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/*-------------------------------------------------------------------------
*
* 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 1.36 2000/03/08 01:46:47 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#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) + strlen(DatabaseRelationName) + 2);
sprintf(dbfname, "%s%c%s", DataDir, SEP_CHAR, DatabaseRelationName);
#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: %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() */
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