Update version number and release date.

[python/dscho.git] / Python / import.c

/* Module definition and import implementation */

#include "Python.h"

#include "node.h"
#include "token.h"
#include "errcode.h"
#include "marshal.h"
#include "compile.h"
#include "eval.h"
#include "osdefs.h"
#include "importdl.h"
#ifdef macintosh
#include "macglue.h"
#endif

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

extern time_t PyOS_GetLastModificationTime(char *, FILE *);
                                                /* In getmtime.c */

/* Magic word to reject .pyc files generated by other Python versions */
/* Change for each incompatible change */
/* 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.
   XXX That probably isn't important anymore.
*/
/* XXX Perhaps the magic number should be frozen and a version field
   added to the .pyc file header? */
/* New way to come up with the low 16 bits of the magic number:
      (YEAR-1995) * 10000 +  MONTH * 100 + DAY
   where MONTH and DAY are 1-based.
   XXX Whatever the "old way" may have been isn't documented.
   XXX This scheme breaks in 2002, as (2002-1995)*10000 = 70000 doesn't
       fit in 16 bits.
   XXX Later, sometimes 1 gets added to MAGIC in order to record that
       the Unicode -U option is in use.  IMO (Tim's), that's a Bad Idea
       (quite apart from that the -U option doesn't work so isn't used
       anyway).

   XXX MAL, 2002-02-07: I had to modify the MAGIC due to a fix of the
       UTF-8 encoder (it previously produced invalid UTF-8 for unpaired
       high surrogates), so I simply bumped the month value to 20 (invalid
       month) and set the day to 1.  This should be recognizable by any
       algorithm relying on the above scheme. Perhaps we should simply
       start counting in increments of 10 from now on ?!

       MWH, 2002-08-03: Removed SET_LINENO.  Couldn't be bothered figuring
       out the MAGIC schemes, so just incremented it by 10.

       GvR, 2002-08-31: Because MWH changed the bytecode again, moved the
       magic number *back* to 62011.  This should get the snake-farm to
       throw away its old .pyc files, amongst others.

   Known values:
       Python 1.5:   20121
       Python 1.5.1: 20121
       Python 1.5.2: 20121
       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 (!)
*/
#define MAGIC (62011 | ((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.
         */
        for (scan = _PyImport_DynLoadFiletab; scan->suffix != NULL; ++scan)
                ++countD;
        for (scan = _PyImport_StandardFiletab; scan->suffix != NULL; ++scan)
                ++countS;
        filetab = PyMem_NEW(struct filedescr, countD + countS + 1);
        memcpy(filetab, _PyImport_DynLoadFiletab,
               countD * sizeof(struct filedescr));
        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 (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 or "
                              "path_importer_cache 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.zimimporter\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_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)
                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;
}

#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;
}

/* 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",
        NULL
};

static char* sys_files[] = {
        "stdin", "__stdin__",
        "stdout", "__stdout__",
        "stderr", "__stderr__",
        NULL
};


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

void
PyImport_Cleanup(void)
{
        int 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);
}


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

long
PyImport_GetMagicNumber(void)
{
        return pyc_magic;
}


/* Magic for extension modules (built-in as well as dynamically
   loaded).  To prevent initializing an extension module more than
   once, we keep a static dictionary 'extensions' keyed by module name
   (for built-in modules) or by filename (for dynamically loaded
   modules), containing these modules.  A copy of the module's
   dictionary is stored by calling _PyImport_FixupExtension()
   immediately after the module initialization function succeeds.  A
   copy can be retrieved from there by calling
   _PyImport_FindExtension(). */

PyObject *
_PyImport_FixupExtension(char *name, char *filename)
{
        PyObject *modules, *mod, *dict, *copy;
        if (extensions == NULL) {
                extensions = PyDict_New();
                if (extensions == NULL)
                        return NULL;
        }
        modules = PyImport_GetModuleDict();
        mod = PyDict_GetItemString(modules, name);
        if (mod == NULL || !PyModule_Check(mod)) {
                PyErr_Format(PyExc_SystemError,
                  "_PyImport_FixupExtension: module %.200s not loaded", name);
                return NULL;
        }
        dict = PyModule_GetDict(mod);
        if (dict == NULL)
                return NULL;
        copy = PyDict_Copy(dict);
        if (copy == NULL)
                return NULL;
        PyDict_SetItemString(extensions, filename, copy);
        Py_DECREF(copy);
        return copy;
}

PyObject *
_PyImport_FindExtension(char *name, char *filename)
{
        PyObject *dict, *mod, *mdict;
        if (extensions == NULL)
                return NULL;
        dict = PyDict_GetItemString(extensions, filename);
        if (dict == NULL)
                return NULL;
        mod = PyImport_AddModule(name);
        if (mod == NULL)
                return NULL;
        mdict = PyModule_GetDict(mod);
        if (mdict == NULL)
                return NULL;
        if (PyDict_Update(mdict, dict))
                return NULL;
        if (Py_VerboseFlag)
                PySys_WriteStderr("import %s # previously loaded (%s)\n",
                        name, filename);
        return mod;
}


/* Get the module object corresponding to a module name.
   First check the modules dictionary if there's one there,
   if not, create a new one and insert in in the modules dictionary.
   Because the former action is most common, THIS DOES NOT RETURN A
   'NEW' REFERENCE! */

PyObject *
PyImport_AddModule(char *name)
{
        PyObject *modules = PyImport_GetModuleDict();
        PyObject *m;

        if ((m = PyDict_GetItemString(modules, name)) != NULL &&
            PyModule_Check(m))
                return m;
        m = PyModule_New(name);
        if (m == NULL)
                return NULL;
        if (PyDict_SetItemString(modules, name, m) != 0) {
                Py_DECREF(m);
                return NULL;
        }
        Py_DECREF(m); /* Yes, it still exists, in modules! */

        return m;
}


/* Execute a code object in a module and return the module object
   WITH INCREMENTED REFERENCE COUNT */

PyObject *
PyImport_ExecCodeModule(char *name, PyObject *co)
{
        return PyImport_ExecCodeModuleEx(name, co, (char *)NULL);
}

PyObject *
PyImport_ExecCodeModuleEx(char *name, PyObject *co, char *pathname)
{
        PyObject *modules = PyImport_GetModuleDict();
        PyObject *m, *d, *v;

        m = PyImport_AddModule(name);
        if (m == NULL)
                return NULL;
        d = PyModule_GetDict(m);
        if (PyDict_GetItemString(d, "__builtins__") == NULL) {
                if (PyDict_SetItemString(d, "__builtins__",
                                         PyEval_GetBuiltins()) != 0)
                        return NULL;
        }
        /* Remember the filename as the __file__ attribute */
        v = NULL;
        if (pathname != NULL) {
                v = PyString_FromString(pathname);
                if (v == NULL)
                        PyErr_Clear();
        }
        if (v == NULL) {
                v = ((PyCodeObject *)co)->co_filename;
                Py_INCREF(v);
        }
        if (PyDict_SetItemString(d, "__file__", v) != 0)
                PyErr_Clear(); /* Not important enough to report */
        Py_DECREF(v);

        v = PyEval_EvalCode((PyCodeObject *)co, d, d);
        if (v == NULL)
                return NULL;
        Py_DECREF(v);

        if ((m = PyDict_GetItemString(modules, name)) == NULL) {
                PyErr_Format(PyExc_ImportError,
                             "Loaded module %.200s not found in sys.modules",
                             name);
                return NULL;
        }

        Py_INCREF(m);

        return m;
}


/* Given a pathname for a Python source file, fill a buffer with the
   pathname for the corresponding compiled file.  Return the pathname
   for the compiled file, or NULL if there's no space in the buffer.
   Doesn't set an exception. */

static char *
make_compiled_pathname(char *pathname, char *buf, size_t buflen)
{
        size_t len = strlen(pathname);
        if (len+2 > buflen)
                return NULL;

#ifdef MS_WINDOWS
        /* Treat .pyw as if it were .py.  The case of ".pyw" must match
           that used in _PyImport_StandardFiletab. */
        if (len >= 4 && strcmp(&pathname[len-4], ".pyw") == 0)
                --len;  /* pretend 'w' isn't there */
#endif
        memcpy(buf, pathname, len);
        buf[len] = Py_OptimizeFlag ? 'o' : 'c';
        buf[len+1] = '\0';

        return buf;
}


/* Given a pathname for a Python source file, its time of last
   modification, and a pathname for a compiled file, check whether the
   compiled file represents the same version of the source.  If so,
   return a FILE pointer for the compiled file, positioned just after
   the header; if not, return NULL.
   Doesn't set an exception. */

static FILE *
check_compiled_module(char *pathname, long mtime, char *cpathname)
{
        FILE *fp;
        long magic;
        long pyc_mtime;

        fp = fopen(cpathname, "rb");
        if (fp == NULL)
                return NULL;
        magic = PyMarshal_ReadLongFromFile(fp);
        if (magic != pyc_magic) {
                if (Py_VerboseFlag)
                        PySys_WriteStderr("# %s has bad magic\n", cpathname);
                fclose(fp);
                return NULL;
        }
        pyc_mtime = PyMarshal_ReadLongFromFile(fp);
        if (pyc_mtime != mtime) {
                if (Py_VerboseFlag)
                        PySys_WriteStderr("# %s has bad mtime\n", cpathname);
                fclose(fp);
                return NULL;
        }
        if (Py_VerboseFlag)
                PySys_WriteStderr("# %s matches %s\n", cpathname, pathname);
        return fp;
}


/* Read a code object from a file and check it for validity */

static PyCodeObject *
read_compiled_module(char *cpathname, FILE *fp)
{
        PyObject *co;

        co = PyMarshal_ReadLastObjectFromFile(fp);
        /* Ugly: rd_object() may return NULL with or without error */
        if (co == NULL || !PyCode_Check(co)) {
                if (!PyErr_Occurred())
                        PyErr_Format(PyExc_ImportError,
                            "Non-code object in %.200s", cpathname);
                Py_XDECREF(co);
                return NULL;
        }
        return (PyCodeObject *)co;
}


/* Load a module from a compiled file, execute it, and return its
   module object WITH INCREMENTED REFERENCE COUNT */

static PyObject *
load_compiled_module(char *name, char *cpathname, FILE *fp)
{
        long magic;
        PyCodeObject *co;
        PyObject *m;

        magic = PyMarshal_ReadLongFromFile(fp);
        if (magic != pyc_magic) {
                PyErr_Format(PyExc_ImportError,
                             "Bad magic number in %.200s", cpathname);
                return NULL;
        }
        (void) PyMarshal_ReadLongFromFile(fp);
        co = read_compiled_module(cpathname, fp);
        if (co == NULL)
                return NULL;
        if (Py_VerboseFlag)
                PySys_WriteStderr("import %s # precompiled from %s\n",
                        name, cpathname);
        m = PyImport_ExecCodeModuleEx(name, (PyObject *)co, cpathname);
        Py_DECREF(co);

        return m;
}

/* Parse a source file and return the corresponding code object */

static PyCodeObject *
parse_source_module(char *pathname, FILE *fp)
{
        PyCodeObject *co;
        node *n;

        n = PyParser_SimpleParseFile(fp, pathname, Py_file_input);
        if (n == NULL)
                return NULL;
        co = PyNode_Compile(n, pathname);
        PyNode_Free(n);

        return co;
}


/* Helper to open a bytecode file for writing in exclusive mode */

static FILE *
open_exclusive(char *filename)
{
#if defined(O_EXCL)&&defined(O_CREAT)&&defined(O_WRONLY)&&defined(O_TRUNC)
        /* Use O_EXCL to avoid a race condition when another process tries to
           write the same file.  When that happens, our open() call fails,
           which is just fine (since it's only a cache).
           XXX If the file exists and is writable but the directory is not
           writable, the file will never be written.  Oh well.
        */
        int fd;
        (void) unlink(filename);
        fd = open(filename, O_EXCL|O_CREAT|O_WRONLY|O_TRUNC
#ifdef O_BINARY
                                |O_BINARY   /* necessary for Windows */
#endif
#ifdef __VMS
                        , 0666, "ctxt=bin", "shr=nil");
#else
                        , 0666);
#endif
        if (fd < 0)
                return NULL;
        return fdopen(fd, "wb");
#else
        /* Best we can do -- on Windows this can't happen anyway */
        return fopen(filename, "wb");
#endif
}


/* Write a compiled module to a file, placing the time of last
   modification of its source into the header.
   Errors are ignored, if a write error occurs an attempt is made to
   remove the file. */

static void
write_compiled_module(PyCodeObject *co, char *cpathname, long mtime)
{
        FILE *fp;

        fp = open_exclusive(cpathname);
        if (fp == NULL) {
                if (Py_VerboseFlag)
                        PySys_WriteStderr(
                                "# can't create %s\n", cpathname);
                return;
        }
        PyMarshal_WriteLongToFile(pyc_magic, fp);
        /* First write a 0 for mtime */
        PyMarshal_WriteLongToFile(0L, fp);
        PyMarshal_WriteObjectToFile((PyObject *)co, fp);
        if (ferror(fp)) {
                if (Py_VerboseFlag)
                        PySys_WriteStderr("# can't write %s\n", cpathname);
                /* Don't keep partial file */
                fclose(fp);
                (void) unlink(cpathname);
                return;
        }
        /* Now write the true mtime */
        fseek(fp, 4L, 0);
        PyMarshal_WriteLongToFile(mtime, fp);
        fflush(fp);
        fclose(fp);
        if (Py_VerboseFlag)
                PySys_WriteStderr("# wrote %s\n", cpathname);
#ifdef macintosh
        PyMac_setfiletype(cpathname, 'Pyth', 'PYC ');
#endif
}


/* Load a source module from a given file and return its module
   object WITH INCREMENTED REFERENCE COUNT.  If there's a matching
   byte-compiled file, use that instead. */

static PyObject *
load_source_module(char *name, char *pathname, FILE *fp)
{
        time_t mtime;
        FILE *fpc;
        char buf[MAXPATHLEN+1];
        char *cpathname;
        PyCodeObject *co;
        PyObject *m;

        mtime = PyOS_GetLastModificationTime(pathname, fp);
        if (mtime == (time_t)(-1))
                return NULL;
#if SIZEOF_TIME_T > 4
        /* Python's .pyc timestamp handling presumes that the timestamp fits
           in 4 bytes. This will be fine until sometime in the year 2038,
           when a 4-byte signed time_t will overflow.
         */
        if (mtime >> 32) {
                PyErr_SetString(PyExc_OverflowError,
                        "modification time overflows a 4 byte field");
                return NULL;
        }
#endif
        cpathname = make_compiled_pathname(pathname, buf,
                                           (size_t)MAXPATHLEN + 1);
        if (cpathname != NULL &&
            (fpc = check_compiled_module(pathname, mtime, cpathname))) {
                co = read_compiled_module(cpathname, fpc);
                fclose(fpc);
                if (co == NULL)
                        return NULL;
                if (Py_VerboseFlag)
                        PySys_WriteStderr("import %s # precompiled from %s\n",
                                name, cpathname);
                pathname = cpathname;
        }
        else {
                co = parse_source_module(pathname, fp);
                if (co == NULL)
                        return NULL;
                if (Py_VerboseFlag)
                        PySys_WriteStderr("import %s # from %s\n",
                                name, pathname);
                write_compiled_module(co, cpathname, mtime);
        }
        m = PyImport_ExecCodeModuleEx(name, (PyObject *)co, pathname);
        Py_DECREF(co);

        return m;
}


/* Forward */
static PyObject *load_module(char *, FILE *, char *, int, PyObject *);
static struct filedescr *find_module(char *, char *, PyObject *,
                                     char *, size_t, FILE **, PyObject **);
static struct _frozen *find_frozen(char *name);

/* Load a package and return its module object WITH INCREMENTED
   REFERENCE COUNT */

static PyObject *
load_package(char *name, char *pathname)
{
        PyObject *m, *d, *file, *path;
        int err;
        char buf[MAXPATHLEN+1];
        FILE *fp = NULL;
        struct filedescr *fdp;

        m = PyImport_AddModule(name);
        if (m == NULL)
                return NULL;
        if (Py_VerboseFlag)
                PySys_WriteStderr("import %s # directory %s\n",
                        name, pathname);
        d = PyModule_GetDict(m);
        file = PyString_FromString(pathname);
        if (file == NULL)
                return NULL;
        path = Py_BuildValue("[O]", file);
        if (path == NULL) {
                Py_DECREF(file);
                return NULL;
        }
        err = PyDict_SetItemString(d, "__file__", file);
        if (err == 0)
                err = PyDict_SetItemString(d, "__path__", path);
        if (err != 0) {
                m = NULL;
                goto cleanup;
        }
        buf[0] = '\0';
        fdp = find_module(name, "__init__", path, buf, sizeof(buf), &fp, NULL);
        if (fdp == NULL) {
                if (PyErr_ExceptionMatches(PyExc_ImportError)) {
                        PyErr_Clear();
                }
                else
                        m = NULL;
                goto cleanup;
        }
        m = load_module(name, fp, buf, fdp->type, NULL);
        if (fp != NULL)
                fclose(fp);
  cleanup:
        Py_XDECREF(path);
        Py_XDECREF(file);
        return m;
}


/* Helper to test for built-in module */

static int
is_builtin(char *name)
{
        int i;
        for (i = 0; PyImport_Inittab[i].name != NULL; i++) {
                if (strcmp(name, PyImport_Inittab[i].name) == 0) {
                        if (PyImport_Inittab[i].initfunc == NULL)
                                return -1;
                        else
                                return 1;
                }
        }
        return 0;
}


/* Return an importer object for a sys.path/pkg.__path__ item 'p',
   possibly by fetching it from the path_importer_cache dict. If it
   wasn't yet cached, traverse path_hooks until it a hook is found
   that can handle the path item. Return None if no hook could;
   this tells our caller it should fall back to the builtin
   import mechanism. Cache the result in path_importer_cache.
   Returns a borrowed reference. */

static PyObject *
get_path_importer(PyObject *path_importer_cache, PyObject *path_hooks,
                  PyObject *p)
{
        PyObject *importer;
        int j, nhooks;

        /* These conditions are the caller's responsibility: */
        assert(PyList_Check(path_hooks));
        assert(PyDict_Check(path_importer_cache));

        nhooks = PyList_Size(path_hooks);
        if (nhooks < 0)
                return NULL; /* Shouldn't happen */

        importer = PyDict_GetItem(path_importer_cache, p);
        if (importer != NULL)
                return importer;

        /* set path_importer_cache[p] to None to avoid recursion */
        if (PyDict_SetItem(path_importer_cache, p, Py_None) != 0)
                return NULL;

        for (j = 0; j < nhooks; j++) {
                PyObject *hook = PyList_GetItem(path_hooks, j);
                if (hook == NULL)
                        return NULL;
                importer = PyObject_CallFunction(hook, "O", p);
                if (importer != NULL)
                        break;

                if (!PyErr_ExceptionMatches(PyExc_ImportError)) {
                        return NULL;
                }
                PyErr_Clear();
        }
        if (importer == NULL)
                importer = Py_None;
        else if (importer != Py_None) {
                int err = PyDict_SetItem(path_importer_cache, p, importer);
                Py_DECREF(importer);
                if (err != 0)
                        return NULL;
        }
        return importer;
}

/* Search the path (default sys.path) for a module.  Return the
   corresponding filedescr struct, and (via return arguments) the
   pathname and an open file.  Return NULL if the module is not found. */

#ifdef MS_COREDLL
extern FILE *PyWin_FindRegisteredModule(const char *, struct filedescr **,
                                        char *, int);
#endif

static int case_ok(char *, int, int, char *);
static int find_init_module(char *); /* Forward */
static struct filedescr importhookdescr = {"", "", IMP_HOOK};

static struct filedescr *
find_module(char *fullname, char *subname, PyObject *path, char *buf,
            size_t buflen, FILE **p_fp, PyObject **p_loader)
{
        int i, npath;
        size_t len, namelen;
        struct filedescr *fdp = NULL;
        char *filemode;
        FILE *fp = NULL;
        PyObject *path_hooks, *path_importer_cache;
#ifndef RISCOS
        struct stat statbuf;
#endif
        static struct filedescr fd_frozen = {"", "", PY_FROZEN};
        static struct filedescr fd_builtin = {"", "", C_BUILTIN};
        static struct filedescr fd_package = {"", "", PKG_DIRECTORY};
        char name[MAXPATHLEN+1];
#if defined(PYOS_OS2)
        size_t saved_len;
        size_t saved_namelen;
        char *saved_buf = NULL;
#endif
        if (p_loader != NULL)
                *p_loader = NULL;

        if (strlen(subname) > MAXPATHLEN) {
                PyErr_SetString(PyExc_OverflowError,
                                "module name is too long");
                return NULL;
        }
        strcpy(name, subname);

        /* sys.meta_path import hook */
        if (p_loader != NULL) {
                PyObject *meta_path;

                meta_path = PySys_GetObject("meta_path");
                if (meta_path == NULL || !PyList_Check(meta_path)) {
                        PyErr_SetString(PyExc_ImportError,
                                        "sys.meta_path must be a list of "
                                        "import hooks");
                        return NULL;
                }
                Py_INCREF(meta_path);  /* zap guard */
                npath = PyList_Size(meta_path);
                for (i = 0; i < npath; i++) {
                        PyObject *loader;
                        PyObject *hook = PyList_GetItem(meta_path, i);
                        loader = PyObject_CallMethod(hook, "find_module",
                                                     "sO", fullname,
                                                     path != NULL ?
                                                     path : Py_None);
                        if (loader == NULL) {
                                Py_DECREF(meta_path);
                                return NULL;  /* true error */
                        }
                        if (loader != Py_None) {
                                /* a loader was found */
                                *p_loader = loader;
                                Py_DECREF(meta_path);
                                return &importhookdescr;
                        }
                        Py_DECREF(loader);
                }
                Py_DECREF(meta_path);
        }

        if (path != NULL && PyString_Check(path)) {
                /* The only type of submodule allowed inside a "frozen"
                   package are other frozen modules or packages. */
                if (PyString_Size(path) + 1 + strlen(name) >= (size_t)buflen) {
                        PyErr_SetString(PyExc_ImportError,
                                        "full frozen module name too long");
                        return NULL;
                }
                strcpy(buf, PyString_AsString(path));
                strcat(buf, ".");
                strcat(buf, name);
                strcpy(name, buf);
#ifdef macintosh
                /* Freezing on the mac works different, and the modules are
                ** actually on sys.path. So we don't take the quick exit but
                ** continue with the normal flow.
                */
                path = NULL;
#else
                if (find_frozen(name) != NULL) {
                        strcpy(buf, name);
                        return &fd_frozen;
                }
                PyErr_Format(PyExc_ImportError,
                             "No frozen submodule named %.200s", name);
                return NULL;
#endif
        }
        if (path == NULL) {
                if (is_builtin(name)) {
                        strcpy(buf, name);
                        return &fd_builtin;
                }
                if ((find_frozen(name)) != NULL) {
                        strcpy(buf, name);
                        return &fd_frozen;
                }

#ifdef MS_COREDLL
                fp = PyWin_FindRegisteredModule(name, &fdp, buf, buflen);
                if (fp != NULL) {
                        *p_fp = fp;
                        return fdp;
                }
#endif
                path = PySys_GetObject("path");
        }
        if (path == NULL || !PyList_Check(path)) {
                PyErr_SetString(PyExc_ImportError,
                                "sys.path must be a list of directory names");
                return NULL;
        }

        path_hooks = PySys_GetObject("path_hooks");
        if (path_hooks == NULL || !PyList_Check(path_hooks)) {
                PyErr_SetString(PyExc_ImportError,
                                "sys.path_hooks must be a list of "
                                "import hooks");
                return NULL;
        }
        path_importer_cache = PySys_GetObject("path_importer_cache");
        if (path_importer_cache == NULL ||
            !PyDict_Check(path_importer_cache)) {
                PyErr_SetString(PyExc_ImportError,
                                "sys.path_importer_cache must be a dict");
                return NULL;
        }

        npath = PyList_Size(path);
        namelen = strlen(name);
        for (i = 0; i < npath; i++) {
                PyObject *copy = NULL;
                PyObject *v = PyList_GetItem(path, i);
#ifdef Py_USING_UNICODE
                if (PyUnicode_Check(v)) {
                        copy = PyUnicode_Encode(PyUnicode_AS_UNICODE(v),
                                PyUnicode_GET_SIZE(v), Py_FileSystemDefaultEncoding, NULL);
                        if (copy == NULL)
                                return NULL;
                        v = copy;
                }
                else
#endif
                if (!PyString_Check(v))
                        continue;
                len = PyString_Size(v);
                if (len + 2 + namelen + MAXSUFFIXSIZE >= buflen) {
                        Py_XDECREF(copy);
                        continue; /* Too long */
                }
                strcpy(buf, PyString_AsString(v));
                if (strlen(buf) != len) {
                        Py_XDECREF(copy);
                        continue; /* v contains '\0' */
                }

                /* sys.path_hooks import hook */
                if (p_loader != NULL) {
                        PyObject *importer;

                        importer = get_path_importer(path_importer_cache,
                                                     path_hooks, v);
                        if (importer == NULL)
                                return NULL;
                        /* Note: importer is a borrowed reference */
                        if (importer != Py_None) {
                                PyObject *loader;
                                loader = PyObject_CallMethod(importer,
                                                             "find_module",
                                                             "s", fullname);
                                if (loader == NULL)
                                        return NULL;  /* error */
                                if (loader != Py_None) {
                                        /* a loader was found */
                                        *p_loader = loader;
                                        return &importhookdescr;
                                }
                                Py_DECREF(loader);
                        }
                        /* no hook was successful, use builtin import */
                }

#ifdef macintosh
                /*
                ** Speedup: each sys.path item is interned, and
                ** FindResourceModule remembers which items refer to
                ** folders (so we don't have to bother trying to look
                ** into them for resources). We only do this for string
                ** items.
                */
                if (PyString_Check(PyList_GET_ITEM(path, i))) {
                        PyString_InternInPlace(&PyList_GET_ITEM(path, i));
                        v = PyList_GET_ITEM(path, i);
                        if (PyMac_FindResourceModule((PyStringObject *)v, name, buf)) {
                                static struct filedescr resfiledescr =
                                        {"", "", PY_RESOURCE};

                                Py_XDECREF(copy);
                                return &resfiledescr;
                        }
                        if (PyMac_FindCodeResourceModule((PyStringObject *)v, name, buf)) {
                                static struct filedescr resfiledescr =
                                        {"", "", PY_CODERESOURCE};

                                Py_XDECREF(copy);
                                return &resfiledescr;
                        }
                }
#endif
                if (len > 0 && buf[len-1] != SEP
#ifdef ALTSEP
                    && buf[len-1] != ALTSEP
#endif
                    )
                        buf[len++] = SEP;
                strcpy(buf+len, name);
                len += namelen;

                /* Check for package import (buf holds a directory name,
                   and there's an __init__ module in that directory */
#ifdef HAVE_STAT
                if (stat(buf, &statbuf) == 0 &&         /* it exists */
                    S_ISDIR(statbuf.st_mode) &&         /* it's a directory */
                    find_init_module(buf) &&            /* it has __init__.py */
                    case_ok(buf, len, namelen, name)) { /* and case matches */
                        Py_XDECREF(copy);
                        return &fd_package;
                }
#else
                /* XXX How are you going to test for directories? */
#ifdef RISCOS
                if (isdir(buf) &&
                    find_init_module(buf) &&
                    case_ok(buf, len, namelen, name)) {
                        Py_XDECREF(copy);
                        return &fd_package;
                }
#endif
#endif
#ifdef macintosh
                fdp = PyMac_FindModuleExtension(buf, &len, name);
                if (fdp) {
#else
#if defined(PYOS_OS2)
                /* take a snapshot of the module spec for restoration
                 * after the 8 character DLL hackery
                 */
                saved_buf = strdup(buf);
                saved_len = len;
                saved_namelen = namelen;
#endif /* PYOS_OS2 */
                for (fdp = _PyImport_Filetab; fdp->suffix != NULL; fdp++) {
#if defined(PYOS_OS2)
                        /* OS/2 limits DLLs to 8 character names (w/o
                           extension)
                         * so if the name is longer than that and its a
                         * dynamically loaded module we're going to try,
                         * truncate the name before trying
                         */
                        if (strlen(subname) > 8) {
                                /* is this an attempt to load a C extension? */
                                const struct filedescr *scan;
                                scan = _PyImport_DynLoadFiletab;
                                while (scan->suffix != NULL) {
                                        if (!strcmp(scan->suffix, fdp->suffix))
                                                break;
                                        else
                                                scan++;
                                }
                                if (scan->suffix != NULL) {
                                        /* yes, so truncate the name */
                                        namelen = 8;
                                        len -= strlen(subname) - namelen;
                                        buf[len] = '\0';
                                }
                        }
#endif /* PYOS_OS2 */
                        strcpy(buf+len, fdp->suffix);
                        if (Py_VerboseFlag > 1)
                                PySys_WriteStderr("# trying %s\n", buf);
#endif /* !macintosh */
                        filemode = fdp->mode;
                        if (filemode[0] == 'U') 
                                filemode = "r" PY_STDIOTEXTMODE;
                        fp = fopen(buf, filemode);
                        if (fp != NULL) {
                                if (case_ok(buf, len, namelen, name))
                                        break;
                                else {   /* continue search */
                                        fclose(fp);
                                        fp = NULL;
                                }
                        }
#if defined(PYOS_OS2)
                        /* restore the saved snapshot */
                        strcpy(buf, saved_buf);
                        len = saved_len;
                        namelen = saved_namelen;
#endif
                }
#if defined(PYOS_OS2)
                /* don't need/want the module name snapshot anymore */
                if (saved_buf)
                {
                        free(saved_buf);
                        saved_buf = NULL;
                }
#endif
                Py_XDECREF(copy);
                if (fp != NULL)
                        break;
        }
        if (fp == NULL) {
                PyErr_Format(PyExc_ImportError,
                             "No module named %.200s", name);
                return NULL;
        }
        *p_fp = fp;
        return fdp;
}

/* case_ok(char* buf, int len, int namelen, char* name)
 * The arguments here are tricky, best shown by example:
 *    /a/b/c/d/e/f/g/h/i/j/k/some_long_module_name.py\0
 *    ^                      ^                   ^    ^
 *    |--------------------- buf ---------------------|
 *    |------------------- len ------------------|
 *                           |------ name -------|
 *                           |----- namelen -----|
 * buf is the full path, but len only counts up to (& exclusive of) the
 * extension.  name is the module name, also exclusive of extension.
 *
 * We've already done a successful stat() or fopen() on buf, so know that
 * there's some match, possibly case-insensitive.
 *
 * case_ok() is to return 1 if there's a case-sensitive match for
 * name, else 0.  case_ok() is also to return 1 if envar PYTHONCASEOK
 * exists.
 *
 * case_ok() is used to implement case-sensitive import semantics even
 * on platforms with case-insensitive filesystems.  It's trivial to implement
 * for case-sensitive filesystems.  It's pretty much a cross-platform
 * nightmare for systems with case-insensitive filesystems.
 */

/* First we may need a pile of platform-specific header files; the sequence
 * of #if's here should match the sequence in the body of case_ok().
 */
#if defined(MS_WINDOWS) || defined(__CYGWIN__)
#include <windows.h>
#ifdef __CYGWIN__
#include <sys/cygwin.h>
#endif

#elif defined(DJGPP)
#include <dir.h>

#elif defined(macintosh)
#include <TextUtils.h>

#elif defined(__MACH__) && defined(__APPLE__) && defined(HAVE_DIRENT_H)
#include <sys/types.h>
#include <dirent.h>

#elif defined(PYOS_OS2)
#define INCL_DOS
#define INCL_DOSERRORS
#define INCL_NOPMAPI
#include <os2.h>

#elif defined(RISCOS)
#include "oslib/osfscontrol.h"
#endif

static int
case_ok(char *buf, int len, int namelen, char *name)
{
/* Pick a platform-specific implementation; the sequence of #if's here should
 * match the sequence just above.
 */

/* MS_WINDOWS || __CYGWIN__ */
#if defined(MS_WINDOWS) || defined(__CYGWIN__)
        WIN32_FIND_DATA data;
        HANDLE h;
#ifdef __CYGWIN__
        char tempbuf[MAX_PATH];
#endif

        if (Py_GETENV("PYTHONCASEOK") != NULL)
                return 1;

#ifdef __CYGWIN__
        cygwin32_conv_to_win32_path(buf, tempbuf);
        h = FindFirstFile(tempbuf, &data);
#else
        h = FindFirstFile(buf, &data);
#endif
        if (h == INVALID_HANDLE_VALUE) {
                PyErr_Format(PyExc_NameError,
                  "Can't find file for module %.100s\n(filename %.300s)",
                  name, buf);
                return 0;
        }
        FindClose(h);
        return strncmp(data.cFileName, name, namelen) == 0;

/* DJGPP */
#elif defined(DJGPP)
        struct ffblk ffblk;
        int done;

        if (Py_GETENV("PYTHONCASEOK") != NULL)
                return 1;

        done = findfirst(buf, &ffblk, FA_ARCH|FA_RDONLY|FA_HIDDEN|FA_DIREC);
        if (done) {
                PyErr_Format(PyExc_NameError,
                  "Can't find file for module %.100s\n(filename %.300s)",
                  name, buf);
                return 0;
        }
        return strncmp(ffblk.ff_name, name, namelen) == 0;

/* macintosh */
#elif defined(macintosh)
        FSSpec fss;
        OSErr err;

        if (Py_GETENV("PYTHONCASEOK") != NULL)
                return 1;

        err = FSMakeFSSpec(0, 0, Pstring(buf), &fss);
        if (err) {
                PyErr_Format(PyExc_NameError,
                     "Can't find file for module %.100s\n(filename %.300s)",
                     name, buf);
                return 0;
        }
        return fss.name[0] >= namelen &&
               strncmp(name, (char *)fss.name+1, namelen) == 0;

/* new-fangled macintosh (macosx) */
#elif defined(__MACH__) && defined(__APPLE__) && defined(HAVE_DIRENT_H)
        DIR *dirp;
        struct dirent *dp;
        char dirname[MAXPATHLEN + 1];
        const int dirlen = len - namelen - 1; /* don't want trailing SEP */

        if (Py_GETENV("PYTHONCASEOK") != NULL)
                return 1;

        /* Copy the dir component into dirname; substitute "." if empty */
        if (dirlen <= 0) {
                dirname[0] = '.';
                dirname[1] = '\0';
        }
        else {
                assert(dirlen <= MAXPATHLEN);
                memcpy(dirname, buf, dirlen);
                dirname[dirlen] = '\0';
        }
        /* Open the directory and search the entries for an exact match. */
        dirp = opendir(dirname);
        if (dirp) {
                char *nameWithExt = buf + len - namelen;
                while ((dp = readdir(dirp)) != NULL) {
                        const int thislen =
#ifdef _DIRENT_HAVE_D_NAMELEN
                                                dp->d_namlen;
#else
                                                strlen(dp->d_name);
#endif
                        if (thislen >= namelen &&
                            strcmp(dp->d_name, nameWithExt) == 0) {
                                (void)closedir(dirp);
                                return 1; /* Found */
                        }
                }
                (void)closedir(dirp);
        }
        return 0 ; /* Not found */

/* RISC OS */
#elif defined(RISCOS)
        char canon[MAXPATHLEN+1]; /* buffer for the canonical form of the path */
        char buf2[MAXPATHLEN+2];
        char *nameWithExt = buf+len-namelen;
        int canonlen;
        os_error *e;

        if (Py_GETENV("PYTHONCASEOK") != NULL)
                return 1;

        /* workaround:
           append wildcard, otherwise case of filename wouldn't be touched */
        strcpy(buf2, buf);
        strcat(buf2, "*");

        e = xosfscontrol_canonicalise_path(buf2,canon,0,0,MAXPATHLEN+1,&canonlen);
        canonlen = MAXPATHLEN+1-canonlen;
        if (e || canonlen<=0 || canonlen>(MAXPATHLEN+1) )
                return 0;
        if (strcmp(nameWithExt, canon+canonlen-strlen(nameWithExt))==0)
                return 1; /* match */

        return 0;

/* OS/2 */
#elif defined(PYOS_OS2)
        HDIR hdir = 1;
        ULONG srchcnt = 1;
        FILEFINDBUF3 ffbuf;
        APIRET rc;

        if (getenv("PYTHONCASEOK") != NULL)
                return 1;

        rc = DosFindFirst(buf,
                          &hdir,
                          FILE_READONLY | FILE_HIDDEN | FILE_SYSTEM | FILE_DIRECTORY,
                          &ffbuf, sizeof(ffbuf),
                          &srchcnt,
                          FIL_STANDARD);
        if (rc != NO_ERROR)
                return 0;
        return strncmp(ffbuf.achName, name, namelen) == 0;

/* assuming it's a case-sensitive filesystem, so there's nothing to do! */
#else
        return 1;

#endif
}


#ifdef HAVE_STAT
/* Helper to look for __init__.py or __init__.py[co] in potential package */
static int
find_init_module(char *buf)
{
        const size_t save_len = strlen(buf);
        size_t i = save_len;
        char *pname;  /* pointer to start of __init__ */
        struct stat statbuf;

/*      For calling case_ok(buf, len, namelen, name):
 *      /a/b/c/d/e/f/g/h/i/j/k/some_long_module_name.py\0
 *      ^                      ^                   ^    ^
 *      |--------------------- buf ---------------------|
 *      |------------------- len ------------------|
 *                             |------ name -------|
 *                             |----- namelen -----|
 */
        if (save_len + 13 >= MAXPATHLEN)
                return 0;
        buf[i++] = SEP;
        pname = buf + i;
        strcpy(pname, "__init__.py");
        if (stat(buf, &statbuf) == 0) {
                if (case_ok(buf,
                            save_len + 9,       /* len("/__init__") */
                            8,                  /* len("__init__") */
                            pname)) {
                        buf[save_len] = '\0';
                        return 1;
                }
        }
        i += strlen(pname);
        strcpy(buf+i, Py_OptimizeFlag ? "o" : "c");
        if (stat(buf, &statbuf) == 0) {
                if (case_ok(buf,
                            save_len + 9,       /* len("/__init__") */
                            8,                  /* len("__init__") */
                            pname)) {
                        buf[save_len] = '\0';
                        return 1;
                }
        }
        buf[save_len] = '\0';
        return 0;
}

#else

#ifdef RISCOS
static int
find_init_module(buf)
        char *buf;
{
        int save_len = strlen(buf);
        int i = save_len;

        if (save_len + 13 >= MAXPATHLEN)
                return 0;
        buf[i++] = SEP;
        strcpy(buf+i, "__init__/py");
        if (isfile(buf)) {
                buf[save_len] = '\0';
                return 1;
        }

        if (Py_OptimizeFlag)
                strcpy(buf+i, "o");
        else
                strcpy(buf+i, "c");
        if (isfile(buf)) {
                buf[save_len] = '\0';
                return 1;
        }
        buf[save_len] = '\0';
        return 0;
}
#endif /*RISCOS*/

#endif /* HAVE_STAT */


static int init_builtin(char *); /* Forward */

/* Load an external module using the default search path and return
   its module object WITH INCREMENTED REFERENCE COUNT */

static PyObject *
load_module(char *name, FILE *fp, char *buf, int type, PyObject *loader)
{
        PyObject *modules;
        PyObject *m;
        int err;

        /* First check that there's an open file (if we need one)  */
        switch (type) {
        case PY_SOURCE:
        case PY_COMPILED:
                if (fp == NULL) {
                        PyErr_Format(PyExc_ValueError,
                           "file object required for import (type code %d)",
                                     type);
                        return NULL;
                }
        }

        switch (type) {

        case PY_SOURCE:
                m = load_source_module(name, buf, fp);
                break;

        case PY_COMPILED:
                m = load_compiled_module(name, buf, fp);
                break;

#ifdef HAVE_DYNAMIC_LOADING
        case C_EXTENSION:
                m = _PyImport_LoadDynamicModule(name, buf, fp);
                break;
#endif

#ifdef macintosh
        case PY_RESOURCE:
                m = PyMac_LoadResourceModule(name, buf);
                break;
        case PY_CODERESOURCE:
                m = PyMac_LoadCodeResourceModule(name, buf);
                break;
#endif

        case PKG_DIRECTORY:
                m = load_package(name, buf);
                break;

        case C_BUILTIN:
        case PY_FROZEN:
                if (buf != NULL && buf[0] != '\0')
                        name = buf;
                if (type == C_BUILTIN)
                        err = init_builtin(name);
                else
                        err = PyImport_ImportFrozenModule(name);
                if (err < 0)
                        return NULL;
                if (err == 0) {
                        PyErr_Format(PyExc_ImportError,
                                     "Purported %s module %.200s not found",
                                     type == C_BUILTIN ?
                                                "builtin" : "frozen",
                                     name);
                        return NULL;
                }
                modules = PyImport_GetModuleDict();
                m = PyDict_GetItemString(modules, name);
                if (m == NULL) {
                        PyErr_Format(
                                PyExc_ImportError,
                                "%s module %.200s not properly initialized",
                                type == C_BUILTIN ?
                                        "builtin" : "frozen",
                                name);
                        return NULL;
                }
                Py_INCREF(m);
                break;

        case IMP_HOOK: {
                if (loader == NULL) {
                        PyErr_SetString(PyExc_ImportError,
                                        "import hook without loader");
                        return NULL;
                }
                m = PyObject_CallMethod(loader, "load_module", "s", name);
                break;
        }

        default:
                PyErr_Format(PyExc_ImportError,
                             "Don't know how to import %.200s (type code %d)",
                              name, type);
                m = NULL;

        }

        return m;
}


/* Initialize a built-in module.
   Return 1 for succes, 0 if the module is not found, and -1 with
   an exception set if the initialization failed. */

static int
init_builtin(char *name)
{
        struct _inittab *p;

        if (_PyImport_FindExtension(name, name) != NULL)
                return 1;

        for (p = PyImport_Inittab; p->name != NULL; p++) {
                if (strcmp(name, p->name) == 0) {
                        if (p->initfunc == NULL) {
                                PyErr_Format(PyExc_ImportError,
                                    "Cannot re-init internal module %.200s",
                                    name);
                                return -1;
                        }
                        if (Py_VerboseFlag)
                                PySys_WriteStderr("import %s # builtin\n", name);
                        (*p->initfunc)();
                        if (PyErr_Occurred())
                                return -1;
                        if (_PyImport_FixupExtension(name, name) == NULL)
                                return -1;
                        return 1;
                }
        }
        return 0;
}


/* Frozen modules */

static struct _frozen *
find_frozen(char *name)
{
        struct _frozen *p;

        for (p = PyImport_FrozenModules; ; p++) {
                if (p->name == NULL)
                        return NULL;
                if (strcmp(p->name, name) == 0)
                        break;
        }
        return p;
}

static PyObject *
get_frozen_object(char *name)
{
        struct _frozen *p = find_frozen(name);
        int size;

        if (p == NULL) {
                PyErr_Format(PyExc_ImportError,
                             "No such frozen object named %.200s",
                             name);
                return NULL;
        }
        if (p->code == NULL) {
                PyErr_Format(PyExc_ImportError,
                             "Excluded frozen object named %.200s",
                             name);
                return NULL;
        }
        size = p->size;
        if (size < 0)
                size = -size;
        return PyMarshal_ReadObjectFromString((char *)p->code, size);
}

/* Initialize a frozen module.
   Return 1 for succes, 0 if the module is not found, and -1 with
   an exception set if the initialization failed.
   This function is also used from frozenmain.c */

int
PyImport_ImportFrozenModule(char *name)
{
        struct _frozen *p = find_frozen(name);
        PyObject *co;
        PyObject *m;
        int ispackage;
        int size;

        if (p == NULL)
                return 0;
        if (p->code == NULL) {
                PyErr_Format(PyExc_ImportError,
                             "Excluded frozen object named %.200s",
                             name);
                return -1;
        }
        size = p->size;
        ispackage = (size < 0);
        if (ispackage)
                size = -size;
        if (Py_VerboseFlag)
                PySys_WriteStderr("import %s # frozen%s\n",
                        name, ispackage ? " package" : "");
        co = PyMarshal_ReadObjectFromString((char *)p->code, size);
        if (co == NULL)
                return -1;
        if (!PyCode_Check(co)) {
                Py_DECREF(co);
                PyErr_Format(PyExc_TypeError,
                             "frozen object %.200s is not a code object",
                             name);
                return -1;
        }
        if (ispackage) {
                /* Set __path__ to the package name */
                PyObject *d, *s;
                int err;
                m = PyImport_AddModule(name);
                if (m == NULL)
                        return -1;
                d = PyModule_GetDict(m);
                s = PyString_InternFromString(name);
                if (s == NULL)
                        return -1;
                err = PyDict_SetItemString(d, "__path__", s);
                Py_DECREF(s);
                if (err != 0)
                        return err;
        }
        m = PyImport_ExecCodeModuleEx(name, co, "<frozen>");
        Py_DECREF(co);
        if (m == NULL)
                return -1;
        Py_DECREF(m);
        return 1;
}


/* Import a module, either built-in, frozen, or external, and return
   its module object WITH INCREMENTED REFERENCE COUNT */

PyObject *
PyImport_ImportModule(char *name)
{
        PyObject *pname;
        PyObject *result;

        pname = PyString_FromString(name);
        if (pname == NULL)
                return NULL;
        result = PyImport_Import(pname);
        Py_DECREF(pname);
        return result;
}

/* Forward declarations for helper routines */
static PyObject *get_parent(PyObject *globals, char *buf, int *p_buflen);
static PyObject *load_next(PyObject *mod, PyObject *altmod,
                           char **p_name, char *buf, int *p_buflen);
static int mark_miss(char *name);
static int ensure_fromlist(PyObject *mod, PyObject *fromlist,
                           char *buf, int buflen, int recursive);
static PyObject * import_submodule(PyObject *mod, char *name, char *fullname);

/* The Magnum Opus of dotted-name import :-) */

static PyObject *
import_module_ex(char *name, PyObject *globals, PyObject *locals,
                 PyObject *fromlist)
{
        char buf[MAXPATHLEN+1];
        int buflen = 0;
        PyObject *parent, *head, *next, *tail;

        parent = get_parent(globals, buf, &buflen);
        if (parent == NULL)
                return NULL;

        head = load_next(parent, Py_None, &name, buf, &buflen);
        if (head == NULL)
                return NULL;

        tail = head;
        Py_INCREF(tail);
        while (name) {
                next = load_next(tail, tail, &name, buf, &buflen);
                Py_DECREF(tail);
                if (next == NULL) {
                        Py_DECREF(head);
                        return NULL;
                }
                tail = next;
        }

        if (fromlist != NULL) {
                if (fromlist == Py_None || !PyObject_IsTrue(fromlist))
                        fromlist = NULL;
        }

        if (fromlist == NULL) {
                Py_DECREF(tail);
                return head;
        }

        Py_DECREF(head);
        if (!ensure_fromlist(tail, fromlist, buf, buflen, 0)) {
                Py_DECREF(tail);
                return NULL;
        }

        return tail;
}

PyObject *
PyImport_ImportModuleEx(char *name, PyObject *globals, PyObject *locals,
                        PyObject *fromlist)
{
        PyObject *result;
        lock_import();
        result = import_module_ex(name, globals, locals, fromlist);
        if (unlock_import() < 0) {
                Py_XDECREF(result);
                PyErr_SetString(PyExc_RuntimeError,
                                "not holding the import lock");
                return NULL;
        }
        return result;
}

static PyObject *
get_parent(PyObject *globals, char *buf, int *p_buflen)
{
        static PyObject *namestr = NULL;
        static PyObject *pathstr = NULL;
        PyObject *modname, *modpath, *modules, *parent;

        if (globals == NULL || !PyDict_Check(globals))
                return Py_None;

        if (namestr == NULL) {
                namestr = PyString_InternFromString("__name__");
                if (namestr == NULL)
                        return NULL;
        }
        if (pathstr == NULL) {
                pathstr = PyString_InternFromString("__path__");
                if (pathstr == NULL)
                        return NULL;
        }

        *buf = '\0';
        *p_buflen = 0;
        modname = PyDict_GetItem(globals, namestr);
        if (modname == NULL || !PyString_Check(modname))
                return Py_None;

        modpath = PyDict_GetItem(globals, pathstr);
        if (modpath != NULL) {
                int len = PyString_GET_SIZE(modname);
                if (len > MAXPATHLEN) {
                        PyErr_SetString(PyExc_ValueError,
                                        "Module name too long");
                        return NULL;
                }
                strcpy(buf, PyString_AS_STRING(modname));
                *p_buflen = len;
        }
        else {
                char *start = PyString_AS_STRING(modname);
                char *lastdot = strrchr(start, '.');
                size_t len;
                if (lastdot == NULL)
                        return Py_None;
                len = lastdot - start;
                if (len >= MAXPATHLEN) {
                        PyErr_SetString(PyExc_ValueError,
                                        "Module name too long");
                        return NULL;
                }
                strncpy(buf, start, len);
                buf[len] = '\0';
                *p_buflen = len;
        }

        modules = PyImport_GetModuleDict();
        parent = PyDict_GetItemString(modules, buf);
        if (parent == NULL)
                parent = Py_None;
        return parent;
        /* We expect, but can't guarantee, if parent != None, that:
           - parent.__name__ == buf
           - parent.__dict__ is globals
           If this is violated...  Who cares? */
}

/* altmod is either None or same as mod */
static PyObject *
load_next(PyObject *mod, PyObject *altmod, char **p_name, char *buf,
          int *p_buflen)
{
        char *name = *p_name;
        char *dot = strchr(name, '.');
        size_t len;
        char *p;
        PyObject *result;

        if (dot == NULL) {
                *p_name = NULL;
                len = strlen(name);
        }
        else {
                *p_name = dot+1;
                len = dot-name;
        }
        if (len == 0) {
                PyErr_SetString(PyExc_ValueError,
                                "Empty module name");
                return NULL;
        }

        p = buf + *p_buflen;
        if (p != buf)
                *p++ = '.';
        if (p+len-buf >= MAXPATHLEN) {
                PyErr_SetString(PyExc_ValueError,
                                "Module name too long");
                return NULL;
        }
        strncpy(p, name, len);
        p[len] = '\0';
        *p_buflen = p+len-buf;

        result = import_submodule(mod, p, buf);
        if (result == Py_None && altmod != mod) {
                Py_DECREF(result);
                /* Here, altmod must be None and mod must not be None */
                result = import_submodule(altmod, p, p);
                if (result != NULL && result != Py_None) {
                        if (mark_miss(buf) != 0) {
                                Py_DECREF(result);
                                return NULL;
                        }
                        strncpy(buf, name, len);
                        buf[len] = '\0';
                        *p_buflen = len;
                }
        }
        if (result == NULL)
                return NULL;

        if (result == Py_None) {
                Py_DECREF(result);
                PyErr_Format(PyExc_ImportError,
                             "No module named %.200s", name);
                return NULL;
        }

        return result;
}

static int
mark_miss(char *name)
{
        PyObject *modules = PyImport_GetModuleDict();
        return PyDict_SetItemString(modules, name, Py_None);
}

static int
ensure_fromlist(PyObject *mod, PyObject *fromlist, char *buf, int buflen,
                int recursive)
{
        int i;

        if (!PyObject_HasAttrString(mod, "__path__"))
                return 1;

        for (i = 0; ; i++) {
                PyObject *item = PySequence_GetItem(fromlist, i);
                int hasit;
                if (item == NULL) {
                        if (PyErr_ExceptionMatches(PyExc_IndexError)) {
                                PyErr_Clear();
                                return 1;
                        }
                        return 0;
                }
                if (!PyString_Check(item)) {
                        PyErr_SetString(PyExc_TypeError,
                                        "Item in ``from list'' not a string");
                        Py_DECREF(item);
                        return 0;
                }
                if (PyString_AS_STRING(item)[0] == '*') {
                        PyObject *all;
                        Py_DECREF(item);
                        /* See if the package defines __all__ */
                        if (recursive)
                                continue; /* Avoid endless recursion */
                        all = PyObject_GetAttrString(mod, "__all__");
                        if (all == NULL)
                                PyErr_Clear();
                        else {
                                if (!ensure_fromlist(mod, all, buf, buflen, 1))
                                        return 0;
                                Py_DECREF(all);
                        }
                        continue;
                }
                hasit = PyObject_HasAttr(mod, item);
                if (!hasit) {
                        char *subname = PyString_AS_STRING(item);
                        PyObject *submod;
                        char *p;
                        if (buflen + strlen(subname) >= MAXPATHLEN) {
                                PyErr_SetString(PyExc_ValueError,
                                                "Module name too long");
                                Py_DECREF(item);
                                return 0;
                        }
                        p = buf + buflen;
                        *p++ = '.';
                        strcpy(p, subname);
                        submod = import_submodule(mod, subname, buf);
                        Py_XDECREF(submod);
                        if (submod == NULL) {
                                Py_DECREF(item);
                                return 0;
                        }
                }
                Py_DECREF(item);
        }

        /* NOTREACHED */
}

static PyObject *
import_submodule(PyObject *mod, char *subname, char *fullname)
{
        PyObject *modules = PyImport_GetModuleDict();
        PyObject *m, *res = NULL;

        /* Require:
           if mod == None: subname == fullname
           else: mod.__name__ + "." + subname == fullname
        */

        if ((m = PyDict_GetItemString(modules, fullname)) != NULL) {
                Py_INCREF(m);
        }
        else {
                PyObject *path, *loader = NULL;
                char buf[MAXPATHLEN+1];
                struct filedescr *fdp;
                FILE *fp = NULL;

                if (mod == Py_None)
                        path = NULL;
                else {
                        path = PyObject_GetAttrString(mod, "__path__");
                        if (path == NULL) {
                                PyErr_Clear();
                                Py_INCREF(Py_None);
                                return Py_None;
                        }
                }

                buf[0] = '\0';
                fdp = find_module(fullname, subname, path, buf, MAXPATHLEN+1,
                                  &fp, &loader);
                Py_XDECREF(path);
                if (fdp == NULL) {
                        if (!PyErr_ExceptionMatches(PyExc_ImportError))
                                return NULL;
                        PyErr_Clear();
                        Py_INCREF(Py_None);
                        return Py_None;
                }
                m = load_module(fullname, fp, buf, fdp->type, loader);
                Py_XDECREF(loader);
                if (fp)
                        fclose(fp);
                if (mod != Py_None) {
                        /* Irrespective of the success of this load, make a
                           reference to it in the parent package module.
                           A copy gets saved in the modules dictionary
                           under the full name, so get a reference from
                           there, if need be.  (The exception is when
                           the load failed with a SyntaxError -- then
                           there's no trace in sys.modules.  In that case,
                           of course, do nothing extra.) */
                        res = m;
                        if (res == NULL)
                                res = PyDict_GetItemString(modules, fullname);
                        if (res != NULL &&
                            PyObject_SetAttrString(mod, subname, res) < 0) {
                                Py_XDECREF(m);
                                m = NULL;
                        }
                }
        }

        return m;
}


/* Re-import a module of any kind and return its module object, WITH
   INCREMENTED REFERENCE COUNT */

PyObject *
PyImport_ReloadModule(PyObject *m)
{
        PyObject *modules = PyImport_GetModuleDict();
        PyObject *path = NULL;
        char *name, *subname;
        char buf[MAXPATHLEN+1];
        struct filedescr *fdp;
        FILE *fp = NULL;

        if (m == NULL || !PyModule_Check(m)) {
                PyErr_SetString(PyExc_TypeError,
                                "reload() argument must be module");
                return NULL;
        }
        name = PyModule_GetName(m);
        if (name == NULL)
                return NULL;
        if (m != PyDict_GetItemString(modules, name)) {
                PyErr_Format(PyExc_ImportError,
                             "reload(): module %.200s not in sys.modules",
                             name);
                return NULL;
        }
        subname = strrchr(name, '.');
        if (subname == NULL)
                subname = name;
        else {
                PyObject *parentname, *parent;
                parentname = PyString_FromStringAndSize(name, (subname-name));
                if (parentname == NULL)
                        return NULL;
                parent = PyDict_GetItem(modules, parentname);
                Py_DECREF(parentname);
                if (parent == NULL) {
                        PyErr_Format(PyExc_ImportError,
                            "reload(): parent %.200s not in sys.modules",
                            name);
                        return NULL;
                }
                subname++;
                path = PyObject_GetAttrString(parent, "__path__");
                if (path == NULL)
                        PyErr_Clear();
        }
        buf[0] = '\0';
        fdp = find_module(name, subname, path, buf, MAXPATHLEN+1, &fp, NULL);
        Py_XDECREF(path);
        if (fdp == NULL)
                return NULL;
        m = load_module(name, fp, buf, fdp->type, NULL);
        if (fp)
                fclose(fp);
        return m;
}


/* Higher-level import emulator which emulates the "import" statement
   more accurately -- it invokes the __import__() function from the
   builtins of the current globals.  This means that the import is
   done using whatever import hooks are installed in the current
   environment, e.g. by "rexec".
   A dummy list ["__doc__"] is passed as the 4th argument so that
   e.g. PyImport_Import(PyString_FromString("win32com.client.gencache"))
   will return <module "gencache"> instead of <module "win32com">. */

PyObject *
PyImport_Import(PyObject *module_name)
{
        static PyObject *silly_list = NULL;
        static PyObject *builtins_str = NULL;
        static PyObject *import_str = NULL;
        PyObject *globals = NULL;
        PyObject *import = NULL;
        PyObject *builtins = NULL;
        PyObject *r = NULL;

        /* Initialize constant string objects */
        if (silly_list == NULL) {
                import_str = PyString_InternFromString("__import__");
                if (import_str == NULL)
                        return NULL;
                builtins_str = PyString_InternFromString("__builtins__");
                if (builtins_str == NULL)
                        return NULL;
                silly_list = Py_BuildValue("[s]", "__doc__");
                if (silly_list == NULL)
                        return NULL;
        }

        /* Get the builtins from current globals */
        globals = PyEval_GetGlobals();
        if (globals != NULL) {
                Py_INCREF(globals);
                builtins = PyObject_GetItem(globals, builtins_str);
                if (builtins == NULL)
                        goto err;
        }
        else {
                /* No globals -- use standard builtins, and fake globals */
                PyErr_Clear();

                builtins = PyImport_ImportModuleEx("__builtin__",
                                                   NULL, NULL, NULL);
                if (builtins == NULL)
                        return NULL;
                globals = Py_BuildValue("{OO}", builtins_str, builtins);
                if (globals == NULL)
                        goto err;
        }

        /* Get the __import__ function from the builtins */
        if (PyDict_Check(builtins)) {
                import = PyObject_GetItem(builtins, import_str);
                if (import == NULL)
                        PyErr_SetObject(PyExc_KeyError, import_str);
        }
        else
                import = PyObject_GetAttr(builtins, import_str);
        if (import == NULL)
                goto err;

        /* Call the _import__ function with the proper argument list */
        r = PyObject_CallFunction(import, "OOOO",
                                  module_name, globals, globals, silly_list);

  err:
        Py_XDECREF(globals);
        Py_XDECREF(builtins);
        Py_XDECREF(import);

        return r;
}


/* Module 'imp' provides Python access to the primitives used for
   importing modules.
*/

static PyObject *
imp_get_magic(PyObject *self, PyObject *noargs)
{
        char buf[4];

        buf[0] = (char) ((pyc_magic >>  0) & 0xff);
        buf[1] = (char) ((pyc_magic >>  8) & 0xff);
        buf[2] = (char) ((pyc_magic >> 16) & 0xff);
        buf[3] = (char) ((pyc_magic >> 24) & 0xff);

        return PyString_FromStringAndSize(buf, 4);
}

static PyObject *
imp_get_suffixes(PyObject *self, PyObject *noargs)
{
        PyObject *list;
        struct filedescr *fdp;

        list = PyList_New(0);
        if (list == NULL)
                return NULL;
        for (fdp = _PyImport_Filetab; fdp->suffix != NULL; fdp++) {
                PyObject *item = Py_BuildValue("ssi",
                                       fdp->suffix, fdp->mode, fdp->type);
                if (item == NULL) {
                        Py_DECREF(list);
                        return NULL;
                }
                if (PyList_Append(list, item) < 0) {
                        Py_DECREF(list);
                        Py_DECREF(item);
                        return NULL;
                }
                Py_DECREF(item);
        }
        return list;
}

static PyObject *
call_find_module(char *name, PyObject *path)
{
        extern int fclose(FILE *);
        PyObject *fob, *ret;
        struct filedescr *fdp;
        char pathname[MAXPATHLEN+1];
        FILE *fp = NULL;

        pathname[0] = '\0';
        if (path == Py_None)
                path = NULL;
        fdp = find_module(NULL, name, path, pathname, MAXPATHLEN+1, &fp, NULL);
        if (fdp == NULL)
                return NULL;
        if (fp != NULL) {
                fob = PyFile_FromFile(fp, pathname, fdp->mode, fclose);
                if (fob == NULL) {
                        fclose(fp);
                        return NULL;
                }
        }
        else {
                fob = Py_None;
                Py_INCREF(fob);
        }
        ret = Py_BuildValue("Os(ssi)",
                      fob, pathname, fdp->suffix, fdp->mode, fdp->type);
        Py_DECREF(fob);
        return ret;
}

static PyObject *
imp_find_module(PyObject *self, PyObject *args)
{
        char *name;
        PyObject *path = NULL;
        if (!PyArg_ParseTuple(args, "s|O:find_module", &name, &path))
                return NULL;
        return call_find_module(name, path);
}

static PyObject *
imp_init_builtin(PyObject *self, PyObject *args)
{
        char *name;
        int ret;
        PyObject *m;
        if (!PyArg_ParseTuple(args, "s:init_builtin", &name))
                return NULL;
        ret = init_builtin(name);
        if (ret < 0)
                return NULL;
        if (ret == 0) {
                Py_INCREF(Py_None);
                return Py_None;
        }
        m = PyImport_AddModule(name);
        Py_XINCREF(m);
        return m;
}

static PyObject *
imp_init_frozen(PyObject *self, PyObject *args)
{
        char *name;
        int ret;
        PyObject *m;
        if (!PyArg_ParseTuple(args, "s:init_frozen", &name))
                return NULL;
        ret = PyImport_ImportFrozenModule(name);
        if (ret < 0)
                return NULL;
        if (ret == 0) {
                Py_INCREF(Py_None);
                return Py_None;
        }
        m = PyImport_AddModule(name);
        Py_XINCREF(m);
        return m;
}

static PyObject *
imp_get_frozen_object(PyObject *self, PyObject *args)
{
        char *name;

        if (!PyArg_ParseTuple(args, "s:get_frozen_object", &name))
                return NULL;
        return get_frozen_object(name);
}

static PyObject *
imp_is_builtin(PyObject *self, PyObject *args)
{
        char *name;
        if (!PyArg_ParseTuple(args, "s:is_builtin", &name))
                return NULL;
        return PyInt_FromLong(is_builtin(name));
}

static PyObject *
imp_is_frozen(PyObject *self, PyObject *args)
{
        char *name;
        struct _frozen *p;
        if (!PyArg_ParseTuple(args, "s:is_frozen", &name))
                return NULL;
        p = find_frozen(name);
        return PyBool_FromLong((long) (p == NULL ? 0 : p->size));
}

static FILE *
get_file(char *pathname, PyObject *fob, char *mode)
{
        FILE *fp;
        if (fob == NULL) {
                if (mode[0] == 'U') 
                        mode = "r" PY_STDIOTEXTMODE;
                fp = fopen(pathname, mode);
                if (fp == NULL)
                        PyErr_SetFromErrno(PyExc_IOError);
        }
        else {
                fp = PyFile_AsFile(fob);
                if (fp == NULL)
                        PyErr_SetString(PyExc_ValueError,
                                        "bad/closed file object");
        }
        return fp;
}

static PyObject *
imp_load_compiled(PyObject *self, PyObject *args)
{
        char *name;
        char *pathname;
        PyObject *fob = NULL;
        PyObject *m;
        FILE *fp;
        if (!PyArg_ParseTuple(args, "ss|O!:load_compiled", &name, &pathname,
                              &PyFile_Type, &fob))
                return NULL;
        fp = get_file(pathname, fob, "rb");
        if (fp == NULL)
                return NULL;
        m = load_compiled_module(name, pathname, fp);
        if (fob == NULL)
                fclose(fp);
        return m;
}

#ifdef HAVE_DYNAMIC_LOADING

static PyObject *
imp_load_dynamic(PyObject *self, PyObject *args)
{
        char *name;
        char *pathname;
        PyObject *fob = NULL;
        PyObject *m;
        FILE *fp = NULL;
        if (!PyArg_ParseTuple(args, "ss|O!:load_dynamic", &name, &pathname,
                              &PyFile_Type, &fob))
                return NULL;
        if (fob) {
                fp = get_file(pathname, fob, "r");
                if (fp == NULL)
                        return NULL;
        }
        m = _PyImport_LoadDynamicModule(name, pathname, fp);
        return m;
}

#endif /* HAVE_DYNAMIC_LOADING */

static PyObject *
imp_load_source(PyObject *self, PyObject *args)
{
        char *name;
        char *pathname;
        PyObject *fob = NULL;
        PyObject *m;
        FILE *fp;
        if (!PyArg_ParseTuple(args, "ss|O!:load_source", &name, &pathname,
                              &PyFile_Type, &fob))
                return NULL;
        fp = get_file(pathname, fob, "r");
        if (fp == NULL)
                return NULL;
        m = load_source_module(name, pathname, fp);
        if (fob == NULL)
                fclose(fp);
        return m;
}

#ifdef macintosh
static PyObject *
imp_load_resource(PyObject *self, PyObject *args)
{
        char *name;
        char *pathname;
        PyObject *m;

        if (!PyArg_ParseTuple(args, "ss:load_resource", &name, &pathname))
                return NULL;
        m = PyMac_LoadResourceModule(name, pathname);
        return m;
}
#endif /* macintosh */

static PyObject *
imp_load_module(PyObject *self, PyObject *args)
{
        char *name;
        PyObject *fob;
        char *pathname;
        char *suffix; /* Unused */
        char *mode;
        int type;
        FILE *fp;

        if (!PyArg_ParseTuple(args, "sOs(ssi):load_module",
                              &name, &fob, &pathname,
                              &suffix, &mode, &type))
                return NULL;
        if (*mode) {
                /* Mode must start with 'r' or 'U' and must not contain '+'.
                   Implicit in this test is the assumption that the mode
                   may contain other modifiers like 'b' or 't'. */

                if (!(*mode == 'r' || *mode == 'U') || strchr(mode, '+')) {
                        PyErr_Format(PyExc_ValueError,
                                     "invalid file open mode %.200s", mode);
                        return NULL;
                }
        }
        if (fob == Py_None)
                fp = NULL;
        else {
                if (!PyFile_Check(fob)) {
                        PyErr_SetString(PyExc_ValueError,
                                "load_module arg#2 should be a file or None");
                        return NULL;
                }
                fp = get_file(pathname, fob, mode);
                if (fp == NULL)
                        return NULL;
        }
        return load_module(name, fp, pathname, type, NULL);
}

static PyObject *
imp_load_package(PyObject *self, PyObject *args)
{
        char *name;
        char *pathname;
        if (!PyArg_ParseTuple(args, "ss:load_package", &name, &pathname))
                return NULL;
        return load_package(name, pathname);
}

static PyObject *
imp_new_module(PyObject *self, PyObject *args)
{
        char *name;
        if (!PyArg_ParseTuple(args, "s:new_module", &name))
                return NULL;
        return PyModule_New(name);
}

/* Doc strings */

PyDoc_STRVAR(doc_imp,
"This module provides the components needed to build your own\n\
__import__ function.  Undocumented functions are obsolete.");

PyDoc_STRVAR(doc_find_module,
"find_module(name, [path]) -> (file, filename, (suffix, mode, type))\n\
Search for a module.  If path is omitted or None, search for a\n\
built-in, frozen or special module and continue search in sys.path.\n\
The module name cannot contain '.'; to search for a submodule of a\n\
package, pass the submodule name and the package's __path__.");

PyDoc_STRVAR(doc_load_module,
"load_module(name, file, filename, (suffix, mode, type)) -> module\n\
Load a module, given information returned by find_module().\n\
The module name must include the full package name, if any.");

PyDoc_STRVAR(doc_get_magic,
"get_magic() -> string\n\
Return the magic number for .pyc or .pyo files.");

PyDoc_STRVAR(doc_get_suffixes,
"get_suffixes() -> [(suffix, mode, type), ...]\n\
Return a list of (suffix, mode, type) tuples describing the files\n\
that find_module() looks for.");

PyDoc_STRVAR(doc_new_module,
"new_module(name) -> module\n\
Create a new module.  Do not enter it in sys.modules.\n\
The module name must include the full package name, if any.");

PyDoc_STRVAR(doc_lock_held,
"lock_held() -> 0 or 1\n\
Return 1 if the import lock is currently held.\n\
On platforms without threads, return 0.");

PyDoc_STRVAR(doc_acquire_lock,
"acquire_lock() -> None\n\
Acquires the interpreter's import lock for the current thread.\n\
This lock should be used by import hooks to ensure thread-safety\n\
when importing modules.\n\
On platforms without threads, this function does nothing.");

PyDoc_STRVAR(doc_release_lock,
"release_lock() -> None\n\
Release the interpreter's import lock.\n\
On platforms without threads, this function does nothing.");

static PyMethodDef imp_methods[] = {
        {"find_module",  imp_find_module,  METH_VARARGS, doc_find_module},
        {"get_magic",    imp_get_magic,    METH_NOARGS,  doc_get_magic},
        {"get_suffixes", imp_get_suffixes, METH_NOARGS,  doc_get_suffixes},
        {"load_module",  imp_load_module,  METH_VARARGS, doc_load_module},
        {"new_module",   imp_new_module,   METH_VARARGS, doc_new_module},
        {"lock_held",    imp_lock_held,    METH_NOARGS,  doc_lock_held},
        {"acquire_lock", imp_acquire_lock, METH_NOARGS,  doc_acquire_lock},
        {"release_lock", imp_release_lock, METH_NOARGS,  doc_release_lock},
        /* The rest are obsolete */
        {"get_frozen_object",   imp_get_frozen_object,  METH_VARARGS},
        {"init_builtin",        imp_init_builtin,       METH_VARARGS},
        {"init_frozen",         imp_init_frozen,        METH_VARARGS},
        {"is_builtin",          imp_is_builtin,         METH_VARARGS},
        {"is_frozen",           imp_is_frozen,          METH_VARARGS},
        {"load_compiled",       imp_load_compiled,      METH_VARARGS},
#ifdef HAVE_DYNAMIC_LOADING
        {"load_dynamic",        imp_load_dynamic,       METH_VARARGS},
#endif
        {"load_package",        imp_load_package,       METH_VARARGS},
#ifdef macintosh
        {"load_resource",       imp_load_resource,      METH_VARARGS},
#endif
        {"load_source",         imp_load_source,        METH_VARARGS},
        {NULL,                  NULL}           /* sentinel */
};

static int
setint(PyObject *d, char *name, int value)
{
        PyObject *v;
        int err;

        v = PyInt_FromLong((long)value);
        err = PyDict_SetItemString(d, name, v);
        Py_XDECREF(v);
        return err;
}

void
initimp(void)
{
        PyObject *m, *d;

        m = Py_InitModule4("imp", imp_methods, doc_imp,
                           NULL, PYTHON_API_VERSION);
        d = PyModule_GetDict(m);

        if (setint(d, "SEARCH_ERROR", SEARCH_ERROR) < 0) goto failure;
        if (setint(d, "PY_SOURCE", PY_SOURCE) < 0) goto failure;
        if (setint(d, "PY_COMPILED", PY_COMPILED) < 0) goto failure;
        if (setint(d, "C_EXTENSION", C_EXTENSION) < 0) goto failure;
        if (setint(d, "PY_RESOURCE", PY_RESOURCE) < 0) goto failure;
        if (setint(d, "PKG_DIRECTORY", PKG_DIRECTORY) < 0) goto failure;
        if (setint(d, "C_BUILTIN", C_BUILTIN) < 0) goto failure;
        if (setint(d, "PY_FROZEN", PY_FROZEN) < 0) goto failure;
        if (setint(d, "PY_CODERESOURCE", PY_CODERESOURCE) < 0) goto failure;
        if (setint(d, "IMP_HOOK", IMP_HOOK) < 0) goto failure;

  failure:
        ;
}


/* API for embedding applications that want to add their own entries
   to the table of built-in modules.  This should normally be called
   *before* Py_Initialize().  When the table resize fails, -1 is
   returned and the existing table is unchanged.

   After a similar function by Just van Rossum. */

int
PyImport_ExtendInittab(struct _inittab *newtab)
{
        static struct _inittab *our_copy = NULL;
        struct _inittab *p;
        int i, n;

        /* Count the number of entries in both tables */
        for (n = 0; newtab[n].name != NULL; n++)
                ;
        if (n == 0)
                return 0; /* Nothing to do */
        for (i = 0; PyImport_Inittab[i].name != NULL; i++)
                ;

        /* Allocate new memory for the combined table */
        p = our_copy;
        PyMem_RESIZE(p, struct _inittab, i+n+1);
        if (p == NULL)
                return -1;

        /* Copy the tables into the new memory */
        if (our_copy != PyImport_Inittab)
                memcpy(p, PyImport_Inittab, (i+1) * sizeof(struct _inittab));
        PyImport_Inittab = our_copy = p;
        memcpy(p+i, newtab, (n+1) * sizeof(struct _inittab));

        return 0;
}

/* Shorthand to add a single entry given a name and a function */

int
PyImport_AppendInittab(char *name, void (*initfunc)(void))
{
        struct _inittab newtab[2];

        memset(newtab, '\0', sizeof newtab);

        newtab[0].name = name;
        newtab[0].initfunc = initfunc;

        return PyImport_ExtendInittab(newtab);
}