ref: 433b9cd26eb5d27977eb8cde6bb1c019606e0ffa
dir: /src/libc/time/mktime.c/
#include <limits.h> #include <time.h> #include "../libc.h" #undef mktime static int norm(int *val, int *next, int max) { int v = *val, n = *next, d; if (v < 0) { d = -v / max + 1; v += d * max; if (n > INT_MAX - d) return 0; n -= d; } if (v >= max) { d = v / max; v -= d * max; if (n < INT_MIN + d) return 0; n += d; } *val = v; *next = n; return 1; } static int normalize(struct tm *tm) { int mon, day, year, yday; /* * Normalize sec so that it doesn't over/underflow min * Normalize min so that it doesn't over/underflow hour * Normalize hour so that it doesn't over/underflow mday * Normalize month so that it doesn't over/underflow year */ if (!norm(&tm->tm_sec, &tm->tm_min, 60) || !norm(&tm->tm_min, &tm->tm_hour, 60) || !norm(&tm->tm_hour, &tm->tm_mday, 24) || !norm(&tm->tm_mon, &tm->tm_year, 12)) return 0; if (tm->tm_year < 0) return 0; day = tm->tm_mday; yday = 0; year = MINYEAR + tm->tm_year; if (year > _MAXYEAR) return 0; _daysmon[FEB] = FEBDAYS(year); /* * Normalize mday so that it doesn't over/underflow month * Normalize month so that it doesn't over/underflow year */ for (mon = tm->tm_mon; day < 1; --mon) { if (mon == JAN) { if (year == MINYEAR) return 0; year--; _daysmon[FEB] = FEBDAYS(year); mon = DEC+1; } day += _daysmon[mon-1]; } for (; day > _daysmon[mon]; ++mon) { day -= _daysmon[mon]; if (mon == DEC) { if (year == _MAXYEAR) return 0; year++; _daysmon[FEB] = FEBDAYS(year); mon = JAN-1; } } for (int i = 0; i < mon; ++i) yday += _daysmon[i]; tm->tm_mon = mon; tm->tm_year = year - MINYEAR; tm->tm_mday = day; tm->tm_yday = yday + day - 1; tm->tm_wday = (_newyear(tm->tm_year) + tm->tm_yday) % 7; tm->tm_isdst = 0; return 1; } time_t mktime(struct tm *tm) { if (!normalize(tm)) return -1; return _systime(tm); }