mystring.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * String functions.
 *
 *	equal(s1, s2)		Return true if strings are equal.
 *	number(s)		Convert a string of digits to an integer.
 *	is_number(s)		Return true if s is a string of digits.
 */

#include <stdlib.h>
#include "shell.h"
#include "syntax.h"
#include "error.h"
#include "mystring.h"


char nullstr[1];		/* zero length string */

/*
 * equal - #defined in mystring.h
 */


/*
 * Convert a string of digits to an integer, printing an error message on
 * failure.
 */

int
number(const char *s)
{
	if (! is_number(s))
		error("Illegal number: %s", s);
	return atoi(s);
}



/*
 * Check for a valid number.  This should be elsewhere.
 */

int
is_number(const char *p)
{
	const char *q;

	if (*p == '\0')
		return 0;
	while (*p == '0')
		p++;
	for (q = p; *q != '\0'; q++)
		if (! is_digit(*q))
			return 0;
	if (q - p > 10 ||
	    (q - p == 10 && memcmp(p, "2147483647", 10) > 0))
		return 0;
	return 1;
}