Invent "trusted" extensions, and remove the pg_pltemplate catalog.

This patch creates a new extension property, "trusted".  An extension
that's marked that way in its control file can be installed by a
non-superuser who has the CREATE privilege on the current database,
even if the extension contains objects that normally would have to be
created by a superuser.  The objects within the extension will (by
default) be owned by the bootstrap superuser, but the extension itself
will be owned by the calling user.  This allows replicating the old
behavior around trusted procedural languages, without all the
special-case logic in CREATE LANGUAGE.  We have, however, chosen to
loosen the rules slightly: formerly, only a database owner could take
advantage of the special case that allowed installation of a trusted
language, but now anyone who has CREATE privilege can do so.

Having done that, we can delete the pg_pltemplate catalog, moving the
knowledge it contained into the extension script files for the various
PLs.  This ends up being no change at all for the in-core PLs, but it is
a large step forward for external PLs: they can now have the same ease
of installation as core PLs do.  The old "trusted PL" behavior was only
available to PLs that had entries in pg_pltemplate, but now any
extension can be marked trusted if appropriate.

This also removes one of the stumbling blocks for our Python 2 -> 3
migration, since the association of "plpythonu" with Python 2 is no
longer hard-wired into pg_pltemplate's initial contents.  Exactly where
we go from here on that front remains to be settled, but one problem
is fixed.

Patch by me, reviewed by Peter Eisentraut, Stephen Frost, and others.

Discussion: https://postgr.es/m/5889.1566415762@sss.pgh.pa.us

8 files changed, 11 insertions, 118 deletions

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 249b1f5a341..b520c050839 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202001251
+#define CATALOG_VERSION_NO	202001291
 
 #endif
diff --git a/src/include/catalog/indexing.h b/src/include/catalog/indexing.h
index 13e07fc314a..8be303870f8 100644
--- a/src/include/catalog/indexing.h
+++ b/src/include/catalog/indexing.h
@@ -206,9 +206,6 @@ DECLARE_UNIQUE_INDEX(pg_opfamily_am_name_nsp_index, 2754, on pg_opfamily using b
 DECLARE_UNIQUE_INDEX(pg_opfamily_oid_index, 2755, on pg_opfamily using btree(oid oid_ops));
 #define OpfamilyOidIndexId	2755
 
-DECLARE_UNIQUE_INDEX(pg_pltemplate_name_index, 1137, on pg_pltemplate using btree(tmplname name_ops));
-#define PLTemplateNameIndexId  1137
-
 DECLARE_UNIQUE_INDEX(pg_proc_oid_index, 2690, on pg_proc using btree(oid oid_ops));
 #define ProcedureOidIndexId  2690
 DECLARE_UNIQUE_INDEX(pg_proc_proname_args_nsp_index, 2691, on pg_proc using btree(proname name_ops, proargtypes oidvector_ops, pronamespace oid_ops));
diff --git a/src/include/catalog/pg_pltemplate.dat b/src/include/catalog/pg_pltemplate.dat
deleted file mode 100644
index 1c96b304319..00000000000
--- a/src/include/catalog/pg_pltemplate.dat
+++ /dev/null
@@ -1,51 +0,0 @@
-#----------------------------------------------------------------------
-#
-# pg_pltemplate.dat
-#    Initial contents of the pg_pltemplate system catalog.
-#
-# Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
-# Portions Copyright (c) 1994, Regents of the University of California
-#
-# src/include/catalog/pg_pltemplate.dat
-#
-#----------------------------------------------------------------------
-
-[
-
-{ tmplname => 'plpgsql', tmpltrusted => 't', tmpldbacreate => 't',
-  tmplhandler => 'plpgsql_call_handler', tmplinline => 'plpgsql_inline_handler',
-  tmplvalidator => 'plpgsql_validator', tmpllibrary => '$libdir/plpgsql',
-  tmplacl => '_null_' },
-{ tmplname => 'pltcl', tmpltrusted => 't', tmpldbacreate => 't',
-  tmplhandler => 'pltcl_call_handler', tmplinline => '_null_',
-  tmplvalidator => '_null_', tmpllibrary => '$libdir/pltcl',
-  tmplacl => '_null_' },
-{ tmplname => 'pltclu', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'pltclu_call_handler', tmplinline => '_null_',
-  tmplvalidator => '_null_', tmpllibrary => '$libdir/pltcl',
-  tmplacl => '_null_' },
-{ tmplname => 'plperl', tmpltrusted => 't', tmpldbacreate => 't',
-  tmplhandler => 'plperl_call_handler', tmplinline => 'plperl_inline_handler',
-  tmplvalidator => 'plperl_validator', tmpllibrary => '$libdir/plperl',
-  tmplacl => '_null_' },
-{ tmplname => 'plperlu', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plperlu_call_handler', tmplinline => 'plperlu_inline_handler',
-  tmplvalidator => 'plperlu_validator', tmpllibrary => '$libdir/plperl',
-  tmplacl => '_null_' },
-{ tmplname => 'plpythonu', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plpython_call_handler',
-  tmplinline => 'plpython_inline_handler',
-  tmplvalidator => 'plpython_validator', tmpllibrary => '$libdir/plpython2',
-  tmplacl => '_null_' },
-{ tmplname => 'plpython2u', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plpython2_call_handler',
-  tmplinline => 'plpython2_inline_handler',
-  tmplvalidator => 'plpython2_validator', tmpllibrary => '$libdir/plpython2',
-  tmplacl => '_null_' },
-{ tmplname => 'plpython3u', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plpython3_call_handler',
-  tmplinline => 'plpython3_inline_handler',
-  tmplvalidator => 'plpython3_validator', tmpllibrary => '$libdir/plpython3',
-  tmplacl => '_null_' },
-
-]
diff --git a/src/include/catalog/pg_pltemplate.h b/src/include/catalog/pg_pltemplate.h
deleted file mode 100644
index b930730e481..00000000000
--- a/src/include/catalog/pg_pltemplate.h
+++ /dev/null
@@ -1,52 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * pg_pltemplate.h
- *	  definition of the "PL template" system catalog (pg_pltemplate)
- *
- *
- * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * src/include/catalog/pg_pltemplate.h
- *
- * NOTES
- *	  The Catalog.pm module reads this file and derives schema
- *	  information.
- *
- *-------------------------------------------------------------------------
- */
-#ifndef PG_PLTEMPLATE_H
-#define PG_PLTEMPLATE_H
-
-#include "catalog/genbki.h"
-#include "catalog/pg_pltemplate_d.h"
-
-/* ----------------
- *		pg_pltemplate definition.  cpp turns this into
- *		typedef struct FormData_pg_pltemplate
- * ----------------
- */
-CATALOG(pg_pltemplate,1136,PLTemplateRelationId) BKI_SHARED_RELATION
-{
-	NameData	tmplname;		/* name of PL */
-	bool		tmpltrusted;	/* PL is trusted? */
-	bool		tmpldbacreate;	/* PL is installable by db owner? */
-
-#ifdef CATALOG_VARLEN			/* variable-length fields start here */
-	text		tmplhandler BKI_FORCE_NOT_NULL; /* name of call handler
-												 * function */
-	text		tmplinline;		/* name of anonymous-block handler, or NULL */
-	text		tmplvalidator;	/* name of validator function, or NULL */
-	text		tmpllibrary BKI_FORCE_NOT_NULL; /* path of shared library */
-	aclitem		tmplacl[1];		/* access privileges for template */
-#endif
-} FormData_pg_pltemplate;
-
-/* ----------------
- *		Form_pg_pltemplate corresponds to a pointer to a row with
- *		the format of pg_pltemplate relation.
- * ----------------
- */
-typedef FormData_pg_pltemplate *Form_pg_pltemplate;
-
-#endif							/* PG_PLTEMPLATE_H */
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index bef50c76d9c..22282569075 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -9496,9 +9496,9 @@
   proname => 'pg_available_extension_versions', procost => '10',
   prorows => '100', proretset => 't', provolatile => 's',
   prorettype => 'record', proargtypes => '',
-  proallargtypes => '{name,text,bool,bool,name,_name,text}',
-  proargmodes => '{o,o,o,o,o,o,o}',
-  proargnames => '{name,version,superuser,relocatable,schema,requires,comment}',
+  proallargtypes => '{name,text,bool,bool,bool,name,_name,text}',
+  proargmodes => '{o,o,o,o,o,o,o,o}',
+  proargnames => '{name,version,superuser,trusted,relocatable,schema,requires,comment}',
   prosrc => 'pg_available_extension_versions' },
 { oid => '3084', descr => 'list an extension\'s version update paths',
   proname => 'pg_extension_update_paths', procost => '10', prorows => '100',
diff --git a/src/include/catalog/toasting.h b/src/include/catalog/toasting.h
index 3281dbd7aaf..51491c45131 100644
--- a/src/include/catalog/toasting.h
+++ b/src/include/catalog/toasting.h
@@ -86,9 +86,6 @@ DECLARE_TOAST(pg_database, 4177, 4178);
 DECLARE_TOAST(pg_db_role_setting, 2966, 2967);
 #define PgDbRoleSettingToastTable 2966
 #define PgDbRoleSettingToastIndex 2967
-DECLARE_TOAST(pg_pltemplate, 4179, 4180);
-#define PgPlTemplateToastTable 4179
-#define PgPlTemplateToastIndex 4180
 DECLARE_TOAST(pg_replication_origin, 4181, 4182);
 #define PgReplicationOriginToastTable 4181
 #define PgReplicationOriginToastIndex 4182
diff --git a/src/include/commands/extension.h b/src/include/commands/extension.h
index 6f10707b00c..7923cdc250d 100644
--- a/src/include/commands/extension.h
+++ b/src/include/commands/extension.h
@@ -47,6 +47,7 @@ extern ObjectAddress ExecAlterExtensionContentsStmt(AlterExtensionContentsStmt *
 
 extern Oid	get_extension_oid(const char *extname, bool missing_ok);
 extern char *get_extension_name(Oid ext_oid);
+extern bool extension_file_exists(const char *extensionName);
 
 extern ObjectAddress AlterExtensionNamespace(const char *extensionName, const char *newschema,
 											 Oid *oldschema);
diff --git a/src/include/commands/proclang.h b/src/include/commands/proclang.h
index 9a4bc75d120..c70f8ec928e 100644
--- a/src/include/commands/proclang.h
+++ b/src/include/commands/proclang.h
@@ -1,11 +1,12 @@
-/*
- * src/include/commands/proclang.h
- *
- *-------------------------------------------------------------------------
+/*-------------------------------------------------------------------------
  *
  * proclang.h
  *	  prototypes for proclang.c.
  *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/commands/proclang.h
  *
  *-------------------------------------------------------------------------
  */
@@ -17,7 +18,7 @@
 
 extern ObjectAddress CreateProceduralLanguage(CreatePLangStmt *stmt);
 extern void DropProceduralLanguageById(Oid langOid);
-extern bool PLTemplateExists(const char *languageName);
+
 extern Oid	get_language_oid(const char *langname, bool missing_ok);
 
 #endif							/* PROCLANG_H */