[3.12] gh-107915: Handle errors in C API functions PyErr_Set*() and PyErr_Format() (GH-107918) (#108134)

* gh-107915: Handle errors in C API functions PyErr_Set*() and PyErr_Format() (GH-107918)

Such C API functions as PyErr_SetString(), PyErr_Format(),
PyErr_SetFromErrnoWithFilename() and many others no longer crash or
ignore errors if it failed to format the error message or decode the
filename. Instead, they keep a corresponding error.
(cherry picked from commit 633ea217a85f6b6ba5bdbc73094254d5811b3485)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

* Define PY_SSIZE_T_CLEAN.

---------

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

2 files changed, 105 insertions, 1 deletions

diff --git a/Modules/_testcapi/clinic/exceptions.c.h b/Modules/_testcapi/clinic/exceptions.c.h
index 01730ff..16954a5 100644
--- a/Modules/_testcapi/clinic/exceptions.c.h
+++ b/Modules/_testcapi/clinic/exceptions.c.h
@@ -215,6 +215,68 @@ exit:
     return return_value;
 }
 
+PyDoc_STRVAR(_testcapi_err_setstring__doc__,
+"err_setstring($module, exc, value, /)\n"
+"--\n"
+"\n");
+
+#define _TESTCAPI_ERR_SETSTRING_METHODDEF    \
+    {"err_setstring", _PyCFunction_CAST(_testcapi_err_setstring), METH_FASTCALL, _testcapi_err_setstring__doc__},
+
+static PyObject *
+_testcapi_err_setstring_impl(PyObject *module, PyObject *exc,
+                             const char *value, Py_ssize_t value_length);
+
+static PyObject *
+_testcapi_err_setstring(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    PyObject *exc;
+    const char *value;
+    Py_ssize_t value_length;
+
+    if (!_PyArg_ParseStack(args, nargs, "Oz#:err_setstring",
+        &exc, &value, &value_length)) {
+        goto exit;
+    }
+    return_value = _testcapi_err_setstring_impl(module, exc, value, value_length);
+
+exit:
+    return return_value;
+}
+
+PyDoc_STRVAR(_testcapi_err_setfromerrnowithfilename__doc__,
+"err_setfromerrnowithfilename($module, error, exc, value, /)\n"
+"--\n"
+"\n");
+
+#define _TESTCAPI_ERR_SETFROMERRNOWITHFILENAME_METHODDEF    \
+    {"err_setfromerrnowithfilename", _PyCFunction_CAST(_testcapi_err_setfromerrnowithfilename), METH_FASTCALL, _testcapi_err_setfromerrnowithfilename__doc__},
+
+static PyObject *
+_testcapi_err_setfromerrnowithfilename_impl(PyObject *module, int error,
+                                            PyObject *exc, const char *value,
+                                            Py_ssize_t value_length);
+
+static PyObject *
+_testcapi_err_setfromerrnowithfilename(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    int error;
+    PyObject *exc;
+    const char *value;
+    Py_ssize_t value_length;
+
+    if (!_PyArg_ParseStack(args, nargs, "iOz#:err_setfromerrnowithfilename",
+        &error, &exc, &value, &value_length)) {
+        goto exit;
+    }
+    return_value = _testcapi_err_setfromerrnowithfilename_impl(module, error, exc, value, value_length);
+
+exit:
+    return return_value;
+}
+
 PyDoc_STRVAR(_testcapi_raise_exception__doc__,
 "raise_exception($module, exception, num_args, /)\n"
 "--\n"
@@ -426,4 +488,4 @@ _testcapi_unstable_exc_prep_reraise_star(PyObject *module, PyObject *const *args
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=fd6aef54f195c77b input=a9049054013a1b77]*/
+/*[clinic end generated code: output=d574342d716e98b5 input=a9049054013a1b77]*/
diff --git a/Modules/_testcapi/exceptions.c b/Modules/_testcapi/exceptions.c
index a627bf1..4ae9ba4 100644
--- a/Modules/_testcapi/exceptions.c
+++ b/Modules/_testcapi/exceptions.c
@@ -1,6 +1,9 @@
+#define PY_SSIZE_T_CLEAN
 #include "parts.h"
 #include "clinic/exceptions.c.h"
 
+#define NULLABLE(x) do { if (x == Py_None) x = NULL; } while (0);
+
 /*[clinic input]
 module _testcapi
 [clinic start generated code]*/
@@ -130,6 +133,43 @@ _testcapi_exc_set_object_fetch_impl(PyObject *module, PyObject *exc,
 }
 
 /*[clinic input]
+_testcapi.err_setstring
+    exc: object
+    value: str(zeroes=True, accept={robuffer, str, NoneType})
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_testcapi_err_setstring_impl(PyObject *module, PyObject *exc,
+                             const char *value, Py_ssize_t value_length)
+/*[clinic end generated code: output=fba8705e5703dd3f input=e8a95fad66d9004b]*/
+{
+    NULLABLE(exc);
+    PyErr_SetString(exc, value);
+    return NULL;
+}
+
+/*[clinic input]
+_testcapi.err_setfromerrnowithfilename
+    error: int
+    exc: object
+    value: str(zeroes=True, accept={robuffer, str, NoneType})
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_testcapi_err_setfromerrnowithfilename_impl(PyObject *module, int error,
+                                            PyObject *exc, const char *value,
+                                            Py_ssize_t value_length)
+/*[clinic end generated code: output=d02df5749a01850e input=ff7c384234bf097f]*/
+{
+    NULLABLE(exc);
+    errno = error;
+    PyErr_SetFromErrnoWithFilename(exc, value);
+    return NULL;
+}
+
+/*[clinic input]
 _testcapi.raise_exception
     exception as exc: object
     num_args: int
@@ -338,6 +378,8 @@ static PyMethodDef test_methods[] = {
     _TESTCAPI_MAKE_EXCEPTION_WITH_DOC_METHODDEF
     _TESTCAPI_EXC_SET_OBJECT_METHODDEF
     _TESTCAPI_EXC_SET_OBJECT_FETCH_METHODDEF
+    _TESTCAPI_ERR_SETSTRING_METHODDEF
+    _TESTCAPI_ERR_SETFROMERRNOWITHFILENAME_METHODDEF
     _TESTCAPI_RAISE_EXCEPTION_METHODDEF
     _TESTCAPI_RAISE_MEMORYERROR_METHODDEF
     _TESTCAPI_SET_EXC_INFO_METHODDEF