xref: /openssl/crypto/o_time.c (revision 8020d79b)
1 /*
2  * Copyright 2001-2021 The OpenSSL Project Authors. All Rights Reserved.
3  *
4  * Licensed under the Apache License 2.0 (the "License").  You may not use
5  * this file except in compliance with the License.  You can obtain a copy
6  * in the file LICENSE in the source distribution or at
7  * https://www.openssl.org/source/license.html
8  */
9 
10 #include <openssl/e_os2.h>
11 #include <string.h>
12 #include <openssl/crypto.h>
13 
OPENSSL_gmtime(const time_t * timer,struct tm * result)14 struct tm *OPENSSL_gmtime(const time_t *timer, struct tm *result)
15 {
16     struct tm *ts = NULL;
17 
18 #if defined(OPENSSL_THREADS) && defined(OPENSSL_SYS_VMS)
19     {
20         /*
21          * On VMS, gmtime_r() takes a 32-bit pointer as second argument.
22          * Since we can't know that |result| is in a space that can easily
23          * translate to a 32-bit pointer, we must store temporarily on stack
24          * and copy the result.  The stack is always reachable with 32-bit
25          * pointers.
26          */
27 #if defined(OPENSSL_SYS_VMS) && __INITIAL_POINTER_SIZE
28 # pragma pointer_size save
29 # pragma pointer_size 32
30 #endif
31         struct tm data, *ts2 = &data;
32 #if defined OPENSSL_SYS_VMS && __INITIAL_POINTER_SIZE
33 # pragma pointer_size restore
34 #endif
35         if (gmtime_r(timer, ts2) == NULL)
36             return NULL;
37         memcpy(result, ts2, sizeof(struct tm));
38         ts = result;
39     }
40 #elif defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32) && !defined(OPENSSL_SYS_MACOSX)
41     if (gmtime_r(timer, result) == NULL)
42         return NULL;
43     ts = result;
44 #elif defined (OPENSSL_SYS_WINDOWS) && defined(_MSC_VER) && _MSC_VER >= 1400 && !defined(_WIN32_WCE)
45     if (gmtime_s(result, timer))
46         return NULL;
47     ts = result;
48 #else
49     ts = gmtime(timer);
50     if (ts == NULL)
51         return NULL;
52 
53     memcpy(result, ts, sizeof(struct tm));
54     ts = result;
55 #endif
56     return ts;
57 }
58 
59 /*
60  * Take a tm structure and add an offset to it. This avoids any OS issues
61  * with restricted date types and overflows which cause the year 2038
62  * problem.
63  */
64 
65 #define SECS_PER_DAY (24 * 60 * 60)
66 
67 static long date_to_julian(int y, int m, int d);
68 static void julian_to_date(long jd, int *y, int *m, int *d);
69 static int julian_adj(const struct tm *tm, int off_day, long offset_sec,
70                       long *pday, int *psec);
71 
OPENSSL_gmtime_adj(struct tm * tm,int off_day,long offset_sec)72 int OPENSSL_gmtime_adj(struct tm *tm, int off_day, long offset_sec)
73 {
74     int time_sec, time_year, time_month, time_day;
75     long time_jd;
76 
77     /* Convert time and offset into Julian day and seconds */
78     if (!julian_adj(tm, off_day, offset_sec, &time_jd, &time_sec))
79         return 0;
80 
81     /* Convert Julian day back to date */
82 
83     julian_to_date(time_jd, &time_year, &time_month, &time_day);
84 
85     if (time_year < 1900 || time_year > 9999)
86         return 0;
87 
88     /* Update tm structure */
89 
90     tm->tm_year = time_year - 1900;
91     tm->tm_mon = time_month - 1;
92     tm->tm_mday = time_day;
93 
94     tm->tm_hour = time_sec / 3600;
95     tm->tm_min = (time_sec / 60) % 60;
96     tm->tm_sec = time_sec % 60;
97 
98     return 1;
99 
100 }
101 
OPENSSL_gmtime_diff(int * pday,int * psec,const struct tm * from,const struct tm * to)102 int OPENSSL_gmtime_diff(int *pday, int *psec,
103                         const struct tm *from, const struct tm *to)
104 {
105     int from_sec, to_sec, diff_sec;
106     long from_jd, to_jd, diff_day;
107     if (!julian_adj(from, 0, 0, &from_jd, &from_sec))
108         return 0;
109     if (!julian_adj(to, 0, 0, &to_jd, &to_sec))
110         return 0;
111     diff_day = to_jd - from_jd;
112     diff_sec = to_sec - from_sec;
113     /* Adjust differences so both positive or both negative */
114     if (diff_day > 0 && diff_sec < 0) {
115         diff_day--;
116         diff_sec += SECS_PER_DAY;
117     }
118     if (diff_day < 0 && diff_sec > 0) {
119         diff_day++;
120         diff_sec -= SECS_PER_DAY;
121     }
122 
123     if (pday)
124         *pday = (int)diff_day;
125     if (psec)
126         *psec = diff_sec;
127 
128     return 1;
129 
130 }
131 
132 /* Convert tm structure and offset into julian day and seconds */
julian_adj(const struct tm * tm,int off_day,long offset_sec,long * pday,int * psec)133 static int julian_adj(const struct tm *tm, int off_day, long offset_sec,
134                       long *pday, int *psec)
135 {
136     int offset_hms;
137     long offset_day, time_jd;
138     int time_year, time_month, time_day;
139     /* split offset into days and day seconds */
140     offset_day = offset_sec / SECS_PER_DAY;
141     /* Avoid sign issues with % operator */
142     offset_hms = offset_sec - (offset_day * SECS_PER_DAY);
143     offset_day += off_day;
144     /* Add current time seconds to offset */
145     offset_hms += tm->tm_hour * 3600 + tm->tm_min * 60 + tm->tm_sec;
146     /* Adjust day seconds if overflow */
147     if (offset_hms >= SECS_PER_DAY) {
148         offset_day++;
149         offset_hms -= SECS_PER_DAY;
150     } else if (offset_hms < 0) {
151         offset_day--;
152         offset_hms += SECS_PER_DAY;
153     }
154 
155     /*
156      * Convert date of time structure into a Julian day number.
157      */
158 
159     time_year = tm->tm_year + 1900;
160     time_month = tm->tm_mon + 1;
161     time_day = tm->tm_mday;
162 
163     time_jd = date_to_julian(time_year, time_month, time_day);
164 
165     /* Work out Julian day of new date */
166     time_jd += offset_day;
167 
168     if (time_jd < 0)
169         return 0;
170 
171     *pday = time_jd;
172     *psec = offset_hms;
173     return 1;
174 }
175 
176 /*
177  * Convert date to and from julian day Uses Fliegel & Van Flandern algorithm
178  */
date_to_julian(int y,int m,int d)179 static long date_to_julian(int y, int m, int d)
180 {
181     return (1461 * (y + 4800 + (m - 14) / 12)) / 4 +
182         (367 * (m - 2 - 12 * ((m - 14) / 12))) / 12 -
183         (3 * ((y + 4900 + (m - 14) / 12) / 100)) / 4 + d - 32075;
184 }
185 
julian_to_date(long jd,int * y,int * m,int * d)186 static void julian_to_date(long jd, int *y, int *m, int *d)
187 {
188     long L = jd + 68569;
189     long n = (4 * L) / 146097;
190     long i, j;
191 
192     L = L - (146097 * n + 3) / 4;
193     i = (4000 * (L + 1)) / 1461001;
194     L = L - (1461 * i) / 4 + 31;
195     j = (80 * L) / 2447;
196     *d = L - (2447 * j) / 80;
197     L = j / 11;
198     *m = j + 2 - (12 * L);
199     *y = 100 * (n - 49) + i + L;
200 }
201