third_party/ulib/musl/src/time/strptime.c

#include <ctype.h>
#include <langinfo.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <time.h>

char* strptime(const char* restrict s, const char* restrict f, struct tm* restrict tm) {
    int i, w, neg, adj, min, range, *dest, dummy;
    const char* ex;
    size_t len;
    int want_century = 0, century = 0;
    while (*f) {
        if (*f != '%') {
            if (isspace(*f))
                for (; *s && isspace(*s); s++)
                    ;
            else if (*s != *f)
                return 0;
            else
                s++;
            f++;
            continue;
        }
        f++;
        if (*f == '+')
            f++;
        if (isdigit(*f))
            w = strtoul(f, (void*)&f, 10);
        else
            w = -1;
        adj = 0;
        switch (*f++) {
        case 'a':
        case 'A':
            dest = &tm->tm_wday;
            min = ABDAY_1;
            range = 7;
            goto symbolic_range;
        case 'b':
        case 'B':
        case 'h':
            dest = &tm->tm_mon;
            min = ABMON_1;
            range = 12;
            goto symbolic_range;
        case 'c':
            s = strptime(s, nl_langinfo(D_T_FMT), tm);
            if (!s)
                return 0;
            break;
        case 'C':
            dest = &century;
            if (w < 0)
                w = 2;
            want_century |= 2;
            goto numeric_digits;
        case 'd':
        case 'e':
            dest = &tm->tm_mday;
            min = 1;
            range = 31;
            goto numeric_range;
        case 'D':
            s = strptime(s, "%m/%d/%y", tm);
            if (!s)
                return 0;
            break;
        case 'H':
            dest = &tm->tm_hour;
            min = 0;
            range = 24;
            goto numeric_range;
        case 'I':
            dest = &tm->tm_hour;
            min = 1;
            range = 12;
            goto numeric_range;
        case 'j':
            dest = &tm->tm_yday;
            min = 1;
            range = 366;
            goto numeric_range;
        case 'm':
            dest = &tm->tm_mon;
            min = 1;
            range = 12;
            adj = 1;
            goto numeric_range;
        case 'M':
            dest = &tm->tm_min;
            min = 0;
            range = 60;
            goto numeric_range;
        case 'n':
        case 't':
            for (; *s && isspace(*s); s++)
                ;
            break;
        case 'p':
            ex = nl_langinfo(AM_STR);
            len = strlen(ex);
            if (!strncasecmp(s, ex, len)) {
                tm->tm_hour %= 12;
                break;
            }
            ex = nl_langinfo(PM_STR);
            len = strlen(ex);
            if (!strncasecmp(s, ex, len)) {
                tm->tm_hour %= 12;
                tm->tm_hour += 12;
                break;
            }
            return 0;
        case 'r':
            s = strptime(s, nl_langinfo(T_FMT_AMPM), tm);
            if (!s)
                return 0;
            break;
        case 'R':
            s = strptime(s, "%H:%M", tm);
            if (!s)
                return 0;
            break;
        case 'S':
            dest = &tm->tm_sec;
            min = 0;
            range = 61;
            goto numeric_range;
        case 'T':
            s = strptime(s, "%H:%M:%S", tm);
            if (!s)
                return 0;
            break;
        case 'U':
        case 'W':
            /* Throw away result, for now. (FIXME?) */
            dest = &dummy;
            min = 0;
            range = 54;
            goto numeric_range;
        case 'w':
            dest = &tm->tm_wday;
            min = 0;
            range = 7;
            goto numeric_range;
        case 'x':
            s = strptime(s, nl_langinfo(D_FMT), tm);
            if (!s)
                return 0;
            break;
        case 'X':
            s = strptime(s, nl_langinfo(T_FMT), tm);
            if (!s)
                return 0;
            break;
        case 'y':
            dest = &tm->tm_year;
            w = 2;
            want_century |= 1;
            goto numeric_digits;
        case 'Y':
            dest = &tm->tm_year;
            if (w < 0)
                w = 4;
            adj = 1900;
            want_century = 0;
            goto numeric_digits;
        case '%':
            if (*s++ != '%')
                return 0;
            break;
        default:
            return 0;
        numeric_range:
            if (!isdigit(*s))
                return 0;
            *dest = 0;
            for (i = 1; i <= min + range && isdigit(*s); i *= 10)
                *dest = *dest * 10 + *s++ - '0';
            if (*dest - min >= (unsigned)range)
                return 0;
            *dest -= adj;
            switch ((char*)dest - (char*)tm) { case offsetof(struct tm, tm_yday):; }
            goto update;
        numeric_digits:
            neg = 0;
            if (*s == '+')
                s++;
            else if (*s == '-')
                neg = 1, s++;
            if (!isdigit(*s))
                return 0;
            for (*dest = i = 0; i < w && isdigit(*s); i++)
                *dest = *dest * 10 + *s++ - '0';
            if (neg)
                *dest = -*dest;
            *dest -= adj;
            goto update;
        symbolic_range:
            for (i = 2 * range - 1; i >= 0; i--) {
                ex = nl_langinfo(min + i);
                len = strlen(ex);
                if (strncasecmp(s, ex, len))
                    continue;
                s += len;
                *dest = i % range;
                break;
            }
            if (i < 0)
                return 0;
            goto update;
        update:
            // FIXME
            ;
        }
    }
    if (want_century) {
        if (want_century & 2)
            tm->tm_year += century * 100 - 1900;
        else if (tm->tm_year <= 68)
            tm->tm_year += 100;
    }
    return (char*)s;
}