Switch some palloc/memset calls to palloc0

Some code paths have been doing some allocations followed by an
immediate memset() to initialize the allocated area with zeros, this is
a bit overkill as there are already interfaces to do both things in one
call.

Author: Daniel Gustafsson
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/vN0OodBPkKs7g2Z1uyk3CUEmhdtspHgYCImhlmSxv1Xn6nY1ZnaaGHL8EWUIQ-NEv36tyc4G5-uA3UXUF2l4sFXtK_EQgLN1hcgunlFVKhA=@yesql.se

contrib/tablefunc/tablefunc.c

@@ -867,11 +867,8 @@ get_crosstab_tuplestore(char *sql,
 							   "tuple has %d columns but crosstab " \
 							   "returns %d.", tupdesc->natts, result_ncols)));
 
-		/* allocate space */
-		values = (char **) palloc(result_ncols * sizeof(char *));
-
-		/* and make sure it's clear */
-		memset(values, '\0', result_ncols * sizeof(char *));
+		/* allocate space and make sure it's clear */
+		values = (char **) palloc0(result_ncols * sizeof(char *));
 
 		for (i = 0; i < proc; i++)
 		{

src/backend/access/gist/gist.c

@@ -43,8 +43,7 @@ static void gistprunepage(Relation rel, Page page, Buffer buffer,
 
 
 #define ROTATEDIST(d) do { \
-	SplitedPageLayout *tmp=(SplitedPageLayout*)palloc(sizeof(SplitedPageLayout)); \
-	memset(tmp,0,sizeof(SplitedPageLayout)); \
+	SplitedPageLayout *tmp=(SplitedPageLayout*)palloc0(sizeof(SplitedPageLayout)); \
 	tmp->block.blkno = InvalidBlockNumber;	\
 	tmp->buffer = InvalidBuffer;	\
 	tmp->next = (d); \

src/bin/pg_dump/pg_backup_archiver.c

@@ -1382,8 +1382,7 @@ SortTocFromFile(Archive *AHX)
 	bool		incomplete_line;
 
 	/* Allocate space for the 'wanted' array, and init it */
-	ropt->idWanted = (bool *) pg_malloc(sizeof(bool) * AH->maxDumpId);
-	memset(ropt->idWanted, 0, sizeof(bool) * AH->maxDumpId);
+	ropt->idWanted = (bool *) pg_malloc0(sizeof(bool) * AH->maxDumpId);
 
 	/* Setup the file */
 	fh = fopen(ropt->tocFile, PG_BINARY_R);

src/bin/pg_dump/pg_dump_sort.c

@@ -320,8 +320,7 @@ TopoSort(DumpableObject **objs,
 	 * We also make a map showing the input-order index of the item with
 	 * dumpId j.
 	 */
-	beforeConstraints = (int *) pg_malloc((maxDumpId + 1) * sizeof(int));
-	memset(beforeConstraints, 0, (maxDumpId + 1) * sizeof(int));
+	beforeConstraints = (int *) pg_malloc0((maxDumpId + 1) * sizeof(int));
 	idMap = (int *) pg_malloc((maxDumpId + 1) * sizeof(int));
 	for (i = 0; i < numObjs; i++)
 	{

src/bin/pgbench/pgbench.c

@@ -5301,8 +5301,7 @@ main(int argc, char **argv)
 	else if ((env = getenv("PGUSER")) != NULL && *env != '\0')
 		login = env;
 
-	state = (CState *) pg_malloc(sizeof(CState));
-	memset(state, 0, sizeof(CState));
+	state = (CState *) pg_malloc0(sizeof(CState));
 
 	/* set random seed early, because it may be used while parsing scripts. */
 	if (!set_random_seed(getenv("PGBENCH_RANDOM_SEED")))