diff options
Diffstat (limited to 'time/mktime.c')
| -rw-r--r-- | time/mktime.c | 164 |
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: */ |