The Tor Browser: nsprpub/pr/include/prtime.h@925c144e1f1f (annotated)

nsprpub/pr/include/prtime.h@925c144e1f1f (annotated)

nsprpub/pr/include/prtime.h

Fri, 16 Jan 2015 18:13:44 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Fri, 16 Jan 2015 18:13:44 +0100
branch: TOR_BUG_9701
changeset 14: 925c144e1f1f
permissions: -rw-r--r--

Integrate suggestion from review to improve consistency with existing code.

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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 http://mozilla.org/MPL/2.0/. */
 /*
  *----------------------------------------------------------------------
  *
  * prtime.h --
  *
  *     NSPR date and time functions
  *
  *-----------------------------------------------------------------------
  */
 #ifndef prtime_h___
 #define prtime_h___
 #include "prlong.h"
 PR_BEGIN_EXTERN_C
 /**********************************************************************/
 /************************* TYPES AND CONSTANTS ************************/
 /**********************************************************************/
 #define PR_MSEC_PER_SEC		1000L
 #define PR_USEC_PER_SEC		1000000L
 #define PR_NSEC_PER_SEC		1000000000L
 #define PR_USEC_PER_MSEC	1000L
 #define PR_NSEC_PER_MSEC	1000000L
 /*
  * PRTime --
  *
  *     NSPR represents basic time as 64-bit signed integers relative
  *     to midnight (00:00:00), January 1, 1970 Greenwich Mean Time (GMT).
  *     (GMT is also known as Coordinated Universal Time, UTC.)
  *     The units of time are in microseconds. Negative times are allowed
  *     to represent times prior to the January 1970 epoch. Such values are
  *     intended to be exported to other systems or converted to human
  *     readable form.
  *
  *     Notes on porting: PRTime corresponds to time_t in ANSI C.  NSPR 1.0
  *     simply uses PRInt64.
  */
 typedef PRInt64 PRTime;
 /*
  * Time zone and daylight saving time corrections applied to GMT to
  * obtain the local time of some geographic location
  */
 typedef struct PRTimeParameters {
     PRInt32 tp_gmt_offset;     /* the offset from GMT in seconds */
     PRInt32 tp_dst_offset;     /* contribution of DST in seconds */
 } PRTimeParameters;
 /*
  * PRExplodedTime --
  *
  *     Time broken down into human-readable components such as year, month,
  *     day, hour, minute, second, and microsecond.  Time zone and daylight
  *     saving time corrections may be applied.  If they are applied, the
  *     offsets from the GMT must be saved in the 'tm_params' field so that
  *     all the information is available to reconstruct GMT.
  *
  *     Notes on porting: PRExplodedTime corrresponds to struct tm in
  *     ANSI C, with the following differences:
  *       - an additional field tm_usec;
  *       - replacing tm_isdst by tm_params;
  *       - the month field is spelled tm_month, not tm_mon;
  *       - we use absolute year, AD, not the year since 1900.
  *     The corresponding type in NSPR 1.0 is called PRTime.  Below is
  *     a table of date/time type correspondence in the three APIs:
  *         API          time since epoch          time in components
  *       ANSI C             time_t                  struct tm
  *       NSPR 1.0           PRInt64                   PRTime
  *       NSPR 2.0           PRTime                  PRExplodedTime
  */
 typedef struct PRExplodedTime {
     PRInt32 tm_usec;		    /* microseconds past tm_sec (0-99999)  */
     PRInt32 tm_sec;             /* seconds past tm_min (0-61, accomodating
                                    up to two leap seconds) */
     PRInt32 tm_min;             /* minutes past tm_hour (0-59) */
     PRInt32 tm_hour;            /* hours past tm_day (0-23) */
     PRInt32 tm_mday;            /* days past tm_mon (1-31, note that it
 				                starts from 1) */
     PRInt32 tm_month;           /* months past tm_year (0-11, Jan = 0) */
     PRInt16 tm_year;            /* absolute year, AD (note that we do not
 				                count from 1900) */
     PRInt8 tm_wday;		        /* calculated day of the week
 				                (0-6, Sun = 0) */
     PRInt16 tm_yday;            /* calculated day of the year
 				                (0-365, Jan 1 = 0) */
     PRTimeParameters tm_params;  /* time parameters used by conversion */
 } PRExplodedTime;
 /*
  * PRTimeParamFn --
  *
  *     A function of PRTimeParamFn type returns the time zone and
  *     daylight saving time corrections for some geographic location,
  *     given the current time in GMT.  The input argument gmt should
  *     point to a PRExplodedTime that is in GMT, i.e., whose
  *     tm_params contains all 0's.
  *
  *     For any time zone other than GMT, the computation is intended to
  *     consist of two steps:
  *       - Figure out the time zone correction, tp_gmt_offset.  This number
  *         usually depends on the geographic location only.  But it may
  *         also depend on the current time.  For example, all of China
  *         is one time zone right now.  But this situation may change
  *         in the future.
  *       - Figure out the daylight saving time correction, tp_dst_offset.
  *         This number depends on both the geographic location and the
  *         current time.  Most of the DST rules are expressed in local
  *         current time.  If so, one should apply the time zone correction
  *         to GMT before applying the DST rules.
  */
 typedef PRTimeParameters (PR_CALLBACK *PRTimeParamFn)(const PRExplodedTime *gmt);
 /**********************************************************************/
 /****************************** FUNCTIONS *****************************/
 /**********************************************************************/
 /*
  * The PR_Now routine returns the current time relative to the
  * epoch, midnight, January 1, 1970 UTC. The units of the returned
  * value are microseconds since the epoch.
  *
  * The values returned are not guaranteed to advance in a linear fashion
  * due to the application of time correction protocols which synchronize
  * computer clocks to some external time source. Consequently it should
  * not be depended on for interval timing.
  *
  * The implementation is machine dependent.
  * Cf. time_t time(time_t *tp) in ANSI C.
  */
 NSPR_API(PRTime)
 PR_Now(void);
 /*
  * Expand time binding it to time parameters provided by PRTimeParamFn.
  * The calculation is envisoned to proceed in the following steps:
  *   - From given PRTime, calculate PRExplodedTime in GMT
  *   - Apply the given PRTimeParamFn to the GMT that we just calculated
  *     to obtain PRTimeParameters.
  *   - Add the PRTimeParameters offsets to GMT to get the local time
  *     as PRExplodedTime.
  */
 NSPR_API(void) PR_ExplodeTime(
     PRTime usecs, PRTimeParamFn params, PRExplodedTime *exploded);
 /* Reverse operation of PR_ExplodeTime */
 NSPR_API(PRTime)
 PR_ImplodeTime(const PRExplodedTime *exploded);
 /*
  * Adjust exploded time to normalize field overflows after manipulation.
  * Note that the following fields of PRExplodedTime should not be
  * manipulated:
  *   - tm_month and tm_year: because the number of days in a month and
  *     number of days in a year are not constant, it is ambiguous to
  *     manipulate the month and year fields, although one may be tempted
  *     to.  For example, what does "a month from January 31st" mean?
  *   - tm_wday and tm_yday: these fields are calculated by NSPR.  Users
  *     should treat them as "read-only".
  */
 NSPR_API(void) PR_NormalizeTime(
     PRExplodedTime *exploded, PRTimeParamFn params);
 /**********************************************************************/
 /*********************** TIME PARAMETER FUNCTIONS *********************/
 /**********************************************************************/
 /* Time parameters that suit current host machine */
 NSPR_API(PRTimeParameters) PR_LocalTimeParameters(const PRExplodedTime *gmt);
 /* Time parameters that represent Greenwich Mean Time */
 NSPR_API(PRTimeParameters) PR_GMTParameters(const PRExplodedTime *gmt);
 /*
  * Time parameters that represent the US Pacific Time Zone, with the
  * current daylight saving time rules (for testing only)
  */
 NSPR_API(PRTimeParameters) PR_USPacificTimeParameters(const PRExplodedTime *gmt);
 /*
  * This parses a time/date string into a PRExplodedTime
  * struct. It populates all fields but it can't split
  * the offset from UTC into tp_gmt_offset and tp_dst_offset in
  * most cases (exceptions: PST/PDT, MST/MDT, CST/CDT, EST/EDT, GMT/BST).
  * In those cases tp_gmt_offset will be the sum of these two and
  * tp_dst_offset will be 0.
  * It returns PR_SUCCESS on success, and PR_FAILURE
  * if the time/date string can't be parsed.
  *
  * Many formats are handled, including:
  *
  *   14 Apr 89 03:20:12
  *   14 Apr 89 03:20 GMT
  *   Fri, 17 Mar 89 4:01:33
  *   Fri, 17 Mar 89 4:01 GMT
  *   Mon Jan 16 16:12 PDT 1989
  *   Mon Jan 16 16:12 +0130 1989
  *   6 May 1992 16:41-JST (Wednesday)
  *   22-AUG-1993 10:59:12.82
  *   22-AUG-1993 10:59pm
  *   22-AUG-1993 12:59am
  *   22-AUG-1993 12:59 PM
  *   Friday, August 04, 1995 3:54 PM
  *   06/21/95 04:24:34 PM
  *   20/06/95 21:07
  *   95-06-08 19:32:48 EDT
  *
  * If the input string doesn't contain a description of the timezone,
  * we consult the `default_to_gmt' to decide whether the string should
  * be interpreted relative to the local time zone (PR_FALSE) or GMT (PR_TRUE).
  * The correct value for this argument depends on what standard specified
  * the time string which you are parsing.
  */
 NSPR_API(PRStatus) PR_ParseTimeStringToExplodedTime (
         const char *string,
         PRBool default_to_gmt,
         PRExplodedTime *result);
 /*
  * This uses PR_ParseTimeStringToExplodedTime to parse
  * a time/date string and PR_ImplodeTime to transform it into
  * a PRTime (microseconds after "1-Jan-1970 00:00:00 GMT").
  * It returns PR_SUCCESS on success, and PR_FAILURE
  * if the time/date string can't be parsed.
  */
 NSPR_API(PRStatus) PR_ParseTimeString (
 	const char *string,
 	PRBool default_to_gmt,
 	PRTime *result);
 /* Format a time value into a buffer. Same semantics as strftime() */
 NSPR_API(PRUint32) PR_FormatTime(char *buf, int buflen, const char *fmt,
                                            const PRExplodedTime *tm);
 /* Format a time value into a buffer. Time is always in US English format, regardless
  * of locale setting.
  */
 NSPR_API(PRUint32)
 PR_FormatTimeUSEnglish( char* buf, PRUint32 bufSize,
                         const char* format, const PRExplodedTime* tm );
 PR_END_EXTERN_C
 #endif /* prtime_h___ */

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nsprpub/pr/include/prtime.h@925c144e1f1f (annotated)

nsprpub/pr/include/prtime.h