Fix varatt versus Datum type confusions

Macros like VARDATA() and VARSIZE() should be thought of as taking
values of type pointer to struct varlena or some other related struct.
The way they are implemented, you can pass anything to it and it will
cast it right.  But this is in principle incorrect.  To fix, add the
required DatumGetPointer() calls.  Or in a couple of cases, remove
superfluous PointerGetDatum() calls.

It is planned in a subsequent patch to change macros like VARDATA()
and VARSIZE() to inline functions, which will enforce stricter typing.
This is in preparation for that.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/928ea48f-77c6-417b-897c-621ef16685a6%40eisentraut.org

src/backend/access/brin/brin_minmax_multi.c

@@ -624,7 +624,7 @@ brin_range_serialize(Ranges *range)
 
 		for (i = 0; i < nvalues; i++)
 		{
-			len += VARSIZE_ANY(range->values[i]);
+			len += VARSIZE_ANY(DatumGetPointer(range->values[i]));
 		}
 	}
 	else if (typlen == -2)		/* cstring */

src/backend/access/common/heaptuple.c

@@ -189,7 +189,7 @@ getmissingattr(TupleDesc tupleDesc,
 			if (att->attlen > 0)
 				key.len = att->attlen;
 			else
-				key.len = VARSIZE_ANY(attrmiss->am_value);
+				key.len = VARSIZE_ANY(DatumGetPointer(attrmiss->am_value));
 			key.value = attrmiss->am_value;
 
 			entry = hash_search(missing_cache, &key, HASH_ENTER, &found);
@@ -901,9 +901,9 @@ expand_tuple(HeapTuple *targetHeapTuple,
 												  att->attlen,
 												  attrmiss[attnum].am_value);
 
-				targetDataLen = att_addlength_pointer(targetDataLen,
-													  att->attlen,
-													  attrmiss[attnum].am_value);
+				targetDataLen = att_addlength_datum(targetDataLen,
+													att->attlen,
+													attrmiss[attnum].am_value);
 			}
 			else
 			{

src/backend/access/common/reloptions.c

@@ -1190,8 +1190,8 @@ transformRelOptions(Datum oldOptions, List *defList, const char *namspace,
 
 		for (i = 0; i < noldoptions; i++)
 		{
-			char	   *text_str = VARDATA(oldoptions[i]);
-			int			text_len = VARSIZE(oldoptions[i]) - VARHDRSZ;
+			char	   *text_str = VARDATA(DatumGetPointer(oldoptions[i]));
+			int			text_len = VARSIZE(DatumGetPointer(oldoptions[i])) - VARHDRSZ;
 
 			/* Search for a match in defList */
 			foreach(cell, defList)
@@ -1456,8 +1456,8 @@ parseRelOptionsInternal(Datum options, bool validate,
 
 	for (i = 0; i < noptions; i++)
 	{
-		char	   *text_str = VARDATA(optiondatums[i]);
-		int			text_len = VARSIZE(optiondatums[i]) - VARHDRSZ;
+		char	   *text_str = VARDATA(DatumGetPointer(optiondatums[i]));
+		int			text_len = VARSIZE(DatumGetPointer(optiondatums[i])) - VARHDRSZ;
 		int			j;
 
 		/* Search for a match in reloptions */

src/backend/access/common/toast_internals.c

@@ -144,7 +144,7 @@ toast_save_datum(Relation rel, Datum value,
 	int			num_indexes;
 	int			validIndex;
 
-	Assert(!VARATT_IS_EXTERNAL(value));
+	Assert(!VARATT_IS_EXTERNAL(dval));
 
 	/*
 	 * Open the toast relation and its indexes.  We can use the index to check

src/backend/access/gin/gininsert.c

@@ -2233,7 +2233,7 @@ _gin_build_tuple(OffsetNumber attrnum, unsigned char category,
 	else if (typlen > 0)
 		keylen = typlen;
 	else if (typlen == -1)
-		keylen = VARSIZE_ANY(key);
+		keylen = VARSIZE_ANY(DatumGetPointer(key));
 	else if (typlen == -2)
 		keylen = strlen(DatumGetPointer(key)) + 1;
 	else

src/backend/access/spgist/spgutils.c

@@ -785,7 +785,7 @@ SpGistGetInnerTypeSize(SpGistTypeDesc *att, Datum datum)
 	else if (att->attlen > 0)
 		size = att->attlen;
 	else
-		size = VARSIZE_ANY(datum);
+		size = VARSIZE_ANY(DatumGetPointer(datum));
 
 	return MAXALIGN(size);
 }
@@ -804,7 +804,7 @@ memcpyInnerDatum(void *target, SpGistTypeDesc *att, Datum datum)
 	}
 	else
 	{
-		size = (att->attlen > 0) ? att->attlen : VARSIZE_ANY(datum);
+		size = (att->attlen > 0) ? att->attlen : VARSIZE_ANY(DatumGetPointer(datum));
 		memcpy(target, DatumGetPointer(datum), size);
 	}
 }

src/backend/access/table/toast_helper.c

@@ -330,7 +330,7 @@ toast_delete_external(Relation rel, const Datum *values, const bool *isnull,
 
 			if (isnull[i])
 				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(value))
+			else if (VARATT_IS_EXTERNAL_ONDISK(DatumGetPointer(value)))
 				toast_delete_datum(rel, value, is_speculative);
 		}
 	}