LibJS+LibC: Add tests for Date tuple ctor overflow and make mktime()/timegm() handle month overflow

3 files changed, 27 insertions, 3 deletions

diff --git a/Libraries/LibC/time.cpp b/Libraries/LibC/time.cpp
index a3fe523de2..018ccf6cda 100644
--- a/Libraries/LibC/time.cpp
+++ b/Libraries/LibC/time.cpp
@@ -103,6 +103,13 @@ static void time_to_tm(struct tm* tm, time_t t)
 
 static time_t tm_to_time(struct tm* tm, long timezone_adjust_seconds)
 {
+    tm->tm_year += tm->tm_mon / 12;
+    tm->tm_mon %= 12;
+    if (tm->tm_mon < 0) {
+        tm->tm_year--;
+        tm->tm_mon += 12;
+    }
+
     int days = 0;
     for (int year = 70; year < tm->tm_year; ++year)
         days += 365 + __is_leap_year(1900 + year);
@@ -110,7 +117,6 @@ static time_t tm_to_time(struct tm* tm, long timezone_adjust_seconds)
         days -= 365 + __is_leap_year(1900 + year);
 
     tm->tm_yday = tm->tm_mday - 1;
-    // FIXME: What if tm->tm_mon < 0 or tm->tm_mon > 12?
     for (int month = 0; month < tm->tm_mon; ++month)
         tm->tm_yday += __days_per_month[month];
     if (tm->tm_mon > 1 && __is_leap_year(1900 + tm->tm_year))
diff --git a/Libraries/LibJS/Runtime/DateConstructor.cpp b/Libraries/LibJS/Runtime/DateConstructor.cpp
index ec91f36897..583230c1b1 100644
--- a/Libraries/LibJS/Runtime/DateConstructor.cpp
+++ b/Libraries/LibJS/Runtime/DateConstructor.cpp
@@ -179,7 +179,6 @@ Value DateConstructor::construct(Interpreter& interpreter, Function&)
             value = parse_simplified_iso8601(value.as_string().string());
         // A timestamp since the epoch, in UTC.
         // FIXME: Date() probably should use a double as internal representation, so that NaN arguments and larger offsets are handled correctly.
-        // FIXME: DateTime::from_timestamp() seems to not support negative offsets.
         double value_as_double = value.to_double(interpreter);
         auto datetime = Core::DateTime::from_timestamp(static_cast<time_t>(value_as_double / 1000));
         auto milliseconds = static_cast<u16>(fmod(value_as_double, 1000));
@@ -187,7 +186,6 @@ Value DateConstructor::construct(Interpreter& interpreter, Function&)
     }
     // A date/time in components, in local time.
     // FIXME: This doesn't construct an "Invalid Date" object if one of the parameters is NaN.
-    // FIXME: This doesn't range-check args and convert months > 12 to year increments etc.
     auto arg_or = [&interpreter](size_t i, i32 fallback) { return interpreter.argument_count() > i ? interpreter.argument(i).to_i32(interpreter) : fallback; };
     int year = interpreter.argument(0).to_i32(interpreter);
     int month_index = interpreter.argument(1).to_i32(interpreter);
diff --git a/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js b/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js
index 8a5c0e09dc..f1194dd495 100644
--- a/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js
+++ b/Libraries/LibJS/Tests/builtins/Date/Date.UTC.js
@@ -25,3 +25,23 @@ test("basic functionality", () => {
 
     expect(Date.UTC(20000, 0)).toBe(568971820800000);
 });
+
+test("out of range", () => {
+    expect(Date.UTC(2020, -20)).toBe(1525132800000);
+    expect(Date.UTC(2020, 20)).toBe(1630454400000);
+
+    expect(Date.UTC(2020, 1, -10)).toBe(1579564800000);
+    expect(Date.UTC(2020, 1, 40)).toBe(1583884800000);
+
+    expect(Date.UTC(2020, 1, 15, -50)).toBe(1581544800000);
+    expect(Date.UTC(2020, 1, 15, 50)).toBe(1581904800000);
+
+    expect(Date.UTC(2020, 1, 15, 12, -123)).toBe(1581760620000);
+    expect(Date.UTC(2020, 1, 15, 12, 123)).toBe(1581775380000);
+
+    expect(Date.UTC(2020, 1, 15, 12, 30, -123)).toBe(1581769677000);
+    expect(Date.UTC(2020, 1, 15, 12, 30, 123)).toBe(1581769923000);
+
+    expect(Date.UTC(2020, 1, 15, 12, 30, 30, -2345)).toBe(1581769827655);
+    expect(Date.UTC(2020, 1, 15, 12, 30, 30, 2345)).toBe(1581769832345);
+});