xref: /external/python/cpython3/Modules/main.c

/* Python interpreter main program */

#include "Python.h"
#include "osdefs.h"
#include "import.h"

#ifdef __VMS
#include <unixlib.h>
#endif

#if defined(MS_WINDOWS) || defined(__CYGWIN__)
#include <windows.h>
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#endif

#ifdef _MSC_VER
#include <crtdbg.h>
#endif

#if (defined(PYOS_OS2) && !defined(PYCC_GCC)) || defined(MS_WINDOWS)
#define PYTHONHOMEHELP "<prefix>\\lib"
#else
#if defined(PYOS_OS2) && defined(PYCC_GCC)
#define PYTHONHOMEHELP "<prefix>/Lib"
#else
#define PYTHONHOMEHELP "<prefix>/pythonX.X"
#endif
#endif

#include "pygetopt.h"

#define COPYRIGHT \
    "Type \"help\", \"copyright\", \"credits\" or \"license\" " \
    "for more information."

#ifdef __cplusplus
extern "C" {
#endif

/* For Py_GetArgcArgv(); set by main() */
static char **orig_argv;
static int  orig_argc;

/* command line options */
#define BASE_OPTS "bBc:dEhim:OStuvVW:xX?"

#define PROGRAM_OPTS BASE_OPTS

/* Short usage message (with %s for argv0) */
static char *usage_line =
"usage: %s [option] ... [-c cmd | -m mod | file | -] [arg] ...\n";

/* Long usage message, split into parts < 512 bytes */
static char *usage_1 = "\
Options and arguments (and corresponding environment variables):\n\
-b     : issue warnings about str(bytes_instance), str(buffer_instance)\n\
         and comparing bytes/buffer with str. (-bb: issue errors)\n\
-B     : don't write .py[co] files on import; also PYTHONDONTWRITEBYTECODE=x\n\
-c cmd : program passed in as string (terminates option list)\n\
-d     : debug output from parser; also PYTHONDEBUG=x\n\
-E     : ignore PYTHON* environment variables (such as PYTHONPATH)\n\
-h     : print this help message and exit (also --help)\n\
";
static char *usage_2 = "\
-i     : inspect interactively after running script; forces a prompt even\n\
         if stdin does not appear to be a terminal; also PYTHONINSPECT=x\n\
-m mod : run library module as a script (terminates option list)\n\
-O     : optimize generated bytecode slightly; also PYTHONOPTIMIZE=x\n\
-OO    : remove doc-strings in addition to the -O optimizations\n\
-S     : don't imply 'import site' on initialization\n\
-t     : issue warnings about inconsistent tab usage (-tt: issue errors)\n\
";
static char *usage_3 = "\
-u     : unbuffered binary stdout and stderr; also PYTHONUNBUFFERED=x\n\
         see man page for details on internal buffering relating to '-u'\n\
-v     : verbose (trace import statements); also PYTHONVERBOSE=x\n\
         can be supplied multiple times to increase verbosity\n\
-V     : print the Python version number and exit (also --version)\n\
-W arg : warning control; arg is action:message:category:module:lineno\n\
-x     : skip first line of source, allowing use of non-Unix forms of #!cmd\n\
";
static char *usage_4 = "\
file   : program read from script file\n\
-      : program read from stdin (default; interactive mode if a tty)\n\
arg ...: arguments passed to program in sys.argv[1:]\n\n\
Other environment variables:\n\
PYTHONSTARTUP: file executed on interactive startup (no default)\n\
PYTHONPATH   : '%c'-separated list of directories prefixed to the\n\
               default module search path.  The result is sys.path.\n\
";
static char *usage_5 = "\
PYTHONHOME   : alternate <prefix> directory (or <prefix>%c<exec_prefix>).\n\
               The default module search path uses %s.\n\
PYTHONCASEOK : ignore case in 'import' statements (Windows).\n\
";


static int
usage(int exitcode, char* program)
{
	FILE *f = exitcode ? stderr : stdout;

	fprintf(f, usage_line, program);
	if (exitcode)
		fprintf(f, "Try `python -h' for more information.\n");
	else {
		fprintf(f, usage_1);
		fprintf(f, usage_2);
		fprintf(f, usage_3);
		fprintf(f, usage_4, DELIM);
		fprintf(f, usage_5, DELIM, PYTHONHOMEHELP);
	}
#if defined(__VMS)
	if (exitcode == 0) {
		/* suppress 'error' message */
		return 1;
	}
	else {
		/* STS$M_INHIB_MSG + SS$_ABORT */
		return 0x1000002c;
	}
#else
	return exitcode;
#endif
	/*NOTREACHED*/
}

static void RunStartupFile(PyCompilerFlags *cf)
{
	char *startup = Py_GETENV("PYTHONSTARTUP");
	if (startup != NULL && startup[0] != '\0') {
		FILE *fp = fopen(startup, "r");
		if (fp != NULL) {
			(void) PyRun_SimpleFileExFlags(fp, startup, 0, cf);
			PyErr_Clear();
			fclose(fp);
		} else {
			int save_errno;

			save_errno = errno;
			PySys_WriteStderr("Could not open PYTHONSTARTUP\n");
			errno = save_errno;
			PyErr_SetFromErrnoWithFilename(PyExc_IOError,
					startup);
			PyErr_Print();
			PyErr_Clear();
		}
	}
}


static int RunModule(char *module, int set_argv0)
{
	PyObject *runpy, *runmodule, *runargs, *result;
	runpy = PyImport_ImportModule("runpy");
	if (runpy == NULL) {
		fprintf(stderr, "Could not import runpy module\n");
		return -1;
	}
	runmodule = PyObject_GetAttrString(runpy, "_run_module_as_main");
	if (runmodule == NULL) {
		fprintf(stderr, "Could not access runpy._run_module_as_main\n");
		Py_DECREF(runpy);
		return -1;
	}
	runargs = Py_BuildValue("(si)", module, set_argv0);
	if (runargs == NULL) {
		fprintf(stderr,
			"Could not create arguments for runpy._run_module_as_main\n");
		Py_DECREF(runpy);
		Py_DECREF(runmodule);
		return -1;
	}
	result = PyObject_Call(runmodule, runargs, NULL);
	if (result == NULL) {
		PyErr_Print();
	}
	Py_DECREF(runpy);
	Py_DECREF(runmodule);
	Py_DECREF(runargs);
	if (result == NULL) {
		return -1;
	}
	Py_DECREF(result);
	return 0;
}

static int RunMainFromImporter(char *filename)
{
	PyObject *argv0 = NULL, *importer = NULL;

	if ((argv0 = PyUnicode_DecodeFSDefault(filename)) &&
	    (importer = PyImport_GetImporter(argv0)) &&
	    (importer->ob_type != &PyNullImporter_Type))
	{
		 /* argv0 is usable as an import source, so
			put it in sys.path[0] and import __main__ */
		PyObject *sys_path = NULL;
		if ((sys_path = PySys_GetObject("path")) &&
		    !PyList_SetItem(sys_path, 0, argv0))
		{
			Py_INCREF(argv0);
			Py_DECREF(importer);
			sys_path = NULL;
			return RunModule("__main__", 0) != 0;
		}
	}
	Py_XDECREF(argv0);
	Py_XDECREF(importer);
        if (PyErr_Occurred()) {
		PyErr_Print();
		return 1;
        }
	else {
		return -1;
	}
}


/* Wait until threading._shutdown completes, provided
   the threading module was imported in the first place.
   The shutdown routine will wait until all non-daemon
   "threading" threads have completed. */
#include "abstract.h"
static void
WaitForThreadShutdown(void)
{
#ifdef WITH_THREAD
	PyObject *result;
	PyThreadState *tstate = PyThreadState_GET();
	PyObject *threading = PyMapping_GetItemString(tstate->interp->modules,
						      "threading");
	if (threading == NULL) {
		/* threading not imported */
		PyErr_Clear();
		return;
	}
	result = PyObject_CallMethod(threading, "_shutdown", "");
	if (result == NULL)
		PyErr_WriteUnraisable(threading);
	else
		Py_DECREF(result);
	Py_DECREF(threading);
#endif
}

/* Main program */

int
Py_Main(int argc, char **argv)
{
	int c;
	int sts;
	char *command = NULL;
	char *filename = NULL;
	char *module = NULL;
	FILE *fp = stdin;
	char *p;
	int unbuffered = 0;
	int skipfirstline = 0;
	int stdin_is_interactive = 0;
	int help = 0;
	int version = 0;
	int saw_unbuffered_flag = 0;
	PyCompilerFlags cf;

	cf.cf_flags = 0;

	orig_argc = argc;	/* For Py_GetArgcArgv() */
	orig_argv = argv;

	PySys_ResetWarnOptions();

	while ((c = _PyOS_GetOpt(argc, argv, PROGRAM_OPTS)) != EOF) {
		if (c == 'c') {
			/* -c is the last option; following arguments
			   that look like options are left for the
			   command to interpret. */
			command = (char *)malloc(strlen(_PyOS_optarg) + 2);
			if (command == NULL)
				Py_FatalError(
				   "not enough memory to copy -c argument");
			strcpy(command, _PyOS_optarg);
			strcat(command, "\n");
			break;
		}

		if (c == 'm') {
			/* -m is the last option; following arguments
			   that look like options are left for the
			   module to interpret. */
			module = (char *)malloc(strlen(_PyOS_optarg) + 2);
			if (module == NULL)
				Py_FatalError(
				   "not enough memory to copy -m argument");
			strcpy(module, _PyOS_optarg);
			break;
		}

		switch (c) {
		case 'b':
			Py_BytesWarningFlag++;
			break;

		case 'd':
			Py_DebugFlag++;
			break;

		case 'i':
			Py_InspectFlag++;
			Py_InteractiveFlag++;
			break;

		case 'O':
			Py_OptimizeFlag++;
			break;

		case 'B':
			Py_DontWriteBytecodeFlag++;
			break;

		case 'S':
			Py_NoSiteFlag++;
			break;

		case 'E':
			Py_IgnoreEnvironmentFlag++;
			break;

		case 't':
			Py_TabcheckFlag++;
			break;

		case 'u':
			unbuffered++;
			saw_unbuffered_flag = 1;
			break;

		case 'v':
			Py_VerboseFlag++;
			break;

		case 'x':
			skipfirstline = 1;
			break;

		case 'h':
		case '?':
			help++;
			break;

		case 'V':
			version++;
			break;

		case 'W':
			PySys_AddWarnOption(_PyOS_optarg);
			break;

		/* This space reserved for other options */

		default:
			return usage(2, argv[0]);
			/*NOTREACHED*/

		}
	}

	if (help)
		return usage(0, argv[0]);

	if (version) {
		fprintf(stderr, "Python %s\n", PY_VERSION);
		return 0;
	}

	if (!Py_InspectFlag &&
	    (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0')
		Py_InspectFlag = 1;
	if (!saw_unbuffered_flag &&
	    (p = Py_GETENV("PYTHONUNBUFFERED")) && *p != '\0')
		unbuffered = 1;

	if (command == NULL && module == NULL && _PyOS_optind < argc &&
	    strcmp(argv[_PyOS_optind], "-") != 0)
	{
#ifdef __VMS
		filename = decc$translate_vms(argv[_PyOS_optind]);
		if (filename == (char *)0 || filename == (char *)-1)
			filename = argv[_PyOS_optind];

#else
		filename = argv[_PyOS_optind];
#endif
	}

	stdin_is_interactive = Py_FdIsInteractive(stdin, (char *)0);

	if (unbuffered) {
#if defined(MS_WINDOWS) || defined(__CYGWIN__)
		_setmode(fileno(stdin), O_BINARY);
		_setmode(fileno(stdout), O_BINARY);
#endif
#ifdef HAVE_SETVBUF
		setvbuf(stdin,  (char *)NULL, _IONBF, BUFSIZ);
		setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ);
		setvbuf(stderr, (char *)NULL, _IONBF, BUFSIZ);
#else /* !HAVE_SETVBUF */
		setbuf(stdin,  (char *)NULL);
		setbuf(stdout, (char *)NULL);
		setbuf(stderr, (char *)NULL);
#endif /* !HAVE_SETVBUF */
	}
	else if (Py_InteractiveFlag) {
#ifdef MS_WINDOWS
		/* Doesn't have to have line-buffered -- use unbuffered */
		/* Any set[v]buf(stdin, ...) screws up Tkinter :-( */
		setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ);
#else /* !MS_WINDOWS */
#ifdef HAVE_SETVBUF
		setvbuf(stdin,  (char *)NULL, _IOLBF, BUFSIZ);
		setvbuf(stdout, (char *)NULL, _IOLBF, BUFSIZ);
#endif /* HAVE_SETVBUF */
#endif /* !MS_WINDOWS */
		/* Leave stderr alone - it should be unbuffered anyway. */
  	}
#ifdef __VMS
	else {
		setvbuf (stdout, (char *)NULL, _IOLBF, BUFSIZ);
	}
#endif /* __VMS */

#ifdef __APPLE__
	/* On MacOS X, when the Python interpreter is embedded in an
	   application bundle, it gets executed by a bootstrapping script
	   that does os.execve() with an argv[0] that's different from the
	   actual Python executable. This is needed to keep the Finder happy,
	   or rather, to work around Apple's overly strict requirements of
	   the process name. However, we still need a usable sys.executable,
	   so the actual executable path is passed in an environment variable.
	   See Lib/plat-mac/bundlebuiler.py for details about the bootstrap
	   script. */
	if ((p = Py_GETENV("PYTHONEXECUTABLE")) && *p != '\0')
		Py_SetProgramName(p);
	else
		Py_SetProgramName(argv[0]);
#else
	Py_SetProgramName(argv[0]);
#endif
	Py_Initialize();

	if (Py_VerboseFlag ||
	    (command == NULL && filename == NULL && module == NULL && stdin_is_interactive)) {
		fprintf(stderr, "Python %s on %s\n",
			Py_GetVersion(), Py_GetPlatform());
 		if (!Py_NoSiteFlag)
 			fprintf(stderr, "%s\n", COPYRIGHT);
	}

	if (command != NULL) {
		/* Backup _PyOS_optind and force sys.argv[0] = '-c' */
		_PyOS_optind--;
		argv[_PyOS_optind] = "-c";
	}

	if (module != NULL) {
		/* Backup _PyOS_optind and force sys.argv[0] = '-c'
		   so that PySys_SetArgv correctly sets sys.path[0] to ''*/
		_PyOS_optind--;
		argv[_PyOS_optind] = "-c";
	}

	PySys_SetArgv(argc-_PyOS_optind, argv+_PyOS_optind);

	if ((Py_InspectFlag || (command == NULL && filename == NULL && module == NULL)) &&
	    isatty(fileno(stdin))) {
		PyObject *v;
		v = PyImport_ImportModule("readline");
		if (v == NULL)
			PyErr_Clear();
		else
			Py_DECREF(v);
	}

	if (command) {
		sts = PyRun_SimpleStringFlags(command, &cf) != 0;
		free(command);
	} else if (module) {
		sts = RunModule(module, 1);
		free(module);
	}
	else {

		if (filename == NULL && stdin_is_interactive) {
			Py_InspectFlag = 0; /* do exit on SystemExit */
			RunStartupFile(&cf);
		}
		/* XXX */

		sts = -1;	/* keep track of whether we've already run __main__ */

		if (filename != NULL) {
			sts = RunMainFromImporter(filename);
		}

		if (sts==-1 && filename!=NULL) {
			if ((fp = fopen(filename, "r")) == NULL) {
#ifdef HAVE_STRERROR
				fprintf(stderr, "%s: can't open file '%s': [Errno %d] %s\n",
					argv[0], filename, errno, strerror(errno));
#else
				fprintf(stderr, "%s: can't open file '%s': Errno %d\n",
					argv[0], filename, errno);
#endif
				return 2;
			}
			else if (skipfirstline) {
				int ch;
				/* Push back first newline so line numbers
				   remain the same */
				while ((ch = getc(fp)) != EOF) {
					if (ch == '\n') {
						(void)ungetc(ch, fp);
						break;
					}
				}
			}
			{
				/* XXX: does this work on Win/Win64? (see posix_fstat) */
				struct stat sb;
				if (fstat(fileno(fp), &sb) == 0 &&
				    S_ISDIR(sb.st_mode)) {
					fprintf(stderr, "%s: '%s' is a directory, cannot continue\n", argv[0], filename);
					return 1;
				}
			}
		}

		if (sts==-1) {
			sts = PyRun_AnyFileExFlags(
				fp,
				filename == NULL ? "<stdin>" : filename,
				filename != NULL, &cf) != 0;
		}

	}

	/* Check this environment variable at the end, to give programs the
	 * opportunity to set it from Python.
	 */
	if (!Py_InspectFlag &&
	    (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0')
	{
		Py_InspectFlag = 1;
	}

	if (Py_InspectFlag && stdin_is_interactive &&
	    (filename != NULL || command != NULL || module != NULL)) {
		Py_InspectFlag = 0;
		/* XXX */
		sts = PyRun_AnyFileFlags(stdin, "<stdin>", &cf) != 0;
	}

	WaitForThreadShutdown();

	Py_Finalize();

#ifdef __INSURE__
	/* Insure++ is a memory analysis tool that aids in discovering
	 * memory leaks and other memory problems.  On Python exit, the
	 * interned string dictionaries are flagged as being in use at exit
	 * (which it is).  Under normal circumstances, this is fine because
	 * the memory will be automatically reclaimed by the system.  Under
	 * memory debugging, it's a huge source of useless noise, so we
	 * trade off slower shutdown for less distraction in the memory
	 * reports.  -baw
	 */
	_Py_ReleaseInternedStrings();
	_Py_ReleaseInternedUnicodeStrings();
#endif /* __INSURE__ */

	return sts;
}

/* this is gonna seem *real weird*, but if you put some other code between
   Py_Main() and Py_GetArgcArgv() you will need to adjust the test in the
   while statement in Misc/gdbinit:ppystack */

/* Make the *original* argc/argv available to other modules.
   This is rare, but it is needed by the secureware extension. */

void
Py_GetArgcArgv(int *argc, char ***argv)
{
	*argc = orig_argc;
	*argv = orig_argv;
}

#ifdef __cplusplus
}
#endif