Make ExecGetInsertedCols() and friends more robust and improve comments.

If ExecGetInsertedCols(), ExecGetUpdatedCols() or ExecGetExtraUpdatedCols()
were called with a ResultRelInfo that's not in the range table and isn't a
partition routing target, the functions would dereference a NULL pointer,
relinfo->ri_RootResultRelInfo. Such ResultRelInfos are created when firing
RI triggers in tables that are not modified directly. None of the current
callers of these functions pass such relations, so this isn't a live bug,
but let's make them more robust.

Also update comment in ResultRelInfo; after commit 6214e2b228,
ri_RangeTableIndex is zero for ResultRelInfos created for partition tuple
routing.

Noted by Coverity. Backpatch down to v11, like commit 6214e2b228.

Reviewed-by: Tom Lane, Amit Langote

diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index 57771ba78f7ad9fe9f60cb12006ab883dd45db19..fe4925f506e579ac15dea81b7e62902399fee61a 100644 (file)
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -1210,10 +1210,10 @@ Bitmapset *
 ExecGetInsertedCols(ResultRelInfo *relinfo, EState *estate)
 {
    /*
-    * The columns are stored in the range table entry. If this ResultRelInfo
-    * doesn't have an entry in the range table (i.e. if it represents a
-    * partition routing target), fetch the parent's RTE and map the columns
-    * to the order they are in the partition.
+    * The columns are stored in the range table entry.  If this ResultRelInfo
+    * represents a partition routing target, and doesn't have an entry of its
+    * own in the range table, fetch the parent's RTE and map the columns to
+    * the order they are in the partition.
     */
    if (relinfo->ri_RangeTableIndex != 0)
    {
@@ -1221,7 +1221,7 @@ ExecGetInsertedCols(ResultRelInfo *relinfo, EState *estate)
 
        return rte->insertedCols;
    }
-   else
+   else if (relinfo->ri_RootResultRelInfo)
    {
        ResultRelInfo *rootRelInfo = relinfo->ri_RootResultRelInfo;
        RangeTblEntry *rte = exec_rt_fetch(rootRelInfo->ri_RangeTableIndex, estate);
@@ -1233,6 +1233,16 @@ ExecGetInsertedCols(ResultRelInfo *relinfo, EState *estate)
        else
            return rte->insertedCols;
    }
+   else
+   {
+       /*
+        * The relation isn't in the range table and it isn't a partition
+        * routing target.  This ResultRelInfo must've been created only for
+        * firing triggers and the relation is not being inserted into.  (See
+        * ExecGetTriggerResultRel.)
+        */
+       return NULL;
+   }
 }
 
 /* Return a bitmap representing columns being updated */
@@ -1246,7 +1256,7 @@ ExecGetUpdatedCols(ResultRelInfo *relinfo, EState *estate)
 
        return rte->updatedCols;
    }
-   else
+   else if (relinfo->ri_RootResultRelInfo)
    {
        ResultRelInfo *rootRelInfo = relinfo->ri_RootResultRelInfo;
        RangeTblEntry *rte = exec_rt_fetch(rootRelInfo->ri_RangeTableIndex, estate);
@@ -1258,6 +1268,8 @@ ExecGetUpdatedCols(ResultRelInfo *relinfo, EState *estate)
        else
            return rte->updatedCols;
    }
+   else
+       return NULL;
 }
 
 /* Return a bitmap representing generated columns being updated */
@@ -1271,7 +1283,7 @@ ExecGetExtraUpdatedCols(ResultRelInfo *relinfo, EState *estate)
 
        return rte->extraUpdatedCols;
    }
-   else
+   else if (relinfo->ri_RootResultRelInfo)
    {
        ResultRelInfo *rootRelInfo = relinfo->ri_RootResultRelInfo;
        RangeTblEntry *rte = exec_rt_fetch(rootRelInfo->ri_RangeTableIndex, estate);
@@ -1283,6 +1295,8 @@ ExecGetExtraUpdatedCols(ResultRelInfo *relinfo, EState *estate)
        else
            return rte->extraUpdatedCols;
    }
+   else
+       return NULL;
 }
 
 /* Return columns being updated, including generated columns */

diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 8e5ccb37c504b3af1f202e009a3cee7f2135a626..3c6fecd2e1e4c7c0b86f283238bccee57db23653 100644 (file)
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -395,12 +395,15 @@ typedef struct OnConflictSetState
  * relation, and perhaps also fire triggers.  ResultRelInfo holds all the
  * information needed about a result relation, including indexes.
  *
- * Normally, a ResultRelInfo refers to a table that is in the query's
- * range table; then ri_RangeTableIndex is the RT index and ri_RelationDesc
- * is just a copy of the relevant es_relations[] entry.  But sometimes,
- * in ResultRelInfos used only for triggers, ri_RangeTableIndex is zero
- * and ri_RelationDesc is a separately-opened relcache pointer that needs
- * to be separately closed.  See ExecGetTriggerResultRel.
+ * Normally, a ResultRelInfo refers to a table that is in the query's range
+ * table; then ri_RangeTableIndex is the RT index and ri_RelationDesc is
+ * just a copy of the relevant es_relations[] entry.  However, in some
+ * situations we create ResultRelInfos for relations that are not in the
+ * range table, namely for targets of tuple routing in a partitioned table,
+ * and when firing triggers in tables other than the target tables (See
+ * ExecGetTriggerResultRel).  In these situations, ri_RangeTableIndex is 0
+ * and ri_RelationDesc is a separately-opened relcache pointer that needs to
+ * be separately closed.
  */
 typedef struct ResultRelInfo
 {