clock:_TOD_To_seconds(): Fix year 2514 overflow

This patch fixes issue #4338 by changing _TOD_Validate()
to only accept years till 2105. This requires another patch
to change the documentation of rtems_clock_set() and other
affected API functions (indicating the end date is 2105 not 2514).

I tried to support till year 2514 but it turned out that
this needs changing the Timer Manager too. That in turn
would mean to change _TOD_Seconds_since_epoch( void )
from 32 to 64 bit. Sebastian pointed out that a naive extension
leads to trouble with 32 bit processors. He deemed a safe
re-implementation too costly performance wise considering
that year 2106 is far away and current binaries using RTEMS
Classic API are unlikely to be in use by 2106.

The constant TOD_SECONDS_AT_2100_03_01_00_00 in
cpukit/rtems/src/clocktodtoseconds.c happens to be wrong by
1 hour. When setting the date 2100-Feb-28 23:59:59 and then
reading the date again you will find yourself in 2100-Feb-27.

Update #4338

3 files changed, 18 insertions, 1 deletions

diff --git a/cpukit/include/rtems/score/todimpl.h b/cpukit/include/rtems/score/todimpl.h
index 9805ec0dfd..316a56ec74 100644
--- a/cpukit/include/rtems/score/todimpl.h
+++ b/cpukit/include/rtems/score/todimpl.h
@@ -124,6 +124,22 @@ extern "C" {
 #define TOD_BASE_YEAR 1988
 
 /**
+ *  @brief Latest year to which a time of day can be initialized.
+ *
+ *  The following constant defines the latest year to which an
+ *  RTEMS time of day can be set using rtems_clock_set().
+ *
+ *  32 bits can accept as latest point in time 2106-Feb-7 6:28:15
+ *  but to simplify the implementation, is was decided to only
+ *  check that the year is not greater than the year of this constant.
+ *
+ *  The internal realtime clock can run centuries longer but in
+ *  contrast to the POSIX API, the RTEMS Classic API does not
+ *  support this for efficiency reasons.
+ */
+#define TOD_LATEST_YEAR 2105
+
+/**
  * @addtogroup RTEMSScoreTOD
  *
  * This handler encapsulates functionality used to manage time of day.
diff --git a/cpukit/rtems/src/clocktodtoseconds.c b/cpukit/rtems/src/clocktodtoseconds.c
index 49ae257243..86e89f86eb 100644
--- a/cpukit/rtems/src/clocktodtoseconds.c
+++ b/cpukit/rtems/src/clocktodtoseconds.c
@@ -23,7 +23,7 @@
 #include <rtems/rtems/clockimpl.h>
 #include <rtems/score/todimpl.h>
 
-#define TOD_SECONDS_AT_2100_03_01_00_00 4107538800UL
+#define TOD_SECONDS_AT_2100_03_01_00_00 4107542400UL
 
 /*
  *  The following array contains the number of days in all months
diff --git a/cpukit/rtems/src/clocktodvalidate.c b/cpukit/rtems/src/clocktodvalidate.c
index d8af275d04..2685bfd6e7 100644
--- a/cpukit/rtems/src/clocktodvalidate.c
+++ b/cpukit/rtems/src/clocktodvalidate.c
@@ -52,6 +52,7 @@ bool _TOD_Validate(
       (the_tod->month  == 0)                      ||
       (the_tod->month  >  TOD_MONTHS_PER_YEAR)    ||
       (the_tod->year   <  TOD_BASE_YEAR)          ||
+      (the_tod->year   >  TOD_LATEST_YEAR)        ||
       (the_tod->day    == 0) )
      return false;