X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fmktime.c;h=b2e63878eb3a1073ae28f5c622ef230f71729543;hb=25a832363606f0a9f987f9242265a5e6e1259228;hp=f759c29bb9658e00d7995f4dde8fbf85e77379eb;hpb=1873f591eb7550c78ccd64129edd77fac4e0f84d;p=gnulib.git

diff --git a/lib/mktime.c b/lib/mktime.c
index f759c29bb..b2e63878e 100644
--- a/lib/mktime.c
+++ b/lib/mktime.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
+/* mktime: convert a `struct tm' to a time_t value
+   Copyright (C) 1993-1997, 1998 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.
@@ -29,7 +30,6 @@
 
 #ifdef _LIBC
 # define HAVE_LIMITS_H 1
-# define HAVE_LOCALTIME_R 1
 # define STDC_HEADERS 1
 #endif
 
@@ -68,21 +68,26 @@
 # define CHAR_BIT 8
 #endif
 
+/* The extra casts work around common compiler bugs.  */
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+/* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
+   It is necessary at least when t == time_t.  */
+#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
+			      ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
+#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
+
 #ifndef INT_MIN
-# define INT_MIN (~0 << (sizeof (int) * CHAR_BIT - 1))
+# define INT_MIN TYPE_MINIMUM (int)
 #endif
 #ifndef INT_MAX
-# define INT_MAX (~0 - INT_MIN)
+# define INT_MAX TYPE_MAXIMUM (int)
 #endif
 
 #ifndef TIME_T_MIN
-/* The outer cast to time_t works around a bug in Cray C 5.0.3.0.  */
-# define TIME_T_MIN ((time_t) \
-		    (0 < (time_t) -1 ? (time_t) 0 \
-		     : ~ (time_t) 0 << (sizeof (time_t) * CHAR_BIT - 1)))
+# define TIME_T_MIN TYPE_MINIMUM (time_t)
 #endif
 #ifndef TIME_T_MAX
-# define TIME_T_MAX (~ (time_t) 0 - TIME_T_MIN)
+# define TIME_T_MAX TYPE_MAXIMUM (time_t)
 #endif
 
 #define TM_YEAR_BASE 1900
@@ -114,16 +119,14 @@ 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
-/* Approximate localtime_r as best we can in its absence.  */
-#  define localtime_r my_mktime_localtime_r
-static struct tm *localtime_r __P ((const time_t *, struct tm *));
+/* 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 *
-localtime_r (t, tp)
-     const time_t *t;
-     struct tm *tp;
+my_mktime_localtime_r (const time_t *t, struct tm *tp)
 {
   struct tm *l = localtime (t);
   if (! l)
@@ -131,7 +134,6 @@ localtime_r (t, tp)
   *tp = *l;
   return tp;
 }
-# endif /* ! HAVE_LOCALTIME_R && ! defined (localtime_r) */
 #endif /* ! _LIBC */
 
 
@@ -142,9 +144,8 @@ 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;
@@ -176,8 +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
@@ -186,17 +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;
 
@@ -243,19 +241,18 @@ 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;
+  time_t t, dt, t0, t1, t2;
   struct tm tm;
 
   /* The maximum number of probes (calls to CONVERT) should be enough
      to handle any combinations of time zone rule changes, solar time,
-     and leap seconds.  POSIX.1 prohibits leap seconds, but some hosts
-     have them anyway.  */
-  int remaining_probes = 4;
+     leap seconds, and oscillations around a spring-forward gap.
+     POSIX.1 prohibits leap seconds, but some hosts have them anyway.  */
+  int remaining_probes = 6;
 
   /* Time requested.  Copy it in case CONVERT modifies *TP; this can
      occur if TP is localtime's returned value and CONVERT is localtime.  */
@@ -301,15 +298,27 @@ __mktime_internal (tp, convert, offset)
   tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
   t0 = ydhms_tm_diff (year, yday, hour, min, sec, &tm);
 
-  for (t = t0 + *offset;
+  for (t = t1 = t2 = t0 + *offset;
        (dt = ydhms_tm_diff (year, yday, hour, min, sec,
 			    ranged_convert (convert, &t, &tm)));
-       t += dt)
-    if (--remaining_probes == 0)
+       t1 = t2, t2 = t, t += dt)
+    if (t == t1 && t != t2
+	&& (isdst < 0 || tm.tm_isdst < 0
+	    || (isdst != 0) != (tm.tm_isdst != 0)))
+      /* We can't possibly find a match, as we are oscillating
+	 between two values.  The requested time probably falls
+	 within a spring-forward gap of size DT.  Follow the common
+	 practice in this case, which is to return a time that is DT
+	 away from the requested time, preferring a time whose
+	 tm_isdst differs from the requested value.  In practice,
+	 this is more useful than returning -1.  */
+      break;
+    else if (--remaining_probes == 0)
       return -1;
 
-  /* Check whether tm.tm_isdst has the requested value, if any.  */
-  if (0 <= isdst && 0 <= tm.tm_isdst)
+  /* 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)
     {
       int dst_diff = (isdst != 0) - (tm.tm_isdst != 0);
       if (dst_diff)
@@ -360,7 +369,15 @@ __mktime_internal (tp, convert, offset)
       double dday = 366 * dyear + mday;
       double dsec = 60 * (60 * (24 * dday + hour) + min) + sec_requested;
 
-      if (TIME_T_MAX / 3 - TIME_T_MIN / 3 < (dsec < 0 ? - dsec : dsec))
+      /* On Irix4.0.5 cc, dividing TIME_T_MIN by 3 does not produce
+	 correct results, ie., it erroneously gives a positive value
+	 of 715827882.  Setting a variable first then doing math on it
+	 seems to work.  (ghazi@caip.rutgers.edu) */
+
+      const time_t time_t_max = TIME_T_MAX;
+      const time_t time_t_min = TIME_T_MIN;
+
+      if (time_t_max / 3 - time_t_min / 3 < (dsec < 0 ? - dsec : dsec))
 	return -1;
     }
 
@@ -512,6 +529,6 @@ 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:
 */