Avoid scribbling on input node tree in CREATE/ALTER DOMAIN.

tglsfdc · tglsfdc · commit 4b8b3562e1e6 · 2021-06-18T12:09:22.000-04:00
This works fine in the "simple Query" code path; but if the statement is in the plan cache then it's corrupted for future re-execution. Apply copyObject() to protect the original tree from modification, as we've done elsewhere. This narrow fix is applied only to the back branches. In HEAD, the problem was fixed more generally by commit 7c337b6; but that changed ProcessUtility's API, so it's infeasible to back-patch. Per bug #17053 from Charles Samborski. Discussion: https://postgr.es/m/931771.1623893989@sss.pgh.pa.us Discussion: https://postgr.es/m/17053-3ca3f501bbc212b4@postgresql.org
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
@@ -908,10 +908,12 @@ DefineDomain(CreateDomainStmt *stmt)
 					pstate = make_parsestate(NULL);
 
 					/*
-					 * Cook the constr->raw_expr into an expression. Note:
-					 * name is strictly for error message
+					 * Cook the constr->raw_expr into an expression; copy it
+					 * in case the input is in plan cache.  Note: name is used
+					 * only for error messages.
 					 */
-					defaultExpr = cookDefault(pstate, constr->raw_expr,
+					defaultExpr = cookDefault(pstate,
+											  copyObject(constr->raw_expr),
 											  basetypeoid,
 											  basetypeMod,
 											  domainName);
@@ -2262,10 +2264,10 @@ AlterDomainDefault(List *names, Node *defaultRaw)
 		pstate = make_parsestate(NULL);
 
 		/*
-		 * Cook the colDef->raw_expr into an expression. Note: Name is
-		 * strictly for error message
+		 * Cook the raw default into an expression; copy it in case the input
+		 * is in plan cache.  Note: name is used only for error messages.
 		 */
-		defaultExpr = cookDefault(pstate, defaultRaw,
+		defaultExpr = cookDefault(pstate, copyObject(defaultRaw),
 								  typTup->typbasetype,
 								  typTup->typtypmod,
 								  NameStr(typTup->typname));
@@ -3136,7 +3138,12 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
 	pstate->p_pre_columnref_hook = replace_domain_constraint_value;
 	pstate->p_ref_hook_state = (void *) domVal;
 
-	expr = transformExpr(pstate, constr->raw_expr, EXPR_KIND_DOMAIN_CHECK);
+	/*
+	 * Transform the expression; first we must copy the input, in case it's in
+	 * plan cache.
+	 */
+	expr = transformExpr(pstate, copyObject(constr->raw_expr),
+						 EXPR_KIND_DOMAIN_CHECK);
 
 	/*
 	 * Make sure it yields a boolean result.
