sysmodule.c revision 23fff911a2e0185d3f4618cd02a7b051b55fdd7e
1
2/* System module */
3
4/*
5Various bits of information used by the interpreter are collected in
6module 'sys'.
7Function member:
8- exit(sts): raise SystemExit
9Data members:
10- stdin, stdout, stderr: standard file objects
11- modules: the table of modules (dictionary)
12- path: module search path (list of strings)
13- argv: script arguments (list of strings)
14- ps1, ps2: optional primary and secondary prompts (strings)
15*/
16
17#include "Python.h"
18#include "compile.h"
19#include "frameobject.h"
20
21#include "osdefs.h"
22
23#ifdef HAVE_UNISTD_H
24#include <unistd.h>
25#endif
26
27#ifdef MS_COREDLL
28extern void *PyWin_DLLhModule;
29/* A string loaded from the DLL at startup: */
30extern const char *PyWin_DLLVersionString;
31#endif
32
33PyObject *
34PySys_GetObject(char *name)
35{
36	PyThreadState *tstate = PyThreadState_Get();
37	PyObject *sd = tstate->interp->sysdict;
38	if (sd == NULL)
39		return NULL;
40	return PyDict_GetItemString(sd, name);
41}
42
43FILE *
44PySys_GetFile(char *name, FILE *def)
45{
46	FILE *fp = NULL;
47	PyObject *v = PySys_GetObject(name);
48	if (v != NULL && PyFile_Check(v))
49		fp = PyFile_AsFile(v);
50	if (fp == NULL)
51		fp = def;
52	return fp;
53}
54
55int
56PySys_SetObject(char *name, PyObject *v)
57{
58	PyThreadState *tstate = PyThreadState_Get();
59	PyObject *sd = tstate->interp->sysdict;
60	if (v == NULL) {
61		if (PyDict_GetItemString(sd, name) == NULL)
62			return 0;
63		else
64			return PyDict_DelItemString(sd, name);
65	}
66	else
67		return PyDict_SetItemString(sd, name, v);
68}
69
70static PyObject *
71sys_exc_info(PyObject *self, PyObject *args)
72{
73	PyThreadState *tstate;
74	if (!PyArg_ParseTuple(args, ":exc_info"))
75		return NULL;
76	tstate = PyThreadState_Get();
77	return Py_BuildValue(
78		"(OOO)",
79		tstate->exc_type != NULL ? tstate->exc_type : Py_None,
80		tstate->exc_value != NULL ? tstate->exc_value : Py_None,
81		tstate->exc_traceback != NULL ?
82			tstate->exc_traceback : Py_None);
83}
84
85static char exc_info_doc[] =
86"exc_info() -> (type, value, traceback)\n\
87\n\
88Return information about the exception that is currently being handled.\n\
89This should be called from inside an except clause only.";
90
91static PyObject *
92sys_exit(PyObject *self, PyObject *args)
93{
94	/* Raise SystemExit so callers may catch it or clean up. */
95	PyErr_SetObject(PyExc_SystemExit, args);
96	return NULL;
97}
98
99static char exit_doc[] =
100"exit([status])\n\
101\n\
102Exit the interpreter by raising SystemExit(status).\n\
103If the status is omitted or None, it defaults to zero (i.e., success).\n\
104If the status numeric, it will be used as the system exit status.\n\
105If it is another kind of object, it will be printed and the system\n\
106exit status will be one (i.e., failure).";
107
108static PyObject *
109sys_getdefaultencoding(PyObject *self, PyObject *args)
110{
111	if (!PyArg_ParseTuple(args, ":getdefaultencoding"))
112		return NULL;
113	return PyString_FromString(PyUnicode_GetDefaultEncoding());
114}
115
116static char getdefaultencoding_doc[] =
117"getdefaultencoding() -> string\n\
118\n\
119Return the current default string encoding used by the Unicode \n\
120implementation.";
121
122static PyObject *
123sys_setdefaultencoding(PyObject *self, PyObject *args)
124{
125	char *encoding;
126	if (!PyArg_ParseTuple(args, "s:setdefaultencoding", &encoding))
127		return NULL;
128	if (PyUnicode_SetDefaultEncoding(encoding))
129	    	return NULL;
130	Py_INCREF(Py_None);
131	return Py_None;
132}
133
134static char setdefaultencoding_doc[] =
135"setdefaultencoding(encoding)\n\
136\n\
137Set the current default string encoding used by the Unicode implementation.";
138
139static PyObject *
140sys_settrace(PyObject *self, PyObject *args)
141{
142	PyThreadState *tstate = PyThreadState_Get();
143	if (args == Py_None)
144		args = NULL;
145	else
146		Py_XINCREF(args);
147	Py_XDECREF(tstate->sys_tracefunc);
148	tstate->sys_tracefunc = args;
149	Py_INCREF(Py_None);
150	return Py_None;
151}
152
153static char settrace_doc[] =
154"settrace(function)\n\
155\n\
156Set the global debug tracing function.  It will be called on each\n\
157function call.  See the debugger chapter in the library manual.";
158
159static PyObject *
160sys_setprofile(PyObject *self, PyObject *args)
161{
162	PyThreadState *tstate = PyThreadState_Get();
163	if (args == Py_None)
164		args = NULL;
165	else
166		Py_XINCREF(args);
167	Py_XDECREF(tstate->sys_profilefunc);
168	tstate->sys_profilefunc = args;
169	Py_INCREF(Py_None);
170	return Py_None;
171}
172
173static char setprofile_doc[] =
174"setprofile(function)\n\
175\n\
176Set the profiling function.  It will be called on each function call\n\
177and return.  See the profiler chapter in the library manual.";
178
179static PyObject *
180sys_setcheckinterval(PyObject *self, PyObject *args)
181{
182	PyThreadState *tstate = PyThreadState_Get();
183	if (!PyArg_ParseTuple(args, "i:setcheckinterval", &tstate->interp->checkinterval))
184		return NULL;
185	Py_INCREF(Py_None);
186	return Py_None;
187}
188
189static char setcheckinterval_doc[] =
190"setcheckinterval(n)\n\
191\n\
192Tell the Python interpreter to check for asynchronous events every\n\
193n instructions.  This also affects how often thread switches occur.";
194
195static PyObject *
196sys_setrecursionlimit(PyObject *self, PyObject *args)
197{
198	int new_limit;
199	if (!PyArg_ParseTuple(args, "i:setrecursionlimit", &new_limit))
200		return NULL;
201	if (new_limit <= 0) {
202		PyErr_SetString(PyExc_ValueError,
203				"recursion limit must be positive");
204		return NULL;
205	}
206	Py_SetRecursionLimit(new_limit);
207	Py_INCREF(Py_None);
208	return Py_None;
209}
210
211static char setrecursionlimit_doc[] =
212"setrecursionlimit(n)\n\
213\n\
214Set the maximum depth of the Python interpreter stack to n.  This\n\
215limit prevents infinite recursion from causing an overflow of the C\n\
216stack and crashing Python.  The highest possible limit is platform-\n\
217dependent.";
218
219static PyObject *
220sys_getrecursionlimit(PyObject *self, PyObject *args)
221{
222	if (!PyArg_ParseTuple(args, ":getrecursionlimit"))
223		return NULL;
224	return PyInt_FromLong(Py_GetRecursionLimit());
225}
226
227static char getrecursionlimit_doc[] =
228"getrecursionlimit()\n\
229\n\
230Return the current value of the recursion limit, the maximum depth\n\
231of the Python interpreter stack.  This limit prevents infinite\n\
232recursion from causing an overflow of the C stack and crashing Python.";
233
234#ifdef USE_MALLOPT
235/* Link with -lmalloc (or -lmpc) on an SGI */
236#include <malloc.h>
237
238static PyObject *
239sys_mdebug(PyObject *self, PyObject *args)
240{
241	int flag;
242	if (!PyArg_ParseTuple(args, "i:mdebug", &flag))
243		return NULL;
244	mallopt(M_DEBUG, flag);
245	Py_INCREF(Py_None);
246	return Py_None;
247}
248#endif /* USE_MALLOPT */
249
250static PyObject *
251sys_getrefcount(PyObject *self, PyObject *args)
252{
253	PyObject *arg;
254	if (!PyArg_ParseTuple(args, "O:getrefcount", &arg))
255		return NULL;
256	return PyInt_FromLong(arg->ob_refcnt);
257}
258
259#ifdef Py_TRACE_REFS
260static PyObject *
261sys_gettotalrefcount(PyObject *self, PyObject *args)
262{
263	extern long _Py_RefTotal;
264	if (!PyArg_ParseTuple(args, ":gettotalrefcount"))
265		return NULL;
266	return PyInt_FromLong(_Py_RefTotal);
267}
268
269#endif /* Py_TRACE_REFS */
270
271static char getrefcount_doc[] =
272"getrefcount(object) -> integer\n\
273\n\
274Return the current reference count for the object.  This includes the\n\
275temporary reference in the argument list, so it is at least 2.";
276
277#ifdef COUNT_ALLOCS
278static PyObject *
279sys_getcounts(PyObject *self, PyObject *args)
280{
281	extern PyObject *get_counts(void);
282
283	if (!PyArg_ParseTuple(args, ":getcounts"))
284		return NULL;
285	return get_counts();
286}
287#endif
288
289static char getframe_doc[] =
290"_getframe([depth]) -> frameobject\n\
291\n\
292Return a frame object from the call stack.  If optional integer depth is\n\
293given, return the frame object that many calls below the top of the stack.\n\
294If that is deeper than the call stack, ValueError is raised.  The default\n\
295for depth is zero, returning the frame at the top of the call stack.\n\
296\n\
297This function should be used for internal and specialized\n\
298purposes only.";
299
300static PyObject *
301sys_getframe(PyObject *self, PyObject *args)
302{
303	PyFrameObject *f = PyThreadState_Get()->frame;
304	int depth = -1;
305
306	if (!PyArg_ParseTuple(args, "|i:_getframe", &depth))
307		return NULL;
308
309	while (depth > 0 && f != NULL) {
310		f = f->f_back;
311		--depth;
312	}
313	if (f == NULL) {
314		PyErr_SetString(PyExc_ValueError,
315				"call stack is not deep enough");
316		return NULL;
317	}
318	Py_INCREF(f);
319	return (PyObject*)f;
320}
321
322
323#ifdef Py_TRACE_REFS
324/* Defined in objects.c because it uses static globals if that file */
325extern PyObject *_Py_GetObjects(PyObject *, PyObject *);
326#endif
327
328#ifdef DYNAMIC_EXECUTION_PROFILE
329/* Defined in ceval.c because it uses static globals if that file */
330extern PyObject *_Py_GetDXProfile(PyObject *,  PyObject *);
331#endif
332
333static PyMethodDef sys_methods[] = {
334	/* Might as well keep this in alphabetic order */
335	{"exc_info",	sys_exc_info, 1, exc_info_doc},
336	{"exit",	sys_exit, 0, exit_doc},
337	{"getdefaultencoding", sys_getdefaultencoding, 1,
338	 getdefaultencoding_doc},
339#ifdef COUNT_ALLOCS
340	{"getcounts",	sys_getcounts, 1},
341#endif
342#ifdef DYNAMIC_EXECUTION_PROFILE
343	{"getdxp",	_Py_GetDXProfile, 1},
344#endif
345#ifdef Py_TRACE_REFS
346	{"getobjects",	_Py_GetObjects, 1},
347	{"gettotalrefcount", sys_gettotalrefcount, 1},
348#endif
349	{"getrefcount",	sys_getrefcount, 1, getrefcount_doc},
350	{"getrecursionlimit", sys_getrecursionlimit, 1,
351	 getrecursionlimit_doc},
352	{"_getframe", sys_getframe, 1, getframe_doc},
353#ifdef USE_MALLOPT
354	{"mdebug",	sys_mdebug, 1},
355#endif
356	{"setdefaultencoding", sys_setdefaultencoding, 1,
357	 setdefaultencoding_doc},
358	{"setcheckinterval",	sys_setcheckinterval, 1,
359	 setcheckinterval_doc},
360	{"setprofile",	sys_setprofile, 0, setprofile_doc},
361	{"setrecursionlimit", sys_setrecursionlimit, 1,
362	 setrecursionlimit_doc},
363	{"settrace",	sys_settrace, 0, settrace_doc},
364	{NULL,		NULL}		/* sentinel */
365};
366
367static PyObject *
368list_builtin_module_names(void)
369{
370	PyObject *list = PyList_New(0);
371	int i;
372	if (list == NULL)
373		return NULL;
374	for (i = 0; PyImport_Inittab[i].name != NULL; i++) {
375		PyObject *name = PyString_FromString(
376			PyImport_Inittab[i].name);
377		if (name == NULL)
378			break;
379		PyList_Append(list, name);
380		Py_DECREF(name);
381	}
382	if (PyList_Sort(list) != 0) {
383		Py_DECREF(list);
384		list = NULL;
385	}
386	if (list) {
387		PyObject *v = PyList_AsTuple(list);
388		Py_DECREF(list);
389		list = v;
390	}
391	return list;
392}
393
394static PyObject *warnoptions = NULL;
395
396void
397PySys_ResetWarnOptions(void)
398{
399	if (warnoptions == NULL || !PyList_Check(warnoptions))
400		return;
401	PyList_SetSlice(warnoptions, 0, PyList_GET_SIZE(warnoptions), NULL);
402}
403
404void
405PySys_AddWarnOption(char *s)
406{
407	PyObject *str;
408
409	if (warnoptions == NULL || !PyList_Check(warnoptions)) {
410		Py_XDECREF(warnoptions);
411		warnoptions = PyList_New(0);
412		if (warnoptions == NULL)
413			return;
414	}
415	str = PyString_FromString(s);
416	if (str != NULL) {
417		PyList_Append(warnoptions, str);
418		Py_DECREF(str);
419	}
420}
421
422/* XXX This doc string is too long to be a single string literal in VC++ 5.0.
423   Two literals concatenated works just fine.  If you have a K&R compiler
424   or other abomination that however *does* understand longer strings,
425   get rid of the !!! comment in the middle and the quotes that surround it. */
426static char sys_doc[] =
427"This module provides access to some objects used or maintained by the\n\
428interpreter and to functions that interact strongly with the interpreter.\n\
429\n\
430Dynamic objects:\n\
431\n\
432argv -- command line arguments; argv[0] is the script pathname if known\n\
433path -- module search path; path[0] is the script directory, else ''\n\
434modules -- dictionary of loaded modules\n\
435exitfunc -- you may set this to a function to be called when Python exits\n\
436\n\
437stdin -- standard input file object; used by raw_input() and input()\n\
438stdout -- standard output file object; used by the print statement\n\
439stderr -- standard error object; used for error messages\n\
440  By assigning another file object (or an object that behaves like a file)\n\
441  to one of these, it is possible to redirect all of the interpreter's I/O.\n\
442\n\
443last_type -- type of last uncaught exception\n\
444last_value -- value of last uncaught exception\n\
445last_traceback -- traceback of last uncaught exception\n\
446  These three are only available in an interactive session after a\n\
447  traceback has been printed.\n\
448\n\
449exc_type -- type of exception currently being handled\n\
450exc_value -- value of exception currently being handled\n\
451exc_traceback -- traceback of exception currently being handled\n\
452  The function exc_info() should be used instead of these three,\n\
453  because it is thread-safe.\n\
454"
455#ifndef MS_WIN16
456/* Concatenating string here */
457"\n\
458Static objects:\n\
459\n\
460maxint -- the largest supported integer (the smallest is -maxint-1)\n\
461builtin_module_names -- tuple of module names built into this intepreter\n\
462version -- the version of this interpreter as a string\n\
463version_info -- version information as a tuple\n\
464hexversion -- version information encoded as a single integer\n\
465copyright -- copyright notice pertaining to this interpreter\n\
466platform -- platform identifier\n\
467executable -- pathname of this Python interpreter\n\
468prefix -- prefix used to find the Python library\n\
469exec_prefix -- prefix used to find the machine-specific Python library\n\
470dllhandle -- [Windows only] integer handle of the Python DLL\n\
471winver -- [Windows only] version number of the Python DLL\n\
472__stdin__ -- the original stdin; don't use!\n\
473__stdout__ -- the original stdout; don't use!\n\
474__stderr__ -- the original stderr; don't use!\n\
475\n\
476Functions:\n\
477\n\
478exc_info() -- return thread-safe information about the current exception\n\
479exit() -- exit the interpreter by raising SystemExit\n\
480getrefcount() -- return the reference count for an object (plus one :-)\n\
481getrecursionlimit() -- return the max recursion depth for the interpreter\n\
482setcheckinterval() -- control how often the interpreter checks for events\n\
483setprofile() -- set the global profiling function\n\
484setrecursionlimit() -- set the max recursion depth for the interpreter\n\
485settrace() -- set the global debug tracing function\n\
486"
487#endif
488/* end of sys_doc */ ;
489
490PyObject *
491_PySys_Init(void)
492{
493	PyObject *m, *v, *sysdict;
494	PyObject *sysin, *sysout, *syserr;
495	char *s;
496
497	m = Py_InitModule3("sys", sys_methods, sys_doc);
498	sysdict = PyModule_GetDict(m);
499
500	sysin = PyFile_FromFile(stdin, "<stdin>", "r", NULL);
501	sysout = PyFile_FromFile(stdout, "<stdout>", "w", NULL);
502	syserr = PyFile_FromFile(stderr, "<stderr>", "w", NULL);
503	if (PyErr_Occurred())
504		return NULL;
505	PyDict_SetItemString(sysdict, "stdin", sysin);
506	PyDict_SetItemString(sysdict, "stdout", sysout);
507	PyDict_SetItemString(sysdict, "stderr", syserr);
508	/* Make backup copies for cleanup */
509	PyDict_SetItemString(sysdict, "__stdin__", sysin);
510	PyDict_SetItemString(sysdict, "__stdout__", sysout);
511	PyDict_SetItemString(sysdict, "__stderr__", syserr);
512	Py_XDECREF(sysin);
513	Py_XDECREF(sysout);
514	Py_XDECREF(syserr);
515	PyDict_SetItemString(sysdict, "version",
516			     v = PyString_FromString(Py_GetVersion()));
517	Py_XDECREF(v);
518	PyDict_SetItemString(sysdict, "hexversion",
519			     v = PyInt_FromLong(PY_VERSION_HEX));
520	Py_XDECREF(v);
521	/*
522	 * These release level checks are mutually exclusive and cover
523	 * the field, so don't get too fancy with the pre-processor!
524	 */
525#if PY_RELEASE_LEVEL == PY_RELEASE_LEVEL_ALPHA
526	s = "alpha";
527#elif PY_RELEASE_LEVEL == PY_RELEASE_LEVEL_BETA
528	s = "beta";
529#elif PY_RELEASE_LEVEL == PY_RELEASE_LEVEL_GAMMA
530	s = "candidate";
531#elif PY_RELEASE_LEVEL == PY_RELEASE_LEVEL_FINAL
532	s = "final";
533#endif
534	PyDict_SetItemString(sysdict, "version_info",
535			     v = Py_BuildValue("iiisi", PY_MAJOR_VERSION,
536					       PY_MINOR_VERSION,
537					       PY_MICRO_VERSION, s,
538					       PY_RELEASE_SERIAL));
539	Py_XDECREF(v);
540	PyDict_SetItemString(sysdict, "copyright",
541			     v = PyString_FromString(Py_GetCopyright()));
542	Py_XDECREF(v);
543	PyDict_SetItemString(sysdict, "platform",
544			     v = PyString_FromString(Py_GetPlatform()));
545	Py_XDECREF(v);
546	PyDict_SetItemString(sysdict, "executable",
547			     v = PyString_FromString(Py_GetProgramFullPath()));
548	Py_XDECREF(v);
549	PyDict_SetItemString(sysdict, "prefix",
550			     v = PyString_FromString(Py_GetPrefix()));
551	Py_XDECREF(v);
552	PyDict_SetItemString(sysdict, "exec_prefix",
553		   v = PyString_FromString(Py_GetExecPrefix()));
554	Py_XDECREF(v);
555	PyDict_SetItemString(sysdict, "maxint",
556			     v = PyInt_FromLong(PyInt_GetMax()));
557	Py_XDECREF(v);
558	PyDict_SetItemString(sysdict, "builtin_module_names",
559		   v = list_builtin_module_names());
560	Py_XDECREF(v);
561	{
562		/* Assumes that longs are at least 2 bytes long.
563		   Should be safe! */
564		unsigned long number = 1;
565		char *value;
566
567		s = (char *) &number;
568		if (s[0] == 0)
569			value = "big";
570		else
571			value = "little";
572		PyDict_SetItemString(sysdict, "byteorder",
573				     v = PyString_FromString(value));
574		Py_XDECREF(v);
575	}
576#ifdef MS_COREDLL
577	PyDict_SetItemString(sysdict, "dllhandle",
578			     v = PyLong_FromVoidPtr(PyWin_DLLhModule));
579	Py_XDECREF(v);
580	PyDict_SetItemString(sysdict, "winver",
581			     v = PyString_FromString(PyWin_DLLVersionString));
582	Py_XDECREF(v);
583#endif
584	if (warnoptions == NULL) {
585		warnoptions = PyList_New(0);
586	}
587	else {
588		Py_INCREF(warnoptions);
589	}
590	if (warnoptions != NULL) {
591		PyDict_SetItemString(sysdict, "warnoptions", v = warnoptions);
592		Py_DECREF(v);
593	}
594
595	if (PyErr_Occurred())
596		return NULL;
597	return m;
598}
599
600static PyObject *
601makepathobject(char *path, int delim)
602{
603	int i, n;
604	char *p;
605	PyObject *v, *w;
606
607	n = 1;
608	p = path;
609	while ((p = strchr(p, delim)) != NULL) {
610		n++;
611		p++;
612	}
613	v = PyList_New(n);
614	if (v == NULL)
615		return NULL;
616	for (i = 0; ; i++) {
617		p = strchr(path, delim);
618		if (p == NULL)
619			p = strchr(path, '\0'); /* End of string */
620		w = PyString_FromStringAndSize(path, (int) (p - path));
621		if (w == NULL) {
622			Py_DECREF(v);
623			return NULL;
624		}
625		PyList_SetItem(v, i, w);
626		if (*p == '\0')
627			break;
628		path = p+1;
629	}
630	return v;
631}
632
633void
634PySys_SetPath(char *path)
635{
636	PyObject *v;
637	if ((v = makepathobject(path, DELIM)) == NULL)
638		Py_FatalError("can't create sys.path");
639	if (PySys_SetObject("path", v) != 0)
640		Py_FatalError("can't assign sys.path");
641	Py_DECREF(v);
642}
643
644static PyObject *
645makeargvobject(int argc, char **argv)
646{
647	PyObject *av;
648	if (argc <= 0 || argv == NULL) {
649		/* Ensure at least one (empty) argument is seen */
650		static char *empty_argv[1] = {""};
651		argv = empty_argv;
652		argc = 1;
653	}
654	av = PyList_New(argc);
655	if (av != NULL) {
656		int i;
657		for (i = 0; i < argc; i++) {
658			PyObject *v = PyString_FromString(argv[i]);
659			if (v == NULL) {
660				Py_DECREF(av);
661				av = NULL;
662				break;
663			}
664			PyList_SetItem(av, i, v);
665		}
666	}
667	return av;
668}
669
670void
671PySys_SetArgv(int argc, char **argv)
672{
673	PyObject *av = makeargvobject(argc, argv);
674	PyObject *path = PySys_GetObject("path");
675	if (av == NULL)
676		Py_FatalError("no mem for sys.argv");
677	if (PySys_SetObject("argv", av) != 0)
678		Py_FatalError("can't assign sys.argv");
679	if (path != NULL) {
680		char *argv0 = argv[0];
681		char *p = NULL;
682		int n = 0;
683		PyObject *a;
684#ifdef HAVE_READLINK
685		char link[MAXPATHLEN+1];
686		char argv0copy[2*MAXPATHLEN+1];
687		int nr = 0;
688		if (argc > 0 && argv0 != NULL)
689			nr = readlink(argv0, link, MAXPATHLEN);
690		if (nr > 0) {
691			/* It's a symlink */
692			link[nr] = '\0';
693			if (link[0] == SEP)
694				argv0 = link; /* Link to absolute path */
695			else if (strchr(link, SEP) == NULL)
696				; /* Link without path */
697			else {
698				/* Must join(dirname(argv0), link) */
699				char *q = strrchr(argv0, SEP);
700				if (q == NULL)
701					argv0 = link; /* argv0 without path */
702				else {
703					/* Must make a copy */
704					strcpy(argv0copy, argv0);
705					q = strrchr(argv0copy, SEP);
706					strcpy(q+1, link);
707					argv0 = argv0copy;
708				}
709			}
710		}
711#endif /* HAVE_READLINK */
712#if SEP == '\\' /* Special case for MS filename syntax */
713		if (argc > 0 && argv0 != NULL) {
714			char *q;
715			p = strrchr(argv0, SEP);
716			/* Test for alternate separator */
717			q = strrchr(p ? p : argv0, '/');
718			if (q != NULL)
719				p = q;
720			if (p != NULL) {
721				n = p + 1 - argv0;
722				if (n > 1 && p[-1] != ':')
723					n--; /* Drop trailing separator */
724			}
725		}
726#else /* All other filename syntaxes */
727		if (argc > 0 && argv0 != NULL)
728			p = strrchr(argv0, SEP);
729		if (p != NULL) {
730			n = p + 1 - argv0;
731#if SEP == '/' /* Special case for Unix filename syntax */
732			if (n > 1)
733				n--; /* Drop trailing separator */
734#endif /* Unix */
735		}
736#endif /* All others */
737		a = PyString_FromStringAndSize(argv0, n);
738		if (a == NULL)
739			Py_FatalError("no mem for sys.path insertion");
740		if (PyList_Insert(path, 0, a) < 0)
741			Py_FatalError("sys.path.insert(0) failed");
742		Py_DECREF(a);
743	}
744	Py_DECREF(av);
745}
746
747
748/* APIs to write to sys.stdout or sys.stderr using a printf-like interface.
749   Adapted from code submitted by Just van Rossum.
750
751   PySys_WriteStdout(format, ...)
752   PySys_WriteStderr(format, ...)
753
754      The first function writes to sys.stdout; the second to sys.stderr.  When
755      there is a problem, they write to the real (C level) stdout or stderr;
756      no exceptions are raised.
757
758      Both take a printf-style format string as their first argument followed
759      by a variable length argument list determined by the format string.
760
761      *** WARNING ***
762
763      The format should limit the total size of the formatted output string to
764      1000 bytes.  In particular, this means that no unrestricted "%s" formats
765      should occur; these should be limited using "%.<N>s where <N> is a
766      decimal number calculated so that <N> plus the maximum size of other
767      formatted text does not exceed 1000 bytes.  Also watch out for "%f",
768      which can print hundreds of digits for very large numbers.
769
770 */
771
772static void
773mywrite(char *name, FILE *fp, const char *format, va_list va)
774{
775	PyObject *file;
776	PyObject *error_type, *error_value, *error_traceback;
777
778	PyErr_Fetch(&error_type, &error_value, &error_traceback);
779	file = PySys_GetObject(name);
780	if (file == NULL || PyFile_AsFile(file) == fp)
781		vfprintf(fp, format, va);
782	else {
783		char buffer[1001];
784		if (vsprintf(buffer, format, va) >= sizeof(buffer))
785		    Py_FatalError("PySys_WriteStdout/err: buffer overrun");
786		if (PyFile_WriteString(buffer, file) != 0) {
787			PyErr_Clear();
788			fputs(buffer, fp);
789		}
790	}
791	PyErr_Restore(error_type, error_value, error_traceback);
792}
793
794void
795PySys_WriteStdout(const char *format, ...)
796{
797	va_list va;
798
799	va_start(va, format);
800	mywrite("stdout", stdout, format, va);
801	va_end(va);
802}
803
804void
805PySys_WriteStderr(const char *format, ...)
806{
807	va_list va;
808
809	va_start(va, format);
810	mywrite("stderr", stderr, format, va);
811	va_end(va);
812}
813