time/time.h

   1 /* Copyright (C) 1991-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 /*
  19  *      ISO C99 Standard: 7.23 Date and time    <time.h>
  20  */
  21
  22 #ifndef _TIME_H
  23 #define _TIME_H 1
  24
  25 #include <features.h>
  26
  27 #define __need_size_t
  28 #define __need_NULL
  29 #include <stddef.h>
  30
  31 /* This defines CLOCKS_PER_SEC, which is the number of processor clock
  32    ticks per second, and possibly a number of other constants.   */
  33 #include <bits/time.h>
  34
  35 /* Many of the typedefs and structs whose official home is this header
  36    may also need to be defined by other headers.  */
  37 #include <bits/types/clock_t.h>
  38 #include <bits/types/time_t.h>
  39 #include <bits/types/struct_tm.h>
  40
  41 #if defined __USE_POSIX199309 || defined __USE_ISOC11
  42 # include <bits/types/struct_timespec.h>
  43 #endif
  44
  45 #ifdef __USE_POSIX199309
  46 # include <bits/types/clockid_t.h>
  47 # include <bits/types/timer_t.h>
  48 # include <bits/types/struct_itimerspec.h>
  49 struct sigevent;
  50 #endif
  51
  52 #ifdef __USE_XOPEN2K
  53 # ifndef __pid_t_defined
  54 typedef __pid_t pid_t;
  55 #  define __pid_t_defined
  56 # endif
  57 #endif
  58
  59 #ifdef __USE_XOPEN2K8
  60 # include <bits/types/locale_t.h>
  61 #endif
  62
  63 #ifdef __USE_ISOC11
  64 /* Time base values for timespec_get.  */
  65 # define TIME_UTC 1
  66 #endif
  67
  68 __BEGIN_DECLS
  69
  70 /* Time used by the program so far (user time + system time).
  71    The result / CLOCKS_PER_SEC is program time in seconds.  */
  72 extern clock_t clock (void) __THROW;
  73
  74 /* Return the current time and put it in *TIMER if TIMER is not NULL.  */
  75 extern time_t time (time_t *__timer) __THROW;
  76
  77 /* Return the difference between TIME1 and TIME0.  */
  78 extern double difftime (time_t __time1, time_t __time0)
  79      __THROW __attribute__ ((__const__));
  80
  81 /* Return the `time_t' representation of TP and normalize TP.  */
  82 extern time_t mktime (struct tm *__tp) __THROW;
  83
  84
  85 /* Format TP into S according to FORMAT.
  86    Write no more than MAXSIZE characters and return the number
  87    of characters written, or 0 if it would exceed MAXSIZE.  */
  88 extern size_t strftime (char *__restrict __s, size_t __maxsize,
  89                         const char *__restrict __format,
  90                         const struct tm *__restrict __tp) __THROW;
  91
  92 #ifdef __USE_XOPEN
  93 /* Parse S according to FORMAT and store binary time information in TP.
  94    The return value is a pointer to the first unparsed character in S.  */
  95 extern char *strptime (const char *__restrict __s,
  96                        const char *__restrict __fmt, struct tm *__tp)
  97      __THROW;
  98 #endif
  99
 100 #ifdef __USE_XOPEN2K8
 101 /* Similar to the two functions above but take the information from
 102    the provided locale and not the global locale.  */
 103
 104 extern size_t strftime_l (char *__restrict __s, size_t __maxsize,
 105                           const char *__restrict __format,
 106                           const struct tm *__restrict __tp,
 107                           locale_t __loc) __THROW;
 108 #endif
 109
 110 #ifdef __USE_GNU
 111 extern char *strptime_l (const char *__restrict __s,
 112                          const char *__restrict __fmt, struct tm *__tp,
 113                          locale_t __loc) __THROW;
 114 #endif
 115
 116
 117 /* Return the `struct tm' representation of *TIMER
 118    in Universal Coordinated Time (aka Greenwich Mean Time).  */
 119 extern struct tm *gmtime (const time_t *__timer) __THROW;
 120
 121 /* Return the `struct tm' representation
 122    of *TIMER in the local timezone.  */
 123 extern struct tm *localtime (const time_t *__timer) __THROW;
 124
 125 #if defined __USE_POSIX || __GLIBC_USE (ISOC2X)
 126 /* Return the `struct tm' representation of *TIMER in UTC,
 127    using *TP to store the result.  */
 128 extern struct tm *gmtime_r (const time_t *__restrict __timer,
 129                             struct tm *__restrict __tp) __THROW;
 130
 131 /* Return the `struct tm' representation of *TIMER in local time,
 132    using *TP to store the result.  */
 133 extern struct tm *localtime_r (const time_t *__restrict __timer,
 134                                struct tm *__restrict __tp) __THROW;
 135 #endif  /* POSIX || C2X */
 136
 137 /* Return a string of the form "Day Mon dd hh:mm:ss yyyy\n"
 138    that is the representation of TP in this format.  */
 139 extern char *asctime (const struct tm *__tp) __THROW;
 140
 141 /* Equivalent to `asctime (localtime (timer))'.  */
 142 extern char *ctime (const time_t *__timer) __THROW;
 143
 144 #if defined __USE_POSIX || __GLIBC_USE (ISOC2X)
 145 /* Reentrant versions of the above functions.  */
 146
 147 /* Return in BUF a string of the form "Day Mon dd hh:mm:ss yyyy\n"
 148    that is the representation of TP in this format.  */
 149 extern char *asctime_r (const struct tm *__restrict __tp,
 150                         char *__restrict __buf) __THROW;
 151
 152 /* Equivalent to `asctime_r (localtime_r (timer, *TMP*), buf)'.  */
 153 extern char *ctime_r (const time_t *__restrict __timer,
 154                       char *__restrict __buf) __THROW;
 155 #endif  /* POSIX || C2X */
 156
 157
 158 /* Defined in localtime.c.  */
 159 extern char *__tzname[2];       /* Current timezone names.  */
 160 extern int __daylight;          /* If daylight-saving time is ever in use.  */
 161 extern long int __timezone;     /* Seconds west of UTC.  */
 162
 163
 164 #ifdef  __USE_POSIX
 165 /* Same as above.  */
 166 extern char *tzname[2];
 167
 168 /* Set time conversion information from the TZ environment variable.
 169    If TZ is not defined, a locale-dependent default is used.  */
 170 extern void tzset (void) __THROW;
 171 #endif
 172
 173 #if defined __USE_MISC || defined __USE_XOPEN
 174 extern int daylight;
 175 extern long int timezone;
 176 #endif
 177
 178
 179 /* Nonzero if YEAR is a leap year (every 4 years,
 180    except every 100th isn't, and every 400th is).  */
 181 #define __isleap(year)  \
 182   ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
 183
 184
 185 #ifdef __USE_MISC
 186 /* Miscellaneous functions many Unices inherited from the public domain
 187    localtime package.  These are included only for compatibility.  */
 188
 189 /* Like `mktime', but for TP represents Universal Time, not local time.  */
 190 extern time_t timegm (struct tm *__tp) __THROW;
 191
 192 /* Another name for `mktime'.  */
 193 extern time_t timelocal (struct tm *__tp) __THROW;
 194
 195 /* Return the number of days in YEAR.  */
 196 extern int dysize (int __year) __THROW  __attribute__ ((__const__));
 197 #endif
 198
 199
 200 #ifdef __USE_POSIX199309
 201 /* Pause execution for a number of nanoseconds.
 202
 203    This function is a cancellation point and therefore not marked with
 204    __THROW.  */
 205 extern int nanosleep (const struct timespec *__requested_time,
 206                       struct timespec *__remaining);
 207
 208
 209 /* Get resolution of clock CLOCK_ID.  */
 210 extern int clock_getres (clockid_t __clock_id, struct timespec *__res) __THROW;
 211
 212 /* Get current value of clock CLOCK_ID and store it in TP.  */
 213 extern int clock_gettime (clockid_t __clock_id, struct timespec *__tp) __THROW;
 214
 215 /* Set clock CLOCK_ID to value TP.  */
 216 extern int clock_settime (clockid_t __clock_id, const struct timespec *__tp)
 217      __THROW;
 218
 219 # ifdef __USE_XOPEN2K
 220 /* High-resolution sleep with the specified clock.
 221
 222    This function is a cancellation point and therefore not marked with
 223    __THROW.  */
 224 extern int clock_nanosleep (clockid_t __clock_id, int __flags,
 225                             const struct timespec *__req,
 226                             struct timespec *__rem);
 227
 228 /* Return clock ID for CPU-time clock.  */
 229 extern int clock_getcpuclockid (pid_t __pid, clockid_t *__clock_id) __THROW;
 230 # endif
 231
 232
 233 /* Create new per-process timer using CLOCK_ID.  */
 234 extern int timer_create (clockid_t __clock_id,
 235                          struct sigevent *__restrict __evp,
 236                          timer_t *__restrict __timerid) __THROW;
 237
 238 /* Delete timer TIMERID.  */
 239 extern int timer_delete (timer_t __timerid) __THROW;
 240
 241 /* Set timer TIMERID to VALUE, returning old value in OVALUE.  */
 242 extern int timer_settime (timer_t __timerid, int __flags,
 243                           const struct itimerspec *__restrict __value,
 244                           struct itimerspec *__restrict __ovalue) __THROW;
 245
 246 /* Get current value of timer TIMERID and store it in VALUE.  */
 247 extern int timer_gettime (timer_t __timerid, struct itimerspec *__value)
 248      __THROW;
 249
 250 /* Get expiration overrun for timer TIMERID.  */
 251 extern int timer_getoverrun (timer_t __timerid) __THROW;
 252 #endif
 253
 254
 255 #ifdef __USE_ISOC11
 256 /* Set TS to calendar time based in time base BASE.  */
 257 extern int timespec_get (struct timespec *__ts, int __base)
 258      __THROW __nonnull ((1));
 259 #endif
 260
 261
 262 #ifdef __USE_XOPEN_EXTENDED
 263 /* Set to one of the following values to indicate an error.
 264      1  the DATEMSK environment variable is null or undefined,
 265      2  the template file cannot be opened for reading,
 266      3  failed to get file status information,
 267      4  the template file is not a regular file,
 268      5  an error is encountered while reading the template file,
 269      6  memory allication failed (not enough memory available),
 270      7  there is no line in the template that matches the input,
 271      8  invalid input specification Example: February 31 or a time is
 272         specified that can not be represented in a time_t (representing
 273         the time in seconds since 00:00:00 UTC, January 1, 1970) */
 274 extern int getdate_err;
 275
 276 /* Parse the given string as a date specification and return a value
 277    representing the value.  The templates from the file identified by
 278    the environment variable DATEMSK are used.  In case of an error
 279    `getdate_err' is set.
 280
 281    This function is a possible cancellation point and therefore not
 282    marked with __THROW.  */
 283 extern struct tm *getdate (const char *__string);
 284 #endif
 285
 286 #ifdef __USE_GNU
 287 /* Since `getdate' is not reentrant because of the use of `getdate_err'
 288    and the static buffer to return the result in, we provide a thread-safe
 289    variant.  The functionality is the same.  The result is returned in
 290    the buffer pointed to by RESBUFP and in case of an error the return
 291    value is != 0 with the same values as given above for `getdate_err'.
 292
 293    This function is not part of POSIX and therefore no official
 294    cancellation point.  But due to similarity with an POSIX interface
 295    or due to the implementation it is a cancellation point and
 296    therefore not marked with __THROW.  */
 297 extern int getdate_r (const char *__restrict __string,
 298                       struct tm *__restrict __resbufp);
 299 #endif
 300
 301 __END_DECLS
 302
 303 #endif /* time.h.  */