Fix mishandling of quoted-list GUC values in pg_dump and ruleutils.c.

Code that prints out the contents of setconfig or proconfig arrays in
SQL format needs to handle GUC_LIST_QUOTE variables differently from
other ones, because for those variables, flatten_set_variable_args()
already applied a layer of quoting.  The value can therefore safely
be printed as-is, and indeed must be, or flatten_set_variable_args()
will muck it up completely on reload.  For all other GUC variables,
it's necessary and sufficient to quote the value as a SQL literal.

We'd recognized the need for this long ago, but mis-analyzed the
need slightly, thinking that all GUC_LIST_INPUT variables needed
the special treatment.  That's actually wrong, since a valid value
of a LIST variable might include characters that need quoting,
although no existing variables accept such values.

More to the point, we hadn't made any particular effort to keep the
various places that deal with this up-to-date with the set of variables
that actually need special treatment, meaning that we'd do the wrong
thing with, for example, temp_tablespaces values.  This affects dumping
of SET clauses attached to functions, as well as ALTER DATABASE/ROLE SET
commands.

In ruleutils.c we can fix it reasonably honestly by exporting a guc.c
function that allows discovering the flags for a given GUC variable.
But pg_dump doesn't have easy access to that, so continue the old method
of having a hard-wired list of affected variable names.  At least we can
fix it to have just one list not two, and update the list to match
current reality.

A remaining problem with this is that it only works for built-in
GUC variables.  pg_dump's list obvious knows nothing of third-party
extensions, and even the "ask guc.c" method isn't bulletproof since
the relevant extension might not be loaded.  There's no obvious
solution to that, so for now, we'll just have to discourage extension
authors from inventing custom GUCs that need GUC_LIST_QUOTE.

This has been busted for a long time, so back-patch to all supported
branches.

Michael Paquier and Tom Lane, reviewed by Kyotaro Horiguchi and
Pavel Stehule

Discussion: https://postgr.es/m/20180111064900.GA51030@paquier.xyz

src/backend/utils/adt/ruleutils.c

@@ -61,6 +61,7 @@
 #include "utils/array.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
+#include "utils/guc.h"
 #include "utils/hsearch.h"
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
@@ -2568,11 +2569,15 @@ pg_get_functiondef(PG_FUNCTION_ARGS)
 								 quote_identifier(configitem));
 
 				/*
-				 * Some GUC variable names are 'LIST' type and hence must not
-				 * be quoted.
+				 * Variables that are marked GUC_LIST_QUOTE were already fully
+				 * quoted by flatten_set_variable_args() before they were put
+				 * into the proconfig array; we mustn't re-quote them or we'll
+				 * make a mess.  Variables that are not so marked should just
+				 * be emitted as simple string literals.  If the variable is
+				 * not known to guc.c, we'll do the latter; this makes it
+				 * unsafe to use GUC_LIST_QUOTE for extension variables.
 				 */
-				if (pg_strcasecmp(configitem, "DateStyle") == 0
-					|| pg_strcasecmp(configitem, "search_path") == 0)
+				if (GetConfigOptionFlags(configitem, true) & GUC_LIST_QUOTE)
 					appendStringInfoString(&buf, pos);
 				else
 					simple_quote_literal(&buf, pos);

src/backend/utils/misc/guc.c

@@ -793,8 +793,8 @@ static const unit_conversion time_unit_conversion_table[] =
  *
  * 6. Don't forget to document the option (at least in config.sgml).
  *
- * 7. If it's a new GUC_LIST option you must edit pg_dumpall.c to ensure
- *	  it is not single quoted at dump time.
+ * 7. If it's a new GUC_LIST_QUOTE option, you must add it to
+ *	  variable_is_guc_list_quote() in src/bin/pg_dump/dumputils.c.
  */
 
 
@@ -6802,6 +6802,30 @@ GetConfigOptionResetString(const char *name)
 	return NULL;
 }
 
+/*
+ * Get the GUC flags associated with the given option.
+ *
+ * If the option doesn't exist, return 0 if missing_ok is true,
+ * otherwise throw an ereport and don't return.
+ */
+int
+GetConfigOptionFlags(const char *name, bool missing_ok)
+{
+	struct config_generic *record;
+
+	record = find_option(name, false, WARNING);
+	if (record == NULL)
+	{
+		if (missing_ok)
+			return 0;
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("unrecognized configuration parameter \"%s\"",
+						name)));
+	}
+	return record->flags;
+}
+
 
 /*
  * flatten_set_variable_args

src/bin/pg_dump/dumputils.c

@@ -846,3 +846,26 @@ buildACLQueries(PQExpBuffer acl_subquery, PQExpBuffer racl_subquery,
 		printfPQExpBuffer(init_racl_subquery, "NULL");
 	}
 }
+
+/*
+ * Detect whether the given GUC variable is of GUC_LIST_QUOTE type.
+ *
+ * It'd be better if we could inquire this directly from the backend; but even
+ * if there were a function for that, it could only tell us about variables
+ * currently known to guc.c, so that it'd be unsafe for extensions to declare
+ * GUC_LIST_QUOTE variables anyway.  Lacking a solution for that, it doesn't
+ * seem worth the work to do more than have this list, which must be kept in
+ * sync with the variables actually marked GUC_LIST_QUOTE in guc.c.
+ */
+bool
+variable_is_guc_list_quote(const char *name)
+{
+	if (pg_strcasecmp(name, "temp_tablespaces") == 0 ||
+		pg_strcasecmp(name, "session_preload_libraries") == 0 ||
+		pg_strcasecmp(name, "shared_preload_libraries") == 0 ||
+		pg_strcasecmp(name, "local_preload_libraries") == 0 ||
+		pg_strcasecmp(name, "search_path") == 0)
+		return true;
+	else
+		return false;
+}

src/bin/pg_dump/dumputils.h

@@ -56,4 +56,6 @@ extern void buildACLQueries(PQExpBuffer acl_subquery, PQExpBuffer racl_subquery,
 				const char *acl_column, const char *acl_owner,
 				const char *obj_kind, bool binary_upgrade);
 
+extern bool variable_is_guc_list_quote(const char *name);
+
 #endif							/* DUMPUTILS_H */

src/bin/pg_dump/pg_dump.c

@@ -11480,11 +11480,15 @@ dumpFunc(Archive *fout, FuncInfo *finfo)
 		appendPQExpBuffer(q, "\n    SET %s TO ", fmtId(configitem));
 
 		/*
-		 * Some GUC variable names are 'LIST' type and hence must not be
-		 * quoted.
+		 * Variables that are marked GUC_LIST_QUOTE were already fully quoted
+		 * by flatten_set_variable_args() before they were put into the
+		 * proconfig array; we mustn't re-quote them or we'll make a mess.
+		 * Variables that are not so marked should just be emitted as simple
+		 * string literals.  If the variable is not known to
+		 * variable_is_guc_list_quote(), we'll do the latter; this makes it
+		 * unsafe to use GUC_LIST_QUOTE for extension variables.
 		 */
-		if (pg_strcasecmp(configitem, "DateStyle") == 0
-			|| pg_strcasecmp(configitem, "search_path") == 0)
+		if (variable_is_guc_list_quote(configitem))
 			appendPQExpBufferStr(q, pos);
 		else
 			appendStringLiteralAH(q, pos, fout);

src/bin/pg_dump/pg_dumpall.c

@@ -1706,10 +1706,15 @@ makeAlterConfigCommand(PGconn *conn, const char *arrayitem,
 	appendPQExpBuffer(buf, "SET %s TO ", fmtId(mine));
 
 	/*
-	 * Some GUC variable names are 'LIST' type and hence must not be quoted.
+	 * Variables that are marked GUC_LIST_QUOTE were already fully quoted by
+	 * flatten_set_variable_args() before they were put into the setconfig
+	 * array; we mustn't re-quote them or we'll make a mess.  Variables that
+	 * are not so marked should just be emitted as simple string literals.  If
+	 * the variable is not known to variable_is_guc_list_quote(), we'll do the
+	 * latter; this makes it unsafe to use GUC_LIST_QUOTE for extension
+	 * variables.
 	 */
-	if (pg_strcasecmp(mine, "DateStyle") == 0
-		|| pg_strcasecmp(mine, "search_path") == 0)
+	if (variable_is_guc_list_quote(mine))
 		appendPQExpBufferStr(buf, pos + 1);
 	else
 		appendStringLiteralConn(buf, pos + 1, conn);

src/include/utils/guc.h

@@ -348,6 +348,7 @@ extern void EmitWarningsOnPlaceholders(const char *className);
 extern const char *GetConfigOption(const char *name, bool missing_ok,
 				bool restrict_superuser);
 extern const char *GetConfigOptionResetString(const char *name);
+extern int	GetConfigOptionFlags(const char *name, bool missing_ok);
 extern void ProcessConfigFile(GucContext context);
 extern void InitializeGUCOptions(void);
 extern bool SelectConfigFiles(const char *userDoption, const char *progname);

src/test/regress/expected/rules.out

@@ -3147,6 +3147,33 @@ SELECT * FROM hat_data WHERE hat_name IN ('h8', 'h9', 'h7') ORDER BY hat_name;
 DROP RULE hat_upsert ON hats;
 drop table hats;
 drop table hat_data;
+-- test for pg_get_functiondef properly regurgitating SET parameters
+-- Note that the function is kept around to stress pg_dump.
+CREATE FUNCTION func_with_set_params() RETURNS integer
+    AS 'select 1;'
+    LANGUAGE SQL
+    SET search_path TO PG_CATALOG
+    SET extra_float_digits TO 2
+    SET work_mem TO '4MB'
+    SET datestyle to iso, mdy
+    SET local_preload_libraries TO "Mixed/Case", 'c:/"a"/path'
+    IMMUTABLE STRICT;
+SELECT pg_get_functiondef('func_with_set_params()'::regprocedure);
+                      pg_get_functiondef                       
+---------------------------------------------------------------
+ CREATE OR REPLACE FUNCTION public.func_with_set_params()     +
+  RETURNS integer                                             +
+  LANGUAGE sql                                                +
+  IMMUTABLE STRICT                                            +
+  SET search_path TO pg_catalog                               +
+  SET extra_float_digits TO '2'                               +
+  SET work_mem TO '4MB'                                       +
+  SET "DateStyle" TO 'iso, mdy'                               +
+  SET local_preload_libraries TO "Mixed/Case", "c:/""a""/path"+
+ AS $function$select 1;$function$                             +
+ 
+(1 row)
+
 -- tests for pg_get_*def with invalid objects
 SELECT pg_get_constraintdef(0);
  pg_get_constraintdef 

src/test/regress/sql/rules.sql

@@ -1155,6 +1155,19 @@ DROP RULE hat_upsert ON hats;
 drop table hats;
 drop table hat_data;
 
+-- test for pg_get_functiondef properly regurgitating SET parameters
+-- Note that the function is kept around to stress pg_dump.
+CREATE FUNCTION func_with_set_params() RETURNS integer
+    AS 'select 1;'
+    LANGUAGE SQL
+    SET search_path TO PG_CATALOG
+    SET extra_float_digits TO 2
+    SET work_mem TO '4MB'
+    SET datestyle to iso, mdy
+    SET local_preload_libraries TO "Mixed/Case", 'c:/"a"/path'
+    IMMUTABLE STRICT;
+SELECT pg_get_functiondef('func_with_set_params()'::regprocedure);
+
 -- tests for pg_get_*def with invalid objects
 SELECT pg_get_constraintdef(0);
 SELECT pg_get_functiondef(0);