X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fmktime.c;h=1feb4046b07f631108526dc655a9723fde1a6710;hb=e9721c2f5a8ea905fba888055ca0fd0767f8873d;hp=70205134435680cad8eb2389bb310e40cc209d43;hpb=599729fb64b937411e7fdbc0884fc3fa09117c33;p=gnulib.git diff --git a/lib/mktime.c b/lib/mktime.c index 702051344..1feb4046b 100644 --- a/lib/mktime.c +++ b/lib/mktime.c @@ -1,5 +1,5 @@ -/* mktime: convert a `struct tm' to a time_t value zzzzzz - Copyright (C) 1993-1997, 1998 Free Software Foundation, Inc. +/* mktime: convert a `struct tm' to a time_t value + Copyright (C) 1993-1998, 1999 Free Software Foundation, Inc. Contributed by Paul Eggert (eggert@twinsun.com). NOTE: The canonical source of this file is maintained with the GNU C Library. @@ -28,19 +28,8 @@ # include #endif -/* Some systems require that one of these symbols be defined in - order to declare localtime_r properly. */ -#ifndef __EXTENSIONS__ -# define __EXTENSIONS__ 1 -#endif -#ifndef _REENTRANT -# define _REENTRANT 1 -#endif - - #ifdef _LIBC # define HAVE_LIMITS_H 1 -# define HAVE_LOCALTIME_R 1 # define STDC_HEADERS 1 #endif @@ -68,7 +57,7 @@ #endif /* DEBUG */ #ifndef __P -# if defined (__GNUC__) || (defined (__STDC__) && __STDC__) +# if defined __GNUC__ || (defined __STDC__ && __STDC__) # define __P(args) args # else # define __P(args) () @@ -130,35 +119,21 @@ time_t __mktime_internal __P ((struct tm *, #ifdef _LIBC -# define localtime_r __localtime_r +# define my_mktime_localtime_r __localtime_r #else -# if HAVE_LOCALTIME_R == defined (localtime_r) -/* Provide our own substitute for a missing or possibly broken localtime_r. */ +/* If we're a mktime substitute in a GNU program, then prefer + localtime to localtime_r, since many localtime_r implementations + are buggy. */ static struct tm *my_mktime_localtime_r __P ((const time_t *, struct tm *)); static struct tm * -my_mktime_localtime_r (t, tp) - const time_t *t; - struct tm *tp; +my_mktime_localtime_r (const time_t *t, struct tm *tp) { -# ifdef localtime_r - /* Digital Unix 4.0A and 4.0D have a macro localtime_r with the - standard meaning, along with an unwanted, nonstandard function - localtime_r. The placeholder function my_mktime_localtime_r - invokes the macro; use that instead of the system's bogus - localtime_r. */ - return localtime_r (t, tp); -# undef localtime_r -# else /* ! defined (localtime_r) */ - /* Approximate localtime_r as best we can in its absence. */ struct tm *l = localtime (t); if (! l) return 0; *tp = *l; return tp; -# endif /* ! defined (localtime_r) */ } -# define localtime_r my_mktime_localtime_r -# endif /* HAVE_LOCALTIME_R == defined (localtime_r) */ #endif /* ! _LIBC */ @@ -169,9 +144,8 @@ my_mktime_localtime_r (t, tp) If TP is null, return a nonzero value. If overflow occurs, yield the low order bits of the correct answer. */ static time_t -ydhms_tm_diff (year, yday, hour, min, sec, tp) - int year, yday, hour, min, sec; - const struct tm *tp; +ydhms_tm_diff (int year, int yday, int hour, int min, int sec, + const struct tm *tp) { if (!tp) return 1; @@ -203,8 +177,7 @@ static time_t localtime_offset; /* Convert *TP to a time_t value. */ time_t -mktime (tp) - struct tm *tp; +mktime (struct tm *tp) { #ifdef _LIBC /* POSIX.1 8.1.1 requires that whenever mktime() is called, the @@ -213,17 +186,15 @@ mktime (tp) __tzset (); #endif - return __mktime_internal (tp, localtime_r, &localtime_offset); + return __mktime_internal (tp, my_mktime_localtime_r, &localtime_offset); } /* Use CONVERT to convert *T to a broken down time in *TP. If *T is out of range for conversion, adjust it so that it is the nearest in-range value and then convert that. */ static struct tm * -ranged_convert (convert, t, tp) - struct tm *(*convert) __P ((const time_t *, struct tm *)); - time_t *t; - struct tm *tp; +ranged_convert (struct tm *(*convert) (const time_t *, struct tm *), + time_t *t, struct tm *tp) { struct tm *r; @@ -270,10 +241,9 @@ ranged_convert (convert, t, tp) compared to what the result would be for UTC without leap seconds. If *OFFSET's guess is correct, only one CONVERT call is needed. */ time_t -__mktime_internal (tp, convert, offset) - struct tm *tp; - struct tm *(*convert) __P ((const time_t *, struct tm *)); - time_t *offset; +__mktime_internal (struct tm *tp, + struct tm *(*convert) (const time_t *, struct tm *), + time_t *offset) { time_t t, dt, t0, t1, t2; struct tm tm; @@ -348,28 +318,32 @@ __mktime_internal (tp, convert, offset) /* If we have a match, check whether tm.tm_isdst has the requested value, if any. */ - if (dt == 0 && 0 <= isdst && 0 <= tm.tm_isdst) + if (dt == 0 && isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst) { - int dst_diff = (isdst != 0) - (tm.tm_isdst != 0); - if (dst_diff) + /* tm.tm_isdst has the wrong value. Look for a neighboring + time with the right value, and use its UTC offset. + Heuristic: probe the previous three calendar quarters (approximately), + looking for the desired isdst. This isn't perfect, + but it's good enough in practice. */ + int quarter = 7889238; /* seconds per average 1/4 Gregorian year */ + int i; + + /* If we're too close to the time_t limit, look in future quarters. */ + if (t < TIME_T_MIN + 3 * quarter) + quarter = -quarter; + + for (i = 1; i <= 3; i++) { - /* Move two hours in the direction indicated by the disagreement, - probe some more, and switch to a new time if found. - The largest known fallback due to daylight savings is two hours: - once, in Newfoundland, 1988-10-30 02:00 -> 00:00. */ - time_t ot = t - 2 * 60 * 60 * dst_diff; - while (--remaining_probes != 0) + time_t ot = t - i * quarter; + struct tm otm; + ranged_convert (convert, &ot, &otm); + if (otm.tm_isdst == isdst) { - struct tm otm; - if (! (dt = ydhms_tm_diff (year, yday, hour, min, sec, - ranged_convert (convert, &ot, &otm)))) - { - t = ot; - tm = otm; - break; - } - if ((ot += dt) == t) - break; /* Avoid a redundant probe. */ + /* We found the desired tm_isdst. + Extrapolate back to the desired time. */ + t = ot + ydhms_tm_diff (year, yday, hour, min, sec, &otm); + ranged_convert (convert, &t, &tm); + break; } } } @@ -559,6 +533,6 @@ main (argc, argv) /* Local Variables: -compile-command: "gcc -DDEBUG -D__EXTENSIONS__ -DHAVE_LIMITS_H -DHAVE_LOCALTIME_R -DSTDC_HEADERS -Wall -W -O -g mktime.c -o mktime" +compile-command: "gcc -DDEBUG -DHAVE_LIMITS_H -DSTDC_HEADERS -Wall -W -O -g mktime.c -o mktime" End: */