sudo/lib/util/strtonum.c

/*
 * Copyright (c) 2013-2014 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, 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.
 */

#include <config.h>

#include <sys/types.h>

#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STRING_H
# include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */

#define DEFAULT_TEXT_DOMAIN	"sudo"
#include "sudo_gettext.h"	/* must be included before sudo_compat.h */

#include "sudo_compat.h"

#ifdef HAVE_STRTONUM

/*
 * The OpenBSD strtonum error string too short to be translated sensibly.
 * This wrapper just changes errstr as follows:
 *  invalid -> invalid value
 *  too large -> value too large
 *  too small -> value too small
 */
long long
sudo_strtonum(const char *str, long long minval, long long maxval,
    const char **errstrp)
{
    long long retval;
    const char *errstr;

# undef strtonum
    retval = strtonum(str, minval, maxval, &errstr);
    if (errstr != NULL) {
	if (errno == EINVAL) {
	    errstr = N_("invalid value");
	} else if (errno == ERANGE) {
	    errstr = strcmp(errstr, "too large") == 0 ?
		N_("value too large") : N_("value too small");
	}
    }
    if (errstrp != NULL)
	*errstrp = errstr;
    return retval;
}

#else

enum strtonum_err {
    STN_VALID,
    STN_INVALID,
    STN_TOOSMALL,
    STN_TOOBIG
};

/*
 * Convert a string to a number in the range [minval, maxval]
 */
long long
sudo_strtonum(const char *str, long long minval, long long maxval,
    const char **errstrp)
{
    const unsigned char *ustr = (const unsigned char *)str;
    enum strtonum_err errval = STN_VALID;
    long long lastval, result = 0;
    unsigned char dig, sign;
    int remainder;

    if (minval > maxval) {
	errval = STN_INVALID;
	goto done;
    }

    /* Trim leading space and check sign, if any. */
    while (isspace(*ustr)) {
	ustr++;
    }
    switch (*ustr) {
    case '-':
	sign = '-';
	ustr++;
	break;
    case '+':
	ustr++;
	/* FALLTHROUGH */
    default:
	sign = '+';
	break;
    }

    /*
     * To prevent overflow we determine the highest (or lowest in
     * the case of negative numbers) value result can have *before*
     * if its multiplied (divided) by 10 as well as the remainder.
     * If result matches this value and the next digit is larger than
     * the remainder, we know the result is out of range.
     * The remainder is always positive since it is compared against
     * an unsigned digit.
     */
    if (sign == '-') {
	lastval = minval / 10;
	remainder = -(minval % 10);
	if (remainder < 0) {
	    lastval += 1;
	    remainder += 10;
	}
	while ((dig = *ustr++) != '\0') {
	    if (!isdigit(dig)) {
		errval = STN_INVALID;
		break;
	    }
	    dig -= '0';
	    if (result < lastval || (result == lastval && dig > remainder)) {
		errval = STN_TOOSMALL;
		break;
	    } else {
		result *= 10;
		result -= dig;
	    }
	}
	if (result > maxval)
	    errval = STN_TOOBIG;
    } else {
	lastval = maxval / 10;
	remainder = maxval % 10;
	while ((dig = *ustr++) != '\0') {
	    if (!isdigit(dig)) {
		errval = STN_INVALID;
		break;
	    }
	    dig -= '0';
	    if (result > lastval || (result == lastval && dig > remainder)) {
		errval = STN_TOOBIG;
		break;
	    } else {
		result *= 10;
		result += dig;
	    }
	}
	if (result < minval)
	    errval = STN_TOOSMALL;
    }

done:
    switch (errval) {
    case STN_VALID:
	if (errstrp != NULL)
	    *errstrp = NULL;
	break;
    case STN_INVALID:
	result = 0;
	errno = EINVAL;
	if (errstrp != NULL)
	    *errstrp = N_("invalid value");
	break;
    case STN_TOOSMALL:
	result = 0;
	errno = ERANGE;
	if (errstrp != NULL)
	    *errstrp = N_("value too small");
	break;
    case STN_TOOBIG:
	result = 0;
	errno = ERANGE;
	if (errstrp != NULL)
	    *errstrp = N_("value too large");
	break;
    }
    return result;
}
#endif /* HAVE_STRTONUM */