diff options
Diffstat (limited to 'src/backend/commands/user.c')
| -rw-r--r-- | src/backend/commands/user.c | 143 |
1 files changed, 79 insertions, 64 deletions
diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index 1b0d972839e..c05b6da5856 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -5,7 +5,7 @@ * * Copyright (c) 1994, Regents of the University of California * - * $Id: user.c,v 1.33 1999/07/30 18:09:47 momjian Exp $ + * $Id: user.c,v 1.34 1999/09/18 19:06:41 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -36,13 +36,15 @@ static void CheckPgUserAclNotNull(void); * * copy the modified contents of pg_shadow to a file used by the postmaster * for user authentication. The file is stored as $PGDATA/pg_pwd. + * + * NB: caller is responsible for ensuring that only one backend can + * execute this routine at a time. Acquiring AccessExclusiveLock on + * pg_shadow is the standard way to do that. *--------------------------------------------------------------------- */ -static -void +static void UpdatePgPwdFile(char *sql, CommandDest dest) { - char *filename, *tempname; int bufsize; @@ -125,17 +127,13 @@ DefineUser(CreateUserStmt *stmt, CommandDest dest) /* * Scan the pg_shadow relation to be certain the user doesn't already - * exist. + * exist. Note we secure exclusive lock, because we also need to be + * sure of what the next usesysid should be, and we need to protect + * our update of the flat password file. */ - pg_shadow_rel = heap_openr(ShadowRelationName); + pg_shadow_rel = heap_openr(ShadowRelationName, AccessExclusiveLock); pg_shadow_dsc = RelationGetDescr(pg_shadow_rel); - /* - * Secure a write lock on pg_shadow so we can be sure of what the next - * usesysid should be. - */ - LockRelation(pg_shadow_rel, AccessExclusiveLock); - scan = heap_beginscan(pg_shadow_rel, false, SnapshotNow, 0, NULL); while (HeapTupleIsValid(tuple = heap_getnext(scan, 0))) { @@ -152,8 +150,7 @@ DefineUser(CreateUserStmt *stmt, CommandDest dest) if (exists) { - UnlockRelation(pg_shadow_rel, AccessExclusiveLock); - heap_close(pg_shadow_rel); + heap_close(pg_shadow_rel, AccessExclusiveLock); UserAbortTransactionBlock(); elog(ERROR, "defineUser: user \"%s\" has already been created", stmt->user); @@ -165,6 +162,12 @@ DefineUser(CreateUserStmt *stmt, CommandDest dest) * * XXX Ugly as this code is, it still fails to cope with ' or \ in any of * the provided strings. + * + * XXX This routine would be *lots* better if it inserted the new + * tuple with formtuple/heap_insert. For one thing, all of the + * transaction-block gamesmanship could be eliminated, because + * it's only there to make the world safe for a recursive call + * to pg_exec_query_dest(). */ snprintf(sql, SQL_LENGTH, "insert into %s (usename,usesysid,usecreatedb,usetrace," @@ -189,17 +192,21 @@ DefineUser(CreateUserStmt *stmt, CommandDest dest) pg_exec_query_dest(sql, dest, false); /* - * Add the stuff here for groups. + * Add stuff here for groups? */ + /* + * Write the updated pg_shadow data to the flat password file. + * Because we are still holding AccessExclusiveLock on pg_shadow, + * we can be sure no other backend will try to write the flat + * file at the same time. + */ UpdatePgPwdFile(sql, dest); /* - * This goes after the UpdatePgPwdFile to be certain that two backends - * to not attempt to write to the pg_pwd file at the same time. + * Now we can clean up. */ - UnlockRelation(pg_shadow_rel, AccessExclusiveLock); - heap_close(pg_shadow_rel); + heap_close(pg_shadow_rel, AccessExclusiveLock); if (IsTransactionBlock() && !inblock) EndTransactionBlock(); @@ -237,70 +244,79 @@ AlterUser(AlterUserStmt *stmt, CommandDest dest) /* * Scan the pg_shadow relation to be certain the user exists. + * Note we secure exclusive lock to protect our update of the + * flat password file. */ - pg_shadow_rel = heap_openr(ShadowRelationName); + pg_shadow_rel = heap_openr(ShadowRelationName, AccessExclusiveLock); pg_shadow_dsc = RelationGetDescr(pg_shadow_rel); - /* - * Secure a write lock on pg_shadow so we can be sure that when the - * dump of the pg_pwd file is done, there is not another backend doing - * the same. - */ - LockRelation(pg_shadow_rel, AccessExclusiveLock); - tuple = SearchSysCacheTuple(USENAME, PointerGetDatum(stmt->user), 0, 0, 0); if (!HeapTupleIsValid(tuple)) { - UnlockRelation(pg_shadow_rel, AccessExclusiveLock); - heap_close(pg_shadow_rel); - UserAbortTransactionBlock(); /* needed? */ + heap_close(pg_shadow_rel, AccessExclusiveLock); + UserAbortTransactionBlock(); elog(ERROR, "alterUser: user \"%s\" does not exist", stmt->user); - return; } /* * Create the update statement to modify the user. + * + * XXX see diatribe in preceding routine. This code is just as bogus. */ snprintf(sql, SQL_LENGTH, "update %s set", ShadowRelationName); if (stmt->password) - snprintf(sql, SQL_LENGTH, "%s passwd = '%s'", pstrdup(sql), stmt->password); + snprintf(sql + strlen(sql), SQL_LENGTH - strlen(sql), + " passwd = '%s'", stmt->password); if (stmt->createdb) { - snprintf(sql, SQL_LENGTH, "%s %susecreatedb='%s'", - pstrdup(sql), stmt->password ? "," : "", + snprintf(sql + strlen(sql), SQL_LENGTH - strlen(sql), + "%s usecreatedb='%s'", + stmt->password ? "," : "", *stmt->createdb ? "t" : "f"); } if (stmt->createuser) { - snprintf(sql, SQL_LENGTH, "%s %susesuper='%s'", - pstrdup(sql), (stmt->password || stmt->createdb) ? "," : "", + snprintf(sql + strlen(sql), SQL_LENGTH - strlen(sql), + "%s usesuper='%s'", + (stmt->password || stmt->createdb) ? "," : "", *stmt->createuser ? "t" : "f"); } if (stmt->validUntil) { - snprintf(sql, SQL_LENGTH, "%s %svaluntil='%s'", - pstrdup(sql), + snprintf(sql + strlen(sql), SQL_LENGTH - strlen(sql), + "%s valuntil='%s'", (stmt->password || stmt->createdb || stmt->createuser) ? "," : "", stmt->validUntil); } - snprintf(sql, SQL_LENGTH, "%s where usename = '%s'", - pstrdup(sql), stmt->user); + snprintf(sql + strlen(sql), SQL_LENGTH - strlen(sql), + " where usename = '%s'", + stmt->user); pg_exec_query_dest(sql, dest, false); - /* do the pg_group stuff here */ + /* + * Add stuff here for groups? + */ + /* + * Write the updated pg_shadow data to the flat password file. + * Because we are still holding AccessExclusiveLock on pg_shadow, + * we can be sure no other backend will try to write the flat + * file at the same time. + */ UpdatePgPwdFile(sql, dest); - UnlockRelation(pg_shadow_rel, AccessExclusiveLock); - heap_close(pg_shadow_rel); + /* + * Now we can clean up. + */ + heap_close(pg_shadow_rel, AccessExclusiveLock); if (IsTransactionBlock() && !inblock) EndTransactionBlock(); @@ -310,7 +326,6 @@ AlterUser(AlterUserStmt *stmt, CommandDest dest) extern void RemoveUser(char *user, CommandDest dest) { - char *pg_shadow; Relation pg_shadow_rel, pg_rel; @@ -318,7 +333,7 @@ RemoveUser(char *user, CommandDest dest) HeapScanDesc scan; HeapTuple tuple; Datum datum; - char sql[512]; + char sql[SQL_LENGTH]; bool n, inblock; int32 usesysid; @@ -341,27 +356,19 @@ RemoveUser(char *user, CommandDest dest) } /* - * Perform a scan of the pg_shadow relation to find the usesysid of - * the user to be deleted. If it is not found, then return a warning - * message. + * Scan the pg_shadow relation to find the usesysid of the user to be + * deleted. Note we secure exclusive lock, because we need to protect + * our update of the flat password file. */ - pg_shadow_rel = heap_openr(ShadowRelationName); + pg_shadow_rel = heap_openr(ShadowRelationName, AccessExclusiveLock); pg_dsc = RelationGetDescr(pg_shadow_rel); - /* - * Secure a write lock on pg_shadow so we can be sure that when the - * dump of the pg_pwd file is done, there is not another backend doing - * the same. - */ - LockRelation(pg_shadow_rel, AccessExclusiveLock); - tuple = SearchSysCacheTuple(USENAME, PointerGetDatum(user), 0, 0, 0); if (!HeapTupleIsValid(tuple)) { - UnlockRelation(pg_shadow_rel, AccessExclusiveLock); - heap_close(pg_shadow_rel); + heap_close(pg_shadow_rel, AccessExclusiveLock); UserAbortTransactionBlock(); elog(ERROR, "removeUser: user \"%s\" does not exist", user); } @@ -372,7 +379,7 @@ RemoveUser(char *user, CommandDest dest) * Perform a scan of the pg_database relation to find the databases * owned by usesysid. Then drop them. */ - pg_rel = heap_openr(DatabaseRelationName); + pg_rel = heap_openr(DatabaseRelationName, AccessExclusiveLock); pg_dsc = RelationGetDescr(pg_rel); scan = heap_beginscan(pg_rel, false, SnapshotNow, 0, NULL); @@ -383,7 +390,7 @@ RemoveUser(char *user, CommandDest dest) if ((int) datum == usesysid) { datum = heap_getattr(tuple, Anum_pg_database_datname, pg_dsc, &n); - if (memcmp((void *) datum, "template1", 9)) + if (memcmp((void *) datum, "template1", 9) != 0) { dbase = (char **) repalloc((void *) dbase, sizeof(char *) * (ndbase + 1)); @@ -394,12 +401,12 @@ RemoveUser(char *user, CommandDest dest) } } heap_endscan(scan); - heap_close(pg_rel); + heap_close(pg_rel, AccessExclusiveLock); while (ndbase--) { elog(NOTICE, "Dropping database %s", dbase[ndbase]); - snprintf(sql, SQL_LENGTH, "drop database %s", dbase[ndbase]); + snprintf(sql, SQL_LENGTH, "DROP DATABASE %s", dbase[ndbase]); pfree((void *) dbase[ndbase]); pg_exec_query_dest(sql, dest, false); } @@ -431,10 +438,18 @@ RemoveUser(char *user, CommandDest dest) "delete from %s where usename = '%s'", ShadowRelationName, user); pg_exec_query_dest(sql, dest, false); + /* + * Write the updated pg_shadow data to the flat password file. + * Because we are still holding AccessExclusiveLock on pg_shadow, + * we can be sure no other backend will try to write the flat + * file at the same time. + */ UpdatePgPwdFile(sql, dest); - UnlockRelation(pg_shadow_rel, AccessExclusiveLock); - heap_close(pg_shadow_rel); + /* + * Now we can clean up. + */ + heap_close(pg_shadow_rel, AccessExclusiveLock); if (IsTransactionBlock() && !inblock) EndTransactionBlock(); |