Support PY_MAIN(:main) in python3

DEVTOOLSSUPPORT-1753

ref:5b3e2df0023ddfd79b969261f07fca8670c22b11

Author: kikht

library/python/runtime_py3/main/get_py_main.cpp

@@ -0,0 +1,8 @@
+#include <library/cpp/resource/resource.h>
+
+#include <stdlib.h>
+
+extern "C" char* GetPyMain() {
+    TString res = NResource::Find("PY_MAIN");
+    return strdup(res.c_str());
+}

library/python/runtime_py3/main/main.c

@@ -5,6 +5,7 @@
 #include <locale.h>
 
 void Py_InitArgcArgv(int argc, wchar_t **argv);
+char* GetPyMain();
 
 static const char* env_entry_point = "Y_PYTHON_ENTRY_POINT";
 
@@ -109,9 +110,26 @@ static int pymain(int argc, char** argv) {
     oldloc = NULL;
 
     const char* entry_point = getenv(env_entry_point);
-    if (entry_point && !strcmp(entry_point, ":main")) {
+    if (entry_point) {
+        entry_point_copy = strdup(entry_point);
+        if (!entry_point_copy) {
+            fprintf(stderr, "out of memory\n");
+            goto error;
+        }
+    } else {
+        entry_point_copy = GetPyMain();
+    }
+
+    if (entry_point_copy == NULL) {
+        fprintf(stderr, "No entry point, did you forget PY_MAIN?\n");
+        goto error;
+    }
+
+    if (entry_point_copy && !strcmp(entry_point_copy, ":main")) {
         unsetenv(env_entry_point);
-        return Py_Main(argc, argv_copy);
+        sts = Py_Main(argc, argv_copy);
+        free(entry_point_copy);
+        return sts;
     }
 
     Py_InitArgcArgv(argc, argv_copy);
@@ -121,8 +139,6 @@ static int pymain(int argc, char** argv) {
 
     PySys_SetArgv(argc, argv_copy);
 
-    PyObject* py_main = NULL;
-
     {
         PyObject* module = PyImport_ImportModule("library.python.runtime_py3.entry_points");
         if (module == NULL) {
@@ -138,37 +154,6 @@ static int pymain(int argc, char** argv) {
         }
     }
 
-    if (entry_point == NULL) {
-        PyObject* res = PyImport_ImportModule("__res");
-        if (res == NULL) {
-            PyErr_Clear();
-        } else {
-            py_main = PyObject_CallMethod(res, "find", "y", "PY_MAIN");
-
-            if (py_main == NULL) {
-                PyErr_Clear();
-            } else {
-                if (PyBytes_Check(py_main)) {
-                    entry_point = PyBytes_AsString(py_main);
-                }
-            }
-
-            Py_DECREF(res);
-        }
-    }
-
-    if (entry_point == NULL) {
-        fprintf(stderr, "No entry point, did you forget PY_MAIN?\n");
-        goto error;
-    }
-
-    entry_point_copy = strdup(entry_point);
-    Py_XDECREF(py_main);
-    if (!entry_point_copy) {
-        fprintf(stderr, "out of memory\n");
-        goto error;
-    }
-
     const char* module_name = entry_point_copy;
     const char* func_name = NULL;
 

library/python/runtime_py3/main/ya.make

@@ -4,6 +4,7 @@ LIBRARY()
 
 PEERDIR(
     contrib/tools/python3/src
+    library/cpp/resource
 )
 
 ADDINCL(
@@ -12,6 +13,7 @@ ADDINCL(
 
 SRCS(
     main.c
+    get_py_main.cpp
 )
 
 END()