bpo-36842: Implement PEP 578 (GH-12613)

Adds sys.audit, sys.addaudithook, io.open_code, and associated C APIs.

Objects/fileobject.c

@@ -2,6 +2,7 @@
 
 #define PY_SSIZE_T_CLEAN
 #include "Python.h"
+#include "pycore_pystate.h"
 
 #if defined(HAVE_GETC_UNLOCKED) && !defined(_Py_MEMORY_SANITIZER)
 /* clang MemorySanitizer doesn't yet understand getc_unlocked. */
@@ -33,7 +34,8 @@ PyFile_FromFd(int fd, const char *name, const char *mode, int buffering, const c
     PyObject *io, *stream;
     _Py_IDENTIFIER(open);
 
-    io = PyImport_ImportModule("io");
+    /* import _io in case we are being used to open io.py */
+    io = PyImport_ImportModule("_io");
     if (io == NULL)
         return NULL;
     stream = _PyObject_CallMethodId(io, &PyId_open, "isisssi", fd, mode,
@@ -514,6 +516,72 @@ PyTypeObject PyStdPrinter_Type = {
 };
 
 
+/* ************************** open_code hook ***************************
+ * The open_code hook allows embedders to override the method used to
+ * open files that are going to be used by the runtime to execute code
+ */
+
+int
+PyFile_SetOpenCodeHook(Py_OpenCodeHookFunction hook, void *userData) {
+    if (Py_IsInitialized() &&
+        PySys_Audit("setopencodehook", NULL) < 0) {
+        return -1;
+    }
+
+    if (_PyRuntime.open_code_hook) {
+        if (Py_IsInitialized()) {
+            PyErr_SetString(PyExc_SystemError,
+                "failed to change existing open_code hook");
+        }
+        return -1;
+    }
+
+    _PyRuntime.open_code_hook = hook;
+    _PyRuntime.open_code_userdata = userData;
+    return 0;
+}
+
+PyObject *
+PyFile_OpenCodeObject(PyObject *path)
+{
+    PyObject *iomod, *f = NULL;
+    _Py_IDENTIFIER(open);
+
+    if (!PyUnicode_Check(path)) {
+        PyErr_Format(PyExc_TypeError, "'path' must be 'str', not '%.200s'",
+                     Py_TYPE(path)->tp_name);
+        return NULL;
+    }
+
+    Py_OpenCodeHookFunction hook = _PyRuntime.open_code_hook;
+    if (hook) {
+        f = hook(path, _PyRuntime.open_code_userdata);
+    } else {
+        iomod = PyImport_ImportModule("_io");
+        if (iomod) {
+            f = _PyObject_CallMethodId(iomod, &PyId_open, "Os",
+                                       path, "rb");
+            Py_DECREF(iomod);
+        }
+    }
+
+    return f;
+}
+
+PyObject *
+PyFile_OpenCode(const char *utf8path)
+{
+    PyObject *pathobj = PyUnicode_FromString(utf8path);
+    PyObject *f;
+    if (!pathobj) {
+        return NULL;
+    }
+    f = PyFile_OpenCodeObject(pathobj);
+    Py_DECREF(pathobj);
+    return f;
+}
+
+
 #ifdef __cplusplus
 }
 #endif