/* Module definition and import implementation */

#include "Python.h"

#include "Python-ast.h"

#undef Yield /* undefine macro conflicting with winbase.h */

#include "pyarena.h"

#include "pythonrun.h"

#include "errcode.h"

#include "marshal.h"

#include "code.h"

#include "compile.h"

#include "eval.h"

#include "osdefs.h"

#include "importdl.h"

#ifdef HAVE_FCNTL_H

#include <fcntl.h>

#endif

#ifdef __cplusplus

extern "C" { 

#endif

#ifdef MS_WINDOWS

/* for stat.st_mode */

typedef unsigned short mode_t;

#endif

extern time_t PyOS_GetLastModificationTime(char *, FILE *);

						/* In getmtime.c */

/* Magic word to reject .pyc files generated by other Python versions.

   It should change for each incompatible change to the bytecode.

   The value of CR and LF is incorporated so if you ever read or write

   a .pyc file in text mode the magic number will be wrong; also, the

   Apple MPW compiler swaps their values, botching string constants.

   The magic numbers must be spaced apart atleast 2 values, as the

   -U interpeter flag will cause MAGIC+1 being used. They have been

   odd numbers for some time now.

   There were a variety of old schemes for setting the magic number.

   The current working scheme is to increment the previous value by

   10.

   Known values:

       Python 1.5:   20121

       Python 1.5.1: 20121

       Python 1.5.2: 20121

       Python 1.6:   50428

       Python 2.0:   50823

       Python 2.0.1: 50823

       Python 2.1:   60202

       Python 2.1.1: 60202

       Python 2.1.2: 60202

       Python 2.2:   60717

       Python 2.3a0: 62011

       Python 2.3a0: 62021

       Python 2.3a0: 62011 (!)

       Python 2.4a0: 62041

       Python 2.4a3: 62051

       Python 2.4b1: 62061

       Python 2.5a0: 62071

       Python 2.5a0: 62081 (ast-branch)

       Python 2.5a0: 62091 (with)

       Python 2.5a0: 62092 (changed WITH_CLEANUP opcode)

       Python 2.5b3: 62101 (fix wrong code: for x, in ...)

       Python 2.5b3: 62111 (fix wrong code: x += yield)

       Python 2.5c1: 62121 (fix wrong lnotab with for loops and

       			    storing constants that should have been removed)

       Python 2.5c2: 62131 (fix wrong code: for x, in ... in listcomp/genexp)

       Python 2.6a0: 62151 (peephole optimizations and STORE_MAP opcode)

       Python 2.6a1: 62161 (WITH_CLEANUP optimization)

.

*/

#define MAGIC (62161 | ((long)'\r'<<16) | ((long)'\n'<<24))

/* Magic word as global; note that _PyImport_Init() can change the

   value of this global to accommodate for alterations of how the

   compiler works which are enabled by command line switches. */

static long pyc_magic = MAGIC;

/* See _PyImport_FixupExtension() below */

static PyObject *extensions = NULL;

/* This table is defined in config.c: */

extern struct _inittab _PyImport_Inittab[];

struct _inittab *PyImport_Inittab = _PyImport_Inittab;

/* these tables define the module suffixes that Python recognizes */

struct filedescr * _PyImport_Filetab = NULL;

#ifdef RISCOS

static const struct filedescr _PyImport_StandardFiletab[] = {

	{"/py", "U", PY_SOURCE},

	{"/pyc", "rb", PY_COMPILED},

	{0, 0}

};

#else

static const struct filedescr _PyImport_StandardFiletab[] = {

	{".py", "U", PY_SOURCE},

#ifdef MS_WINDOWS

	{".pyw", "U", PY_SOURCE},

#endif

	{".pyc", "rb", PY_COMPILED},

	{0, 0}

};

#endif

/* Initialize things */

void

_PyImport_Init(void)

{

	const struct filedescr *scan;

	struct filedescr *filetab;

	int countD = 0;

	int countS = 0;

	/* prepare _PyImport_Filetab: copy entries from

	   _PyImport_DynLoadFiletab and _PyImport_StandardFiletab.

	 */

#ifdef HAVE_DYNAMIC_LOADING

	for (scan = _PyImport_DynLoadFiletab; scan->suffix != NULL; ++scan)

		++countD;

#endif

	for (scan = _PyImport_StandardFiletab; scan->suffix != NULL; ++scan)

		++countS;

	filetab = PyMem_NEW(struct filedescr, countD + countS + 1);

	if (filetab == NULL)

		Py_FatalError("Can't initialize import file table.");

#ifdef HAVE_DYNAMIC_LOADING

	memcpy(filetab, _PyImport_DynLoadFiletab,

	       countD * sizeof(struct filedescr));

#endif

	memcpy(filetab + countD, _PyImport_StandardFiletab,

	       countS * sizeof(struct filedescr));

	filetab[countD + countS].suffix = NULL;

	_PyImport_Filetab = filetab;

	if (Py_OptimizeFlag) {

		/* Replace ".pyc" with ".pyo" in _PyImport_Filetab */

		for (; filetab->suffix != NULL; filetab++) {

#ifndef RISCOS

			if (strcmp(filetab->suffix, ".pyc") == 0)

				filetab->suffix = ".pyo";

#else

			if (strcmp(filetab->suffix, "/pyc") == 0)

				filetab->suffix = "/pyo";

#endif

		}

	}

	if (Py_UnicodeFlag) {

		/* Fix the pyc_magic so that byte compiled code created

		   using the all-Unicode method doesn't interfere with

		   code created in normal operation mode. */

		pyc_magic = MAGIC + 1;

	}

}

void

_PyImportHooks_Init(void)

{

	PyObject *v, *path_hooks = NULL, *zimpimport;

	int err = 0;

	/* adding sys.path_hooks and sys.path_importer_cache, setting up

	   zipimport */

	if (PyType_Ready(&PyNullImporter_Type) < 0)

		goto error;

	if (Py_VerboseFlag)

		PySys_WriteStderr("# installing zipimport hook\n");

	v = PyList_New(0);

	if (v == NULL)

		goto error;

	err = PySys_SetObject("meta_path", v);

	Py_DECREF(v);

	if (err)

		goto error;

	v = PyDict_New();

	if (v == NULL)

		goto error;

	err = PySys_SetObject("path_importer_cache", v);

	Py_DECREF(v);

	if (err)

		goto error;

	path_hooks = PyList_New(0);

	if (path_hooks == NULL)

		goto error;

	err = PySys_SetObject("path_hooks", path_hooks);

	if (err) {

  error:

		PyErr_Print();

		Py_FatalError("initializing sys.meta_path, sys.path_hooks, "

			      "path_importer_cache, or NullImporter failed"

			      );

	}

	zimpimport = PyImport_ImportModule("zipimport");

	if (zimpimport == NULL) {

		PyErr_Clear(); /* No zip import module -- okay */

		if (Py_VerboseFlag)

			PySys_WriteStderr("# can't import zipimport\n");

	}

	else {

		PyObject *zipimporter = PyObject_GetAttrString(zimpimport,

							       "zipimporter");

		Py_DECREF(zimpimport);

		if (zipimporter == NULL) {

			PyErr_Clear(); /* No zipimporter object -- okay */

			if (Py_VerboseFlag)

				PySys_WriteStderr(

				    "# can't import zipimport.zipimporter\n");

		}

		else {

			/* sys.path_hooks.append(zipimporter) */

			err = PyList_Append(path_hooks, zipimporter);

			Py_DECREF(zipimporter);

			if (err)

				goto error;

			if (Py_VerboseFlag)

				PySys_WriteStderr(

					"# installed zipimport hook\n");

		}

	}

	Py_DECREF(path_hooks);

}

void

_PyImport_Fini(void)

{

	Py_XDECREF(extensions);

	extensions = NULL;

	PyMem_DEL(_PyImport_Filetab);

	_PyImport_Filetab = NULL;

}

/* Locking primitives to prevent parallel imports of the same module

   in different threads to return with a partially loaded module.

   These calls are serialized by the global interpreter lock. */

#ifdef WITH_THREAD

#include "pythread.h"

static PyThread_type_lock import_lock = 0;

static long import_lock_thread = -1;

static int import_lock_level = 0;

static void

lock_import(void)

{

	long me = PyThread_get_thread_ident();

	if (me == -1)

		return; /* Too bad */

	if (import_lock == NULL) {

		import_lock = PyThread_allocate_lock();

		if (import_lock == NULL)

			return;  /* Nothing much we can do. */

	}

	if (import_lock_thread == me) {

		import_lock_level++;

		return;

	}

	if (import_lock_thread != -1 || !PyThread_acquire_lock(import_lock, 0))

	{

		PyThreadState *tstate = PyEval_SaveThread();

		PyThread_acquire_lock(import_lock, 1);

		PyEval_RestoreThread(tstate);

	}

	import_lock_thread = me;

	import_lock_level = 1;

}

static int

unlock_import(void)

{

	long me = PyThread_get_thread_ident();

	if (me == -1 || import_lock == NULL)

		return 0; /* Too bad */

	if (import_lock_thread != me)

		return -1;

	import_lock_level--;

	if (import_lock_level == 0) {

		import_lock_thread = -1;

		PyThread_release_lock(import_lock);

	}

	return 1;

}

/* This function is called from PyOS_AfterFork to ensure that newly

   created child processes do not share locks with the parent. */

void

_PyImport_ReInitLock(void)

{

#ifdef _AIX

	if (import_lock != NULL)

		import_lock = PyThread_allocate_lock();

#endif

}

#else

#define lock_import()

#define unlock_import() 0

#endif

static PyObject *

imp_lock_held(PyObject *self, PyObject *noargs)

{

#ifdef WITH_THREAD

	return PyBool_FromLong(import_lock_thread != -1);

#else

	return PyBool_FromLong(0);

#endif

}

static PyObject *

imp_acquire_lock(PyObject *self, PyObject *noargs)

{

#ifdef WITH_THREAD

	lock_import();

#endif

	Py_INCREF(Py_None);

	return Py_None;

}

static PyObject *

imp_release_lock(PyObject *self, PyObject *noargs)

{

#ifdef WITH_THREAD

	if (unlock_import() < 0) {

		PyErr_SetString(PyExc_RuntimeError,

				"not holding the import lock");

		return NULL;

	}

#endif

	Py_INCREF(Py_None);

	return Py_None;

}

static void

imp_modules_reloading_clear(void)

{

	PyInterpreterState *interp = PyThreadState_Get()->interp;

	if (interp->modules_reloading != NULL)

		PyDict_Clear(interp->modules_reloading);

}

/* Helper for sys */

PyObject *

PyImport_GetModuleDict(void)

{

	PyInterpreterState *interp = PyThreadState_GET()->interp;

	if (interp->modules == NULL)

		Py_FatalError("PyImport_GetModuleDict: no module dictionary!");

	return interp->modules;

}

/* List of names to clear in sys */

static char* sys_deletes[] = {

	"path", "argv", "ps1", "ps2", "exitfunc",

	"exc_type", "exc_value", "exc_traceback",

	"last_type", "last_value", "last_traceback",

	"path_hooks", "path_importer_cache", "meta_path",

	/* misc stuff */

	"flags", "float_info",

	NULL

};

static char* sys_files[] = {

	"stdin", "__stdin__",

	"stdout", "__stdout__",

	"stderr", "__stderr__",

	NULL

};

/* Un-initialize things, as good as we can */

void

PyImport_Cleanup(void)

{

	Py_ssize_t pos, ndone;

	char *name;

	PyObject *key, *value, *dict;

	PyInterpreterState *interp = PyThreadState_GET()->interp;

	PyObject *modules = interp->modules;

	if (modules == NULL)

		return; /* Already done */

	/* Delete some special variables first.  These are common

	   places where user values hide and people complain when their

	   destructors fail.  Since the modules containing them are

	   deleted *last* of all, they would come too late in the normal

	   destruction order.  Sigh. */

	value = PyDict_GetItemString(modules, "__builtin__");

	if (value != NULL && PyModule_Check(value)) {

		dict = PyModule_GetDict(value);

		if (Py_VerboseFlag)

			PySys_WriteStderr("# clear __builtin__._\n");

		PyDict_SetItemString(dict, "_", Py_None);

	}

	value = PyDict_GetItemString(modules, "sys");

	if (value != NULL && PyModule_Check(value)) {

		char **p;

		PyObject *v;

		dict = PyModule_GetDict(value);

		for (p = sys_deletes; *p != NULL; p++) {

			if (Py_VerboseFlag)

				PySys_WriteStderr("# clear sys.%s\n", *p);

			PyDict_SetItemString(dict, *p, Py_None);

		}

		for (p = sys_files; *p != NULL; p+=2) {

			if (Py_VerboseFlag)

				PySys_WriteStderr("# restore sys.%s\n", *p);

			v = PyDict_GetItemString(dict, *(p+1));

			if (v == NULL)

				v = Py_None;

			PyDict_SetItemString(dict, *p, v);

		}

	}

	/* First, delete __main__ */

	value = PyDict_GetItemString(modules, "__main__");

	if (value != NULL && PyModule_Check(value)) {

		if (Py_VerboseFlag)

			PySys_WriteStderr("# cleanup __main__\n");

		_PyModule_Clear(value);

		PyDict_SetItemString(modules, "__main__", Py_None);

	}

	/* The special treatment of __builtin__ here is because even

	   when it's not referenced as a module, its dictionary is

	   referenced by almost every module's __builtins__.  Since

	   deleting a module clears its dictionary (even if there are

	   references left to it), we need to delete the __builtin__

	   module last.  Likewise, we don't delete sys until the very

	   end because it is implicitly referenced (e.g. by print).

	   Also note that we 'delete' modules by replacing their entry

	   in the modules dict with None, rather than really deleting

	   them; this avoids a rehash of the modules dictionary and

	   also marks them as "non existent" so they won't be

	   re-imported. */

	/* Next, repeatedly delete modules with a reference count of

	   one (skipping __builtin__ and sys) and delete them */

	do {

		ndone = 0;

		pos = 0;

		while (PyDict_Next(modules, &pos, &key, &value)) {

			if (value->ob_refcnt != 1)

				continue;

			if (PyString_Check(key) && PyModule_Check(value)) {

				name = PyString_AS_STRING(key);

				if (strcmp(name, "__builtin__") == 0)

					continue;

				if (strcmp(name, "sys") == 0)

					continue;

				if (Py_VerboseFlag)

					PySys_WriteStderr(

						"# cleanup[1] %s\n", name);

				_PyModule_Clear(value);

				PyDict_SetItem(modules, key, Py_None);

				ndone++;

			}

		}

	} while (ndone > 0);

	/* Next, delete all modules (still skipping __builtin__ and sys) */

	pos = 0;

	while (PyDict_Next(modules, &pos, &key, &value)) {

		if (PyString_Check(key) && PyModule_Check(value)) {

			name = PyString_AS_STRING(key);

			if (strcmp(name, "__builtin__") == 0)

				continue;

			if (strcmp(name, "sys") == 0)

				continue;

			if (Py_VerboseFlag)

				PySys_WriteStderr("# cleanup[2] %s\n", name);

			_PyModule_Clear(value);

			PyDict_SetItem(modules, key, Py_None);

		}

	}

	/* Next, delete sys and __builtin__ (in that order) */

	value = PyDict_GetItemString(modules, "sys");

	if (value != NULL && PyModule_Check(value)) {

		if (Py_VerboseFlag)

			PySys_WriteStderr("# cleanup sys\n");

		_PyModule_Clear(value);

		PyDict_SetItemString(modules, "sys", Py_None);

	}

	value = PyDict_GetItemString(modules, "__builtin__");

	if (value != NULL && PyModule_Check(value)) {

		if (Py_VerboseFlag)

			PySys_WriteStderr("# cleanup __builtin__\n");

		_PyModule_Clear(value);

		PyDict_SetItemString(modules, "__builtin__", Py_None);

	}

	/* Finally, clear and delete the modules directory */

	PyDict_Clear(modules);

	interp->modules = NULL;

	Py_DECREF(modules);

	Py_CLEAR(interp->modules_reloading);

}

/* Helper for pythonrun.c -- return magic number */

long

PyImport_GetMagicNumber(void)