[vlc-commits] gmtime_r: rewrite, now truly thread-safe
Rémi Denis-Courmont
git at videolan.org
Mon Apr 16 22:29:27 CEST 2012
vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Mon Apr 16 23:26:25 2012 +0300| [c05b7fdf1e417f484c0451ec59297dea38afa8dc] | committer: Rémi Denis-Courmont
gmtime_r: rewrite, now truly thread-safe
> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=c05b7fdf1e417f484c0451ec59297dea38afa8dc
---
compat/gmtime_r.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++-----
1 files changed, 67 insertions(+), 7 deletions(-)
diff --git a/compat/gmtime_r.c b/compat/gmtime_r.c
index 8bbee20..cb7cba8 100644
--- a/compat/gmtime_r.c
+++ b/compat/gmtime_r.c
@@ -1,7 +1,7 @@
/*****************************************************************************
* gmtime_r.c: POSIX gmtime_r() replacement
*****************************************************************************
- * Copyright © 1998-2008 VLC authors and VideoLAN
+ * Copyright © 2011-2012 Rémi Denis-Courmont
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
@@ -23,13 +23,73 @@
#endif
#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
-struct tm *gmtime_r (const time_t *timep, struct tm *result)
+struct tm *gmtime_r (const time_t *timep, struct tm *tm)
{
- struct tm *s = gmtime (timep);
- if (s == NULL)
- return NULL;
+ static const unsigned short normal[12] =
+ { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+ static const unsigned short leap[12] =
+ { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+ lldiv_t d;
+ const unsigned short *months;
- *result = *s;
- return result;
+ /* Rebase from 1970 Unix epoch to fictitious year 0 (i.e. would-be
+ * year 1 BC had the Gregorian calendar already existed then) */
+ d.quot = 60LL * 60 * 24 * (4 * 146097 + 135140) + *timep;
+
+ d = lldiv (d.quot, 60); /* 60 seconds per minute */
+ if (*timep < 0)
+ {
+ d.rem += 60;
+ d.quot--;
+ }
+ tm->tm_sec = d.rem;
+
+ d = lldiv (d.quot, 60); /* 60 minutes per hour */
+ tm->tm_min = d.rem;
+
+ d = lldiv (d.quot, 24); /* 24 hours per day */
+ tm->tm_hour = d.rem;
+
+ tm->tm_wday = (d.quot + 6) % 7; /* 7 days per week */
+
+ d = lldiv (d.quot, 146097); /* 146097 days per 4 centuries */
+ tm->tm_year = 400 * d.quot;
+
+ if (d.rem >= 36525)
+ { /* Century with 24 leap years */
+ d.rem -= 36525;
+ tm->tm_year += 100;
+
+ d = lldiv (d.rem, 36524); /* 36524 days per normal century */
+ tm->tm_year += d.quot * 100;
+ if (d.rem >= 59) /* not in January or February of year 00 */
+ d.rem++; /* insert missing February 29th 00*/
+ }
+ tm->tm_year -= 1900; /* Rebase to 1900 for struct tm */
+
+ d = lldiv (d.rem, 1461); /* 1461 days per 4 years */
+ tm->tm_year += 4 * d.quot;
+
+ if (d.rem >= 366)
+ { /* Non-leap year */
+ d.rem -= 366;
+ tm->tm_year++;
+
+ d = lldiv (d.rem, 365); /* 365 days per normal year */
+ tm->tm_year += d.quot;
+ months = normal;
+ }
+ else
+ months = leap;
+ tm->tm_yday = d.rem;
+
+ for (tm->tm_mon = 0; d.rem >= months[tm->tm_mon]; tm->tm_mon++)
+ d.rem -= months[tm->tm_mon]; /* 28 to 31 days in a month */
+ tm->tm_mday = d.rem + 1;
+
+ tm->tm_isdst = 0; /* UTC time */
+ return tm;
}
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