cpython/Modules/main.c

/* Python interpreter main program */

#include "Python.h"
#include "osdefs.h"
#include "compile.h" /* For CO_FUTURE_DIVISION */
#include "import.h"

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

#if defined(MS_WINDOWS) || defined(__CYGWIN__)
#include <fcntl.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."

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

/* command line options */
#define BASE_OPTS "c:dEhim:OQ:StuUvVW:xX"

#ifndef RISCOS
#define PROGRAM_OPTS BASE_OPTS
#else /*RISCOS*/
/* extra option saying that we are running under a special task window
   frontend; especially my_readline will behave different */
#define PROGRAM_OPTS BASE_OPTS "w"
/* corresponding flag */
extern int Py_RISCOSWimpFlag;
#endif /*RISCOS*/

/* 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\
-c cmd : program passed in as string (terminates option list)\n\
-d     : debug output from parser (also PYTHONDEBUG=x)\n\
-E     : ignore environment variables (such as PYTHONPATH)\n\
-h     : print this help message and exit\n\
-i     : inspect interactively after running script, (also PYTHONINSPECT=x)\n\
         and force prompts, even if stdin does not appear to be a terminal\n\
";
static char *usage_2 = "\
-m mod : run library module as a script (terminates option list)\n\
-O     : optimize generated bytecode (a tad; also PYTHONOPTIMIZE=x)\n\
-OO    : remove doc-strings in addition to the -O optimizations\n\
-Q arg : division options: -Qold (default), -Qwarn, -Qwarnall, -Qnew\n\
-S     : don't imply 'import site' on initialization\n\
-t     : issue warnings about inconsistent tab usage (-tt: issue errors)\n\
-u     : unbuffered binary stdout and stderr (also PYTHONUNBUFFERED=x)\n\
";
static char *usage_3 = "\
         see man page for details on internal buffering relating to '-u'\n\
-v     : verbose (trace import statements) (also PYTHONVERBOSE=x)\n\
-V     : print the Python version number and exit\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\
file   : program read from script file\n\
-      : program read from stdin (default; interactive mode if a tty)\n\
";
static char *usage_4 = "\
arg ...: arguments passed to program in sys.argv[1:]\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\
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, 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);
		}
	}
}

/* Get the path to a top-level module */
static struct filedescr * FindModule(const char *module,
				     FILE **fp, char **filename)
{
	struct filedescr *fdescr = NULL;
	*fp = NULL;
	*filename = malloc(MAXPATHLEN);

	if (*filename == NULL)
		return NULL;

	/* Find the actual module source code */
	fdescr = _PyImport_FindModule(module, NULL,
					*filename, MAXPATHLEN, fp, NULL);

	if (fdescr == NULL) {
		free(*filename);
		*filename = NULL;
	}

	return fdescr;
}

/* 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 inspect = 0;
	int unbuffered = 0;
	int skipfirstline = 0;
	int stdin_is_interactive = 0;
	int help = 0;
	int version = 0;
	int saw_inspect_flag = 0;
	int saw_unbuffered_flag = 0;
	PyCompilerFlags cf;

	cf.cf_flags = 0;

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

#ifdef RISCOS
	Py_RISCOSWimpFlag = 0;
#endif

	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 = 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 = 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 'd':
			Py_DebugFlag++;
			break;

		case 'Q':
			if (strcmp(_PyOS_optarg, "old") == 0) {
				Py_DivisionWarningFlag = 0;
				break;
			}
			if (strcmp(_PyOS_optarg, "warn") == 0) {
				Py_DivisionWarningFlag = 1;
				break;
			}
			if (strcmp(_PyOS_optarg, "warnall") == 0) {
				Py_DivisionWarningFlag = 2;
				break;
			}
			if (strcmp(_PyOS_optarg, "new") == 0) {
				/* This only affects __main__ */
				cf.cf_flags |= CO_FUTURE_DIVISION;
				/* And this tells the eval loop to treat
				   BINARY_DIVIDE as BINARY_TRUE_DIVIDE */
				_Py_QnewFlag = 1;
				break;
			}
			fprintf(stderr,
				"-Q option should be `-Qold', "
				"`-Qwarn', `-Qwarnall', or `-Qnew' only\n");
			return usage(2, argv[0]);
			/* NOTREACHED */

		case 'i':
			inspect++;
			saw_inspect_flag = 1;
			Py_InteractiveFlag++;
			break;

		case 'O':
			Py_OptimizeFlag++;
			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;

#ifdef RISCOS
		case 'w':
			Py_RISCOSWimpFlag = 1;
			break;
#endif

		case 'x':
			skipfirstline = 1;
			break;

		case 'U':
			Py_UnicodeFlag++;
			break;
		case 'h':
			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 (!saw_inspect_flag &&
	    (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0')
		inspect = 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
		if (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;
					}
				}
			}
		}
	}

	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 find the real file */
                struct filedescr *fdescr = NULL;
		_PyOS_optind--;
		if ((fdescr = FindModule(module, &fp, &filename))) {
			argv[_PyOS_optind] = filename;
		} else {
			fprintf(stderr, "%s: module %s not found\n",
				argv[0], module);
			return 2;
		}
		if (!fp) {
			fprintf(stderr,
				"%s: module %s has no associated file\n",
				argv[0], module);
			return 2;
		}
		if (!_PyImport_IsScript(fdescr)) {
			fprintf(stderr,
				"%s: module %s not usable as script\n  (%s)\n",
				argv[0], module, filename);
			return 2;
		}
	}

	PySys_SetArgv(argc-_PyOS_optind, argv+_PyOS_optind);

	if ((inspect || (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 = PyRun_AnyFileExFlags(fp, filename, 1, &cf) != 0;
		free(module);
		free(filename);
	}
	else {
		if (filename == NULL && stdin_is_interactive) {
			RunStartupFile(&cf);
		}
		/* XXX */
		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 (!saw_inspect_flag &&
	    (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0')
	{
		inspect = 1;
	}

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

	Py_Finalize();
#ifdef RISCOS
	if (Py_RISCOSWimpFlag)
                fprintf(stderr, "\x0cq\x0c"); /* make frontend quit */
#endif

#ifdef __INSURE__
	/* Insure++ is a memory analysis tool that aids in discovering
	 * memory leaks and other memory problems.  On Python exit, the
	 * interned string dictionary is 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();
#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;
}