Add build system scaffolding and libc headers

1 files changed, 58 insertions, 0 deletions

diff --git a/lib/libc/time/tzset.c b/lib/libc/time/tzset.c
new file mode 100644
index 00000000..96f33702
--- /dev/null
+++ b/lib/libc/time/tzset.c
@@ -0,0 +1,58 @@
+#include <time.h>
+#include <ctype.h>
+
+int daylight = 0;
+long timezone = 0;
+char *tzname[2] = { "UTC", "UTC" };
+
+void tzset(void)
+{
+	const char *tz = NULL; // getenv("TZ");
+
+	if (tz == NULL || *tz == '\0') {
+		timezone = 0;
+		daylight = 0;
+		tzname[0] = tzname[1] = "UTC";
+		return;
+	}
+
+	const char *p = tz;
+	char sign = 0;
+	int hours = 0, mins = 0;
+
+	static char stdname[8];
+	int i = 0;
+	while (*p && !isdigit((unsigned char)*p) && *p != '+' && *p != '-' &&
+	       i < 7) {
+		stdname[i++] = *p++;
+	}
+
+	stdname[i] = '\0';
+	if (stdname[0])
+		tzname[0] = stdname;
+	else
+		tzname[0] = "LCL";
+
+	if (*p == '+' || *p == '-')
+		sign = *p++;
+
+	while (isdigit((unsigned char)*p))
+		hours = hours * 10 + (*p++ - '0');
+
+	if (*p == ':') {
+		p++;
+		while (isdigit((unsigned char)*p))
+			mins = mins * 10 + (*p++ - '0');
+	}
+
+	int total = hours * 3600 + mins * 60;
+	if (sign == '+')
+		timezone = -total;
+	else if (sign == '-')
+		timezone = total;
+	else
+		timezone = 0;
+
+	daylight = 0;
+	tzname[1] = tzname[0];
+}