Add a "fork" of musl as //fusl.

fusl/src/time/strftime.c

Index: fusl/src/time/strftime.c
diff --git a/fusl/src/time/strftime.c b/fusl/src/time/strftime.c
new file mode 100644
index 0000000000000000000000000000000000000000..f1ccc4dd5e848c734767f34f206daf9b173675df
--- /dev/null
+++ b/fusl/src/time/strftime.c
@@ -0,0 +1,274 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <langinfo.h>
+#include <locale.h>
+#include <time.h>
+#include <limits.h>
+#include "locale_impl.h"
+#include "libc.h"
+#include "time_impl.h"
+
+const char *__nl_langinfo_l(nl_item, locale_t);
+
+static int is_leap(int y)
+{
+	/* Avoid overflow */
+	if (y>INT_MAX-1900) y -= 2000;
+	y += 1900;
+	return !(y%4) && ((y%100) || !(y%400));
+}
+
+static int week_num(const struct tm *tm)
+{
+	int val = (tm->tm_yday + 7U - (tm->tm_wday+6U)%7) / 7;
+	/* If 1 Jan is just 1-3 days past Monday,
+	 * the previous week is also in this year. */
+	if ((tm->tm_wday + 371U - tm->tm_yday - 2) % 7 <= 2)
+		val++;
+	if (!val) {
+		val = 52;
+		/* If 31 December of prev year a Thursday,
+		 * or Friday of a leap year, then the
+		 * prev year has 53 weeks. */
+		int dec31 = (tm->tm_wday + 7U - tm->tm_yday - 1) % 7;
+		if (dec31 == 4 || (dec31 == 5 && is_leap(tm->tm_year%400-1)))
+			val++;
+	} else if (val == 53) {
+		/* If 1 January is not a Thursday, and not
+		 * a Wednesday of a leap year, then this
+		 * year has only 52 weeks. */
+		int jan1 = (tm->tm_wday + 371U - tm->tm_yday) % 7;
+		if (jan1 != 4 && (jan1 != 3 || !is_leap(tm->tm_year)))
+			val = 1;
+	}
+	return val;
+}
+
+const char *__tm_to_tzname(const struct tm *);
+size_t __strftime_l(char *restrict, size_t, const char *restrict, const struct tm *restrict, locale_t);
+
+const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc)
+{
+	nl_item item;
+	long long val;
+	const char *fmt = "-";
+	int width = 2;
+
+	switch (f) {
+	case 'a':
+		if (tm->tm_wday > 6U) goto string;
+		item = ABDAY_1 + tm->tm_wday;
+		goto nl_strcat;
+	case 'A':
+		if (tm->tm_wday > 6U) goto string;
+		item = DAY_1 + tm->tm_wday;
+		goto nl_strcat;
+	case 'h':
+	case 'b':
+		if (tm->tm_mon > 11U) goto string;
+		item = ABMON_1 + tm->tm_mon;
+		goto nl_strcat;
+	case 'B':
+		if (tm->tm_mon > 11U) goto string;
+		item = MON_1 + tm->tm_mon;
+		goto nl_strcat;
+	case 'c':
+		item = D_T_FMT;
+		goto nl_strftime;
+	case 'C':
+		val = (1900LL+tm->tm_year) / 100;
+		goto number;
+	case 'd':
+		val = tm->tm_mday;
+		goto number;
+	case 'D':
+		fmt = "%m/%d/%y";
+		goto recu_strftime;
+	case 'e':
+		*l = snprintf(*s, sizeof *s, "%2d", tm->tm_mday);
+		return *s;
+	case 'F':
+		fmt = "%Y-%m-%d";
+		goto recu_strftime;
+	case 'g':
+	case 'G':
+		val = tm->tm_year + 1900LL;
+		if (tm->tm_yday < 3 && week_num(tm) != 1) val--;
+		else if (tm->tm_yday > 360 && week_num(tm) == 1) val++;
+		if (f=='g') val %= 100;
+		else width = 4;
+		goto number;
+	case 'H':
+		val = tm->tm_hour;
+		goto number;
+	case 'I':
+		val = tm->tm_hour;
+		if (!val) val = 12;
+		else if (val > 12) val -= 12;
+		goto number;
+	case 'j':
+		val = tm->tm_yday+1;
+		width = 3;
+		goto number;
+	case 'm':
+		val = tm->tm_mon+1;
+		goto number;
+	case 'M':
+		val = tm->tm_min;
+		goto number;
+	case 'n':
+		*l = 1;
+		return "\n";
+	case 'p':
+		item = tm->tm_hour >= 12 ? PM_STR : AM_STR;
+		goto nl_strcat;
+	case 'r':
+		item = T_FMT_AMPM;
+		goto nl_strftime;
+	case 'R':
+		fmt = "%H:%M";
+		goto recu_strftime;
+	case 's':
+		val = __tm_to_secs(tm) - tm->__tm_gmtoff;
+		width = 1;
+		goto number;
+	case 'S':
+		val = tm->tm_sec;
+		goto number;
+	case 't':
+		*l = 1;
+		return "\t";
+	case 'T':
+		fmt = "%H:%M:%S";
+		goto recu_strftime;
+	case 'u':
+		val = tm->tm_wday ? tm->tm_wday : 7;
+		width = 1;
+		goto number;
+	case 'U':
+		val = (tm->tm_yday + 7U - tm->tm_wday) / 7;
+		goto number;
+	case 'W':
+		val = (tm->tm_yday + 7U - (tm->tm_wday+6U)%7) / 7;
+		goto number;
+	case 'V':
+		val = week_num(tm);
+		goto number;
+	case 'w':
+		val = tm->tm_wday;
+		width = 1;
+		goto number;
+	case 'x':
+		item = D_FMT;
+		goto nl_strftime;
+	case 'X':
+		item = T_FMT;
+		goto nl_strftime;
+	case 'y':
+		val = tm->tm_year % 100;
+		goto number;
+	case 'Y':
+		val = tm->tm_year + 1900LL;
+		if (val >= 10000) {
+			*l = snprintf(*s, sizeof *s, "+%lld", val);
+			return *s;
+		}
+		width = 4;
+		goto number;
+	case 'z':
+		if (tm->tm_isdst < 0) {
+			*l = 0;
+			return "";
+		}
+		*l = snprintf(*s, sizeof *s, "%+.2d%.2d",
+			(tm->__tm_gmtoff)/3600,
+			abs(tm->__tm_gmtoff%3600)/60);
+		return *s;
+	case 'Z':
+		if (tm->tm_isdst < 0) {
+			*l = 0;
+			return "";
+		}
+		fmt = __tm_to_tzname(tm);
+		goto string;
+	case '%':
+		*l = 1;
+		return "%";
+	default:
+		return 0;
+	}
+number:
+	*l = snprintf(*s, sizeof *s, "%0*lld", width, val);
+	return *s;
+nl_strcat:
+	fmt = __nl_langinfo_l(item, loc);
+string:
+	*l = strlen(fmt);
+	return fmt;
+nl_strftime:
+	fmt = __nl_langinfo_l(item, loc);
+recu_strftime:
+	*l = __strftime_l(*s, sizeof *s, fmt, tm, loc);
+	if (!*l) return 0;
+	return *s;
+}
+
+size_t __strftime_l(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm, locale_t loc)
+{
+	size_t l, k;
+	char buf[100];
+	char *p;
+	const char *t;
+	int plus;
+	unsigned long width;
+	for (l=0; l<n; f++) {
+		if (!*f) {
+			s[l] = 0;
+			return l;
+		}
+		if (*f != '%') {
+			s[l++] = *f;
+			continue;
+		}
+		f++;
+		if ((plus = (*f == '+'))) f++;
+		width = strtoul(f, &p, 10);
+		if (*p == 'C' || *p == 'F' || *p == 'G' || *p == 'Y') {
+			if (!width && p!=f) width = 1;
+		} else {
+			width = 0;
+		}
+		f = p;
+		if (*f == 'E' || *f == 'O') f++;
+		t = __strftime_fmt_1(&buf, &k, *f, tm, loc);
+		if (!t) break;
+		if (width) {
+			for (; *t=='+' || *t=='-' || (*t=='0'&&t[1]); t++, k--);
+			width--;
+			if (plus && tm->tm_year >= 10000-1900)
+				s[l++] = '+';
+			else if (tm->tm_year < -1900)
+				s[l++] = '-';
+			else
+				width++;
+			for (; width > k && l < n; width--)
+				s[l++] = '0';
+		}
+		if (k > n-l) k = n-l;
+		memcpy(s+l, t, k);
+		l += k;
+	}
+	if (n) {
+		if (l==n) l=n-1;
+		s[l] = 0;
+	}
+	return 0;
+}
+
+size_t strftime(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm)
+{
+	return __strftime_l(s, n, f, tm, CURRENT_LOCALE);
+}
+
+weak_alias(__strftime_l, strftime_l);