pythongh-107954, PEP 741: Add PyInitConfig C API

Add Doc/c-api/config.rst documentation.

Author: vstinner

Doc/c-api/config.rst

@@ -0,0 +1,227 @@
+.. highlight:: c
+
+.. _config-c-api:
+
+********************
+Python Configuration
+********************
+
+.. versionadded:: 3.14
+
+C API to configure the Python initialization (:pep:`741`).
+
+See also :ref:`Python Initialization Configuration <init-config>`.
+
+
+Initialize Python
+=================
+
+Create Config
+-------------
+
+.. c:struct:: PyInitConfig
+
+   Opaque structure to configure the Python initialization.
+
+
+.. c:function:: PyInitConfig* PyInitConfig_Create(void)
+
+   Create a new initialization configuration using :ref:`Isolated Configuration
+   <init-isolated-conf>` default values.
+
+   It must be freed by :c:func:`PyInitConfig_Free`.
+
+   Return ``NULL`` on memory allocation failure.
+
+
+.. c:function:: void PyInitConfig_Free(PyInitConfig *config)
+
+   Free memory of the initialization configuration *config*.
+
+
+Get Options
+-----------
+
+The configuration option *name* parameter must be a non-NULL
+null-terminated UTF-8 encoded string.
+
+.. c:function:: int PyInitConfig_HasOption(PyInitConfig *config, const char *name)
+
+   Test if the configuration has an option called *name*.
+
+   Return ``1`` if the option exists, or return ``0`` otherwise.
+
+
+.. c:function:: int PyInitConfig_GetInt(PyInitConfig *config, const char *name, int64_t *value)
+
+   Get an integer configuration option.
+
+   * Set *\*value*, and return ``0`` on success.
+   * Set an error in *config* and return ``-1`` on error.
+
+
+.. c:function:: int PyInitConfig_GetStr(PyInitConfig *config, const char *name, char **value)
+
+   Get a string configuration option as a null-terminated UTF-8
+   encoded string.
+
+   * Set *\*value*, and return ``0`` on success.
+   * Set an error in *config* and return ``-1`` on error.
+
+   On success, the string must be released with ``free(value)``.
+
+
+.. c:function:: int PyInitConfig_GetStrList(PyInitConfig *config, const char *name, size_t *length, char ***items)
+
+   Get a string list configuration option as an array of
+   null-terminated UTF-8 encoded strings.
+
+   * Set *\*length* and *\*value*, and return ``0`` on success.
+   * Set an error in *config* and return ``-1`` on error.
+
+   On success, the string list must be released with
+   ``PyInitConfig_FreeStrList(length, items)``.
+
+
+.. c:function:: void PyInitConfig_FreeStrList(size_t length, char **items)
+
+   Free memory of a string list created by
+   ``PyInitConfig_GetStrList()``.
+
+
+Set Options
+-----------
+
+The configuration option *name* parameter must be a non-NULL null-terminated
+UTF-8 encoded string.
+
+Some configuration options have side effects on other options. This logic is
+only implemented when ``Py_InitializeFromInitConfig()`` is called, not by the
+"Set" functions below. For example, setting ``dev_mode`` to ``1`` does not set
+``faulthandler`` to ``1``.
+
+.. c:function:: int PyInitConfig_SetInt(PyInitConfig *config, const char *name, int64_t value)
+
+   Set an integer configuration option.
+
+   * Return ``0`` on success.
+   * Set an error in *config* and return ``-1`` on error.
+
+
+.. c:function:: int PyInitConfig_SetStr(PyInitConfig *config, const char *name, const char *value)
+
+   Set a string configuration option from a null-terminated UTF-8
+   encoded string. The string is copied.
+
+   * Return ``0`` on success.
+   * Set an error in *config* and return ``-1`` on error.
+
+
+.. c:function:: int PyInitConfig_SetStrList(PyInitConfig *config, const char *name, size_t length, char * const *items)
+
+   Set a string list configuration option from an array of
+   null-terminated UTF-8 encoded strings. The string list is copied.
+
+   * Return ``0`` on success.
+   * Set an error in *config* and return ``-1`` on error.
+
+
+Initialize Python
+-----------------
+
+.. c:function:: int Py_InitializeFromInitConfig(PyInitConfig *config)
+
+   Initialize Python from the initialization configuration.
+
+   * Return ``0`` on success.
+   * Set an error in *config* and return ``-1`` on error.
+   * Set an exit code in *config* and return ``-1`` if Python wants to
+     exit.
+
+   See ``PyInitConfig_GetExitcode()`` for the exit code case.
+
+
+Error Handling
+--------------
+
+.. c:function:: int PyInitConfig_GetError(PyInitConfig* config, const char **err_msg)
+
+   Get the *config* error message.
+
+   * Set *\*err_msg* and return ``1`` if an error is set.
+   * Set *\*err_msg* to ``NULL`` and return ``0`` otherwise.
+
+   An error message is an UTF-8 encoded string.
+
+   If *config* has an exit code, format the exit code as an error
+   message.
+
+   The error message remains valid until another ``PyInitConfig``
+   function is called with *config*. The caller doesn't have to free the
+   error message.
+
+
+.. c:function:: int PyInitConfig_GetExitCode(PyInitConfig* config, int *exitcode)
+
+   Get the *config* exit code.
+
+   * Set *\*exitcode* and return ``1`` if Python wants to exit.
+   * Return ``0`` if *config* has no exit code set.
+
+   Only the ``Py_InitializeFromInitConfig()`` function can set an exit
+   code if the ``parse_argv`` option is non-zero.
+
+   An exit code can be set when parsing the command line failed (exit
+   code ``2``) or when a command line option asks to display the command
+   line help (exit code ``0``).
+
+
+Example
+=======
+
+Example initializing Python, set configuration options of various types,
+return ``-1`` on error:
+
+.. code-block:: c
+
+    int init_python(void)
+    {
+        PyInitConfig *config = PyInitConfig_Create();
+        if (config == NULL) {
+            printf("PYTHON INIT ERROR: memory allocation failed\n");
+            return -1;
+        }
+
+        // Set an integer (dev mode)
+        if (PyInitConfig_SetInt(config, "dev_mode", 1) < 0) {
+            goto error;
+        }
+
+        // Set a list of UTF-8 strings (argv)
+        char *argv[] = {"my_program", "-c", "pass"};
+        if (PyInitConfig_SetStrList(config, "argv",
+                                     Py_ARRAY_LENGTH(argv), argv) < 0) {
+            goto error;
+        }
+
+        // Set a UTF-8 string (program name)
+        if (PyInitConfig_SetStr(config, "program_name", L"my_program") < 0) {
+            goto error;
+        }
+
+        // Initialize Python with the configuration
+        if (Py_InitializeFromInitConfig(config) < 0) {
+            goto error;
+        }
+        PyInitConfig_Free(config);
+        return 0;
+
+    error:
+        // Display the error message
+        const char *err_msg;
+        (void)PyInitConfig_GetError(config, &err_msg);
+        printf("PYTHON INIT ERROR: %s\n", err_msg);
+        PyInitConfig_Free(config);
+
+        return -1;
+    }

Doc/c-api/index.rst

@@ -22,6 +22,7 @@ document the API functions in detail.
    concrete.rst
    init.rst
    init_config.rst
+   config.rst
    memory.rst
    objimpl.rst
    apiabiversion.rst

Doc/c-api/init.rst

@@ -7,7 +7,8 @@
 Initialization, Finalization, and Threads
 *****************************************
 
-See also :ref:`Python Initialization Configuration <init-config>`.
+See also the :ref:`Python Initialization Configuration <init-config>`
+and the :ref:`Python Configuration <config-c-api>`
 
 .. _pre-init-safe:
 

Doc/c-api/init_config.rst

@@ -27,7 +27,8 @@ There are two kinds of configuration:
 The :c:func:`Py_RunMain` function can be used to write a customized Python
 program.
 
-See also :ref:`Initialization, Finalization, and Threads <initialization>`.
+See also :ref:`Initialization, Finalization, and Threads <initialization>`
+and the :ref:`Python Configuration <config-c-api>`.
 
 .. seealso::
    :pep:`587` "Python Initialization Configuration".

Doc/whatsnew/3.14.rst

@@ -489,6 +489,24 @@ New Features
   similar to ``sep.join(iterable)`` in Python.
   (Contributed by Victor Stinner in :gh:`121645`.)
 
+* Add functions to configure the Python initialization:
+
+  * :c:func:`PyInitConfig_Create`
+  * :c:func:`PyInitConfig_Free`
+  * :c:func:`PyInitConfig_HasOption`
+  * :c:func:`PyInitConfig_GetInt`
+  * :c:func:`PyInitConfig_GetStr`
+  * :c:func:`PyInitConfig_GetStrList`
+  * :c:func:`PyInitConfig_FreeStrList`
+  * :c:func:`PyInitConfig_SetInt`
+  * :c:func:`PyInitConfig_SetStr`
+  * :c:func:`PyInitConfig_SetStrList`
+  * :c:func:`Py_InitializeFromInitConfig`
+  * :c:func:`PyInitConfig_GetError`
+  * :c:func:`PyInitConfig_GetExitCode`
+
+  (Contributed by Victor Stinner in :gh:`107954`.)
+
 
 Porting to Python 3.14
 ----------------------

Include/cpython/initconfig.h

@@ -267,6 +267,66 @@ PyAPI_FUNC(PyStatus) PyConfig_SetWideStringList(PyConfig *config,
    See also PyConfig.orig_argv. */
 PyAPI_FUNC(void) Py_GetArgcArgv(int *argc, wchar_t ***argv);
 
+
+// --- PyInitConfig ---------------------------------------------------------
+
+typedef struct PyInitConfig PyInitConfig;
+
+// Create a new initialization configuration using the Isolated configuration
+// defaults.
+// It must be freed by PyInitConfig_Free().
+// Return NULL on memory allocation failure.
+PyAPI_FUNC(PyInitConfig*) PyInitConfig_Create(void);
+
+// Free memory of a initialization configuration.
+PyAPI_FUNC(void) PyInitConfig_Free(PyInitConfig *config);
+
+// Set an integer configuration option.
+// Return 0 on success, or return -1 on error.
+PyAPI_FUNC(int) PyInitConfig_SetInt(
+    PyInitConfig *config,
+    const char *name,
+    int64_t value);
+
+// Set a string configuration option from a bytes string.
+//
+// The bytes string is decoded by Py_DecodeLocale(). Preinitialize Python if
+// needed to ensure that encodings are properly configured.
+//
+// Return 0 on success, or return -1 on error.
+PyAPI_FUNC(int) PyInitConfig_SetStr(
+    PyInitConfig *config,
+    const char *name,
+    const char *value);
+
+// Set a string list configuration option from bytes strings.
+//
+// The bytes strings are decoded by Py_DecodeLocale(). Preinitialize Python if
+// needed to ensure that encodings are properly configured.
+//
+// Return 0 on success, or return -1 on error.
+PyAPI_FUNC(int) PyInitConfig_SetStrList(
+    PyInitConfig *config,
+    const char *name,
+    size_t length,
+    char * const *items);
+
+// Initialize Python from the initialization configuration.
+// Return 0 on success.
+// Return -1 if Python wants to exit and on error
+PyAPI_FUNC(int) Py_InitializeFromInitConfig(PyInitConfig *config);
+
+// Get the error message.
+// Set *err_msg and return 1 if an error is set.
+// Set *err_msg to NULL and return 0 otherwise.
+PyAPI_FUNC(int) PyInitConfig_GetError(PyInitConfig* config, const char **err_msg);
+
+// Get the exit code.
+// Set '*exitcode' and return 1 if an exit code is set.
+// Return 0 otherwise.
+PyAPI_FUNC(int) PyInitConfig_GetExitCode(PyInitConfig* config, int *exitcode);
+
+
 #ifdef __cplusplus
 }
 #endif

Include/internal/pycore_initconfig.h

@@ -62,6 +62,10 @@ extern int _PyWideStringList_Copy(PyWideStringList *list,
 extern PyStatus _PyWideStringList_Extend(PyWideStringList *list,
     const PyWideStringList *list2);
 extern PyObject* _PyWideStringList_AsList(const PyWideStringList *list);
+extern PyStatus _PyWideStringList_FromBytes(
+    PyWideStringList *list,
+    Py_ssize_t length,
+    char * const *items);
 
 
 /* --- _PyArgv ---------------------------------------------------- */