naruse	2018-11-26 01:23:18 +0900 (Mon, 26 Nov 2018)

  New Revision: 65974

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=65974

  Log:
    Normalize month-mday before finding epoch
    
    Especially over the year 2038, 30 Feb and so on may cause odd behavior
    on validating found epoch with given year-month-day [Bug #15340]

  Modified files:
    trunk/test/ruby/test_time.rb
    trunk/time.c
Index: time.c
===================================================================
--- time.c	(revision 65973)
+++ time.c	(revision 65974)
@@ -2876,6 +2876,29 @@ time_arg(int argc, const VALUE *argv, st https://github.com/ruby/ruby/blob/trunk/time.c#L2876
 	vtm->mday = obj2ubits(v[2], 5);
     }
 
+    /* normalize month-mday */
+    switch (vtm->mon) {
+      case 2:
+        {
+            /* this drops higher bits but it's not a problem to calc leap year */
+            unsigned int mday2 = leap_year_v_p(vtm->year) ? 29 : 28;
+            if (vtm->mday > mday2) {
+                vtm->mday -= mday2;
+                vtm->mon++;
+            }
+        }
+        break;
+      case 4:
+      case 6:
+      case 9:
+      case 11:
+        if (vtm->mday == 31) {
+            vtm->mon++;
+            vtm->mday = 1;
+        }
+        break;
+    }
+
     vtm->hour = NIL_P(v[3])?0:obj2ubits(v[3], 5);
 
     vtm->min  = NIL_P(v[4])?0:obj2ubits(v[4], 6);
Index: test/ruby/test_time.rb
===================================================================
--- test/ruby/test_time.rb	(revision 65973)
+++ test/ruby/test_time.rb	(revision 65974)
@@ -1056,6 +1056,29 @@ class TestTime < Test::Unit::TestCase https://github.com/ruby/ruby/blob/trunk/test/ruby/test_time.rb#L1056
       assert_equal(min, t.min)
       assert_equal(sec, t.sec)
     }
+    assert_equal(Time.local(2038,3,1), Time.local(2038,2,29))
+    assert_equal(Time.local(2038,3,2), Time.local(2038,2,30))
+    assert_equal(Time.local(2038,3,3), Time.local(2038,2,31))
+    assert_equal(Time.local(2040,2,29), Time.local(2040,2,29))
+    assert_equal(Time.local(2040,3,1), Time.local(2040,2,30))
+    assert_equal(Time.local(2040,3,2), Time.local(2040,2,31))
+    n = 2 ** 64
+    n += 400 - n % 400 # n is over 2^64 and multiple of 400
+    assert_equal(Time.local(n,2,29),Time.local(n,2,29))
+    assert_equal(Time.local(n,3,1), Time.local(n,2,30))
+    assert_equal(Time.local(n,3,2), Time.local(n,2,31))
+    n += 100
+    assert_equal(Time.local(n,3,1), Time.local(n,2,29))
+    assert_equal(Time.local(n,3,2), Time.local(n,2,30))
+    assert_equal(Time.local(n,3,3), Time.local(n,2,31))
+    n += 4
+    assert_equal(Time.local(n,2,29),Time.local(n,2,29))
+    assert_equal(Time.local(n,3,1), Time.local(n,2,30))
+    assert_equal(Time.local(n,3,2), Time.local(n,2,31))
+    n += 1
+    assert_equal(Time.local(n,3,1), Time.local(n,2,29))
+    assert_equal(Time.local(n,3,2), Time.local(n,2,30))
+    assert_equal(Time.local(n,3,3), Time.local(n,2,31))
   end
 
   def test_future

--
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