/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2007 Eric Anderson <anderson@FreeBSD.org>
 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
 * Copyright (c) 2025 Dag-Erling Smørgrav <des@FreeBSD.org>
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
 */

#include <sys/types.h>

#include <ctype.h>
#include <errno.h>
#include <inttypes.h>
#include <libutil.h>
#include <stdbool.h>
#include <stdint.h>

static int
expand_impl(const char *buf, uint64_t *num, bool *neg)
{
        char *endptr;
        uintmax_t number;
        unsigned int shift;
        int serrno;

        /*
         * Skip whitespace and optional sign.
         */
        while (isspace((unsigned char)*buf))
                buf++;
        if (*buf == '-') {
                *neg = true;
                buf++;
        } else {
                *neg = false;
                if (*buf == '+')
                        buf++;
        }

        /*
         * The next character should be the first digit of the number.  If
         * we don't enforce this ourselves, strtoumax() will allow further
         * whitespace and a (second?) sign.
         */
        if (!isdigit((unsigned char)*buf)) {
                errno = EINVAL;
                return (-1);
        }

        serrno = errno;
        errno = 0;
        number = strtoumax(buf, &endptr, 0);
        if (errno != 0)
                return (-1);
        errno = serrno;

        switch (tolower((unsigned char)*endptr)) {
        case 'e':
                shift = 60;
                endptr++;
                break;
        case 'p':
                shift = 50;
                endptr++;
                break;
        case 't':
                shift = 40;
                endptr++;
                break;
        case 'g':
                shift = 30;
                endptr++;
                break;
        case 'm':
                shift = 20;
                endptr++;
                break;
        case 'k':
                shift = 10;
                endptr++;
                break;
        default:
                shift = 0;
        }

        /*
         * Treat 'b' as an ignored suffix for all unit except 'b',
         * otherwise there should be no remaining character(s).
         */
        if (tolower((unsigned char)*endptr) == 'b')
                endptr++;
        if (*endptr != '\0') {
                errno = EINVAL;
                return (-1);
        }

        /*
         * Apply the shift and check for overflow.
         */
        if ((number << shift) >> shift != number) {
                /* Overflow */
                errno = ERANGE;
                return (-1);
        }
        number <<= shift;

        *num = number;
        return (0);
}

int
(expand_number)(const char *buf, int64_t *num)
{
        uint64_t number;
        bool neg;

        /*
         * Parse the number.
         */
        if (expand_impl(buf, &number, &neg) != 0)
                return (-1);

        /*
         * Apply the sign and check for overflow.
         */
        if (neg) {
                if (number > 0x8000000000000000LLU /* -INT64_MIN */) {
                        errno = ERANGE;
                        return (-1);
                }
                *num = -number;
        } else {
                if (number > INT64_MAX) {
                        errno = ERANGE;
                        return (-1);
                }
                *num = number;
        }

        return (0);
}

int
expand_unsigned(const char *buf, uint64_t *num)
{
        uint64_t number;
        bool neg;

        /*
         * Parse the number.
         */
        if (expand_impl(buf, &number, &neg) != 0)
                return (-1);

        /*
         * Negative numbers are out of range.
         */
        if (neg && number > 0) {
                errno = ERANGE;
                return (-1);
        }

        *num = number;
        return (0);
}