Print);
+DECLPROC(PyErr_Fetch);
 
 DECLPROC(PyImport_AddModule);
 DECLPROC(PyImport_ExecCodeModule);
@@ -66,7 +67,10 @@ DECLPROC(PyList_New);
 DECLPROC(PyLong_AsLong);
 DECLPROC(PyModule_GetDict);
 DECLPROC(PyObject_CallFunction);
+DECLPROC(PyObject_CallFunctionObjArgs);
 DECLPROC(PyObject_SetAttrString);
+DECLPROC(PyObject_GetAttrString);
+DECLPROC(PyObject_Str);
 DECLPROC(PyRun_SimpleString);
 DECLPROC(PySys_AddWarnOption);
 DECLPROC(PySys_SetArgvEx);
@@ -79,6 +83,7 @@ DECLPROC(Py_DecodeLocale);
 DECLPROC(PyUnicode_FromFormat);
 DECLPROC(PyUnicode_DecodeFSDefault);
 DECLPROC(PyUnicode_Decode);
+DECLPROC(PyUnicode_AsUTF8);
 
 DECLPROC(PyEval_EvalCode);
 DECLPROC(PyMarshal_ReadObjectFromString);
@@ -116,6 +121,7 @@ pyi_python_map_names(HMODULE dll, int pyvers)
     GETPROC(dll, PyErr_Clear);
     GETPROC(dll, PyErr_Occurred);
     GETPROC(dll, PyErr_Print);
+    GETPROC(dll, PyErr_Fetch);
     GETPROC(dll, PyImport_AddModule);
     GETPROC(dll, PyImport_ExecCodeModule);
     GETPROC(dll, PyImport_ImportModule);
@@ -124,7 +130,11 @@ pyi_python_map_names(HMODULE dll, int pyvers)
     GETPROC(dll, PyLong_AsLong);
     GETPROC(dll, PyModule_GetDict);
     GETPROC(dll, PyObject_CallFunction);
+    GETPROC(dll, PyObject_CallFunctionObjArgs);
     GETPROC(dll, PyObject_SetAttrString);
+    GETPROC(dll, PyObject_GetAttrString);
+    GETPROC(dll, PyObject_Str);
+
     GETPROC(dll, PyRun_SimpleString);
 
     GETPROC(dll, PySys_AddWarnOption);
@@ -142,6 +152,7 @@ pyi_python_map_names(HMODULE dll, int pyvers)
     GETPROC(dll, PyUnicode_FromFormat);
     GETPROC(dll, PyUnicode_Decode);
     GETPROC(dll, PyUnicode_DecodeFSDefault);
+    GETPROC(dll, PyUnicode_AsUTF8);
 
     VS("LOADER: Loaded functions from Python library.\n");
 

bootloader/src/pyi_python.h

@@ -123,6 +123,7 @@ EXTDECLPROC(PyObject *, Py_BuildValue, (char *, ...));
 /* Create a Unicode object from the char buffer. The bytes will be interpreted as being UTF-8 encoded. */
 EXTDECLPROC(PyObject *, PyUnicode_FromString, (const char *));
 EXTDECLPROC(PyObject *, PyObject_CallFunction, (PyObject *, char *, ...));
+EXTDECLPROC(PyObject *, PyObject_CallFunctionObjArgs, (PyObject *, ...));
 EXTDECLPROC(PyObject *, PyModule_GetDict, (PyObject *));
 EXTDECLPROC(PyObject *, PyDict_GetItemString, (PyObject *, char *));
 EXTDECLPROC(void, PyErr_Clear, (void) );
@@ -151,6 +152,12 @@ EXTDECLPROC(PyObject *, PyUnicode_Decode,
 EXTDECLPROC(PyObject *, PyEval_EvalCode, (PyObject *, PyObject *, PyObject *));
 EXTDECLPROC(PyObject *, PyMarshal_ReadObjectFromString, (const char *, size_t));  /* Py_ssize_t */
 
+/* Used to get traceback information while launching run scripts */
+EXTDECLPROC(void, PyErr_Fetch, (PyObject **, PyObject **, PyObject **));
+EXTDECLPROC(PyObject *, PyObject_Str, (PyObject *));
+EXTDECLPROC(PyObject *, PyObject_GetAttrString, (PyObject *, const char *));
+EXTDECLPROC(const char *, PyUnicode_AsUTF8, (PyObject *));
+
 /*
  * Macros for reference counting through exported functions
  * (that is: without binding to the binary structure of a PyObject.

news/4213.bootloader.rst

@@ -0,0 +1 @@
+In debug and windowed mode, print traceback to help debug pyiboot01_bootstrap errors.

news/4592.bootloader.rst

@@ -0,0 +1 @@
+In debug and windowed mode, print traceback to help debug pyiboot01_bootstrap errors.