From bbd6fc7e77dbd33ae7d3670eaf7800b5d3ff42d3 Mon Sep 17 00:00:00 2001

From: Victor Stinner <vstinner@redhat.com>

Date: Fri, 20 Jul 2018 17:34:23 +0200

Subject: [PATCH] bpo-34008: Allow to call Py_Main() after Py_Initialize()

 (GH-8043)

Py_Main() can again be called after Py_Initialize(), as in Python

3.6. The new configuration is ignored, except of

_PyMainInterpreterConfig.argv which is used to update sys.argv.

(cherry picked from commit fb47bca9ee2d07ce96df94b4e4abafd11826eb01)

Co-authored-by: Victor Stinner <vstinner@redhat.com>

---

 Lib/test/test_embed.py                             |  8 ++++++++

 .../C API/2018-07-02-10-58-11.bpo-34008.COewz-.rst |  1 +

 Modules/main.c                                     | 10 +++++++---

 Programs/_testembed.c                              | 16 +++++++++++++++

 Python/pylifecycle.c                               | 23 +++++++++++++++++++---

 5 files changed, 52 insertions(+), 6 deletions(-)

 create mode 100644 Misc/NEWS.d/next/C API/2018-07-02-10-58-11.bpo-34008.COewz-.rst

diff --git a/Lib/test/test_embed.py b/Lib/test/test_embed.py

index f3b60433ccc1..024c3f99a85d 100644

--- a/Lib/test/test_embed.py

+++ b/Lib/test/test_embed.py

@@ -238,6 +238,14 @@ def test_initialize_twice(self):

         self.assertEqual(out, '')

         self.assertEqual(err, '')

+    def test_initialize_pymain(self):

+        """

+        bpo-34008: Calling Py_Main() after Py_Initialize() must not fail.

+        """

+        out, err = self.run_embedded_interpreter("initialize_pymain")

+        self.assertEqual(out.rstrip(), "Py_Main() after Py_Initialize: sys.argv=['-c', 'arg2']")

+        self.assertEqual(err, '')

+

 if __name__ == "__main__":

     unittest.main()

diff --git a/Misc/NEWS.d/next/C API/2018-07-02-10-58-11.bpo-34008.COewz-.rst b/Misc/NEWS.d/next/C API/2018-07-02-10-58-11.bpo-34008.COewz-.rst

new file mode 100644

index 000000000000..d9881b9945df

--- /dev/null

+++ b/Misc/NEWS.d/next/C API/2018-07-02-10-58-11.bpo-34008.COewz-.rst	

@@ -0,0 +1 @@

+Py_Main() can again be called after Py_Initialize(), as in Python 3.6.

diff --git a/Modules/main.c b/Modules/main.c

index 3809fa4abef5..31ebbceb83e0 100644

--- a/Modules/main.c

+++ b/Modules/main.c

@@ -2647,9 +2647,13 @@ pymain_main(_PyMain *pymain)

     pymain_init_stdio(pymain);

-    pymain->err = _Py_InitializeCore(&pymain->config);

-    if (_Py_INIT_FAILED(pymain->err)) {

-        _Py_FatalInitError(pymain->err);

+    /* bpo-34008: For backward compatibility reasons, calling Py_Main() after

+       Py_Initialize() ignores the new configuration. */

+    if (!_PyRuntime.initialized) {

+        pymain->err = _Py_InitializeCore(&pymain->config);

+        if (_Py_INIT_FAILED(pymain->err)) {

+            _Py_FatalInitError(pymain->err);

+        }

     }

     if (pymain_init_python_main(pymain) < 0) {

diff --git a/Programs/_testembed.c b/Programs/_testembed.c

index b8827f074b9c..b1be682f7adc 100644

--- a/Programs/_testembed.c

+++ b/Programs/_testembed.c

@@ -276,6 +276,21 @@ static int test_initialize_twice(void)

     return 0;

 }

+static int test_initialize_pymain(void)

+{

+    wchar_t *argv[] = {L"PYTHON", L"-c",

+                       L"import sys; print(f'Py_Main() after Py_Initialize: sys.argv={sys.argv}')",

+                       L"arg2"};

+    _testembed_Py_Initialize();

+

+    /* bpo-34008: Calling Py_Main() after Py_Initialize() must not crash */

+    Py_Main(Py_ARRAY_LENGTH(argv), argv);

+

+    Py_Finalize();

+

+    return 0;

+}

+

 /* *********************************************************

  * List of test cases and the function that implements it.

@@ -302,6 +317,7 @@ static struct TestCase TestCases[] = {

     { "pre_initialization_sys_options", test_pre_initialization_sys_options },

     { "bpo20891", test_bpo20891 },

     { "initialize_twice", test_initialize_twice },

+    { "initialize_pymain", test_initialize_pymain },

     { NULL, NULL }

 };

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c

index fdb759f480be..219a46558825 100644

--- a/Python/pylifecycle.c

+++ b/Python/pylifecycle.c

@@ -775,6 +775,22 @@ _Py_InitializeCore(const _PyCoreConfig *core_config)

     return _Py_INIT_OK();

 }

+/* Py_Initialize() has already been called: update the main interpreter

+   configuration. Example of bpo-34008: Py_Main() called after

+   Py_Initialize(). */

+static _PyInitError

+_Py_ReconfigureMainInterpreter(PyInterpreterState *interp,

+                               const _PyMainInterpreterConfig *config)

+{

+    if (config->argv != NULL) {

+        int res = PyDict_SetItemString(interp->sysdict, "argv", config->argv);

+        if (res < 0) {

+            return _Py_INIT_ERR("fail to set sys.argv");

+        }

+    }

+    return _Py_INIT_OK();

+}

+

 /* Update interpreter state based on supplied configuration settings

  *

  * After calling this function, most of the restrictions on the interpreter

@@ -796,9 +812,6 @@ _Py_InitializeMainInterpreter(const _PyMainInterpreterConfig *config)

     if (!_PyRuntime.core_initialized) {

         return _Py_INIT_ERR("runtime core not initialized");

     }

-    if (_PyRuntime.initialized) {

-        return _Py_INIT_ERR("main interpreter already initialized");

-    }

     /* Get current thread state and interpreter pointer */

     tstate = PyThreadState_GET();

@@ -813,6 +826,10 @@ _Py_InitializeMainInterpreter(const _PyMainInterpreterConfig *config)

         return _Py_INIT_ERR("failed to copy main interpreter config");

     }

+    if (_PyRuntime.initialized) {

+        return _Py_ReconfigureMainInterpreter(interp, config);

+    }

+

     if (interp->core_config._disable_importlib) {

         /* Special mode for freeze_importlib: run with no import system

          *