MDEV-34621 Fix division by zero in mariadb-slap when iterations=0

mariadb-slap crashes with a floating point exception when run with
-iterations=0 due to division by zero in generate_stats(). This occurs
when calculating average timing by dividing by the number of iterations.

To fix this, the solution checks if iterations == 0 before performing
the division, and returns early from the function in such cases.

Author: KhaledR57

client/mysqlslap.c

@@ -2237,6 +2237,13 @@ generate_stats(conclusions *con, option_string *eng, stats *sptr)
   stats *ptr;
   unsigned int x;
 
+  if (eng && eng->string)
+    con->engine= eng->string;
+
+  /* Early return when iterations is 0 to avoid accessing uninitialized sptr */
+  if (iterations == 0)
+    return;
+
   con->min_timing= sptr->timing; 
   con->max_timing= sptr->timing;
   con->min_rows= sptr->rows;
@@ -2257,11 +2264,6 @@ generate_stats(conclusions *con, option_string *eng, stats *sptr)
       con->min_timing= ptr->timing;
   }
   con->avg_timing= con->avg_timing/iterations;
-
-  if (eng && eng->string)
-    con->engine= eng->string;
-  else
-    con->engine= NULL;
 }
 
 void

mysql-test/main/mysqlslap.result

@@ -260,3 +260,6 @@ DROP TABLE t1;
 #
 # Bug MDEV-15789 (Upstream: #80329): MYSQLSLAP OPTIONS --AUTO-GENERATE-SQL-GUID-PRIMARY and --AUTO-GENERATE-SQL-SECONDARY-INDEXES DONT WORK
 #
+#
+# Bug MDEV-34621: Fix division by zero in mariadb-slap when iterations=0
+#

mysql-test/main/mysqlslap.test

@@ -88,3 +88,9 @@ DROP TABLE t1;
 --exec $MYSQL_SLAP --concurrency=1 --silent --iterations=1 --number-int-cols=2 --number-char-cols=3 --auto-generate-sql --auto-generate-sql-guid-primary --create-schema=slap
 
 --exec $MYSQL_SLAP --concurrency=1 --silent --iterations=1 --number-int-cols=2 --number-char-cols=3 --auto-generate-sql --auto-generate-sql-secondary-indexes=1 --create-schema=slap
+
+--echo #
+--echo # Bug MDEV-34621: Fix division by zero in mariadb-slap when iterations=0
+--echo #
+
+--exec $MYSQL_SLAP -i0 --only-print