/*------------------------------------------------------------------------- * * database.c *	  miscellanious initialization support stuff * * Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION *	  $Header: /usr/local/cvsroot/pgsql/src/backend/utils/misc/database.c,v 1.24.2.1 1999/08/02 05:25:14 scrappy Exp $ * *------------------------------------------------------------------------- */#include <unistd.h>#include <fcntl.h>#include "postgres.h"#include "access/xact.h"#include "catalog/pg_database.h"#include "miscadmin.h"#include "utils/syscache.h"#ifdef MULTIBYTE#include "mb/pg_wchar.h"#endif#ifdef NOT_USED/* GetDatabaseInfo() * Pull database information from pg_database. */intGetDatabaseInfo(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);	if (!RelationIsValid(dbrel))		elog(FATAL, "GetDatabaseInfo: cannot open relation \"%-.*s\"",			 DatabaseRelationName);	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);		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);	owner = palloc(sizeof(Oid));	*owner = dbowner;	path = palloc(strlen(dbpath) + 1);	strcpy(path, dbpath);	return FALSE;}	/* GetDatabaseInfo() */#endifchar *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 algorithm relies on the fact that first attribute in the *		pg_database relation schema is the database name.  It also knows *		about the internal format of tuples on disk and the length of *		the datname attribute.	It knows the location of the pg_database *		file. *		Actually, the code looks as though it is using the pg_database *		tuple definition to locate the database name, so the above statement *		seems to be no longer correct. - thomas 1997-11-01 * *		This code is called from InitPostgres(), before we chdir() to the *		local database directory and before we open any relations. *		Used to be called after the chdir(), but we now want to confirm *		the location of the target database using pg_database info. *		- thomas 1997-11-01 * -------------------------------- */voidGetRawDatabaseInfo(char *name, int4 *owner, Oid *db_id, char *path, int *encoding){	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 this at init time is to paw over			 * the log relation by hand, too.  let's be optimistic.			 *			 * XXX This is an evil type cast.  tup->t_xmax is char[5] while			 * TransactionId is struct * { char data[5] }.	It works but			 * if data is ever moved and no longer the first field this			 * will be broken!! -mer 11 Nov 1991.			 */			if (TransactionIdIsValid((TransactionId) tup.t_data->t_xmax))				continue;			/*			 * Okay, see if this is the one we want. XXX 1 july 91:  mao			 * and mer discover that tuples now squash t_bits.	Why is			 * this?			 *			 * 24 july 92:	mer realizes that the t_bits field is only used			 * in the event of null values.  If no fields are null we			 * reduce the header size by doing the squash.	t_hoff tells			 * you exactly how big the header actually is. use the PC			 * means of getting at sys cat attrs.			 */			tup_db = (Form_pg_database) GETSTRUCT(&tup);#ifdef MULTIBYTE			/*			 * get encoding from template database. This is the "default			 * for default" for create database command.			 */			if (strcmp("template1", tup_db->datname.data) == 0)				SetTemplateEncoding(tup_db->encoding);#endif			if (strcmp(name, tup_db->datname.data) == 0)			{				*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';#ifdef MULTIBYTE				*encoding = tup_db->encoding;#endif				goto done;			}		}	}done:	close(dbfd);	pfree(pg);}	/* GetRawDatabaseInfo() */