v25-0001-Disallow-compressed-data-inside-container-types.patch

From e6aaafe34f9fe4cbecbba2403a3d6248a12ca88d Mon Sep 17 00:00:00 2001
From: Dilip Kumar <dilipkumar@localhost.localdomain>
Date: Fri, 19 Feb 2021 17:57:05 +0530
Subject: [PATCH v25 1/3] Disallow compressed data inside container types

Currently, we have a general rule that Datums of container types
(rows, arrays, ranges, etc) must not contain any external TOAST
pointers.  But the rule for the compressed data is not defined
and no specific rule is followed e.g. while constructing the array
we decompress the comprassed field but while contructing the row
in some cases we don't decompress the compressed data whereas in
the other cases we onlle decompress while flattening the external
toast pointers.  This patch make a general rule for the compressed
data i.e. we don't allow the compressed data in the container type.
---
 src/backend/access/heap/heaptoast.c    |  4 +-
 src/backend/executor/execExprInterp.c  | 15 ++++++-
 src/backend/utils/adt/expandedrecord.c | 76 ++++++++++++----------------------
 3 files changed, 43 insertions(+), 52 deletions(-)

diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 55bbe1d..b094623 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -589,9 +589,9 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 			struct varlena *new_value;
 
 			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
+			if (VARATT_IS_EXTERNAL(new_value) || VARATT_IS_COMPRESSED(new_value))
 			{
-				new_value = detoast_external_attr(new_value);
+				new_value = detoast_attr(new_value);
 				new_values[i] = PointerGetDatum(new_value);
 				freeable_values[num_to_free++] = (Pointer) new_value;
 			}
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 6308286..5684a6d 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -2840,12 +2840,25 @@ ExecEvalRow(ExprState *state, ExprEvalStep *op)
 {
 	HeapTuple	tuple;
 
+	/* Retrieve externally stored values and decompress. */
+	for (int i = 0; i < op->d.row.tupdesc->natts; i++)
+	{
+		Form_pg_attribute attr = TupleDescAttr(op->d.row.tupdesc, i);
+
+		if (op->d.row.elemnulls[i] || attr->attlen != -1 ||
+			!(VARATT_IS_EXTERNAL((struct varlena *) DatumGetPointer(op->d.row.elemvalues[i])) ||
+			  VARATT_IS_COMPRESSED((struct varlena *) DatumGetPointer(op->d.row.elemvalues[i]))))
+			continue;
+		op->d.row.elemvalues[i] =
+			PointerGetDatum(PG_DETOAST_DATUM_PACKED(op->d.row.elemvalues[i]));
+	}
+
 	/* build tuple from evaluated field values */
 	tuple = heap_form_tuple(op->d.row.tupdesc,
 							op->d.row.elemvalues,
 							op->d.row.elemnulls);
 
-	*op->resvalue = HeapTupleGetDatum(tuple);
+	*op->resvalue = PointerGetDatum(tuple->t_data);
 	*op->resnull = false;
 }
 
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index e19491e..66031a5 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -673,14 +673,6 @@ ER_get_flat_size(ExpandedObjectHeader *eohptr)
 		erh->er_typmod = tupdesc->tdtypmod;
 	}
 
-	/*
-	 * If we have a valid flattened value without out-of-line fields, we can
-	 * just use it as-is.
-	 */
-	if (erh->flags & ER_FLAG_FVALUE_VALID &&
-		!(erh->flags & ER_FLAG_HAVE_EXTERNAL))
-		return erh->fvalue->t_len;
-
 	/* If we have a cached size value, believe that */
 	if (erh->flat_size)
 		return erh->flat_size;
@@ -693,38 +685,36 @@ ER_get_flat_size(ExpandedObjectHeader *eohptr)
 	tupdesc = erh->er_tupdesc;
 
 	/*
-	 * Composite datums mustn't contain any out-of-line values.
+	 * Composite datums mustn't contain any out-of-line/compressed values.
 	 */
-	if (erh->flags & ER_FLAG_HAVE_EXTERNAL)
+	for (i = 0; i < erh->nfields; i++)
 	{
-		for (i = 0; i < erh->nfields; i++)
-		{
-			Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
+		Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
 
-			if (!erh->dnulls[i] &&
-				!attr->attbyval && attr->attlen == -1 &&
-				VARATT_IS_EXTERNAL(DatumGetPointer(erh->dvalues[i])))
-			{
-				/*
-				 * expanded_record_set_field_internal can do the actual work
-				 * of detoasting.  It needn't recheck domain constraints.
-				 */
-				expanded_record_set_field_internal(erh, i + 1,
-												   erh->dvalues[i], false,
-												   true,
-												   false);
-			}
+		if (!erh->dnulls[i] &&
+			!attr->attbyval && attr->attlen == -1 &&
+			(VARATT_IS_EXTERNAL(DatumGetPointer(erh->dvalues[i])) ||
+			 VARATT_IS_COMPRESSED(DatumGetPointer(erh->dvalues[i]))))
+		{
+			/*
+				* expanded_record_set_field_internal can do the actual work
+				* of detoasting.  It needn't recheck domain constraints.
+				*/
+			expanded_record_set_field_internal(erh, i + 1,
+												erh->dvalues[i], false,
+												true,
+												false);
 		}
-
-		/*
-		 * We have now removed all external field values, so we can clear the
-		 * flag about them.  This won't cause ER_flatten_into() to mistakenly
-		 * take the fast path, since expanded_record_set_field() will have
-		 * cleared ER_FLAG_FVALUE_VALID.
-		 */
-		erh->flags &= ~ER_FLAG_HAVE_EXTERNAL;
 	}
 
+	/*
+	 * We have now removed all external field values, so we can clear the
+	 * flag about them.  This won't cause ER_flatten_into() to mistakenly
+	 * take the fast path, since expanded_record_set_field() will have
+	 * cleared ER_FLAG_FVALUE_VALID.
+	 */
+	erh->flags &= ~ER_FLAG_HAVE_EXTERNAL;
+
 	/* Test if we currently have any null values */
 	hasnull = false;
 	for (i = 0; i < erh->nfields; i++)
@@ -770,19 +760,6 @@ ER_flatten_into(ExpandedObjectHeader *eohptr,
 
 	Assert(erh->er_magic == ER_MAGIC);
 
-	/* Easy if we have a valid flattened value without out-of-line fields */
-	if (erh->flags & ER_FLAG_FVALUE_VALID &&
-		!(erh->flags & ER_FLAG_HAVE_EXTERNAL))
-	{
-		Assert(allocated_size == erh->fvalue->t_len);
-		memcpy(tuphdr, erh->fvalue->t_data, allocated_size);
-		/* The original flattened value might not have datum header fields */
-		HeapTupleHeaderSetDatumLength(tuphdr, allocated_size);
-		HeapTupleHeaderSetTypeId(tuphdr, erh->er_typeid);
-		HeapTupleHeaderSetTypMod(tuphdr, erh->er_typmod);
-		return;
-	}
-
 	/* Else allocation should match previous get_flat_size result */
 	Assert(allocated_size == erh->flat_size);
 
@@ -1155,11 +1132,12 @@ expanded_record_set_field_internal(ExpandedRecordHeader *erh, int fnumber,
 		if (expand_external)
 		{
 			if (attr->attlen == -1 &&
-				VARATT_IS_EXTERNAL(DatumGetPointer(newValue)))
+				(VARATT_IS_EXTERNAL(DatumGetPointer(newValue)) ||
+				 VARATT_IS_COMPRESSED(DatumGetPointer(newValue))))
 			{
 				/* Detoasting should be done in short-lived context. */
 				oldcxt = MemoryContextSwitchTo(get_short_term_cxt(erh));
-				newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
+				newValue = PointerGetDatum(detoast_attr((struct varlena *) DatumGetPointer(newValue)));
 				MemoryContextSwitchTo(oldcxt);
 			}
 			else
-- 
1.8.3.1