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diff --git a/lib/isc/tm.c b/lib/isc/tm.c
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+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0 AND BSD-2-Clause
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*-
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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 <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <isc/tm.h>
+#include <isc/util.h>
+
+/*
+ * Portable conversion routines for struct tm, replacing
+ * timegm() and strptime(), which are not available on all
+ * platforms and don't always behave the same way when they
+ * are.
+ */
+
+/*
+ * We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+#define ALT_E 0x01
+#define ALT_O 0x02
+#define LEGAL_ALT(x) \
+ { \
+ if ((alt_format & ~(x)) != 0) \
+ return ((0)); \
+ }
+
+#ifndef TM_YEAR_BASE
+#define TM_YEAR_BASE 1900
+#endif /* ifndef TM_YEAR_BASE */
+
+static const char *day[7] = { "Sunday", "Monday", "Tuesday", "Wednesday",
+ "Thursday", "Friday", "Saturday" };
+static const char *abday[7] = {
+ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+};
+static const char *mon[12] = {
+ "January", "February", "March", "April", "May", "June",
+ "July", "August", "September", "October", "November", "December"
+};
+static const char *abmon[12] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
+static const char *am_pm[2] = { "AM", "PM" };
+
+static int
+conv_num(const char **buf, int *dest, int llim, int ulim) {
+ int result = 0;
+
+ /* The limit also determines the number of valid digits. */
+ int rulim = ulim;
+
+ if (!isdigit((unsigned char)**buf)) {
+ return (0);
+ }
+
+ do {
+ result *= 10;
+ result += *(*buf)++ - '0';
+ rulim /= 10;
+ } while ((result * 10 <= ulim) && rulim && **buf >= '0' &&
+ **buf <= '9');
+
+ if (result < llim || result > ulim) {
+ return (0);
+ }
+
+ *dest = result;
+ return (1);
+}
+
+time_t
+isc_tm_timegm(struct tm *tm) {
+ time_t ret;
+ int i, yday = 0, leapday;
+ int mdays[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30 };
+
+ leapday = ((((tm->tm_year + 1900) % 4) == 0 &&
+ ((tm->tm_year + 1900) % 100) != 0) ||
+ ((tm->tm_year + 1900) % 400) == 0)
+ ? 1
+ : 0;
+ mdays[1] += leapday;
+
+ yday = tm->tm_mday - 1;
+ for (i = 1; i <= tm->tm_mon; i++) {
+ yday += mdays[i - 1];
+ }
+ ret = tm->tm_sec + (60 * tm->tm_min) + (3600 * tm->tm_hour) +
+ (86400 *
+ (yday + ((tm->tm_year - 70) * 365) + ((tm->tm_year - 69) / 4) -
+ ((tm->tm_year - 1) / 100) + ((tm->tm_year + 299) / 400)));
+ return (ret);
+}
+
+char *
+isc_tm_strptime(const char *buf, const char *fmt, struct tm *tm) {
+ char c, *ret;
+ const char *bp;
+ size_t len = 0;
+ int alt_format, i, split_year = 0;
+
+ REQUIRE(buf != NULL);
+ REQUIRE(fmt != NULL);
+ REQUIRE(tm != NULL);
+
+ memset(tm, 0, sizeof(struct tm));
+
+ bp = buf;
+
+ while ((c = *fmt) != '\0') {
+ /* Clear `alternate' modifier prior to new conversion. */
+ alt_format = 0;
+
+ /* Eat up white-space. */
+ if (isspace((unsigned char)c)) {
+ while (isspace((unsigned char)*bp)) {
+ bp++;
+ }
+
+ fmt++;
+ continue;
+ }
+
+ if ((c = *fmt++) != '%') {
+ goto literal;
+ }
+
+ again:
+ switch (c = *fmt++) {
+ case '%': /* "%%" is converted to "%". */
+ literal:
+ if (c != *bp++) {
+ return (0);
+ }
+ break;
+
+ /*
+ * "Alternative" modifiers. Just set the appropriate flag
+ * and start over again.
+ */
+ case 'E': /* "%E?" alternative conversion modifier. */
+ LEGAL_ALT(0);
+ alt_format |= ALT_E;
+ goto again;
+
+ case 'O': /* "%O?" alternative conversion modifier. */
+ LEGAL_ALT(0);
+ alt_format |= ALT_O;
+ goto again;
+
+ /*
+ * "Complex" conversion rules, implemented through recursion.
+ */
+ case 'c': /* Date and time, using the locale's format. */
+ LEGAL_ALT(ALT_E);
+ if (!(bp = isc_tm_strptime(bp, "%x %X", tm))) {
+ return (0);
+ }
+ break;
+
+ case 'D': /* The date as "%m/%d/%y". */
+ LEGAL_ALT(0);
+ if (!(bp = isc_tm_strptime(bp, "%m/%d/%y", tm))) {
+ return (0);
+ }
+ break;
+
+ case 'R': /* The time as "%H:%M". */
+ LEGAL_ALT(0);
+ if (!(bp = isc_tm_strptime(bp, "%H:%M", tm))) {
+ return (0);
+ }
+ break;
+
+ case 'r': /* The time in 12-hour clock representation. */
+ LEGAL_ALT(0);
+ if (!(bp = isc_tm_strptime(bp, "%I:%M:%S %p", tm))) {
+ return (0);
+ }
+ break;
+
+ case 'T': /* The time as "%H:%M:%S". */
+ LEGAL_ALT(0);
+ if (!(bp = isc_tm_strptime(bp, "%H:%M:%S", tm))) {
+ return (0);
+ }
+ break;
+
+ case 'X': /* The time, using the locale's format. */
+ LEGAL_ALT(ALT_E);
+ if (!(bp = isc_tm_strptime(bp, "%H:%M:%S", tm))) {
+ return (0);
+ }
+ break;
+
+ case 'x': /* The date, using the locale's format. */
+ LEGAL_ALT(ALT_E);
+ if (!(bp = isc_tm_strptime(bp, "%m/%d/%y", tm))) {
+ return (0);
+ }
+ break;
+
+ /*
+ * "Elementary" conversion rules.
+ */
+ case 'A': /* The day of week, using the locale's form. */
+ case 'a':
+ LEGAL_ALT(0);
+ for (i = 0; i < 7; i++) {
+ /* Full name. */
+ len = strlen(day[i]);
+ if (strncasecmp(day[i], bp, len) == 0) {
+ break;
+ }
+
+ /* Abbreviated name. */
+ len = strlen(abday[i]);
+ if (strncasecmp(abday[i], bp, len) == 0) {
+ break;
+ }
+ }
+
+ /* Nothing matched. */
+ if (i == 7) {
+ return (0);
+ }
+
+ tm->tm_wday = i;
+ bp += len;
+ break;
+
+ case 'B': /* The month, using the locale's form. */
+ case 'b':
+ case 'h':
+ LEGAL_ALT(0);
+ for (i = 0; i < 12; i++) {
+ /* Full name. */
+ len = strlen(mon[i]);
+ if (strncasecmp(mon[i], bp, len) == 0) {
+ break;
+ }
+
+ /* Abbreviated name. */
+ len = strlen(abmon[i]);
+ if (strncasecmp(abmon[i], bp, len) == 0) {
+ break;
+ }
+ }
+
+ /* Nothing matched. */
+ if (i == 12) {
+ return (0);
+ }
+
+ tm->tm_mon = i;
+ bp += len;
+ break;
+
+ case 'C': /* The century number. */
+ LEGAL_ALT(ALT_E);
+ if (!(conv_num(&bp, &i, 0, 99))) {
+ return (0);
+ }
+
+ if (split_year) {
+ tm->tm_year = (tm->tm_year % 100) + (i * 100);
+ } else {
+ tm->tm_year = i * 100;
+ split_year = 1;
+ }
+ break;
+
+ case 'd': /* The day of month. */
+ case 'e':
+ LEGAL_ALT(ALT_O);
+ if (!(conv_num(&bp, &tm->tm_mday, 1, 31))) {
+ return (0);
+ }
+ break;
+
+ case 'k': /* The hour (24-hour clock representation). */
+ LEGAL_ALT(0);
+ FALLTHROUGH;
+ case 'H':
+ LEGAL_ALT(ALT_O);
+ if (!(conv_num(&bp, &tm->tm_hour, 0, 23))) {
+ return (0);
+ }
+ break;
+
+ case 'l': /* The hour (12-hour clock representation). */
+ LEGAL_ALT(0);
+ FALLTHROUGH;
+ case 'I':
+ LEGAL_ALT(ALT_O);
+ if (!(conv_num(&bp, &tm->tm_hour, 1, 12))) {
+ return (0);
+ }
+ if (tm->tm_hour == 12) {
+ tm->tm_hour = 0;
+ }
+ break;
+
+ case 'j': /* The day of year. */
+ LEGAL_ALT(0);
+ if (!(conv_num(&bp, &i, 1, 366))) {
+ return (0);
+ }
+ tm->tm_yday = i - 1;
+ break;
+
+ case 'M': /* The minute. */
+ LEGAL_ALT(ALT_O);
+ if (!(conv_num(&bp, &tm->tm_min, 0, 59))) {
+ return (0);
+ }
+ break;
+
+ case 'm': /* The month. */
+ LEGAL_ALT(ALT_O);
+ if (!(conv_num(&bp, &i, 1, 12))) {
+ return (0);
+ }
+ tm->tm_mon = i - 1;
+ break;
+
+ case 'p': /* The locale's equivalent of AM/PM. */
+ LEGAL_ALT(0);
+ /* AM? */
+ if (strcasecmp(am_pm[0], bp) == 0) {
+ if (tm->tm_hour > 11) {
+ return (0);
+ }
+
+ bp += strlen(am_pm[0]);
+ break;
+ }
+ /* PM? */
+ else if (strcasecmp(am_pm[1], bp) == 0)
+ {
+ if (tm->tm_hour > 11) {
+ return (0);
+ }
+
+ tm->tm_hour += 12;
+ bp += strlen(am_pm[1]);
+ break;
+ }
+
+ /* Nothing matched. */
+ return (0);
+
+ case 'S': /* The seconds. */
+ LEGAL_ALT(ALT_O);
+ if (!(conv_num(&bp, &tm->tm_sec, 0, 61))) {
+ return (0);
+ }
+ break;
+
+ case 'U': /* The week of year, beginning on sunday. */
+ case 'W': /* The week of year, beginning on monday. */
+ LEGAL_ALT(ALT_O);
+ /*
+ * XXX This is bogus, as we can not assume any valid
+ * information present in the tm structure at this
+ * point to calculate a real value, so just check the
+ * range for now.
+ */
+ if (!(conv_num(&bp, &i, 0, 53))) {
+ return (0);
+ }
+ break;
+
+ case 'w': /* The day of week, beginning on sunday. */
+ LEGAL_ALT(ALT_O);
+ if (!(conv_num(&bp, &tm->tm_wday, 0, 6))) {
+ return (0);
+ }
+ break;
+
+ case 'Y': /* The year. */
+ LEGAL_ALT(ALT_E);
+ if (!(conv_num(&bp, &i, 0, 9999))) {
+ return (0);
+ }
+
+ tm->tm_year = i - TM_YEAR_BASE;
+ break;
+
+ case 'y': /* The year within 100 years of the epoch. */
+ LEGAL_ALT(ALT_E | ALT_O);
+ if (!(conv_num(&bp, &i, 0, 99))) {
+ return (0);
+ }
+
+ if (split_year) {
+ tm->tm_year = ((tm->tm_year / 100) * 100) + i;
+ break;
+ }
+ split_year = 1;
+ if (i <= 68) {
+ tm->tm_year = i + 2000 - TM_YEAR_BASE;
+ } else {
+ tm->tm_year = i + 1900 - TM_YEAR_BASE;
+ }
+ break;
+
+ /*
+ * Miscellaneous conversions.
+ */
+ case 'n': /* Any kind of white-space. */
+ case 't':
+ LEGAL_ALT(0);
+ while (isspace((unsigned char)*bp)) {
+ bp++;
+ }
+ break;
+
+ default: /* Unknown/unsupported conversion. */
+ return (0);
+ }
+ }
+
+ /* LINTED functional specification */
+ DE_CONST(bp, ret);
+ return (ret);
+}
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