Mercurial > cpython-lru_cache-weakref

view Python/getopt.c @ 23295:6fa76b4e59fe legacy-trunk

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Repair widespread misuse of _PyString_Resize. Since it's clear people don't understand how this function works, also beefed up the docs. The most common usage error is of this form (often spread out across gotos): if (_PyString_Resize(&s, n) < 0) { Py_DECREF(s); s = NULL; goto outtahere; } The error is that if _PyString_Resize runs out of memory, it automatically decrefs the input string object s (which also deallocates it, since its refcount must be 1 upon entry), and sets s to NULL. So if the "if" branch ever triggers, it's an error to call Py_DECREF(s): s is already NULL! A correct way to write the above is the simpler (and intended) if (_PyString_Resize(&s, n) < 0) goto outtahere; Bugfix candidate.
author Tim Peters <tim.peters@gmail.com>
date Sat, 27 Apr 2002 18:44:32 +0000
parents a826a46bae54
children 2f3f2e32dfd9
line wrap: on
line source

/*---------------------------------------------------------------------------*
 * <RCS keywords>
 *
 * C++ Library
 *
 * Copyright 1992-1994, David Gottner
 *
 *                    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, this permission notice and
 * the following disclaimer notice appear unmodified in all copies.
 *
 * I DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL I
 * 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.
 *
 * Nevertheless, I would like to know about bugs in this library or
 * suggestions for improvment.  Send bug reports and feedback to
 * davegottner@delphi.com.
 *---------------------------------------------------------------------------*/

#include <stdio.h>
#include <string.h>

int _PyOS_opterr = 1;          /* generate error messages */
int _PyOS_optind = 1;          /* index into argv array   */
char *_PyOS_optarg = NULL;     /* optional argument       */

int _PyOS_GetOpt(int argc, char **argv, char *optstring)
{
	static char *opt_ptr = "";
	char *ptr;
	int option;

	if (*opt_ptr == '\0') {

		if (_PyOS_optind >= argc || argv[_PyOS_optind][0] != '-' ||
		    argv[_PyOS_optind][1] == '\0' /* lone dash */ )
			return -1;

		else if (strcmp(argv[_PyOS_optind], "--") == 0) {
			++_PyOS_optind;
			return -1;
		}

		opt_ptr = &argv[_PyOS_optind++][1]; 
	}

	if ( (option = *opt_ptr++) == '\0')
		return -1;
	
	if ((ptr = strchr(optstring, option)) == NULL) {
		if (_PyOS_opterr)
			fprintf(stderr, "Unknown option: -%c\n", option);

		return '?';
	}

	if (*(ptr + 1) == ':') {
		if (*opt_ptr != '\0') {
			_PyOS_optarg  = opt_ptr;
			opt_ptr = "";
		}

		else {
			if (_PyOS_optind >= argc) {
				if (_PyOS_opterr)
					fprintf(stderr,
			    "Argument expected for the -%c option\n", option);
				return '?';
			}

			_PyOS_optarg = argv[_PyOS_optind++];
		}
	}

	return option;
}