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-rw-r--r--time/mktime.c164
1 files changed, 124 insertions, 40 deletions
diff --git a/time/mktime.c b/time/mktime.c
index 7a94c21244..406f55e170 100644
--- a/time/mktime.c
+++ b/time/mktime.c
@@ -102,6 +102,9 @@ const unsigned short int __mon_yday[2][13] =
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
+static struct tm *ranged_convert __P ((struct tm *(*) __P ((const time_t *,
+ struct tm *)),
+ time_t *, struct tm *));
static time_t ydhms_tm_diff __P ((int, int, int, int, int, const struct tm *));
time_t __mktime_internal __P ((struct tm *,
struct tm *(*) (const time_t *, struct tm *),
@@ -134,30 +137,36 @@ localtime_r (t, 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 (year, yday, hour, min, sec, tp)
int year, yday, hour, min, sec;
const struct tm *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));
+ if (!tp)
+ return 1;
+ else
+ {
+ /* 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));
+ }
}
@@ -178,6 +187,54 @@ mktime (tp)
return __mktime_internal (tp, 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;
+{
+ struct tm *r;
+
+ if (! (r = (*convert) (t, tp)) && *t)
+ {
+ time_t bad = *t;
+ time_t ok = 0;
+ struct tm tm;
+
+ /* BAD is a known unconvertible time_t, and OK is a known good one.
+ Use binary search to narrow the range between BAD and OK until
+ they differ by 1. */
+ while (bad != ok + (bad < 0 ? -1 : 1))
+ {
+ time_t mid = *t = (bad < 0
+ ? bad + ((ok - bad) >> 1)
+ : ok + ((bad - ok) >> 1));
+ if ((r = (*convert) (t, tp)))
+ {
+ tm = *r;
+ ok = mid;
+ }
+ else
+ bad = mid;
+ }
+
+ if (!r && ok)
+ {
+ /* The last conversion attempt failed;
+ revert to the most recent successful attempt. */
+ *t = ok;
+ *tp = tm;
+ r = tp;
+ }
+ }
+
+ return r;
+}
+
+
/* Convert *TP to a time_t value, inverting
the monotonic and mostly-unit-linear conversion function CONVERT.
Use *OFFSET to keep track of a guess at the offset of the result,
@@ -243,7 +300,8 @@ __mktime_internal (tp, convert, offset)
t0 = ydhms_tm_diff (year, yday, hour, min, sec, &tm);
for (t = t0 + *offset;
- (dt = ydhms_tm_diff (year, yday, hour, min, sec, (*convert) (&t, &tm)));
+ (dt = ydhms_tm_diff (year, yday, hour, min, sec,
+ ranged_convert (convert, &t, &tm)));
t += dt)
if (--remaining_probes == 0)
return -1;
@@ -263,7 +321,7 @@ __mktime_internal (tp, convert, offset)
{
struct tm otm;
if (! (dt = ydhms_tm_diff (year, yday, hour, min, sec,
- (*convert) (&ot, &otm))))
+ ranged_convert (convert, &ot, &otm))))
{
t = ot;
tm = otm;
@@ -283,7 +341,8 @@ __mktime_internal (tp, convert, offset)
/* 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);
- (*convert) (&t, &tm);
+ if (! (*convert) (&t, &tm))
+ return -1;
}
#endif
@@ -333,25 +392,28 @@ static void
print_tm (tp)
struct tm *tp;
{
- printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
- tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday,
- tp->tm_hour, tp->tm_min, tp->tm_sec,
- tp->tm_yday, tp->tm_wday, tp->tm_isdst);
+ if (tp)
+ printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
+ tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday,
+ tp->tm_hour, tp->tm_min, tp->tm_sec,
+ tp->tm_yday, tp->tm_wday, tp->tm_isdst);
+ else
+ printf ("0");
}
static int
-check_result (tk, tmk, tl, tml)
+check_result (tk, tmk, tl, lt)
time_t tk;
struct tm tmk;
time_t tl;
- struct tm tml;
+ struct tm *lt;
{
- if (tk != tl || not_equal_tm (&tmk, &tml))
+ if (tk != tl || !lt || not_equal_tm (&tmk, lt))
{
printf ("mktime (");
print_tm (&tmk);
printf (")\nyields (");
- print_tm (&tml);
+ print_tm (lt);
printf (") == %ld, should be %ld\n", (long) tl, (long) tk);
return 1;
}
@@ -366,6 +428,7 @@ main (argc, argv)
{
int status = 0;
struct tm tm, tmk, tml;
+ struct tm *lt;
time_t tk, tl;
char trailer;
@@ -382,11 +445,16 @@ main (argc, argv)
tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
tmk = tm;
tl = mktime (&tmk);
- tml = *localtime (&tl);
+ lt = localtime (&tl);
+ if (lt)
+ {
+ tml = *lt;
+ lt = &tml;
+ }
printf ("mktime returns %ld == ", (long) tl);
print_tm (&tmk);
printf ("\n");
- status = check_result (tl, tmk, tl, tml);
+ status = check_result (tl, tmk, tl, lt);
}
else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
{
@@ -397,19 +465,35 @@ main (argc, argv)
if (argc == 4)
for (tl = from; tl <= to; tl += by)
{
- tml = *localtime (&tl);
- tmk = tml;
- tk = mktime (&tmk);
- status |= check_result (tk, tmk, tl, tml);
+ lt = localtime (&tl);
+ if (lt)
+ {
+ tmk = tml = *lt;
+ tk = mktime (&tmk);
+ status |= check_result (tk, tmk, tl, tml);
+ }
+ else
+ {
+ printf ("localtime (%ld) yields 0\n", (long) tl);
+ status = 1;
+ }
}
else
for (tl = from; tl <= to; tl += by)
{
/* Null benchmark. */
- tml = *localtime (&tl);
- tmk = tml;
- tk = tl;
- status |= check_result (tk, tmk, tl, tml);
+ lt = localtime (&tl);
+ if (lt)
+ {
+ tmk = tml = *lt;
+ tk = tl;
+ status |= check_result (tk, tmk, tl, tml);
+ }
+ else
+ {
+ printf ("localtime (%ld) yields 0\n", (long) tl);
+ status = 1;
+ }
}
}
else
@@ -426,6 +510,6 @@ main (argc, argv)
/*
Local Variables:
-compile-command: "gcc -DDEBUG=1 -Wall -O -g mktime.c -o mktime"
+compile-command: "gcc -DDEBUG -D__EXTENSIONS__ -DHAVE_LIMITS_H -DHAVE_LOCALTIME_R -DSTDC_HEADERS -Wall -W -O -g mktime.c -o mktime"
End:
*/
generated by cgit v1.2.3 (git 2.39.1) at 2024-04-27 18:14:48 +0000