be-fsstubs.c

PostgreSQL7.4.6 for Linux

/*-------------------------------------------------------------------------
 *
 * be-fsstubs.c
 *	  support for filesystem operations on large objects
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.68 2003/08/04 02:39:59 momjian Exp $
 *
 * NOTES
 *	  This should be moved to a more appropriate place.  It is here
 *	  for lack of a better place.
 *
 *	  Builtin functions for open/close/read/write operations on large objects.
 *
 *	  These functions operate in a private MemoryContext, which means
 *	  that large object descriptors hang around until we destroy the context.
 *	  That happens in lo_commit().	It'd be possible to prolong the lifetime
 *	  of the context so that LO FDs are good across transactions (for example,
 *	  we could release the context only if we see that no FDs remain open).
 *	  But we'd need additional state in order to do the right thing at the
 *	  end of an aborted transaction.  FDs opened during an aborted xact would
 *	  still need to be closed, since they might not be pointing at valid
 *	  relations at all.  Locking semantics are also an interesting problem
 *	  if LOs stay open across transactions.  For now, we'll stick with the
 *	  existing documented semantics of LO FDs: they're only good within a
 *	  transaction.
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>

#include "libpq/be-fsstubs.h"
#include "libpq/libpq-fs.h"
#include "miscadmin.h"
#include "storage/large_object.h"
#include "utils/memutils.h"


/* [PA] is Pascal Andr