bpo-40910: Export Py_GetArgcArgv() function (GH-20721)

Export explicitly the Py_GetArgcArgv() function to the C API and
document the function. Previously, it was exported implicitly which
no longer works since Python is built with -fvisibility=hidden.

* Add PyConfig._orig_argv member.
* Py_InitializeFromConfig() no longer calls _PyConfig_Write() twice.
* PyConfig_Read() no longer initializes Py_GetArgcArgv(): it is now
  _PyConfig_Write() responsibility.
* _PyConfig_Write() result type becomes PyStatus instead of void.
* Write an unit test on Py_GetArgcArgv().

1 files changed, 42 insertions, 0 deletions

diff --git a/Programs/_testembed.c b/Programs/_testembed.c
index 11524dfbc0..d89f6be657 100644
--- a/Programs/_testembed.c
+++ b/Programs/_testembed.c
@@ -1334,6 +1334,7 @@ static int test_init_read_set(void)
     return 0;
 
 fail:
+    PyConfig_Clear(&config);
     Py_ExitStatusException(status);
 }
 
@@ -1592,6 +1593,46 @@ static int test_run_main(void)
 }
 
 
+static int test_get_argc_argv(void)
+{
+    PyConfig config;
+    PyConfig_InitPythonConfig(&config);
+
+    wchar_t *argv[] = {L"python3", L"-c",
+                       (L"import sys; "
+                        L"print(f'Py_RunMain(): sys.argv={sys.argv}')"),
+                       L"arg2"};
+    config_set_argv(&config, Py_ARRAY_LENGTH(argv), argv);
+    config_set_string(&config, &config.program_name, L"./python3");
+
+    // Calling PyConfig_Read() twice must not change Py_GetArgcArgv() result.
+    // The second call is done by Py_InitializeFromConfig().
+    PyStatus status = PyConfig_Read(&config);
+    if (PyStatus_Exception(status)) {
+        PyConfig_Clear(&config);
+        Py_ExitStatusException(status);
+    }
+
+    init_from_config_clear(&config);
+
+    int get_argc;
+    wchar_t **get_argv;
+    Py_GetArgcArgv(&get_argc, &get_argv);
+    printf("argc: %i\n", get_argc);
+    assert(get_argc == Py_ARRAY_LENGTH(argv));
+    for (int i=0; i < get_argc; i++) {
+        printf("argv[%i]: %ls\n", i, get_argv[i]);
+        assert(wcscmp(get_argv[i], argv[i]) == 0);
+    }
+
+    Py_Finalize();
+
+    printf("\n");
+    printf("test ok\n");
+    return 0;
+}
+
+
 /* *********************************************************
  * List of test cases and the function that implements it.
  *
@@ -1649,6 +1690,7 @@ static struct TestCase TestCases[] = {
     {"test_init_setpythonhome", test_init_setpythonhome},
     {"test_init_warnoptions", test_init_warnoptions},
     {"test_run_main", test_run_main},
+    {"test_get_argc_argv", test_get_argc_argv},
 
     {"test_open_code_hook", test_open_code_hook},
     {"test_audit", test_audit},