Add build system scaffolding and libc headers

1 files changed, 562 insertions, 0 deletions

diff --git a/lib/libc/time/strftime.c b/lib/libc/time/strftime.c
new file mode 100644
index 00000000..d359140b
--- /dev/null
+++ b/lib/libc/time/strftime.c
@@ -0,0 +1,562 @@
+#include <time.h>
+#include <libc.h>
+#include <string.h>
+
+static size_t append_string(char *restrict *s, size_t *remaining,
+			    const char *str)
+{
+	size_t len = strlen(str);
+	if (len >= *remaining) {
+		return 0;
+	}
+	strcpy(*s, str);
+	*s += len;
+	*remaining -= len;
+	return len;
+}
+
+static size_t append_char(char *restrict *s, size_t *remaining, char c)
+{
+	if (*remaining <= 1) {
+		return 0;
+	}
+	**s = c;
+	(*s)++;
+	(*remaining)--;
+	return 1;
+}
+
+static size_t format_int(char *restrict *s, size_t *remaining, int value,
+			 int width, char pad, int show_sign)
+{
+	char buffer[32];
+	char *ptr = buffer + sizeof(buffer) - 1;
+	*ptr = '\0';
+
+	int negative = 0;
+	if (value < 0) {
+		negative = 1;
+		value = -value;
+	}
+
+	do {
+		*--ptr = '0' + (value % 10);
+		value /= 10;
+	} while (value > 0);
+
+	if (negative) {
+		*--ptr = '-';
+	} else if (show_sign && value >= 0) {
+		*--ptr = '+';
+	}
+
+	int len = (buffer + sizeof(buffer) - 1) - ptr;
+
+	while (len < width) {
+		*--ptr = pad;
+		len++;
+	}
+
+	return append_string(s, remaining, ptr);
+}
+
+static const char *weekday_abbr[] = { "Sun", "Mon", "Tue", "Wed",
+				      "Thu", "Fri", "Sat" };
+static const char *weekday_full[] = { "Sunday",	   "Monday",   "Tuesday",
+				      "Wednesday", "Thursday", "Friday",
+				      "Saturday" };
+
+static const char *month_abbr[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+				    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
+static const char *month_full[] = { "January", "February", "March",
+				    "April",   "May",	   "June",
+				    "July",    "August",   "September",
+				    "October", "November", "December" };
+
+static int day_of_year(const struct tm *tm)
+{
+	static const int days_to_month[] = { 0,	  31,  59,  90,	 120, 151,
+					     181, 212, 243, 273, 304, 334 };
+	int days = days_to_month[tm->tm_mon] + tm->tm_mday;
+
+	if (tm->tm_mon > 1) {
+		int year = tm->tm_year + 1900;
+		if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
+			days++;
+		}
+	}
+	return days;
+}
+
+static int iso_week_number(const struct tm *tm, int *week_year)
+{
+	int year = tm->tm_year + 1900;
+	int yday = tm->tm_yday + 1;
+	int wday;
+
+	int jan4_wday = (4 + year + (year - 1) / 4 - (year - 1) / 100 +
+			 (year - 1) / 400) %
+			7;
+	if (jan4_wday == 0)
+		jan4_wday = 7;
+
+	int week1_start = 4 - jan4_wday + 1;
+
+	int week = (yday - week1_start + 7) / 7;
+
+	if (week < 1) {
+		*week_year = year - 1;
+
+		int prev_jan4_wday = (jan4_wday - 1 + 7) % 7;
+		if (prev_jan4_wday == 0)
+			prev_jan4_wday = 7;
+		int prev_week1_start = 4 - prev_jan4_wday + 1;
+		int prev_year_days = 365;
+		if (((year - 1) % 4 == 0 && (year - 1) % 100 != 0) ||
+		    ((year - 1) % 400 == 0)) {
+			prev_year_days = 366;
+		}
+		week = (prev_year_days - prev_week1_start + 8) / 7;
+	} else {
+		*week_year = year;
+
+		int year_days = 365;
+		if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
+			year_days = 366;
+		}
+		if (week1_start + (week - 1) * 7 > year_days - 3) {
+			if (yday > year_days - (7 - jan4_wday)) {
+				*week_year = year + 1;
+				week = 1;
+			}
+		}
+	}
+
+	return week;
+}
+
+size_t strftime(char *restrict s, size_t maxsize, const char *restrict format,
+		const struct tm *restrict timeptr)
+{
+	if (maxsize == 0)
+		return 0;
+
+	char *orig_s = s;
+	size_t remaining = maxsize - 1;
+	const char *ptr = format;
+
+	while (*ptr && remaining > 0) {
+		if (*ptr != '%') {
+			if (!append_char(&s, &remaining, *ptr)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			ptr++;
+			continue;
+		}
+
+		ptr++;
+		if (!*ptr)
+			break;
+
+		char pad_char = ' ';
+		int show_sign = 0;
+		int min_width = 0;
+
+		if (*ptr == '0') {
+			pad_char = '0';
+			ptr++;
+		} else if (*ptr == '+') {
+			pad_char = '0';
+			show_sign = 1;
+			ptr++;
+		}
+
+		while (*ptr >= '0' && *ptr <= '9') {
+			min_width = min_width * 10 + (*ptr - '0');
+			ptr++;
+		}
+
+		if (*ptr == 'E' || *ptr == 'O') {
+			ptr++;
+		}
+
+		switch (*ptr) {
+		case 'a':
+			if (!append_string(&s, &remaining,
+					   weekday_abbr[timeptr->tm_wday])) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'A':
+			if (!append_string(&s, &remaining,
+					   weekday_full[timeptr->tm_wday])) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'b':
+		case 'h':
+			if (!append_string(&s, &remaining,
+					   month_abbr[timeptr->tm_mon])) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'B':
+			if (!append_string(&s, &remaining,
+					   month_full[timeptr->tm_mon])) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'c':
+			if (!append_string(&s, &remaining,
+					   weekday_abbr[timeptr->tm_wday]) ||
+			    !append_char(&s, &remaining, ' ') ||
+			    !append_string(&s, &remaining,
+					   month_abbr[timeptr->tm_mon]) ||
+			    !append_char(&s, &remaining, ' ') ||
+			    !format_int(&s, &remaining, timeptr->tm_mday, 2,
+					' ', 0) ||
+			    !append_char(&s, &remaining, ' ') ||
+			    !format_int(&s, &remaining, timeptr->tm_hour, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_min, 2, '0',
+					0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_sec, 2, '0',
+					0) ||
+			    !append_char(&s, &remaining, ' ') ||
+			    !format_int(&s, &remaining, timeptr->tm_year + 1900,
+					4, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'C':
+			if (!format_int(&s, &remaining,
+					(timeptr->tm_year + 1900) / 100,
+					min_width ? min_width : 2, pad_char,
+					show_sign)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'd':
+			if (!format_int(&s, &remaining, timeptr->tm_mday, 2,
+					'0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'D':
+			if (!format_int(&s, &remaining, timeptr->tm_mon + 1, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, '/') ||
+			    !format_int(&s, &remaining, timeptr->tm_mday, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, '/') ||
+			    !format_int(&s, &remaining, timeptr->tm_year % 100,
+					2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'e':
+			if (!format_int(&s, &remaining, timeptr->tm_mday, 2,
+					' ', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'F': {
+			int width = min_width ? min_width - 6 : 4;
+			if (width < 4)
+				width = 4;
+			if (!format_int(&s, &remaining, timeptr->tm_year + 1900,
+					width, pad_char, show_sign) ||
+			    !append_char(&s, &remaining, '-') ||
+			    !format_int(&s, &remaining, timeptr->tm_mon + 1, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, '-') ||
+			    !format_int(&s, &remaining, timeptr->tm_mday, 2,
+					'0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'g': {
+			int week_year;
+			iso_week_number(timeptr, &week_year);
+			if (!format_int(&s, &remaining, week_year % 100, 2, '0',
+					0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'G': {
+			int week_year;
+			iso_week_number(timeptr, &week_year);
+			if (!format_int(&s, &remaining, week_year,
+					min_width ? min_width : 4, pad_char,
+					show_sign)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'H':
+			if (!format_int(&s, &remaining, timeptr->tm_hour, 2,
+					'0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'I': {
+			int hour12 = timeptr->tm_hour % 12;
+			if (hour12 == 0)
+				hour12 = 12;
+			if (!format_int(&s, &remaining, hour12, 2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'j':
+			if (!format_int(&s, &remaining, timeptr->tm_yday + 1, 3,
+					'0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'm':
+			if (!format_int(&s, &remaining, timeptr->tm_mon + 1, 2,
+					'0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'M':
+			if (!format_int(&s, &remaining, timeptr->tm_min, 2, '0',
+					0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'n':
+			if (!append_char(&s, &remaining, '\n')) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'p':
+			if (!append_string(&s, &remaining,
+					   timeptr->tm_hour < 12 ? "AM" :
+								   "PM")) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'r': {
+			int hour12 = timeptr->tm_hour % 12;
+			if (hour12 == 0)
+				hour12 = 12;
+			if (!format_int(&s, &remaining, hour12, 2, '0', 0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_min, 2, '0',
+					0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_sec, 2, '0',
+					0) ||
+			    !append_char(&s, &remaining, ' ') ||
+			    !append_string(&s, &remaining,
+					   timeptr->tm_hour < 12 ? "AM" :
+								   "PM")) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'R':
+			if (!format_int(&s, &remaining, timeptr->tm_hour, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_min, 2, '0',
+					0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 's':
+
+			if (!append_char(&s, &remaining, '0')) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'S':
+			if (!format_int(&s, &remaining, timeptr->tm_sec, 2, '0',
+					0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 't':
+			if (!append_char(&s, &remaining, '\t')) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'T':
+			if (!format_int(&s, &remaining, timeptr->tm_hour, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_min, 2, '0',
+					0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_sec, 2, '0',
+					0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'u': {
+			int wday = timeptr->tm_wday;
+			if (wday == 0)
+				wday = 7;
+			if (!format_int(&s, &remaining, wday, 1, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'U': {
+			int week =
+				(timeptr->tm_yday + 7 - timeptr->tm_wday) / 7;
+			if (!format_int(&s, &remaining, week, 2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'V': {
+			int week_year;
+			int week = iso_week_number(timeptr, &week_year);
+			if (!format_int(&s, &remaining, week, 2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'w':
+			if (!format_int(&s, &remaining, timeptr->tm_wday, 1,
+					'0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'W': {
+			int wday = timeptr->tm_wday;
+			if (wday == 0)
+				wday = 7;
+			int week = (timeptr->tm_yday + 7 - wday + 1) / 7;
+			if (!format_int(&s, &remaining, week, 2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'x':
+			if (!format_int(&s, &remaining, timeptr->tm_mon + 1, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, '/') ||
+			    !format_int(&s, &remaining, timeptr->tm_mday, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, '/') ||
+			    !format_int(&s, &remaining, timeptr->tm_year % 100,
+					2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'X':
+			if (!format_int(&s, &remaining, timeptr->tm_hour, 2,
+					'0', 0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_min, 2, '0',
+					0) ||
+			    !append_char(&s, &remaining, ':') ||
+			    !format_int(&s, &remaining, timeptr->tm_sec, 2, '0',
+					0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'y':
+			if (!format_int(&s, &remaining, timeptr->tm_year % 100,
+					2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'Y':
+			if (!format_int(&s, &remaining, timeptr->tm_year + 1900,
+					min_width ? min_width : 4, pad_char,
+					show_sign)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		case 'z': {
+			if (timeptr->tm_isdst < 0) {
+				break;
+			}
+			long offset = timeptr->tm_gmtoff;
+			char sign = '+';
+			if (offset < 0) {
+				sign = '-';
+				offset = -offset;
+			}
+			int hours = offset / 3600;
+			int minutes = (offset % 3600) / 60;
+			if (!append_char(&s, &remaining, sign) ||
+			    !format_int(&s, &remaining, hours, 2, '0', 0) ||
+			    !format_int(&s, &remaining, minutes, 2, '0', 0)) {
+				*orig_s = '\0';
+				return 0;
+			}
+		} break;
+		case 'Z':
+			if (timeptr->tm_zone) {
+				if (!append_string(&s, &remaining,
+						   timeptr->tm_zone)) {
+					*orig_s = '\0';
+					return 0;
+				}
+			}
+			break;
+		case '%':
+			if (!append_char(&s, &remaining, '%')) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		default:
+
+			if (!append_char(&s, &remaining, '%') ||
+			    !append_char(&s, &remaining, *ptr)) {
+				*orig_s = '\0';
+				return 0;
+			}
+			break;
+		}
+		ptr++;
+	}
+
+	*s = '\0';
+	return s - orig_s;
+}
+
+weak size_t strftime_l(char *restrict s, size_t maxsize,
+		       const char *restrict format,
+		       const struct tm *restrict timeptr,
+		       locale_t unused locale)
+{
+	return strftime(s, maxsize, format, timeptr);
+}