ns_cache_door.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include <pwd.h>
#include <stdio.h>
#include <synch.h>
#include <fcntl.h>
#include <unistd.h>
#include "ns_cache_door.h"
#include <door.h>
/*
*
* Routine that actually performs the door call.
* Note that we cache a file descriptor. We do
* the following to prevent disasters:
*
* 1) Never use 0,1 or 2; if we get this from the open
* we dup it upwards.
*
* 2) Set the close on exec flags so descriptor remains available
* to child processes.
*
* 3) Verify that the door is still the same one we had before
* by using door_info on the client side.
*
* Note that we never close the file descriptor if it isn't one
* we allocated; we check this with door info. The rather tricky
* logic is designed to be fast in the normal case (fd is already
* allocated and is ok) while handling the case where the application
* closed it underneath us or where the nscd dies or re-execs itself
* and we're a multi-threaded application. Note that we cannot protect
* the application if it closes the fd and it is multi-threaded.
*
* int _cache_trydoorcall(void *dptr, int *bufsize, int *actualsize);
*
* *dptr IN: points to arg buffer OUT: points to results buffer
* *bufsize IN: overall size of buffer OUT: overall size of buffer
* *actualsize IN: size of call data OUT: size of return data
*
* Note that *dptr may change if provided space as defined by *bufsize is
* inadequate. In this case the door call mmaps more space and places
* the answer there and sets dptr to contain a pointer to the space, which
* should be freed with munmap.
*
* Returns 0 if the door call reached the server, -1 if contact was not made.
*
*/
extern int errno;
int
{
static int doorfd = -1;
static door_info_t real_door;
/*
* the first time in we try and open and validate the door.
* the validations are that the door must have been
* created with the name service door cookie and
* that the file attached to the door is owned by root
* and readonly by user, group and other. If any of these
* validations fail we refuse to use the door.
*/
(void) mutex_lock(&_door_lock);
if (doorfd == -1) {
int tbc[3];
int i;
== -1) {
(void) mutex_unlock(&_door_lock);
return (NOSERVER);
}
/*
* dup up the file descriptor if we have 0 - 2
*/
i = 0;
while (i--)
doorfd = -1;
(void) mutex_unlock(&_door_lock);
return (NOSERVER);
}
}
while (i--)
/*
* mark this door descriptor as close on exec
*/
/*
* we should close doorfd because we just opened it
*/
doorfd = -1;
(void) mutex_unlock(&_door_lock);
return (NOSERVER);
}
doorfd = -1;
(void) mutex_unlock(&_door_lock);
return (NOSERVER);
}
} else {
/*
* don't close it -
* someone else has clobbered fd
*/
doorfd = -1;
goto try_again;
}
goto try_again;
}
}
(void) mutex_unlock(&_door_lock);
return (NOSERVER);
}
return (NOSERVER);
}
}
/*
* routine to check if server is already running
*/
int
{
int ndata;
int adata;
}
#endif /* PIC */