/*------------------------------------------------------------------------- * * database.c * miscellaneous initialization support stuff * * Portions Copyright (c) 1996-2000, PostgreSQL, Inc * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/utils/misc/Attic/database.c,v 1.39 2000/07/03 20:48:42 petere Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include #include #include #include #include "access/xact.h" #include "catalog/catname.h" #include "catalog/pg_database.h" #include "miscadmin.h" #include "utils/syscache.h" /* * ExpandDatabasePath resolves a proposed database path (obtained from * pg_database.datpath) to a full absolute path for further consumption. * NULL means an error, which the caller should process. One reason for * such an error would be an absolute alternative path when no absolute * paths are alllowed. */ char * ExpandDatabasePath(const char *dbpath) { char buf[MAXPGPATH]; const char *cp; int len; AssertArg(dbpath); Assert(DataDir); if (strlen(dbpath) >= MAXPGPATH) return NULL; /* ain't gonna fit nohow */ /* leading path delimiter? then already absolute path */ if (*dbpath == SEP_CHAR) { #ifdef ALLOW_ABSOLUTE_DBPATHS cp = strrchr(dbpath, SEP_CHAR); len = cp - dbpath; strncpy(buf, dbpath, len); snprintf(&buf[len], MAXPGPATH - len, "%cbase%c%s", SEP_CHAR, SEP_CHAR, (cp + 1)); #else return NULL; #endif } /* path delimiter somewhere? then has leading environment variable */ else if ((cp = strchr(dbpath, SEP_CHAR)) != NULL) { const char *envvar; len = cp - dbpath; strncpy(buf, dbpath, len); buf[len] = '\0'; envvar = getenv(buf); if (envvar == NULL) return NULL; snprintf(buf, sizeof(buf), "%s%cbase%c%s", envvar, SEP_CHAR, SEP_CHAR, (cp + 1)); } else { /* no path delimiter? then add the default path prefix */ snprintf(buf, sizeof(buf), "%s%cbase%c%s", DataDir, SEP_CHAR, SEP_CHAR, dbpath); } /* * check for illegal characters in dbpath these should really throw an * error, shouldn't they? or else all callers need to test for NULL */ for (cp = buf; *cp; cp++) { /* * The following characters will not be allowed anywhere in the * database path. (Do not include the slash or '.' here.) */ char illegal_dbpath_chars[] = "\001\002\003\004\005\006\007\010" "\011\012\013\014\015\016\017\020" "\021\022\023\024\025\026\027\030" "\031\032\033\034\035\036\037" "'`"; const char *cx; for (cx = illegal_dbpath_chars; *cx; cx++) if (*cp == *cx) return NULL; /* don't allow access to parent dirs */ if (strncmp(cp, "/../", 4) == 0) return NULL; } return pstrdup(buf); } /* 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(const char *name, Oid *db_id, char *path) { int dbfd; int nbytes; int max, i; HeapTupleData tup; Page pg; PageHeader ph; char *dbfname; Form_pg_database tup_db; dbfname = (char *) palloc(strlen(DataDir) + 8 + strlen(DatabaseRelationName) + 2); sprintf(dbfname, "%s/global/%s", DataDir, DatabaseRelationName); if ((dbfd = open(dbfname, O_RDONLY | PG_BINARY, 0)) < 0) elog(FATAL, "cannot open %s: %s", dbfname, strerror(errno)); 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_datamcxt = NULL; 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, NameStr(tup_db->datname)) == 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() */