Allow CURRENT/SESSION_USER to be used in certain commands

Commands such as ALTER USER, ALTER GROUP, ALTER ROLE, GRANT, and the
various ALTER OBJECT / OWNER TO, as well as ad-hoc clauses related to
roles such as the AUTHORIZATION clause of CREATE SCHEMA, the FOR clause
of CREATE USER MAPPING, and the FOR ROLE clause of ALTER DEFAULT
PRIVILEGES can now take the keywords CURRENT_USER and SESSION_USER as
user specifiers in place of an explicit user name.

This commit also fixes some quite ugly handling of special standards-
mandated syntax in CREATE USER MAPPING, which in particular would fail
to work in presence of a role named "current_user".

The special role specifiers PUBLIC and NONE also have more consistent
handling now.

Also take the opportunity to add location tracking to user specifiers.

Authors: Kyotaro Horiguchi.  Heavily reworked by Álvaro Herrera.
Reviewed by: Rushabh Lathia, Adam Brightwell, Marti Raudsepp.

1 files changed, 59 insertions, 57 deletions

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 0ba7ba0c20f..c14465eb87b 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -49,10 +49,10 @@ extern bool Password_encryption;
 check_password_hook_type check_password_hook = NULL;
 
 static void AddRoleMems(const char *rolename, Oid roleid,
-			List *memberNames, List *memberIds,
+			List *memberSpecs, List *memberIds,
 			Oid grantorId, bool admin_opt);
 static void DelRoleMems(const char *rolename, Oid roleid,
-			List *memberNames, List *memberIds,
+			List *memberSpecs, List *memberIds,
 			bool admin_opt);
 
 
@@ -443,10 +443,10 @@ CreateRole(CreateRoleStmt *stmt)
 	 * option, rolemembers don't.
 	 */
 	AddRoleMems(stmt->role, roleid,
-				adminmembers, roleNamesToIds(adminmembers),
+				adminmembers, roleSpecsToIds(adminmembers),
 				GetUserId(), true);
 	AddRoleMems(stmt->role, roleid,
-				rolemembers, roleNamesToIds(rolemembers),
+				rolemembers, roleSpecsToIds(rolemembers),
 				GetUserId(), false);
 
 	/* Post creation hook for new role */
@@ -478,7 +478,9 @@ AlterRole(AlterRoleStmt *stmt)
 	TupleDesc	pg_authid_dsc;
 	HeapTuple	tuple,
 				new_tuple;
+	Form_pg_authid authform;
 	ListCell   *option;
+	char	   *rolename = NULL;
 	char	   *password = NULL;	/* user password */
 	bool		encrypt_password = Password_encryption; /* encrypt password? */
 	char		encrypted_password[MD5_PASSWD_LEN + 1];
@@ -647,33 +649,30 @@ AlterRole(AlterRoleStmt *stmt)
 	pg_authid_rel = heap_open(AuthIdRelationId, RowExclusiveLock);
 	pg_authid_dsc = RelationGetDescr(pg_authid_rel);
 
-	tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(stmt->role));
-	if (!HeapTupleIsValid(tuple))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("role \"%s\" does not exist", stmt->role)));
-
+	tuple = get_rolespec_tuple(stmt->role);
+	authform = (Form_pg_authid) GETSTRUCT(tuple);
+	rolename = pstrdup(NameStr(authform->rolname));
 	roleid = HeapTupleGetOid(tuple);
 
 	/*
 	 * To mess with a superuser you gotta be superuser; else you need
 	 * createrole, or just want to change your own password
 	 */
-	if (((Form_pg_authid) GETSTRUCT(tuple))->rolsuper || issuper >= 0)
+	if (authform->rolsuper || issuper >= 0)
 	{
 		if (!superuser())
 			ereport(ERROR,
 					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 					 errmsg("must be superuser to alter superusers")));
 	}
-	else if (((Form_pg_authid) GETSTRUCT(tuple))->rolreplication || isreplication >= 0)
+	else if (authform->rolreplication || isreplication >= 0)
 	{
 		if (!superuser())
 			ereport(ERROR,
 					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 					 errmsg("must be superuser to alter replication users")));
 	}
-	else if (((Form_pg_authid) GETSTRUCT(tuple))->rolbypassrls || bypassrls >= 0)
+	else if (authform->rolbypassrls || bypassrls >= 0)
 	{
 		if (!superuser())
 			ereport(ERROR,
@@ -718,11 +717,11 @@ AlterRole(AlterRoleStmt *stmt)
 	 * Call the password checking hook if there is one defined
 	 */
 	if (check_password_hook && password)
-		(*check_password_hook) (stmt->role,
-								password,
-			   isMD5(password) ? PASSWORD_TYPE_MD5 : PASSWORD_TYPE_PLAINTEXT,
-								validUntil_datum,
-								validUntil_null);
+		(*check_password_hook)(rolename ,
+							   password,
+			 isMD5(password) ? PASSWORD_TYPE_MD5 : PASSWORD_TYPE_PLAINTEXT,
+							   validUntil_datum,
+							   validUntil_null);
 
 	/*
 	 * Build an updated tuple, perusing the information just obtained
@@ -784,7 +783,7 @@ AlterRole(AlterRoleStmt *stmt)
 				CStringGetTextDatum(password);
 		else
 		{
-			if (!pg_md5_encrypt(password, stmt->role, strlen(stmt->role),
+			if (!pg_md5_encrypt(password, rolename, strlen(rolename),
 								encrypted_password))
 				elog(ERROR, "password encryption failed");
 			new_record[Anum_pg_authid_rolpassword - 1] =
@@ -831,12 +830,12 @@ AlterRole(AlterRoleStmt *stmt)
 		CommandCounterIncrement();
 
 	if (stmt->action == +1)		/* add members to role */
-		AddRoleMems(stmt->role, roleid,
-					rolemembers, roleNamesToIds(rolemembers),
+		AddRoleMems(rolename, roleid,
+					rolemembers, roleSpecsToIds(rolemembers),
 					GetUserId(), false);
 	else if (stmt->action == -1)	/* drop members from role */
-		DelRoleMems(stmt->role, roleid,
-					rolemembers, roleNamesToIds(rolemembers),
+		DelRoleMems(rolename, roleid,
+					rolemembers, roleSpecsToIds(rolemembers),
 					false);
 
 	/*
@@ -860,13 +859,7 @@ AlterRoleSet(AlterRoleSetStmt *stmt)
 
 	if (stmt->role)
 	{
-		roletuple = SearchSysCache1(AUTHNAME, PointerGetDatum(stmt->role));
-
-		if (!HeapTupleIsValid(roletuple))
-			ereport(ERROR,
-					(errcode(ERRCODE_UNDEFINED_OBJECT),
-					 errmsg("role \"%s\" does not exist", stmt->role)));
-
+		roletuple = get_rolespec_tuple(stmt->role);
 		roleid = HeapTupleGetOid(roletuple);
 
 		/*
@@ -955,7 +948,8 @@ DropRole(DropRoleStmt *stmt)
 
 	foreach(item, stmt->roles)
 	{
-		const char *role = strVal(lfirst(item));
+		RoleSpec   *rolspec = lfirst(item);
+		char	   *role;
 		HeapTuple	tuple,
 					tmp_tuple;
 		ScanKeyData scankey;
@@ -964,6 +958,12 @@ DropRole(DropRoleStmt *stmt)
 		SysScanDesc sscan;
 		Oid			roleid;
 
+		if (rolspec->roletype != ROLESPEC_CSTRING)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("cannot use special role specifier in \"%s\"", "DROP ROLE")));
+		role = rolspec->rolename;
+
 		tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role));
 		if (!HeapTupleIsValid(tuple))
 		{
@@ -1233,11 +1233,11 @@ GrantRole(GrantRoleStmt *stmt)
 	ListCell   *item;
 
 	if (stmt->grantor)
-		grantor = get_role_oid(stmt->grantor, false);
+		grantor = get_rolespec_oid(stmt->grantor, false);
 	else
 		grantor = GetUserId();
 
-	grantee_ids = roleNamesToIds(stmt->grantee_roles);
+	grantee_ids = roleSpecsToIds(stmt->grantee_roles);
 
 	/* AccessShareLock is enough since we aren't modifying pg_authid */
 	pg_authid_rel = heap_open(AuthIdRelationId, AccessShareLock);
@@ -1286,7 +1286,7 @@ GrantRole(GrantRoleStmt *stmt)
 void
 DropOwnedObjects(DropOwnedStmt *stmt)
 {
-	List	   *role_ids = roleNamesToIds(stmt->roles);
+	List	   *role_ids = roleSpecsToIds(stmt->roles);
 	ListCell   *cell;
 
 	/* Check privileges */
@@ -1312,7 +1312,7 @@ DropOwnedObjects(DropOwnedStmt *stmt)
 void
 ReassignOwnedObjects(ReassignOwnedStmt *stmt)
 {
-	List	   *role_ids = roleNamesToIds(stmt->roles);
+	List	   *role_ids = roleSpecsToIds(stmt->roles);
 	ListCell   *cell;
 	Oid			newrole;
 
@@ -1328,7 +1328,7 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
 	}
 
 	/* Must have privileges on the receiving side too */
-	newrole = get_role_oid(stmt->newrole, false);
+	newrole = get_rolespec_oid(stmt->newrole, false);
 
 	if (!has_privs_of_role(GetUserId(), newrole))
 		ereport(ERROR,
@@ -1340,22 +1340,24 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
 }
 
 /*
- * roleNamesToIds
+ * roleSpecsToIds
+ *
+ * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
  *
- * Given a list of role names (as String nodes), generate a list of role OIDs
- * in the same order.
+ * ROLESPEC_PUBLIC is not allowed.
  */
 List *
-roleNamesToIds(List *memberNames)
+roleSpecsToIds(List *memberNames)
 {
 	List	   *result = NIL;
 	ListCell   *l;
 
 	foreach(l, memberNames)
 	{
-		char	   *rolename = strVal(lfirst(l));
-		Oid			roleid = get_role_oid(rolename, false);
+		Node   *rolespec = (Node *) lfirst(l);
+		Oid		roleid;
 
+		roleid = get_rolespec_oid(rolespec, false);
 		result = lappend_oid(result, roleid);
 	}
 	return result;
@@ -1366,7 +1368,7 @@ roleNamesToIds(List *memberNames)
  *
  * rolename: name of role to add to (used only for error messages)
  * roleid: OID of role to add to
- * memberNames: list of names of roles to add (used only for error messages)
+ * memberSpecs: list of RoleSpec of roles to add (used only for error messages)
  * memberIds: OIDs of roles to add
  * grantorId: who is granting the membership
  * admin_opt: granting admin option?
@@ -1375,15 +1377,15 @@ roleNamesToIds(List *memberNames)
  */
 static void
 AddRoleMems(const char *rolename, Oid roleid,
-			List *memberNames, List *memberIds,
+			List *memberSpecs, List *memberIds,
 			Oid grantorId, bool admin_opt)
 {
 	Relation	pg_authmem_rel;
 	TupleDesc	pg_authmem_dsc;
-	ListCell   *nameitem;
+	ListCell   *specitem;
 	ListCell   *iditem;
 
-	Assert(list_length(memberNames) == list_length(memberIds));
+	Assert(list_length(memberSpecs) == list_length(memberIds));
 
 	/* Skip permission check if nothing to do */
 	if (!memberIds)
@@ -1428,9 +1430,9 @@ AddRoleMems(const char *rolename, Oid roleid,
 	pg_authmem_rel = heap_open(AuthMemRelationId, RowExclusiveLock);
 	pg_authmem_dsc = RelationGetDescr(pg_authmem_rel);
 
-	forboth(nameitem, memberNames, iditem, memberIds)
+	forboth(specitem, memberSpecs, iditem, memberIds)
 	{
-		const char *membername = strVal(lfirst(nameitem));
+		RoleSpec   *memberRole = lfirst(specitem);
 		Oid			memberid = lfirst_oid(iditem);
 		HeapTuple	authmem_tuple;
 		HeapTuple	tuple;
@@ -1449,7 +1451,7 @@ AddRoleMems(const char *rolename, Oid roleid,
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_GRANT_OPERATION),
 					 (errmsg("role \"%s\" is a member of role \"%s\"",
-							 rolename, membername))));
+							 rolename, get_rolespec_name((Node *) memberRole)))));
 
 		/*
 		 * Check if entry for this role/member already exists; if so, give
@@ -1464,7 +1466,7 @@ AddRoleMems(const char *rolename, Oid roleid,
 		{
 			ereport(NOTICE,
 					(errmsg("role \"%s\" is already a member of role \"%s\"",
-							membername, rolename)));
+							get_rolespec_name((Node *) memberRole), rolename)));
 			ReleaseSysCache(authmem_tuple);
 			continue;
 		}
@@ -1513,7 +1515,7 @@ AddRoleMems(const char *rolename, Oid roleid,
  *
  * rolename: name of role to del from (used only for error messages)
  * roleid: OID of role to del from
- * memberNames: list of names of roles to del (used only for error messages)
+ * memberSpecs: list of RoleSpec of roles to del (used only for error messages)
  * memberIds: OIDs of roles to del
  * admin_opt: remove admin option only?
  *
@@ -1521,15 +1523,15 @@ AddRoleMems(const char *rolename, Oid roleid,
  */
 static void
 DelRoleMems(const char *rolename, Oid roleid,
-			List *memberNames, List *memberIds,
+			List *memberSpecs, List *memberIds,
 			bool admin_opt)
 {
 	Relation	pg_authmem_rel;
 	TupleDesc	pg_authmem_dsc;
-	ListCell   *nameitem;
+	ListCell   *specitem;
 	ListCell   *iditem;
 
-	Assert(list_length(memberNames) == list_length(memberIds));
+	Assert(list_length(memberSpecs) == list_length(memberIds));
 
 	/* Skip permission check if nothing to do */
 	if (!memberIds)
@@ -1559,9 +1561,9 @@ DelRoleMems(const char *rolename, Oid roleid,
 	pg_authmem_rel = heap_open(AuthMemRelationId, RowExclusiveLock);
 	pg_authmem_dsc = RelationGetDescr(pg_authmem_rel);
 
-	forboth(nameitem, memberNames, iditem, memberIds)
+	forboth(specitem, memberSpecs, iditem, memberIds)
 	{
-		const char *membername = strVal(lfirst(nameitem));
+		RoleSpec   *memberRole = lfirst(specitem);
 		Oid			memberid = lfirst_oid(iditem);
 		HeapTuple	authmem_tuple;
 
@@ -1575,7 +1577,7 @@ DelRoleMems(const char *rolename, Oid roleid,
 		{
 			ereport(WARNING,
 					(errmsg("role \"%s\" is not a member of role \"%s\"",
-							membername, rolename)));
+							get_rolespec_name((Node *) memberRole), rolename)));
 			continue;
 		}