cpython/Python/import.c

/***********************************************************
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in 
supporting documentation, and that the names of Stichting Mathematisch
Centrum or CWI not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior permission.

STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

******************************************************************/

/* Module definition and import implementation */

#include "allobjects.h"

#include "node.h"
#include "token.h"
#include "graminit.h"
#include "import.h"
#include "errcode.h"
#include "sysmodule.h"
#include "bltinmodule.h"
#include "pythonrun.h"
#include "marshal.h"
#include "compile.h"
#include "eval.h"
#include "osdefs.h"
#include "importdl.h"

extern int verbose; /* Defined in pythonrun.c */

extern long getmtime(); /* In getmtime.c */

/* Magic word to reject .pyc files generated by other Python versions */
#define MAGIC 0x999903L /* Increment by one for each incompatible change */

object *import_modules; /* This becomes sys.modules */


/* Initialize things */

void
initimport()
{
	if (import_modules != NULL)
		fatal("duplicate initimport() call");
	if ((import_modules = newdictobject()) == NULL)
		fatal("no mem for dictionary of modules");
}


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

void
doneimport()
{
	if (import_modules != NULL) {
		object *tmp = import_modules;
		import_modules = NULL;
		/* This deletes all modules from sys.modules.
		   When a module is deallocated, it in turn clears its dictionary,
		   thus hopefully breaking any circular references between modules
		   and between a module's dictionary and its functions.
		   Note that "import" will fail while we are cleaning up.
		   */
		mappingclear(tmp);
		DECREF(tmp);
	}
}


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

long
get_pyc_magic()
{
	return MAGIC;
}


/* Helper for sysmodule.c -- return modules dictionary */

object *
get_modules()
{
	return import_modules;
}


/* 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! */

object *
add_module(name)
	char *name;
{
	object *m;

	if (import_modules == NULL) {
		err_setstr(SystemError, "sys.modules has been deleted");
		return NULL;
	}
	if ((m = dictlookup(import_modules, name)) != NULL &&
	    is_moduleobject(m))
		return m;
	m = newmoduleobject(name);
	if (m == NULL)
		return NULL;
	if (dictinsert(import_modules, name, m) != 0) {
		DECREF(m);
		return NULL;
	}
	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 */

static object *
exec_code_module(name, co)
	char *name;
	codeobject *co;
{
	object *m, *d, *v;

	m = add_module(name);
	if (m == NULL)
		return NULL;
	d = getmoduledict(m);
	if (dictlookup(d, "__builtins__") == NULL) {
		if (dictinsert(d, "__builtins__", getbuiltins()) != 0)
			return NULL;
	}
	v = eval_code((codeobject *)co, d, d, d, (object *)NULL);
	if (v == NULL)
		return NULL;
	DECREF(v);
	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(pathname, buf, buflen)
	char *pathname;
	char *buf;
	int buflen;
{
	int len;

	len = strlen(pathname);
	if (len+2 > buflen)
		return NULL;
	strcpy(buf, pathname);
	strcpy(buf+len, "c");

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

	fp = fopen(cpathname, "rb");
	if (fp == NULL)
		return NULL;
	magic = rd_long(fp);
	if (magic != MAGIC) {
		if (verbose)
			fprintf(stderr, "# %s has bad magic\n", cpathname);
		fclose(fp);
		return NULL;
	}
	pyc_mtime = rd_long(fp);
	if (pyc_mtime != mtime) {
		if (verbose)
			fprintf(stderr, "# %s has bad mtime\n", cpathname);
		fclose(fp);
		return NULL;
	}
	if (verbose)
		fprintf(stderr, "# %s matches %s\n", cpathname, pathname);
	return fp;
}


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

static codeobject *
read_compiled_module(fp)
	FILE *fp;
{
	object *co;

	co = rd_object(fp);
	/* Ugly: rd_object() may return NULL with or without error */
	if (co == NULL || !is_codeobject(co)) {
		if (!err_occurred())
			err_setstr(ImportError,
				   "Non-code object in .pyc file");
		XDECREF(co);
		return NULL;
	}
	return (codeobject *)co;
}


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

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

	magic = rd_long(fp);
	if (magic != MAGIC) {
		err_setstr(ImportError, "Bad magic number in .pyc file");
		return NULL;
	}
	(void) rd_long(fp);
	co = read_compiled_module(fp);
	if (co == NULL)
		return NULL;
	if (verbose)
		fprintf(stderr, "import %s # precompiled from %s\n",
			name, cpathname);
	m = exec_code_module(name, co);
	DECREF(co);

	return m;
}


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

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

	n = parse_file(fp, pathname, file_input);
	if (n == NULL)
		return NULL;
	co = compile(n, pathname);
	freetree(n);

	return co;
}


/* 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(co, cpathname, mtime)
	codeobject *co;
	char *cpathname;
	long mtime;
{
	FILE *fp;

	fp = fopen(cpathname, "wb");
	if (fp == NULL) {
		if (verbose)
			fprintf(stderr,
				"# can't create %s\n", cpathname);
		return;
	}
	wr_long(MAGIC, fp);
	/* First write a 0 for mtime */
	wr_long(0L, fp);
	wr_object((object *)co, fp);
	if (ferror(fp)) {
		if (verbose)
			fprintf(stderr, "# 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);
	wr_long(mtime, fp);
	fflush(fp);
	fclose(fp);
	if (verbose)
		fprintf(stderr, "# wrote %s\n", cpathname);
#ifdef macintosh
	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 object *
load_source_module(name, pathname, fp)
	char *name;
	char *pathname;
	FILE *fp;
{
	long mtime;
	FILE *fpc;
	char buf[MAXPATHLEN+1];
	char *cpathname;
	codeobject *co;
	object *m;

	mtime = getmtime(pathname);
	cpathname = make_compiled_pathname(pathname, buf, MAXPATHLEN+1);
	if (cpathname != NULL &&
	    (fpc = check_compiled_module(pathname, mtime, cpathname))) {
		co = read_compiled_module(fpc);
		fclose(fpc);
		if (co == NULL)
			return NULL;
		if (verbose)
			fprintf(stderr, "import %s # precompiled from %s\n",
				name, cpathname);
	}
	else {
		co = parse_source_module(pathname, fp);
		if (co == NULL)
			return NULL;
		if (verbose)
			fprintf(stderr, "import %s # from %s\n",
				name, pathname);
		write_compiled_module(co, cpathname, mtime);
	}
	m = exec_code_module(name, co);
	DECREF(co);

	return m;
}


/* 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. */

static struct filedescr *
find_module(name, path, buf, buflen, p_fp)
	char *name;
	object *path;
	/* Output parameters: */
	char *buf;
	int buflen;
	FILE **p_fp;
{
	int i, npath, len, namelen;
	struct filedescr *fdp;
	FILE *fp;

	if (path == NULL)
		path = sysget("path");
	if (path == NULL || !is_listobject(path)) {
		err_setstr(ImportError,
		    "module search path must be list of directory names");
		return NULL;
	}
	npath = getlistsize(path);
	namelen = strlen(name);
	for (i = 0; i < npath; i++) {
		object *v = getlistitem(path, i);
		if (!is_stringobject(v))
			continue;
		len = getstringsize(v);
		if (len + 2 + namelen + import_maxsuffixsize >= buflen)
			continue; /* Too long */
		strcpy(buf, getstringvalue(v));
		if (strlen(buf) != len)
			continue; /* v contains '\0' */
		if (len > 0 && buf[len-1] != SEP)
			buf[len++] = SEP;
		strcpy(buf+len, name);
		len += namelen;
		for (fdp = import_filetab; fdp->suffix != NULL; fdp++) {
			strcpy(buf+len, fdp->suffix);
			if (verbose > 1)
				fprintf(stderr, "# trying %s\n", buf);
			fp = fopen(buf, fdp->mode);
			if (fp != NULL)
				break;
		}
		if (fp != NULL)
			break;
	}
	if (fp == NULL) {
		char buf[256];
		sprintf(buf, "No module named %.200s", name);
		err_setstr(ImportError, buf);
		return NULL;
	}

	*p_fp = fp;
	return fdp;
}


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

static object *
load_module(name)
	char *name;
{
	char buf[MAXPATHLEN+1];
	struct filedescr *fdp;
	FILE *fp = NULL;
	object *m;

	fdp = find_module(name, (object *)NULL, buf, MAXPATHLEN+1, &fp);
	if (fdp == NULL)
		return NULL;

	switch (fdp->type) {

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

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

	case C_EXTENSION:
		m = load_dynamic_module(name, buf);
		break;

	default:
		err_setstr(SystemError,
			   "find_module returned unexpected result");
		m = NULL;

	}
	fclose(fp);

	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(name)
	char *name;
{
	int i;
	for (i = 0; inittab[i].name != NULL; i++) {
		if (strcmp(name, inittab[i].name) == 0) {
			if (inittab[i].initfunc == NULL) {
				err_setstr(ImportError,
					   "cannot re-init internal module");
				return -1;
			}
			if (verbose)
				fprintf(stderr, "import %s # builtin\n",
					name);
			(*inittab[i].initfunc)();
			if (err_occurred())
				return -1;
			return 1;
		}
	}
	return 0;
}


/* 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. */

extern struct frozen {
	char *name;
	char *code;
	int size;
} frozen_modules[];

/* This function is also used from frozenmain.c */

int
init_frozen(name)
	char *name;
{
	struct frozen *p;
	object *co;
	object *m;
	for (p = frozen_modules; ; p++) {
		if (p->name == NULL)
			return 0;
		if (strcmp(p->name, name) == 0)
			break;
	}
	if (verbose)
		fprintf(stderr, "import %s # frozen\n", name);
	co = rds_object(p->code, p->size);
	if (co == NULL)
		return -1;
	if (!is_codeobject(co)) {
		DECREF(co);
		err_setstr(SystemError, "frozen object is not a code object");
		return -1;
	}
	m = exec_code_module(name, (codeobject *)co);
	DECREF(co);
	if (m == NULL)
		return -1;
	DECREF(m);
	return 1;
}


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

object *
import_module(name)
	char *name;
{
	object *m;

	if (import_modules == NULL) {
		err_setstr(SystemError, "sys.modules has been deleted");
		return NULL;
	}
	if ((m = dictlookup(import_modules, name)) != NULL) {
		INCREF(m);
	}
	else {
		int i;
		if ((i = init_builtin(name)) || (i = init_frozen(name))) {
			if (i < 0)
				return NULL;
			if ((m = dictlookup(import_modules, name)) == NULL) {
			    if (err_occurred() == NULL)
			        err_setstr(SystemError,
				 "built-in module not initialized properly");
			}
			else
				INCREF(m);
		}
		else
			m = load_module(name);
	}

	return m;
}


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

object *
reload_module(m)
	object *m;
{
	char *name;
	int i;

	if (m == NULL || !is_moduleobject(m)) {
		err_setstr(TypeError, "reload() argument must be module");
		return NULL;
	}
	name = getmodulename(m);
	if (name == NULL)
		return NULL;
	if (import_modules == NULL) {
		err_setstr(SystemError, "sys.modules has been deleted");
		return NULL;
	}
	if (m != dictlookup(import_modules, name)) {
		err_setstr(ImportError, "reload() module not in sys.modules");
		return NULL;
	}
	/* Check for built-in and frozen modules */
	if ((i = init_builtin(name)) || (i = init_frozen(name))) {
		if (i < 0)
			return NULL;
		INCREF(m);
	}
	else
		m = load_module(name);
	return m;
}


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

static object *
imp_get_magic(self, args)
	object *self;
	object *args;
{
	char buf[4];

	if (!newgetargs(args, ""))
		return NULL;
	buf[0] = (MAGIC >>  0) & 0xff;
	buf[1] = (MAGIC >>  8) & 0xff;
	buf[2] = (MAGIC >> 16) & 0xff;
	buf[3] = (MAGIC >> 24) & 0xff;

	return newsizedstringobject(buf, 4);
}

static object *
imp_get_suffixes(self, args)
	object *self;
	object *args;
{
	object *list;
	struct filedescr *fdp;

	if (!newgetargs(args, ""))
		return NULL;
	list = newlistobject(0);
	if (list == NULL)
		return NULL;
	for (fdp = import_filetab; fdp->suffix != NULL; fdp++) {
		object *item = mkvalue("ssi",
				       fdp->suffix, fdp->mode, fdp->type);
		if (item == NULL) {
			DECREF(list);
			return NULL;
		}
		if (addlistitem(list, item) < 0) {
			DECREF(list);
			DECREF(item);
			return NULL;
		}
		DECREF(item);
	}
	return list;
}

static object *
imp_find_module(self, args)
	object *self;
	object *args;
{
	extern int fclose PROTO((FILE *));
	char *name;
	object *path = NULL;
	object *fob, *ret;
	struct filedescr *fdp;
	char pathname[MAXPATHLEN+1];
	FILE *fp;
	if (!newgetargs(args, "s|O!", &name, &Listtype, &path))
		return NULL;
	fdp = find_module(name, path, pathname, MAXPATHLEN+1, &fp);
	if (fdp == NULL)
		return NULL;
	fob = newopenfileobject(fp, pathname, fdp->mode, fclose);
	if (fob == NULL) {
		fclose(fp);
		return NULL;
	}
	ret = mkvalue("Os(ssi)",
		      fob, pathname, fdp->suffix, fdp->mode, fdp->type);
	DECREF(fob);
	return ret;
}

static object *
imp_init_builtin(self, args)
	object *self;
	object *args;
{
	char *name;
	int ret;
	object *m;
	if (!newgetargs(args, "s", &name))
		return NULL;
	ret = init_builtin(name);
	if (ret < 0)
		return NULL;
	if (ret == 0) {
		INCREF(None);
		return None;
	}
	m = add_module(name);
	XINCREF(m);
	return m;
}

static object *
imp_init_frozen(self, args)
	object *self;
	object *args;
{
	char *name;
	int ret;
	object *m;
	if (!newgetargs(args, "s", &name))
		return NULL;
	ret = init_frozen(name);
	if (ret < 0)
		return NULL;
	if (ret == 0) {
		INCREF(None);
		return None;
	}
	m = add_module(name);
	XINCREF(m);
	return m;
}

static object *
imp_is_builtin(self, args)
	object *self;
	object *args;
{
	int i;
	char *name;
	if (!newgetargs(args, "s", &name))
		return NULL;
	for (i = 0; inittab[i].name != NULL; i++) {
		if (strcmp(name, inittab[i].name) == 0) {
			if (inittab[i].initfunc == NULL)
				return newintobject(-1);
			else
				return newintobject(1);
		}
	}
	return newintobject(0);
}

static object *
imp_is_frozen(self, args)
	object *self;
	object *args;
{
	struct frozen *p;
	char *name;
	if (!newgetargs(args, "s", &name))
		return NULL;
	for (p = frozen_modules; ; p++) {
		if (p->name == NULL)
			break;
		if (strcmp(p->name, name) == 0)
			return newintobject(1);
	}
	return newintobject(0);
}

static FILE *
get_file(pathname, fob, mode)
	char *pathname;
	object *fob;
	char *mode;
{
	FILE *fp;
	if (fob == NULL) {
		fp = fopen(pathname, mode);
		if (fp == NULL)
			err_errno(IOError);
	}
	else {
		fp = getfilefile(fob);
		if (fp == NULL)
			err_setstr(ValueError, "bad/closed file object");
	}
	return fp;
}

static object *
imp_load_compiled(self, args)
	object *self;
	object *args;
{
	char *name;
	char *pathname;
	object *fob = NULL;
	object *m;
	FILE *fp;
	if (!newgetargs(args, "ss|O!", &name, &pathname, &Filetype, &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;
}

static object *
imp_load_dynamic(self, args)
	object *self;
	object *args;
{
	char *name;
	char *pathname;
	object *dummy;
	if (!newgetargs(args, "ss|O", &name, &pathname, &dummy))
		return NULL;
	return load_dynamic_module(name, pathname);
}

static object *
imp_load_source(self, args)
	object *self;
	object *args;
{
	char *name;
	char *pathname;
	object *fob = NULL;
	object *m;
	FILE *fp;
	if (!newgetargs(args, "ss|O!", &name, &pathname, &Filetype, &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;
}

static object *
imp_new_module(self, args)
	object *self;
	object *args;
{
	char *name;
	if (!newgetargs(args, "s", &name))
		return NULL;
	return newmoduleobject(name);
}

static struct methodlist imp_methods[] = {
	{"get_magic",		imp_get_magic,		1},
	{"get_suffixes",	imp_get_suffixes,	1},
	{"find_module",		imp_find_module,	1},
	{"init_builtin",	imp_init_builtin,	1},
	{"init_frozen",		imp_init_frozen,	1},
	{"is_builtin",		imp_is_builtin,		1},
	{"is_frozen",		imp_is_frozen,		1},
	{"load_compiled",	imp_load_compiled,	1},
	{"load_dynamic",	imp_load_dynamic,	1},
	{"load_source",		imp_load_source,	1},
	{"new_module",		imp_new_module,		1},
	{NULL,			NULL}		/* sentinel */
};

void
initimp()
{
	object *m, *d, *v;

	m = initmodule("imp", imp_methods);
	d = getmoduledict(m);

	v = newintobject(SEARCH_ERROR);
	dictinsert(d, "SEARCH_ERROR", v);
	XDECREF(v);

	v = newintobject(PY_SOURCE);
	dictinsert(d, "PY_SOURCE", v);
	XDECREF(v);

	v = newintobject(PY_COMPILED);
	dictinsert(d, "PY_COMPILED", v);
	XDECREF(v);

	v = newintobject(C_EXTENSION);
	dictinsert(d, "C_EXTENSION", v);
	XDECREF(v);

	if (err_occurred())
		fatal("imp module initialization failed");
}