[rtems commit] clock:_TOD_To_seconds(): Fix year 2514 overflow

[Sebastian Huber]

Module:    rtems
Branch:    master
Commit:    7bbbe4225c92b646faa14e5f5800ed2feba09899
Changeset: http://git.rtems.org/rtems/commit/?id=7bbbe4225c92b646faa14e5f5800ed2feba09899

Author:    Frank Kühndel <frank.kuehndel at embedded-brains.de>
Date:      Thu Apr  8 15:41:15 2021 +0200

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

---

 cpukit/include/rtems/score/todimpl.h | 16 ++++++++++++++++
 cpukit/rtems/src/clocktodtoseconds.c |  2 +-
 cpukit/rtems/src/clocktodvalidate.c  |  1 +
 testsuites/sptests/sp2038/init.c     | 28 ++++++++++++++++++----------
 4 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/cpukit/include/rtems/score/todimpl.h b/cpukit/include/rtems/score/todimpl.h
index 9805ec0..316a56e 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 49ae257..86e89f8 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 d8af275..2685bfd 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;
 
diff --git a/testsuites/sptests/sp2038/init.c b/testsuites/sptests/sp2038/init.c
index a3f09d4..10850d9 100644
--- a/testsuites/sptests/sp2038/init.c
+++ b/testsuites/sptests/sp2038/init.c
@@ -149,8 +149,7 @@ static const uint32_t sample_seconds [] = {
   4168736895UL,
   4200272895UL,
   4231808895UL,
-  4263431295UL,
-  4294967295UL
+  4263431295UL
 };
 
 static const rtems_time_of_day nearly_problem_2038 = {
@@ -171,8 +170,8 @@ static const rtems_time_of_day problem_2038 = {
   .second = 8
 };
 
-static const rtems_time_of_day nearly_problem_2106 = {
-  .year = 2106,
+static const rtems_time_of_day tod_to_seconds_base = {
+  .year = 0,
   .month = 2,
   .day = 7,
   .hour = 6,
@@ -180,13 +179,22 @@ static const rtems_time_of_day nearly_problem_2106 = {
   .second = 15
 };
 
+static const rtems_time_of_day nearly_problem_2106 = {
+  .year = 2105,
+  .month = 12,
+  .day = 31,
+  .hour = 23,
+  .minute = 59,
+  .second = 59
+};
+
 static const rtems_time_of_day problem_2106 = {
   .year = 2106,
-  .month = 2,
-  .day = 7,
-  .hour = 6,
-  .minute = 28,
-  .second = 16
+  .month = 1,
+  .day = 1,
+  .hour = 0,
+  .minute = 0,
+  .second = 0
 };
 
 static const rtems_time_of_day problem_2100 = {
@@ -214,7 +222,7 @@ static void test_tod_to_seconds(void)
   size_t n = sizeof(sample_seconds) / sizeof(sample_seconds [0]);
 
   for (i = 0; i < n; ++i) {
-    rtems_time_of_day tod = nearly_problem_2106;
+    rtems_time_of_day tod = tod_to_seconds_base;
     uint32_t seconds = 0;
     rtems_interval seconds_as_interval = 0;