commit b42df63c757bf5ff715052a401aba37691a7e2b8
Author: anastasia <a.lubennikova@postgrespro.ru>
Date:   Wed Nov 25 17:19:33 2020 +0300

    Handle negative number of tuples passed to normal_rand()
    
    The function converts the first argument i.e. the number of tuples to
    return into an unsigned integer which turns out to be huge number when a
    negative value is passed. This causes the function to take much longer
    time to execute. Instead throw an error about invalid parameter value.
    
    While at it, improve SQL test to test the number of tuples returned by
    this function.
    
    Authors: Ashutosh Bapat, Anastasia Lubennikova

diff --git a/contrib/tablefunc/expected/tablefunc.out b/contrib/tablefunc/expected/tablefunc.out
index fffadc6e1b4..97bfd690841 100644
--- a/contrib/tablefunc/expected/tablefunc.out
+++ b/contrib/tablefunc/expected/tablefunc.out
@@ -3,10 +3,20 @@ CREATE EXTENSION tablefunc;
 -- normal_rand()
 -- no easy way to do this for regression testing
 --
-SELECT avg(normal_rand)::int FROM normal_rand(100, 250, 0.2);
- avg 
------
- 250
+SELECT avg(normal_rand)::int, count(*) FROM normal_rand(100, 250, 0.2);
+ avg | count 
+-----+-------
+ 250 |   100
+(1 row)
+
+-- negative number of tuples
+SELECT avg(normal_rand)::int, count(*) FROM normal_rand(-1, 250, 0.2);
+ERROR:  invalid number of tuples: -1
+-- zero number of tuples
+SELECT avg(normal_rand)::int, count(*) FROM normal_rand(0, 250, 0.2);
+ avg | count 
+-----+-------
+     |     0
 (1 row)
 
 --
diff --git a/contrib/tablefunc/sql/tablefunc.sql b/contrib/tablefunc/sql/tablefunc.sql
index ec375b05c63..5341c005f91 100644
--- a/contrib/tablefunc/sql/tablefunc.sql
+++ b/contrib/tablefunc/sql/tablefunc.sql
@@ -4,7 +4,11 @@ CREATE EXTENSION tablefunc;
 -- normal_rand()
 -- no easy way to do this for regression testing
 --
-SELECT avg(normal_rand)::int FROM normal_rand(100, 250, 0.2);
+SELECT avg(normal_rand)::int, count(*) FROM normal_rand(100, 250, 0.2);
+-- negative number of tuples
+SELECT avg(normal_rand)::int, count(*) FROM normal_rand(-1, 250, 0.2);
+-- zero number of tuples
+SELECT avg(normal_rand)::int, count(*) FROM normal_rand(0, 250, 0.2);
 
 --
 -- crosstab()
diff --git a/contrib/tablefunc/tablefunc.c b/contrib/tablefunc/tablefunc.c
index 02f02eab574..c6d32d46f01 100644
--- a/contrib/tablefunc/tablefunc.c
+++ b/contrib/tablefunc/tablefunc.c
@@ -174,6 +174,7 @@ normal_rand(PG_FUNCTION_ARGS)
 	FuncCallContext *funcctx;
 	uint64		call_cntr;
 	uint64		max_calls;
+	int32		num_tuples;
 	normal_rand_fctx *fctx;
 	float8		mean;
 	float8		stddev;
@@ -193,7 +194,14 @@ normal_rand(PG_FUNCTION_ARGS)
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 
 		/* total number of tuples to be returned */
-		funcctx->max_calls = PG_GETARG_UINT32(0);
+		num_tuples = PG_GETARG_INT32(0);
+
+		if (num_tuples < 0)
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("invalid number of tuples: %d", num_tuples)));
+
+		funcctx->max_calls = num_tuples;
 
 		/* allocate memory for user context */
 		fctx = (normal_rand_fctx *) palloc(sizeof(normal_rand_fctx));