text: /*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2013-2019 Damien P. George
   * Copyright (c) 2014 Paul Sokolovsky
   * Copyright (c) 2021 Jim Mussared
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include <stdio.h>
  #include <string.h>
  #include <assert.h>
  
  #include "py/compile.h"
  #include "py/objmodule.h"
  #include "py/persistentcode.h"
  #include "py/runtime.h"
  #include "py/builtin.h"
  #include "py/frozenmod.h"
  
  #if MICROPY_DEBUG_VERBOSE // print debugging info
  #define DEBUG_PRINT (1)
  #define DEBUG_printf DEBUG_printf
  #else // don't print debugging info
  #define DEBUG_PRINT (0)
  #define DEBUG_printf(...) (void)0
  #endif
  
  #if MICROPY_ENABLE_EXTERNAL_IMPORT
  
  // Must be a string of one byte.
  #define PATH_SEP_CHAR "/"
  
  // Virtual sys.path entry that maps to the frozen modules.
  #define MP_FROZEN_PATH_PREFIX ".frozen/"
  
  bool mp_obj_is_package(mp_obj_t module) {
      mp_obj_t dest[2];
      mp_load_method_maybe(module, MP_QSTR___path__, dest);
      return dest[0] != MP_OBJ_NULL;
  }
  
  // Wrapper for mp_import_stat (which is provided by the port, and typically
  // uses mp_vfs_import_stat) to also search frozen modules. Given an exact
  // path to a file or directory (e.g. "foo/bar", foo/bar.py" or "foo/bar.mpy"),
  // will return whether the path is a file, directory, or doesn't exist.
  STATIC mp_import_stat_t stat_path_or_frozen(const char *path) {
      #if MICROPY_MODULE_FROZEN
      // Only try and load as a frozen module if it starts with .frozen/.
      const int frozen_path_prefix_len = strlen(MP_FROZEN_PATH_PREFIX);
      if (strncmp(path, MP_FROZEN_PATH_PREFIX, frozen_path_prefix_len) == 0) {
          return mp_find_frozen_module(path + frozen_path_prefix_len, NULL, NULL);
      }
      #endif
      return mp_import_stat(path);
  }
  
  // Given a path to a .py file, try and find this path as either a .py or .mpy
  // in either the filesystem or frozen modules.
  STATIC mp_import_stat_t stat_file_py_or_mpy(vstr_t *path) {
      mp_import_stat_t stat = stat_path_or_frozen(vstr_null_terminated_str(path));
      if (stat == MP_IMPORT_STAT_FILE) {
          return stat;
      }
  
      #if MICROPY_PERSISTENT_CODE_LOAD
      // Didn't find .py -- try the .mpy instead by inserting an 'm' into the '.py'.
      vstr_ins_byte(path, path->len - 2, 'm');
      stat = stat_path_or_frozen(vstr_null_terminated_str(path));
      if (stat == MP_IMPORT_STAT_FILE) {
          return stat;
      }
      #endif
  
      return MP_IMPORT_STAT_NO_EXIST;
  }
  
  // Given an import path (e.g. "foo/bar"), try and find "foo/bar" (a directory)
  // or "foo/bar.(m)py" in either the filesystem or frozen modules.
  STATIC mp_import_stat_t stat_dir_or_file(vstr_t *path) {
      mp_import_stat_t stat = stat_path_or_frozen(vstr_null_terminated_str(path));
      DEBUG_printf("stat %s: %d\n", vstr_str(path), stat);
      if (stat == MP_IMPORT_STAT_DIR) {
          return stat;
      }
  
      // not a directory, add .py and try as a file
      vstr_add_str(path, ".py");
      return stat_file_py_or_mpy(path);
  }
  
  // Given a top-level module, try and find it in each of the sys.path entries
  // via stat_dir_or_file.
  STATIC mp_import_stat_t stat_top_level_dir_or_file(qstr mod_name, vstr_t *dest) {
      DEBUG_printf("stat_top_level_dir_or_file: '%s'\n", qstr_str(mod_name));
      #if MICROPY_PY_SYS
      size_t path_num;
      mp_obj_t *path_items;
      mp_obj_list_get(mp_sys_path, &path_num, &path_items);
  
      if (path_num > 0) {
          // go through each path looking for a directory or file
          for (size_t i = 0; i < path_num; i++) {
              vstr_reset(dest);
              size_t p_len;
              const char *p = mp_obj_str_get_data(path_items[i], &p_len);
              if (p_len > 0) {
                  vstr_add_strn(dest, p, p_len);
                  vstr_add_char(dest, PATH_SEP_CHAR[0]);
              }
              vstr_add_str(dest, qstr_str(mod_name));
              mp_import_stat_t stat = stat_dir_or_file(dest);
              if (stat != MP_IMPORT_STAT_NO_EXIST) {
                  return stat;
              }
          }
  
          // could not find a directory or file
          return MP_IMPORT_STAT_NO_EXIST;
      }
      #endif
  
      // mp_sys_path is empty (or not enabled), so just stat the given path
      // directly.
      vstr_add_str(dest, qstr_str(mod_name));
      return stat_dir_or_file(dest);
  }
  
  #if MICROPY_MODULE_FROZEN_STR || MICROPY_ENABLE_COMPILER
  STATIC void do_load_from_lexer(mp_module_context_t *context, mp_lexer_t *lex) {
      #if MICROPY_PY___FILE__
      qstr source_name = lex->source_name;
      mp_store_attr(MP_OBJ_FROM_PTR(&context->module), MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
      #endif
  
      // parse, compile and execute the module in its context
      mp_obj_dict_t *mod_globals = context->module.globals;
      mp_parse_compile_execute(lex, MP_PARSE_FILE_INPUT, mod_globals, mod_globals);
  }
  #endif
  
  #if (MICROPY_HAS_FILE_READER && MICROPY_PERSISTENT_CODE_LOAD) || MICROPY_MODULE_FROZEN_MPY
  STATIC void do_execute_raw_code(mp_module_context_t *context, const mp_raw_code_t *rc, const mp_module_context_t *mc, const char *source_name) {
      (void)source_name;
  
      #if MICROPY_PY___FILE__
      mp_store_attr(MP_OBJ_FROM_PTR(&context->module), MP_QSTR___file__, MP_OBJ_NEW_QSTR(qstr_from_str(source_name)));
      #endif
  
      // execute the module in its context
      mp_obj_dict_t *mod_globals = context->module.globals;
  
      // save context
      mp_obj_dict_t *volatile old_globals = mp_globals_get();
      mp_obj_dict_t *volatile old_locals = mp_locals_get();
  
      // set new context
      mp_globals_set(mod_globals);
      mp_locals_set(mod_globals);
  
      nlr_buf_t nlr;
      if (nlr_push(&nlr) == 0) {
          mp_obj_t module_fun = mp_make_function_from_raw_code(rc, mc, NULL);
          mp_call_function_0(module_fun);
  
          // finish nlr block, restore context
          nlr_pop();
          mp_globals_set(old_globals);
          mp_locals_set(old_locals);
      } else {
          // exception; restore context and re-raise same exception
          mp_globals_set(old_globals);
          mp_locals_set(old_locals);
          nlr_jump(nlr.ret_val);
      }
  }
  #endif
  
  STATIC void do_load(mp_module_context_t *module_obj, vstr_t *file) {
      #if MICROPY_MODULE_FROZEN || MICROPY_ENABLE_COMPILER || (MICROPY_PERSISTENT_CODE_LOAD && MICROPY_HAS_FILE_READER)
      const char *file_str = vstr_null_terminated_str(file);
      #endif
  
      // If we support frozen modules (either as str or mpy) then try to find the
      // requested filename in the list of frozen module filenames.
      #if MICROPY_MODULE_FROZEN
      void *modref;
      int frozen_type;
      const int frozen_path_prefix_len = strlen(MP_FROZEN_PATH_PREFIX);
      if (strncmp(file_str, MP_FROZEN_PATH_PREFIX, frozen_path_prefix_len) == 0) {
          mp_find_frozen_module(file_str + frozen_path_prefix_len, &frozen_type, &modref);
  
          // If we support frozen str modules and the compiler is enabled, and we
          // found the filename in the list of frozen files, then load and execute it.
          #if MICROPY_MODULE_FROZEN_STR
          if (frozen_type == MP_FROZEN_STR) {
              do_load_from_lexer(module_obj, modref);
              return;
          }
          #endif
  
          // If we support frozen mpy modules and we found a corresponding file (and
          // its data) in the list of frozen files, execute it.
          #if MICROPY_MODULE_FROZEN_MPY
          if (frozen_type == MP_FROZEN_MPY) {
              const mp_frozen_module_t *frozen = modref;
              module_obj->constants = frozen->constants;
              do_execute_raw_code(module_obj, frozen->rc, module_obj, file_str + frozen_path_prefix_len);
              return;
          }
          #endif
      }
  
      #endif // MICROPY_MODULE_FROZEN
  
      // If we support loading .mpy files then check if the file extension is of
      // the correct format and, if so, load and execute the file.
      #if MICROPY_HAS_FILE_READER && MICROPY_PERSISTENT_CODE_LOAD
      if (file_str[file->len - 3] == 'm') {
          mp_compiled_module_t cm = mp_raw_code_load_file(file_str, module_obj);
          do_execute_raw_code(module_obj, cm.rc, cm.context, file_str);
          return;
      }
      #endif
  
      // If we can compile scripts then load the file and compile and execute it.
      #if MICROPY_ENABLE_COMPILER
      {
          mp_lexer_t *lex = mp_lexer_new_from_file(file_str);
          do_load_from_lexer(module_obj, lex);
          return;
      }
      #else
      // If we get here then the file was not frozen and we can't compile scripts.
      mp_raise_msg(&mp_type_ImportError, MP_ERROR_TEXT("script compilation not supported"));
      #endif
  }
  
  // Convert a relative (to the current module) import, going up "level" levels,
  // into an absolute import.
  STATIC void evaluate_relative_import(mp_int_t level, const char **module_name, size_t *module_name_len) {
      // What we want to do here is to take the name of the current module,
      // remove <level> trailing components, and concatenate the passed-in
      // module name.
      // For example, level=3, module_name="foo.bar", __name__="a.b.c.d" --> "a.foo.bar"
      // "Relative imports use a module's __name__ attribute to determine that
      // module's position in the package hierarchy."
      // http://legacy.python.org/dev/peps/pep-0328/#relative-imports-and-name
  
      mp_obj_t current_module_name_obj = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___name__));
      assert(current_module_name_obj != MP_OBJ_NULL);
  
      #if MICROPY_MODULE_OVERRIDE_MAIN_IMPORT && MICROPY_CPYTHON_COMPAT
      if (MP_OBJ_QSTR_VALUE(current_module_name_obj) == MP_QSTR___main__) {
          // This is a module loaded by -m command-line switch (e.g. unix port),
          // and so its __name__ has been set to "__main__". Get its real name
          // that we stored during import in the __main__ attribute.
          current_module_name_obj = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
      }
      #endif
  
      // If we have a __path__ in the globals dict, then we're a package.
      bool is_pkg = mp_map_lookup(&mp_globals_get()->map, MP_OBJ_NEW_QSTR(MP_QSTR___path__), MP_MAP_LOOKUP);
  
      #if DEBUG_PRINT
      DEBUG_printf("Current module/package: ");
      mp_obj_print_helper(MICROPY_DEBUG_PRINTER, current_module_name_obj, PRINT_REPR);
      DEBUG_printf(", is_package: %d", is_pkg);
      DEBUG_printf("\n");
      #endif
  
      size_t current_module_name_len;
      const char *current_module_name = mp_obj_str_get_data(current_module_name_obj, &current_module_name_len);
  
      const char *p = current_module_name + current_module_name_len;
      if (is_pkg) {
          // If we're evaluating relative to a package, then take off one fewer
          // level (i.e. the relative search starts inside the package, rather
          // than as a sibling of the package).
          --level;
      }
  
      // Walk back 'level' dots (or run out of path).
      while (level && p > current_module_name) {
          if (*--p == '.') {
              --level;
          }
      }
  
      // We must have some component left over to import from.
      if (p == current_module_name) {
          mp_raise_msg(&mp_type_ImportError, MP_ERROR_TEXT("can't perform relative import"));
      }
  
      // New length is len("<chopped path>.<module_name>"). Note: might be one byte
      // more than we need if module_name is empty (for the extra . we will
      // append).
      uint new_module_name_len = (size_t)(p - current_module_name) + 1 + *module_name_len;
      char *new_mod = mp_local_alloc(new_module_name_len);
      memcpy(new_mod, current_module_name, p - current_module_name);
  
      // Only append ".<module_name>" if there was one).
      if (*module_name_len != 0) {
          new_mod[p - current_module_name] = '.';
          memcpy(new_mod + (p - current_module_name) + 1, *module_name, *module_name_len);
      } else {
          --new_module_name_len;
      }
  
      // Copy into a QSTR.
      qstr new_mod_q = qstr_from_strn(new_mod, new_module_name_len);
      mp_local_free(new_mod);
  
      DEBUG_printf("Resolved base name for relative import: '%s'\n", qstr_str(new_mod_q));
      *module_name = qstr_str(new_mod_q);
      *module_name_len = new_module_name_len;
  }
  
  // Load a module at the specified absolute path, possibly as a submodule of the given outer module.
  // full_mod_name:    The full absolute path to this module (e.g. "foo.bar.baz").
  // level_mod_name:   The final component of the path (e.g. "baz").
  // outer_module_obj: The parent module (we need to store this module as an
  //                   attribute on it) (or MP_OBJ_NULL for top-level).
  // path:             The filesystem path where we found the parent module
  //                   (or empty for a top level module).
  // override_main:    Whether to set the __name__ to "__main__" (and use __main__
  //                   for the actual path).
  STATIC mp_obj_t process_import_at_level(qstr full_mod_name, qstr level_mod_name, mp_obj_t outer_module_obj, vstr_t *path, bool override_main) {
      mp_import_stat_t stat = MP_IMPORT_STAT_NO_EXIST;
  
      // Exact-match of built-in (or already-loaded) takes priority.
      mp_obj_t module_obj = mp_module_get_loaded_or_builtin(full_mod_name);
  
      // Even if we find the module, go through the motions of searching for it
      // because we may actually be in the process of importing a sub-module.
      // So we need to (re-)find the correct path to be finding the sub-module
      // on the next iteration of process_import_at_level.
  
      if (outer_module_obj == MP_OBJ_NULL) {
          DEBUG_printf("Searching for top-level module\n");
  
          // First module in the dotted-name; search for a directory or file
          // relative to all the locations in sys.path.
          stat = stat_top_level_dir_or_file(full_mod_name, path);
  
          // If the module "foo" doesn't exist on the filesystem, and it's not a
          // builtin, try and find "ufoo" as a built-in. (This feature was
          // formerly known as "weak links").
          #if MICROPY_MODULE_WEAK_LINKS
          if (stat == MP_IMPORT_STAT_NO_EXIST && module_obj == MP_OBJ_NULL) {
              char *umodule_buf = vstr_str(path);
              umodule_buf[0] = 'u';
              strcpy(umodule_buf + 1, qstr_str(level_mod_name));
              qstr umodule_name = qstr_from_str(umodule_buf);
              module_obj = mp_module_get_builtin(umodule_name);
          }
          #elif MICROPY_PY_SYS
          if (stat == MP_IMPORT_STAT_NO_EXIST && module_obj == MP_OBJ_NULL && level_mod_name == MP_QSTR_sys) {
              module_obj = MP_OBJ_FROM_PTR(&mp_module_sys);
          }
          #endif
      } else {
          DEBUG_printf("Searching for sub-module\n");
  
          // Add the current part of the module name to the path.
          vstr_add_char(path, PATH_SEP_CHAR[0]);
          vstr_add_str(path, qstr_str(level_mod_name));
  
          // Because it's not top level, we already know which path the parent was found in.
          stat = stat_dir_or_file(path);
      }
      DEBUG_printf("Current path: %.*s\n", (int)vstr_len(path), vstr_str(path));
  
      if (module_obj == MP_OBJ_NULL) {
          // Not a built-in and not already-loaded.
  
          if (stat == MP_IMPORT_STAT_NO_EXIST) {
              // And the file wasn't found -- fail.
              #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
              mp_raise_msg(&mp_type_ImportError, MP_ERROR_TEXT("module not found"));
              #else
              mp_raise_msg_varg(&mp_type_ImportError, MP_ERROR_TEXT("no module named '%q'"), full_mod_name);
              #endif
          }
  
          // Not a built-in but found on the filesystem, try and load it.
  
          DEBUG_printf("Found path: %.*s\n", (int)vstr_len(path), vstr_str(path));
  
          // Prepare for loading from the filesystem. Create a new shell module.
          module_obj = mp_obj_new_module(full_mod_name);
  
          #if MICROPY_MODULE_OVERRIDE_MAIN_IMPORT
          // If this module is being loaded via -m on unix, then
          // override __name__ to "__main__". Do this only for *modules*
          // however - packages never have their names replaced, instead
          // they're -m'ed using a special __main__ submodule in them. (This all
          // apparently is done to not touch the package name itself, which is
          // important for future imports).
          if (override_main && stat != MP_IMPORT_STAT_DIR) {
              mp_obj_module_t *o = MP_OBJ_TO_PTR(module_obj);
              mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
              #if MICROPY_CPYTHON_COMPAT
              // Store module as "__main__" in the dictionary of loaded modules (returned by sys.modules).
              mp_obj_dict_store(MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_loaded_modules_dict)), MP_OBJ_NEW_QSTR(MP_QSTR___main__), module_obj);
              // Store real name in "__main__" attribute. Need this for
              // resolving relative imports later. "__main__ was chosen
              // semi-randonly, to reuse existing qstr's.
              mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___main__), MP_OBJ_NEW_QSTR(full_mod_name));
              #endif
          }
          #endif // MICROPY_MODULE_OVERRIDE_MAIN_IMPORT
  
          if (stat == MP_IMPORT_STAT_DIR) {
              // Directory -- execute "path/__init__.py".
              DEBUG_printf("%.*s is dir\n", (int)vstr_len(path), vstr_str(path));
              // Store the __path__ attribute onto this module.
              // https://docs.python.org/3/reference/import.html
              // "Specifically, any module that contains a __path__ attribute is considered a package."
              mp_store_attr(module_obj, MP_QSTR___path__, mp_obj_new_str(vstr_str(path), vstr_len(path)));
              size_t orig_path_len = path->len;
              vstr_add_str(path, PATH_SEP_CHAR "__init__.py");
              if (stat_file_py_or_mpy(path) == MP_IMPORT_STAT_FILE) {
                  do_load(MP_OBJ_TO_PTR(module_obj), path);
              } else {
                  // No-op. Nothing to load.
                  // mp_warning("%s is imported as namespace package", vstr_str(&path));
              }
              // Remove /__init__.py suffix.
              path->len = orig_path_len;
          } else { // MP_IMPORT_STAT_FILE
              // File -- execute "path.(m)py".
              do_load(MP_OBJ_TO_PTR(module_obj), path);
              // Note: This should be the last component in the import path.  If
              // there are remaining components then it's an ImportError
              // because the current path(the module that was just loaded) is
              // not a package.  This will be caught on the next iteration
              // because the file will not exist.
          }
      }
  
      if (outer_module_obj != MP_OBJ_NULL) {
          // If it's a sub-module (not a built-in one), then make it available on
          // the parent module.
          mp_store_attr(outer_module_obj, level_mod_name, module_obj);
      }
  
      return module_obj;
  }
  
  mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
      #if DEBUG_PRINT
      DEBUG_printf("__import__:\n");
      for (size_t i = 0; i < n_args; i++) {
          DEBUG_printf("  ");
          mp_obj_print_helper(MICROPY_DEBUG_PRINTER, args[i], PRINT_REPR);
          DEBUG_printf("\n");
      }
      #endif
  
      // This is the import path, with any leading dots stripped.
      // "import foo.bar" --> module_name="foo.bar"
      // "from foo.bar import baz" --> module_name="foo.bar"
      // "from . import foo" --> module_name=""
      // "from ...foo.bar import baz" --> module_name="foo.bar"
      mp_obj_t module_name_obj = args[0];
  
      // These are the imported names.
      // i.e. "from foo.bar import baz, zap" --> fromtuple=("baz", "zap",)
      // Note: There's a special case on the Unix port, where this is set to mp_const_false which means that it's __main__.
      mp_obj_t fromtuple = mp_const_none;
  
      // Level is the number of leading dots in a relative import.
      // i.e. "from . import foo" --> level=1
      // i.e. "from ...foo.bar import baz" --> level=3
      mp_int_t level = 0;
  
      if (n_args >= 4) {
          fromtuple = args[3];
          if (n_args >= 5) {
              level = MP_OBJ_SMALL_INT_VALUE(args[4]);
              if (level < 0) {
                  mp_raise_ValueError(NULL);
              }
          }
      }
  
      size_t module_name_len;
      const char *module_name = mp_obj_str_get_data(module_name_obj, &module_name_len);
  
      if (level != 0) {
          // Turn "foo.bar" into "<current module minus 3 components>.foo.bar".
          evaluate_relative_import(level, &module_name, &module_name_len);
      }
  
      if (module_name_len == 0) {
          mp_raise_ValueError(NULL);
      }
  
      DEBUG_printf("Starting module search for '%s'\n", module_name);
  
      VSTR_FIXED(path, MICROPY_ALLOC_PATH_MAX)
      mp_obj_t top_module_obj = MP_OBJ_NULL;
      mp_obj_t outer_module_obj = MP_OBJ_NULL;
  
      // Search for the end of each component.
      size_t current_component_start = 0;
      for (size_t i = 1; i <= module_name_len; i++) {
          if (i == module_name_len || module_name[i] == '.') {
              // The module name up to this depth (e.g. foo.bar.baz).
              qstr full_mod_name = qstr_from_strn(module_name, i);
              // The current level name (e.g. baz).
              qstr level_mod_name = qstr_from_strn(module_name + current_component_start, i - current_component_start);
  
              DEBUG_printf("Processing module: '%s' at level '%s'\n", qstr_str(full_mod_name), qstr_str(level_mod_name));
              DEBUG_printf("Previous path: =%.*s=\n", (int)vstr_len(&path), vstr_str(&path));
  
              #if MICROPY_MODULE_OVERRIDE_MAIN_IMPORT
              // On unix, if this is being loaded via -m (magic mp_const_false),
              // then handle that if it's the final component.
              bool override_main = (i == module_name_len && fromtuple == mp_const_false);
              #else
              bool override_main = false;
              #endif
  
              // Import this module.
              mp_obj_t module_obj = process_import_at_level(full_mod_name, level_mod_name, outer_module_obj, &path, override_main);
  
              // Set this as the parent module, and remember the top-level module if it's the first.
              outer_module_obj = module_obj;
              if (top_module_obj == MP_OBJ_NULL) {
                  top_module_obj = module_obj;
              }
  
              current_component_start = i + 1;
          }
      }
  
      if (fromtuple != mp_const_none) {
          // If fromtuple is not empty, return leaf module
          return outer_module_obj;
      } else {
          // Otherwise, we need to return top-level package
          return top_module_obj;
      }
  }
  
  #else // MICROPY_ENABLE_EXTERNAL_IMPORT
  
  mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
      // Check that it's not a relative import
      if (n_args >= 5 && MP_OBJ_SMALL_INT_VALUE(args[4]) != 0) {
          mp_raise_NotImplementedError(MP_ERROR_TEXT("relative import"));
      }
  
      // Check if module already exists, and return it if it does
      qstr module_name_qstr = mp_obj_str_get_qstr(args[0]);
      mp_obj_t module_obj = mp_module_get_loaded_or_builtin(module_name_qstr);
      if (module_obj != MP_OBJ_NULL) {
          return module_obj;
      }
  
      #if MICROPY_MODULE_WEAK_LINKS
      // Check if there is a weak link to this module
      char umodule_buf[MICROPY_ALLOC_PATH_MAX];
      umodule_buf[0] = 'u';
      strcpy(umodule_buf + 1, args[0]);
      qstr umodule_name_qstr = qstr_from_str(umodule_buf);
      module_obj = mp_module_get_loaded_or_builtin(umodule_name_qstr);
      if (module_obj != MP_OBJ_NULL) {
          return module_obj;
      }
      #endif
  
      // Couldn't find the module, so fail
      #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
      mp_raise_msg(&mp_type_ImportError, MP_ERROR_TEXT("module not found"));
      #else
      mp_raise_msg_varg(&mp_type_ImportError, MP_ERROR_TEXT("no module named '%q'"), module_name_qstr);
      #endif
  }
  
  #endif // MICROPY_ENABLE_EXTERNAL_IMPORT
  
  MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin___import___obj, 1, 5, mp_builtin___import__);
  