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Update from gnulib.

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This commit is contained in:
Jim Meyering
2003-07-09 17:54:54 +00:00
parent e496ebd4f9
commit 3bfb395872
1 changed files with 255 additions and 133 deletions
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lib/mktime.c
+255 -133
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@@ -65,16 +65,33 @@
#ifndef TIME_T_MAX
# define TIME_T_MAX TYPE_MAXIMUM (time_t)
#endif
#define TIME_T_MIDPOINT (((TIME_T_MIN + TIME_T_MAX) >> 1) + 1)
/* Verify a requirement at compile-time (unlike assert, which is runtime). */
#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
verify (time_t_is_integer, (time_t) 0.5 == 0);
verify (twos_complement_arithmetic, -1 == ~1 + 1);
verify (right_shift_propagates_sign, -1 >> 1 == -1);
/* The code also assumes that signed integer overflow silently wraps
around, but this assumption can't be stated without causing a
diagnostic on some hosts. */
#define TM_YEAR_BASE 1900
#define EPOCH_YEAR 1970
#define TM_YEAR_BASE 1900
verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0);
#ifndef __isleap
/* Nonzero if YEAR is a leap year (every 4 years,
except every 100th isn't, and every 400th is). */
# define __isleap(year) \
((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
#endif
/* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */
static inline int
leapyear (int year)
{
/* Don't add YEAR to TM_YEAR_BASE, as that might overflow.
Also, work even if YEAR is negative. */
return
((year & 3) == 0
&& (year % 100 != 0
|| ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3)));
}
/* How many days come before each month (0-12). */
#ifndef _LIBC
@@ -106,40 +123,74 @@ my_mktime_localtime_r (const time_t *t, struct tm *tp)
}
#endif /* ! _LIBC */
/* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) -
(YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks
were not adjusted between the time stamps.
/* Yield the difference between (YEAR-YDAY HOUR:MIN:SEC) and (*TP),
measured in seconds, ignoring leap seconds.
YEAR uses the same numbering as TM->tm_year.
All values are in range, except possibly YEAR.
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 (int year, int yday, int hour, int min, int sec,
const struct tm *tp)
The YEAR values uses the same numbering as TP->tm_year. Values
need not be in the usual range. However, YEAR1 must not be less
than 2 * INT_MIN or greater than 2 * INT_MAX.
The result may overflow. It is the caller's responsibility to
detect overflow. */
static inline time_t
ydhms_diff (long int year1, long int yday1, int hour1, int min1, int sec1,
int year0, int yday0, int hour0, int min0, int sec0)
{
if (!tp)
return 1;
else
verify (C99_integer_division, -1 / 2 == 0);
verify (long_int_year_and_yday_are_wide_enough,
INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
/* Compute intervening leap days correctly even if year is negative.
Take care to avoid integer overflow here. */
int a4 = (year1 >> 2) + (TM_YEAR_BASE >> 2) - ! (year1 & 3);
int b4 = (year0 >> 2) + (TM_YEAR_BASE >> 2) - ! (year0 & 3);
int a100 = a4 / 25 - (a4 % 25 < 0);
int b100 = b4 / 25 - (b4 % 25 < 0);
int a400 = a100 >> 2;
int b400 = b100 >> 2;
int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
/* Compute the desired time in time_t precision. Overflow might
occur here. */
time_t tyear1 = year1;
time_t years = tyear1 - year0;
time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
time_t hours = 24 * days + hour1 - hour0;
time_t minutes = 60 * hours + min1 - min0;
time_t seconds = 60 * minutes + sec1 - sec0;
return seconds;
}
/* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
assuming that *T corresponds to *TP and that no clock adjustments
occurred between *TP and the desired time.
If TP is null, return a value not equal to *T; this avoids false matches.
If overflow occurs, yield the minimal or maximal value, except do not
yield a value equal to *T. */
static time_t
guess_time_tm (long int year, long int yday, int hour, int min, int sec,
const time_t *t, const struct tm *tp)
{
if (tp)
{
/* Compute intervening leap days correctly even if year is negative.
Take care to avoid int overflow. time_t overflow is OK, since
only the low order bits of the correct time_t answer are needed.
Don't convert to time_t until after all divisions are done, since
time_t might be unsigned. */
int a4 = (year >> 2) + (TM_YEAR_BASE >> 2) - ! (year & 3);
int b4 = (tp->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (tp->tm_year & 3);
int a100 = a4 / 25 - (a4 % 25 < 0);
int b100 = b4 / 25 - (b4 % 25 < 0);
int a400 = a100 >> 2;
int b400 = b100 >> 2;
int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
time_t years = year - (time_t) tp->tm_year;
time_t days = (365 * years + intervening_leap_days
+ (yday - tp->tm_yday));
return (60 * (60 * (24 * days + (hour - tp->tm_hour))
+ (min - tp->tm_min))
+ (sec - tp->tm_sec));
time_t d = ydhms_diff (year, yday, hour, min, sec,
tp->tm_year, tp->tm_yday,
tp->tm_hour, tp->tm_min, tp->tm_sec);
time_t t1 = *t + d;
if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d))
return t1;
}
/* Overflow occurred one way or another. Return the nearest result
that is actually in range, except don't report a zero difference
if the actual difference is nonzero, as that would cause a false
match. */
return (*t < TIME_T_MIDPOINT
? TIME_T_MIN + (*t == TIME_T_MIN)
: TIME_T_MAX - (*t == TIME_T_MAX));
}
/* Use CONVERT to convert *T to a broken down time in *TP.
@@ -199,9 +250,9 @@ static
time_t
__mktime_internal (struct tm *tp,
struct tm *(*convert) (const time_t *, struct tm *),
long int *offset)
time_t *offset)
{
time_t t, dt, t0, t1, t2;
time_t t, gt, t0, t1, t2;
struct tm tm;
/* The maximum number of probes (calls to CONVERT) should be enough
@@ -227,7 +278,8 @@ __mktime_internal (struct tm *tp,
int mon_remainder = mon % 12;
int negative_mon_remainder = mon_remainder < 0;
int mon_years = mon / 12 - negative_mon_remainder;
int year = year_requested + mon_years;
long int lyear_requested = year_requested;
long int year = lyear_requested + mon_years;
/* The other values need not be in range:
the remaining code handles minor overflows correctly,
@@ -236,35 +288,95 @@ __mktime_internal (struct tm *tp,
/* Calculate day of year from year, month, and day of month.
The result need not be in range. */
int yday = ((__mon_yday[__isleap (year + TM_YEAR_BASE)]
[mon_remainder + 12 * negative_mon_remainder])
+ mday - 1);
int mon_yday = ((__mon_yday[leapyear (year)]
[mon_remainder + 12 * negative_mon_remainder])
- 1);
long int lmday = mday;
long int yday = mon_yday + lmday;
time_t guessed_offset = *offset;
int sec_requested = sec;
#if LEAP_SECONDS_POSSIBLE
/* Handle out-of-range seconds specially,
since ydhms_tm_diff assumes every minute has 60 seconds. */
if (sec < 0)
sec = 0;
if (59 < sec)
sec = 59;
#endif
if (LEAP_SECONDS_POSSIBLE)
{
/* Handle out-of-range seconds specially,
since ydhms_tm_diff assumes every minute has 60 seconds. */
if (sec < 0)
sec = 0;
if (59 < sec)
sec = 59;
}
/* Invert CONVERT by probing. First assume the same offset as last time.
Then repeatedly use the error to improve the guess. */
/* Invert CONVERT by probing. First assume the same offset as last
time. */
tm.tm_year = EPOCH_YEAR - TM_YEAR_BASE;
tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
t0 = ydhms_tm_diff (year, yday, hour, min, sec, &tm);
t = t0 + *offset;
if ((t < t0) != (*offset < 0))
t = t0;
t0 = ydhms_diff (year, yday, hour, min, sec,
EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
for (t1 = t2 = t, dst2 = 0;
(dt = ydhms_tm_diff (year, yday, hour, min, sec,
ranged_convert (convert, &t, &tm)));
t1 = t2, t2 = t, t += dt, dst2 = tm.tm_isdst != 0)
if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
{
/* time_t isn't large enough to rule out overflows, so check
for major overflows. A gross check suffices, since if t0
has overflowed, it is off by a multiple of TIME_T_MAX -
TIME_T_MIN + 1. So ignore any component of the difference
that is bounded by a small value. */
/* Approximate log base 2 of the number of time units per
biennium. A biennium is 2 years; use this unit instead of
years to avoid integer overflow. For example, 2 average
Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
which is 63113904 seconds, and rint (log2 (63113904)) is
26. */
int ALOG2_SECONDS_PER_BIENNIUM = 26;
int ALOG2_MINUTES_PER_BIENNIUM = 20;
int ALOG2_HOURS_PER_BIENNIUM = 14;
int ALOG2_DAYS_PER_BIENNIUM = 10;
int LOG2_YEARS_PER_BIENNIUM = 1;
int approx_requested_biennia =
((year_requested >> LOG2_YEARS_PER_BIENNIUM)
- ((EPOCH_YEAR - TM_YEAR_BASE) >> LOG2_YEARS_PER_BIENNIUM)
+ (mday >> ALOG2_DAYS_PER_BIENNIUM)
+ (hour >> ALOG2_HOURS_PER_BIENNIUM)
+ (min >> ALOG2_MINUTES_PER_BIENNIUM)
+ (LEAP_SECONDS_POSSIBLE ? 0 : sec >> ALOG2_SECONDS_PER_BIENNIUM));
int approx_biennia = t0 >> ALOG2_SECONDS_PER_BIENNIUM;
int diff = approx_biennia - approx_requested_biennia;
int abs_diff = diff < 0 ? - diff : diff;
/* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously
gives a positive value of 715827882. Setting a variable
first then doing math on it seems to work.
(ghazi@caip.rutgers.edu) */
time_t time_t_max = TIME_T_MAX;
time_t time_t_min = TIME_T_MIN;
time_t overflow_threshold =
(time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
if (overflow_threshold < abs_diff)
{
/* Overflow occurred. Try repairing it; this might work if
the time zone offset is enough to undo the overflow. */
time_t repaired_t0 = -1 - t0;
approx_biennia = repaired_t0 >> ALOG2_SECONDS_PER_BIENNIUM;
diff = approx_biennia - approx_requested_biennia;
abs_diff = diff < 0 ? - diff : diff;
if (overflow_threshold < abs_diff)
return -1;
guessed_offset += repaired_t0 - t0;
t0 = repaired_t0;
}
}
/* Repeatedly use the error to improve the guess. */
for (t = t1 = t2 = t0, dst2 = 0;
(gt = guess_time_tm (year, yday, hour, min, sec, &t,
ranged_convert (convert, &t, &tm)),
t != gt);
t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
if (t == t1 && t != t2
&& (tm.tm_isdst < 0
|| (isdst < 0
@@ -272,83 +384,83 @@ __mktime_internal (struct tm *tp,
: (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
within a spring-forward gap of size GT - T. Follow the common
practice in this case, which is to return a time that is GT - T
away from the requested time, preferring a time whose
tm_isdst differs from the requested value. (If no tm_isdst
was requested and only one of the two values has a nonzero
tm_isdst, prefer that value.) In practice, this is more
useful than returning -1. */
break;
goto offset_found;
else if (--remaining_probes == 0)
return -1;
/* If we have a match, check whether tm.tm_isdst has the requested
/* We have a match. Check whether tm.tm_isdst has the requested
value, if any. */
if (dt == 0 && isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
{
/* 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;
Heuristic: probe the adjacent timestamps in both directions,
looking for the desired isdst. This should work for all real
time zone histories in the tz database. */
for (i = 1; i <= 3; i++)
{
time_t ot = t - i * quarter;
struct tm otm;
ranged_convert (convert, &ot, &otm);
if (otm.tm_isdst == isdst)
{
/* 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;
}
}
/* Distance between probes when looking for a DST boundary. In
tzdata2003a, the shortest period of DST is 601200 seconds
(e.g., America/Recife starting 2000-10-08 01:00), and the
shortest period of non-DST surrounded by DST is 694800
seconds (Africa/Tunis starting 1943-04-17 01:00). Use the
minimum of these two values, so we don't miss these short
periods when probing. */
int stride = 601200;
/* The longest period of DST in tzdata2003a is 536454000 seconds
(e.g., America/Jujuy starting 1946-10-01 01:00). The longest
period of non-DST is much longer, but it makes no real sense
to search for more than a year of non-DST, so use the DST
max. */
int duration_max = 536454000;
/* Search in both directions, so the maximum distance is half
the duration; add the stride to avoid off-by-1 problems. */
int delta_bound = duration_max / 2 + stride;
int delta, direction;
for (delta = stride; delta < delta_bound; delta += stride)
for (direction = -1; direction <= 1; direction += 2)
{
time_t ot = t + delta * direction;
if ((ot < t) == (direction < 0))
{
struct tm otm;
ranged_convert (convert, &ot, &otm);
if (otm.tm_isdst == isdst)
{
/* We found the desired tm_isdst.
Extrapolate back to the desired time. */
t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
ranged_convert (convert, &t, &tm);
goto offset_found;
}
}
}
}
*offset = t - t0;
offset_found:
*offset = guessed_offset + t - t0;
#if LEAP_SECONDS_POSSIBLE
if (sec_requested != tm.tm_sec)
if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
{
/* Adjust time to reflect the tm_sec requested, not the normalized value.
Also, repair any damage from a false match due to a leap second. */
t += sec_requested - sec + (sec == 0 && tm.tm_sec == 60);
if (! (*convert) (&t, &tm))
return -1;
}
#endif
if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
{
/* time_t isn't large enough to rule out overflows in ydhms_tm_diff,
so check for major overflows. A gross check suffices,
since if t has overflowed, it is off by a multiple of
TIME_T_MAX - TIME_T_MIN + 1. So ignore any component of
the difference that is bounded by a small value. */
double dyear = (double) year_requested + mon_years - tm.tm_year;
double dday = 366 * dyear + mday;
double dsec = 60 * (60 * (24 * dday + hour) + min) + sec_requested;
/* 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))
int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
t1 = t + sec_requested;
t2 = t1 + sec_adjustment;
if (((t1 < t) != (sec_requested < 0))
| ((t2 < t1) != (sec_adjustment < 0))
| ! (*convert) (&t, &tm))
return -1;
}
@@ -357,7 +469,11 @@ __mktime_internal (struct tm *tp,
}
static long int localtime_offset;
/* FIXME: This should use a signed type wide enough to hold any UTC
offset in seconds. 'int' should be good enough for GNU code. We
can't fix this unilaterally though, as other modules invoke
__mktime_internal. */
static time_t localtime_offset;
/* Convert *TP to a time_t value. */
time_t
@@ -385,7 +501,7 @@ libc_hidden_weak (timelocal)
#if DEBUG
static int
not_equal_tm (struct tm const *a, struct tm const *b)
not_equal_tm (const struct tm *a, const struct tm *b)
{
return ((a->tm_sec ^ b->tm_sec)
| (a->tm_min ^ b->tm_min)
@@ -399,7 +515,7 @@ not_equal_tm (struct tm const *a, struct tm const *b)
}
static void
print_tm (struct tm const *tp)
print_tm (const struct tm *tp)
{
if (tp)
printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
@@ -411,15 +527,15 @@ print_tm (struct tm const *tp)
}
static int
check_result (time_t tk, struct tm tmk, time_t tl, struct tm const *lt)
check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt)
{
if (tk != tl || !lt || not_equal_tm (&tmk, lt))
{
printf ("mktime (");
print_tm (&tmk);
printf (")\nyields (");
print_tm (lt);
printf (") == %ld, should be %ld\n", (long) tl, (long) tk);
printf (")\nyields (");
print_tm (&tmk);
printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl);
return 1;
}
@@ -432,7 +548,7 @@ main (int argc, char **argv)
int status = 0;
struct tm tm, tmk, tml;
struct tm *lt;
time_t tk, tl;
time_t tk, tl, tl1;
char trailer;
if ((argc == 3 || argc == 4)
@@ -454,7 +570,7 @@ main (int argc, char **argv)
tml = *lt;
lt = &tml;
}
printf ("mktime returns %ld == ", (long) tl);
printf ("mktime returns %ld == ", (long int) tl);
print_tm (&tmk);
printf ("\n");
status = check_result (tl, tmk, tl, lt);
@@ -466,7 +582,7 @@ main (int argc, char **argv)
time_t to = atol (argv[3]);
if (argc == 4)
for (tl = from; tl <= to; tl += by)
for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
{
lt = localtime (&tl);
if (lt)
@@ -477,12 +593,15 @@ main (int argc, char **argv)
}
else
{
printf ("localtime (%ld) yields 0\n", (long) tl);
printf ("localtime (%ld) yields 0\n", (long int) tl);
status = 1;
}
tl1 = tl + by;
if ((tl1 < tl) != (by < 0))
break;
}
else
for (tl = from; tl <= to; tl += by)
for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
{
/* Null benchmark. */
lt = localtime (&tl);
@@ -494,9 +613,12 @@ main (int argc, char **argv)
}
else
{
printf ("localtime (%ld) yields 0\n", (long) tl);
printf ("localtime (%ld) yields 0\n", (long int) tl);
status = 1;
}
tl1 = tl + by;
if ((tl1 < tl) != (by < 0))
break;
}
}
else