/*------------------------------------------------------------------------- * * database.c * miscellaneous initialization support stuff * * Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/utils/misc/Attic/database.c,v 1.30 1999/09/24 00:25:04 tgl Exp $ * *------------------------------------------------------------------------- */ #include #include #include "postgres.h" #include "access/xact.h" #include "catalog/pg_database.h" #include "miscadmin.h" #include "utils/syscache.h" #ifdef NOT_USED /* GetDatabaseInfo() * Pull database information from pg_database. */ int GetDatabaseInfo(char *name, int4 *owner, char *path) { Oid dbowner, dbid; char dbpath[MAXPGPATH + 1]; text *dbtext; Relation dbrel; HeapTuple dbtup; HeapTuple tup; HeapScanDesc scan; ScanKeyData scanKey; dbrel = heap_openr(DatabaseRelationName, AccessShareLock); ScanKeyEntryInitialize(&scanKey, 0, Anum_pg_database_datname, F_NAMEEQ, NameGetDatum(name)); scan = heap_beginscan(dbrel, 0, SnapshotNow, 1, &scanKey); if (!HeapScanIsValid(scan)) elog(ERROR, "GetDatabaseInfo: cannot begin scan of %s", DatabaseRelationName); /* * Since we're going to close the relation, copy the tuple. */ tup = heap_getnext(scan, 0); if (HeapTupleIsValid(tup)) dbtup = heap_copytuple(tup); else dbtup = tup; heap_endscan(scan); if (!HeapTupleIsValid(dbtup)) { elog(NOTICE, "GetDatabaseInfo: %s entry not found %s", DatabaseRelationName, name); heap_close(dbrel, AccessShareLock); return TRUE; } dbowner = (Oid) heap_getattr(dbtup, Anum_pg_database_datdba, RelationGetDescr(dbrel), (char *) NULL); dbid = dbtup->t_oid; dbtext = (text *) heap_getattr(dbtup, Anum_pg_database_datpath, RelationGetDescr(dbrel), (char *) NULL); memcpy(dbpath, VARDATA(dbtext), (VARSIZE(dbtext) - VARHDRSZ)); *(dbpath + (VARSIZE(dbtext) - VARHDRSZ)) = '\0'; heap_close(dbrel, AccessShareLock); owner = palloc(sizeof(Oid)); *owner = dbowner; path = palloc(strlen(dbpath) + 1); strcpy(path, dbpath); return FALSE; } /* GetDatabaseInfo() */ #endif char * ExpandDatabasePath(char *dbpath) { char *path; char *cp; char buf[MAXPGPATH + 1]; /* leading path delimiter? then already absolute path */ if (*dbpath == SEP_CHAR) { #ifdef ALLOW_ABSOLUTE_DBPATHS cp = strrchr(dbpath, SEP_CHAR); strncpy(buf, dbpath, (cp - dbpath)); sprintf(&buf[cp - dbpath], "%cbase%c%s", SEP_CHAR, SEP_CHAR, (cp + 1)); #else return NULL; #endif } /* path delimiter somewhere? then has leading environment variable */ else if (strchr(dbpath, SEP_CHAR) != NULL) { cp = strchr(dbpath, SEP_CHAR); strncpy(buf, dbpath, (cp - dbpath)); buf[cp - dbpath] = '\0'; path = getenv(buf); /* * problem getting environment variable? let calling routine * handle it */ if (path == NULL) return path; sprintf(buf, "%s%cbase%c%s", path, SEP_CHAR, SEP_CHAR, (cp + 1)); } /* no path delimiter? then add the default path prefixes */ else sprintf(buf, "%s%cbase%c%s", DataDir, SEP_CHAR, SEP_CHAR, dbpath); path = palloc(strlen(buf) + 1); strcpy(path, buf); return path; } /* ExpandDatabasePath() */ /* -------------------------------- * GetRawDatabaseInfo() -- Find the OID and path of the database. * * The database's oid forms half of the unique key for the system * caches and lock tables. We therefore want it initialized before * we open any relations, since opening relations puts things in the * cache. To get around this problem, this code opens and scans the * pg_database relation by hand. * * This code knows way more than it should about the layout of * tuples on disk, but there seems to be no help for that. * We're pulling ourselves up by the bootstraps here... * -------------------------------- */ void GetRawDatabaseInfo(char *name, Oid *db_id, char *path) { int dbfd; int fileflags; int nbytes; int max, i; HeapTupleData tup; Page pg; PageHeader ph; char *dbfname; Form_pg_database tup_db; dbfname = (char *) palloc(strlen(DataDir) + strlen("pg_database") + 2); sprintf(dbfname, "%s%cpg_database", DataDir, SEP_CHAR); fileflags = O_RDONLY; #ifndef __CYGWIN32__ if ((dbfd = open(dbfname, O_RDONLY, 0)) < 0) #else if ((dbfd = open(dbfname, O_RDONLY | O_BINARY, 0)) < 0) #endif elog(FATAL, "Cannot open %s", dbfname); pfree(dbfname); /* ---------------- * read and examine every page in pg_database * * Raw I/O! Read those tuples the hard way! Yow! * * Why don't we use the access methods or move this code * someplace else? This is really pg_database schema dependent * code. Perhaps it should go in lib/catalog/pg_database? * -cim 10/3/90 * * mao replies 4 apr 91: yeah, maybe this should be moved to * lib/catalog. however, we CANNOT use the access methods since * those use the buffer cache, which uses the relation cache, which * requires that the dbid be set, which is what we're trying to do * here. * ---------------- */ pg = (Page) palloc(BLCKSZ); ph = (PageHeader) pg; while ((nbytes = read(dbfd, pg, BLCKSZ)) == BLCKSZ) { max = PageGetMaxOffsetNumber(pg); /* look at each tuple on the page */ for (i = 0; i <= max; i++) { int offset; /* if it's a freed tuple, ignore it */ if (!(ph->pd_linp[i].lp_flags & LP_USED)) continue; /* get a pointer to the tuple itself */ offset = (int) ph->pd_linp[i].lp_off; tup.t_data = (HeapTupleHeader) (((char *) pg) + offset); /* * if the tuple has been deleted (the database was destroyed), * skip this tuple. XXX warning, will robinson: violation of * transaction semantics happens right here. we should check * to be sure that the xact that deleted this tuple actually * committed. Only way to do that at init time is to paw over * the log relation by hand, too. Instead we take the * conservative assumption that if someone tried to delete it, * it's gone. The other side of the coin is that we might * accept a tuple that was stored and never committed. All in * all, this code is pretty shaky. We will cross-check our * result in ReverifyMyDatabase() in postinit.c. * * NOTE: if a bogus tuple in pg_database prevents connection * to a valid database, a fix is to connect to another database * and do "select * from pg_database". That should cause * committed and dead tuples to be marked with correct states. * * XXX wouldn't it be better to let new backends read the * database OID from a flat file, handled the same way * we handle the password relation? */ if (TransactionIdIsValid((TransactionId) tup.t_data->t_xmax)) continue; /* * Okay, see if this is the one we want. */ tup_db = (Form_pg_database) GETSTRUCT(&tup); if (strcmp(name, tup_db->datname.data) == 0) { /* Found it; extract the OID and the database path. */ *db_id = tup.t_data->t_oid; strncpy(path, VARDATA(&(tup_db->datpath)), (VARSIZE(&(tup_db->datpath)) - VARHDRSZ)); *(path + VARSIZE(&(tup_db->datpath)) - VARHDRSZ) = '\0'; goto done; } } } done: close(dbfd); pfree(pg); } /* GetRawDatabaseInfo() */