Code cleanup of user name and user id handling in the backend. The current

user is now defined in terms of the user id, the user name is only computed
upon request (for display purposes). This is kind of the opposite of the
previous state, which would maintain the user name and compute the user id
for permission checks.

Besides perhaps saving a few cycles (integer vs string), this now creates a
single point of attack for changing the user id during a connection, for
purposes of "setuid" functions, etc.

1 files changed, 10 insertions, 15 deletions

diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 1c2df9c5eb8..f320979af99 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/dbcommands.c,v 1.59 2000/08/03 16:34:01 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/dbcommands.c,v 1.60 2000/09/06 14:15:16 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,7 +37,7 @@
 
 /* non-export function prototypes */
 static bool
-			get_user_info(const char *name, int4 *use_sysid, bool *use_super, bool *use_createdb);
+			get_user_info(Oid use_sysid, bool *use_super, bool *use_createdb);
 
 static bool
 			get_db_info(const char *name, char *dbpath, Oid *dbIdP, int4 *ownerIdP);
@@ -54,7 +54,6 @@ createdb(const char *dbname, const char *dbpath, int encoding)
 	char		buf[2 * MAXPGPATH + 100];
 	char	   *loc;
 	char		locbuf[512];
-	int4		user_id;
 	int			ret;
 	bool		use_super,
 				use_createdb;
@@ -64,7 +63,7 @@ createdb(const char *dbname, const char *dbpath, int encoding)
 	Datum		new_record[Natts_pg_database];
 	char		new_record_nulls[Natts_pg_database] = {' ', ' ', ' ', ' '};
 
-	if (!get_user_info(GetPgUserName(), &user_id, &use_super, &use_createdb))
+	if (!get_user_info(GetUserId(), &use_super, &use_createdb))
 		elog(ERROR, "current user name is invalid");
 
 	if (!use_createdb && !use_super)
@@ -100,7 +99,7 @@ createdb(const char *dbname, const char *dbpath, int encoding)
 	/* Form tuple */
 	new_record[Anum_pg_database_datname - 1] = DirectFunctionCall1(namein,
 													CStringGetDatum(dbname));
-	new_record[Anum_pg_database_datdba - 1] = Int32GetDatum(user_id);
+	new_record[Anum_pg_database_datdba - 1] = Int32GetDatum(GetUserId());
 	new_record[Anum_pg_database_encoding - 1] = Int32GetDatum(encoding);
 	new_record[Anum_pg_database_datpath - 1] = DirectFunctionCall1(textin,
 													CStringGetDatum(locbuf));
@@ -174,8 +173,7 @@ createdb(const char *dbname, const char *dbpath, int encoding)
 void
 dropdb(const char *dbname)
 {
-	int4		user_id,
-				db_owner;
+	int4		db_owner;
 	bool		use_super;
 	Oid			db_id;
 	char	   *path,
@@ -197,13 +195,13 @@ dropdb(const char *dbname)
 	if (IsTransactionBlock())
 		elog(ERROR, "DROP DATABASE: May not be called in a transaction block");
 
-	if (!get_user_info(GetPgUserName(), &user_id, &use_super, NULL))
+	if (!get_user_info(GetUserId(), &use_super, NULL))
 		elog(ERROR, "Current user name is invalid");
 
 	if (!get_db_info(dbname, dbpath, &db_id, &db_owner))
 		elog(ERROR, "DROP DATABASE: Database \"%s\" does not exist", dbname);
 
-	if (user_id != db_owner && !use_super)
+	if (GetUserId() != db_owner && !use_super)
 		elog(ERROR, "DROP DATABASE: Permission denied");
 
 	path = ExpandDatabasePath(dbpath);
@@ -374,20 +372,17 @@ get_db_info(const char *name, char *dbpath, Oid *dbIdP, int4 *ownerIdP)
 
 
 static bool
-get_user_info(const char *name, int4 *use_sysid, bool *use_super, bool *use_createdb)
+get_user_info(Oid use_sysid, bool *use_super, bool *use_createdb)
 {
 	HeapTuple	utup;
 
-	AssertArg(name);
-	utup = SearchSysCacheTuple(SHADOWNAME,
-							   PointerGetDatum(name),
+	utup = SearchSysCacheTuple(SHADOWSYSID,
+							   ObjectIdGetDatum(use_sysid),
 							   0, 0, 0);
 
 	if (!HeapTupleIsValid(utup))
 		return false;
 
-	if (use_sysid)
-		*use_sysid = ((Form_pg_shadow) GETSTRUCT(utup))->usesysid;
 	if (use_super)
 		*use_super = ((Form_pg_shadow) GETSTRUCT(utup))->usesuper;
 	if (use_createdb)