path: root/source3/locking/locking.c

/* 
   Unix SMB/CIFS implementation.
   Locking functions
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1992-2006
   Copyright (C) Volker Lendecke 2005
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   Revision History:

   12 aug 96: Erik.Devriendt@te6.siemens.be
   added support for shared memory implementation of share mode locking

   May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode
   locking to deal with multiple share modes per open file.

   September 1997. Jeremy Allison (jallison@whistle.com). Added oplock
   support.

   rewrtten completely to use new tdb code. Tridge, Dec '99

   Added POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
   Added Unix Extensions POSIX locking support. Jeremy Allison Mar 2006.
*/

#include "includes.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

#define NO_LOCKING_COUNT (-1)

/* the locking database handle */
static struct db_context *lock_db;

/****************************************************************************
 Debugging aids :-).
****************************************************************************/

const char *lock_type_name(enum brl_type lock_type)
{
	switch (lock_type) {
		case READ_LOCK:
			return "READ";
		case WRITE_LOCK:
			return "WRITE";
		case PENDING_READ_LOCK:
			return "PENDING_READ";
		case PENDING_WRITE_LOCK:
			return "PENDING_WRITE";
		default:
			return "other";
	}
}

const char *lock_flav_name(enum brl_flavour lock_flav)
{
	return (lock_flav == WINDOWS_LOCK) ? "WINDOWS_LOCK" : "POSIX_LOCK";
}

/****************************************************************************
 Utility function called to see if a file region is locked.
 Called in the read/write codepath.
****************************************************************************/

void init_strict_lock_struct(files_struct *fsp,
				uint32 smbpid,
				br_off start,
				br_off size,
				enum brl_type lock_type,
				struct lock_struct *plock)
{
	SMB_ASSERT(lock_type == READ_LOCK || lock_type == WRITE_LOCK);

	plock->context.smbpid = smbpid;
        plock->context.tid = fsp->conn->cnum;
        plock->context.pid = procid_self();
        plock->start = start;
        plock->size = size;
        plock->fnum = fsp->fnum;
        plock->lock_type = lock_type;
        plock->lock_flav = lp_posix_cifsu_locktype(fsp);
}

bool strict_lock_default(files_struct *fsp, struct lock_struct *plock)
{
	int strict_locking = lp_strict_locking(fsp->conn->params);
	bool ret = False;

	if (plock->size == 0) {
		return True;
	}

	if (!lp_locking(fsp->conn->params) || !strict_locking) {
		return True;
	}

	if (strict_locking == Auto) {
		if  (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && (plock->lock_type == READ_LOCK || plock->lock_type == WRITE_LOCK)) {
			DEBUG(10,("is_locked: optimisation - exclusive oplock on file %s\n", fsp_str_dbg(fsp)));
			ret = True;
		} else if ((fsp->oplock_type == LEVEL_II_OPLOCK) &&
			   (plock->lock_type == READ_LOCK)) {
			DEBUG(10,("is_locked: optimisation - level II oplock on file %s\n", fsp_str_dbg(fsp)));
			ret = True;
		} else {
			struct byte_range_lock *br_lck = brl_get_locks_readonly(talloc_tos(), fsp);
			if (!br_lck) {
				return True;
			}
			ret = brl_locktest(br_lck,
					plock->context.smbpid,
					plock->context.pid,
					plock->start,
					plock->size,
					plock->lock_type,
					plock->lock_flav);
			TALLOC_FREE(br_lck);
		}
	} else {
		struct byte_range_lock *br_lck = brl_get_locks_readonly(talloc_tos(), fsp);
		if (!br_lck) {
			return True;
		}
		ret = brl_locktest(br_lck,
				plock->context.smbpid,
				plock->context.pid,
				plock->start,
				plock->size,
				plock->lock_type,
				plock->lock_flav);
		TALLOC_FREE(br_lck);
	}

	DEBUG(10,("strict_lock_default: flavour = %s brl start=%.0f "
			"len=%.0f %s for fnum %d file %s\n",
			lock_flav_name(plock->lock_flav),
			(double)plock->start, (double)plock->size,
			ret ? "unlocked" : "locked",
			plock->fnum, fsp_str_dbg(fsp)));

	return ret;
}

void strict_unlock_default(files_struct *fsp, struct lock_struct *plock)
{
}

/****************************************************************************
 Find out if a lock could be granted - return who is blocking us if we can't.
****************************************************************************/

NTSTATUS query_lock(files_struct *fsp,
			uint32 *psmbpid,