Fix Bug #9191 "TIMESTAMP/from_unixtime() no longer accepts 2^31-1"

(4.1 version, with post-review fixes)
  
  The fix for another Bug (6439) limited FROM_UNIXTIME() to
  TIMESTAMP_MAX_VALUE which is 2145916799 or 2037-12-01 23:59:59 GMT,
  however unix timestamp in general is not considered to be limited 
  by this value. All dates up to power(2,31)-1 are valid.
  
  This patch extends allowed TIMESTAMP range so, that max
  TIMESTAMP value is power(2,31)-1. It also corrects
  FROM_UNIXTIME() and UNIX_TIMESTAMP() functions, so that
  max allowed UNIX_TIMESTAMP() is power(2,31)-1. FROM_UNIXTIME()
  is fixed accordingly to allow conversion of dates up to
  2038-01-19 03:14:07 UTC. The patch also fixes CONVERT_TZ()
  function to allow extended range of dates.
  
  The main problem solved in the patch is possible overflows
  of variables, used in broken-time representation to time_t
  conversion (required for UNIX_TIMESTAMP).

1 files changed, 32 insertions, 0 deletions

diff --git a/include/my_time.h b/include/my_time.h
index 94701e159c4..dd149d19b10 100644
--- a/include/my_time.h
+++ b/include/my_time.h
@@ -38,6 +38,14 @@ typedef long my_time_t;
 #define MY_TIME_T_MAX LONG_MAX
 #define MY_TIME_T_MIN LONG_MIN
 
+
+/* Time handling defaults */
+#define TIMESTAMP_MAX_YEAR 2038
+#define YY_PART_YEAR	   70
+#define TIMESTAMP_MIN_YEAR (1900 + YY_PART_YEAR - 1)
+#define TIMESTAMP_MAX_VALUE INT_MAX32
+#define TIMESTAMP_MIN_VALUE 1
+
 #define YY_PART_YEAR	   70
 
 /* Flags to str_to_datetime */
@@ -55,6 +63,30 @@ long calc_daynr(uint year,uint month,uint day);
 
 void init_time(void);
 
+
+/*
+  Function to check sanity of a TIMESTAMP value
+
+  DESCRIPTION
+    Check if a given MYSQL_TIME value fits in TIMESTAMP range.
+    This function doesn't make precise check, but rather a rough
+    estimate.
+
+  RETURN VALUES
+    FALSE   The value seems sane
+    TRUE    The MYSQL_TIME value is definitely out of range
+*/
+
+static inline bool validate_timestamp_range(const MYSQL_TIME *t)
+{
+  if ((t->year > TIMESTAMP_MAX_YEAR || t->year < TIMESTAMP_MIN_YEAR) ||
+      (t->year == TIMESTAMP_MAX_YEAR && (t->month > 1 || t->day > 19)) ||
+      (t->year == TIMESTAMP_MIN_YEAR && (t->month < 12 || t->day < 31)))
+    return FALSE;
+
+  return TRUE;
+}
+
 my_time_t 
 my_system_gmt_sec(const MYSQL_TIME *t, long *my_timezone, bool *in_dst_time_gap);