bpo-36142: Add _PyPreConfig.allocator (GH-12181)

* Move 'allocator' and 'dev_mode' fields from _PyCoreConfig
  to _PyPreConfig.
* Fix InitConfigTests of test_embed: dev_mode sets allocator to
  "debug", add a new tests for env vars with dev mode enabled.

4 files changed, 72 insertions, 23 deletions

diff --git a/Python/coreconfig.c b/Python/coreconfig.c
index e372de4824..42441e24aa 100644
--- a/Python/coreconfig.c
+++ b/Python/coreconfig.c
@@ -521,8 +521,6 @@ _PyCoreConfig_Copy(_PyCoreConfig *config, const _PyCoreConfig *config2)
     COPY_ATTR(use_hash_seed);
     COPY_ATTR(hash_seed);
     COPY_ATTR(_install_importlib);
-    COPY_ATTR(allocator);
-    COPY_ATTR(dev_mode);
     COPY_ATTR(faulthandler);
     COPY_ATTR(tracemalloc);
     COPY_ATTR(import_time);
@@ -931,10 +929,6 @@ config_read_env_vars(_PyCoreConfig *config)
                  "PYTHONLEGACYWINDOWSSTDIO");
 #endif
 
-    if (config->allocator == NULL) {
-        config->allocator = _PyCoreConfig_GetEnv(config, "PYTHONMALLOC");
-    }
-
     if (_PyCoreConfig_GetEnv(config, "PYTHONDUMPREFS")) {
         config->dump_refs = 1;
     }
@@ -1059,11 +1053,6 @@ config_read_complex_options(_PyCoreConfig *config)
        || config_get_xoption(config, L"importtime")) {
         config->import_time = 1;
     }
-    if (config_get_xoption(config, L"dev" ) ||
-        _PyCoreConfig_GetEnv(config, "PYTHONDEVMODE"))
-    {
-        config->dev_mode = 1;
-    }
 
     _PyInitError err;
     if (config->tracemalloc < 0) {
@@ -1427,13 +1416,10 @@ _PyCoreConfig_Read(_PyCoreConfig *config, const _PyPreConfig *preconfig)
     }
 
     /* default values */
-    if (config->dev_mode) {
+    if (config->preconfig.dev_mode) {
         if (config->faulthandler < 0) {
             config->faulthandler = 1;
         }
-        if (config->allocator == NULL) {
-            config->allocator = "debug";
-        }
     }
     if (config->use_hash_seed < 0) {
         config->use_hash_seed = 0;
@@ -1572,8 +1558,6 @@ _PyCoreConfig_AsDict(const _PyCoreConfig *config)
     SET_ITEM_INT(install_signal_handlers);
     SET_ITEM_INT(use_hash_seed);
     SET_ITEM_UINT(hash_seed);
-    SET_ITEM_STR(allocator);
-    SET_ITEM_INT(dev_mode);
     SET_ITEM_INT(faulthandler);
     SET_ITEM_INT(tracemalloc);
     SET_ITEM_INT(import_time);
@@ -1950,7 +1934,7 @@ config_init_warnoptions(_PyCoreConfig *config, const _PyCmdline *cmdline)
      * the lowest precedence entries first so that later entries override them.
      */
 
-    if (config->dev_mode) {
+    if (config->preconfig.dev_mode) {
         err = _Py_wstrlist_append(&config->nwarnoption,
                                   &config->warnoptions,
                                   L"default");
diff --git a/Python/preconfig.c b/Python/preconfig.c
index 3befecfaa0..98e0edead1 100644
--- a/Python/preconfig.c
+++ b/Python/preconfig.c
@@ -125,6 +125,15 @@ precmdline_clear(_PyPreCmdline *cmdline)
 void
 _PyPreConfig_Clear(_PyPreConfig *config)
 {
+#define CLEAR(ATTR) \
+    do { \
+        PyMem_RawFree(ATTR); \
+        ATTR = NULL; \
+    } while (0)
+
+    CLEAR(config->allocator);
+
+#undef CLEAR
 }
 
 
@@ -134,6 +143,15 @@ _PyPreConfig_Copy(_PyPreConfig *config, const _PyPreConfig *config2)
     _PyPreConfig_Clear(config);
 
 #define COPY_ATTR(ATTR) config->ATTR = config2->ATTR
+#define COPY_STR_ATTR(ATTR) \
+    do { \
+        if (config2->ATTR != NULL) { \
+            config->ATTR = _PyMem_RawStrdup(config2->ATTR); \
+            if (config->ATTR == NULL) { \
+                return -1; \
+            } \
+        } \
+    } while (0)
 
     COPY_ATTR(isolated);
     COPY_ATTR(use_environment);
@@ -143,8 +161,11 @@ _PyPreConfig_Copy(_PyPreConfig *config, const _PyPreConfig *config2)
     COPY_ATTR(legacy_windows_fs_encoding);
 #endif
     COPY_ATTR(utf8_mode);
+    COPY_ATTR(dev_mode);
+    COPY_STR_ATTR(allocator);
 
 #undef COPY_ATTR
+#undef COPY_STR_ATTR
     return 0;
 }
 
@@ -345,6 +366,7 @@ preconfig_read(_PyPreConfig *config, const _PyPreCmdline *cmdline)
 {
     _PyPreConfig_GetGlobalConfig(config);
 
+    /* isolated and use_environment */
     if (config->isolated > 0) {
         config->use_environment = 0;
     }
@@ -354,6 +376,7 @@ preconfig_read(_PyPreConfig *config, const _PyPreCmdline *cmdline)
         config->use_environment = 0;
     }
 
+    /* legacy_windows_fs_encoding, utf8_mode, coerce_c_locale */
     if (config->use_environment) {
 #ifdef MS_WINDOWS
         _Py_get_env_flag(config, &config->legacy_windows_fs_encoding,
@@ -414,11 +437,43 @@ preconfig_read(_PyPreConfig *config, const _PyPreCmdline *cmdline)
     if (config->utf8_mode < 0) {
         config->utf8_mode = 0;
     }
+    if (config->coerce_c_locale < 0) {
+        config->coerce_c_locale = 0;
+    }
+
+    /* dev_mode */
+    if ((cmdline && _Py_get_xoption(cmdline->nxoption, cmdline->xoptions, L"dev"))
+        || _PyPreConfig_GetEnv(config, "PYTHONDEVMODE"))
+    {
+        config->dev_mode = 1;
+    }
+    if (config->dev_mode < 0) {
+        config->dev_mode = 0;
+    }
+
+    /* allocator */
+    if (config->dev_mode && config->allocator == NULL) {
+        config->allocator = _PyMem_RawStrdup("debug");
+        if (config->allocator == NULL) {
+            return _Py_INIT_NO_MEMORY();
+        }
+    }
+
+    if (config->allocator == NULL) {
+        const char *allocator = _PyPreConfig_GetEnv(config, "PYTHONMALLOC");
+        if (allocator) {
+            config->allocator = _PyMem_RawStrdup(allocator);
+            if (config->allocator == NULL) {
+                return _Py_INIT_NO_MEMORY();
+            }
+        }
+    }
 
     assert(config->coerce_c_locale >= 0);
     assert(config->utf8_mode >= 0);
     assert(config->isolated >= 0);
     assert(config->use_environment >= 0);
+    assert(config->dev_mode >= 0);
 
     return _Py_INIT_OK();
 }
@@ -448,6 +503,12 @@ _PyPreConfig_AsDict(const _PyPreConfig *config, PyObject *dict)
         } while (0)
 #define SET_ITEM_INT(ATTR) \
     SET_ITEM(#ATTR, PyLong_FromLong(config->ATTR))
+#define FROM_STRING(STR) \
+    ((STR != NULL) ? \
+        PyUnicode_FromString(STR) \
+        : (Py_INCREF(Py_None), Py_None))
+#define SET_ITEM_STR(ATTR) \
+    SET_ITEM(#ATTR, FROM_STRING(config->ATTR))
 
     SET_ITEM_INT(isolated);
     SET_ITEM_INT(use_environment);
@@ -457,13 +518,17 @@ _PyPreConfig_AsDict(const _PyPreConfig *config, PyObject *dict)
 #ifdef MS_WINDOWS
     SET_ITEM_INT(legacy_windows_fs_encoding);
 #endif
+    SET_ITEM_INT(dev_mode);
+    SET_ITEM_STR(allocator);
     return 0;
 
 fail:
     return -1;
 
+#undef FROM_STRING
 #undef SET_ITEM
 #undef SET_ITEM_INT
+#undef SET_ITEM_STR
 }
 
 
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index dec890485b..c955a1d94f 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -482,9 +482,9 @@ _Py_Initialize_ReconfigureCore(PyInterpreterState **interp_p,
 
     /* bpo-34008: For backward compatibility reasons, calling Py_Main() after
        Py_Initialize() ignores the new configuration. */
-    if (core_config->allocator != NULL) {
+    if (core_config->preconfig.allocator != NULL) {
         const char *allocator = _PyMem_GetAllocatorsName();
-        if (allocator == NULL || strcmp(core_config->allocator, allocator) != 0) {
+        if (allocator == NULL || strcmp(core_config->preconfig.allocator, allocator) != 0) {
             return _Py_INIT_USER_ERR("cannot modify memory allocator "
                                      "after first Py_Initialize()");
         }
@@ -521,8 +521,8 @@ pycore_init_runtime(const _PyCoreConfig *core_config)
         return err;
     }
 
-    if (core_config->allocator != NULL) {
-        if (_PyMem_SetupAllocators(core_config->allocator) < 0) {
+    if (core_config->preconfig.allocator != NULL) {
+        if (_PyMem_SetupAllocators(core_config->preconfig.allocator) < 0) {
             return _Py_INIT_USER_ERR("Unknown PYTHONMALLOC allocator");
         }
     }
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 50ba1a71e4..99fd460ff5 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -2180,7 +2180,7 @@ make_flags(void)
     SetFlag(config->quiet);
     SetFlag(config->use_hash_seed == 0 || config->hash_seed != 0);
     SetFlag(config->preconfig.isolated);
-    PyStructSequence_SET_ITEM(seq, pos++, PyBool_FromLong(config->dev_mode));
+    PyStructSequence_SET_ITEM(seq, pos++, PyBool_FromLong(config->preconfig.dev_mode));
     SetFlag(config->preconfig.utf8_mode);
 #undef SetFlag