path: root/source3/locking/locking.c

/* 
   Unix SMB/Netbios implementation.
   Version 3.0
   Locking functions
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1992-2000
   
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

   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.
*/

#include "includes.h"
extern int DEBUGLEVEL;
uint16 global_smbpid;

/* the locking database handle */
static TDB_CONTEXT *tdb;

/****************************************************************************
 Debugging aid :-).
****************************************************************************/

static const char *lock_type_name(enum brl_type lock_type)
{
	return (lock_type == READ_LOCK) ? "READ" : "WRITE";
}

/****************************************************************************
 Utility function called to see if a file region is locked.
 If check_self is True, then checks on our own fd with the same locking context
 are still made. If check_self is False, then checks are not made on our own fd
 with the same locking context are not made.
****************************************************************************/

BOOL is_locked(files_struct *fsp,connection_struct *conn,
	       SMB_BIG_UINT count,SMB_BIG_UINT offset, 
	       enum brl_type lock_type, BOOL check_self)
{
	int snum = SNUM(conn);
	BOOL ret;
	
	if (count == 0)
		return(False);

	if (!lp_locking(snum) || !lp_strict_locking(snum))
		return(False);

	ret = !brl_locktest(fsp->dev, fsp->inode, fsp->fnum,
			     global_smbpid, sys_getpid(), conn->cnum, 
			     offset, count, lock_type, check_self);

	DEBUG(10,("is_locked: brl start=%.0f len=%.0f %s for file %s\n",
			(double)offset, (double)count, ret ? "locked" : "unlocked",
			fsp->fsp_name ));

	/*
	 * There is no lock held by an SMB daemon, check to
	 * see if there is a POSIX lock from a UNIX or NFS process.
	 */

	if(!ret && lp_posix_locking(snum)) {
		ret = is_posix_locked(fsp, offset, count, lock_type);

		DEBUG(10,("is_locked: posix start=%.0f len=%.0f %s for file %s\n",
				(double)offset, (double)count, ret ? "locked" : "unlocked",
				fsp->fsp_name ));
	}

	return ret;
}

/****************************************************************************
 Utility function called by locking requests.
****************************************************************************/

BOOL do_lock(files_struct *fsp,connection_struct *conn, uint16 lock_pid,
             SMB_BIG_UINT count,SMB_BIG_UINT offset,enum brl_type lock_type,
             int *eclass,uint32 *ecode)
{
	BOOL ok = False;

	if (!lp_locking(SNUM(conn)))
		return(True);

	if (count == 0) {
		*eclass = ERRDOS;
		*ecode = ERRnoaccess;
		return False;
	}
	
	DEBUG(10,("do_lock: lock type %s start=%.0f len=%.0f requested for file %s\n",
		  lock_type_name(lock_type), (double)offset, (double)count, fsp->fsp_name ));

	if (OPEN_FSP(fsp) && fsp->can_lock && (fsp->conn == conn)) {
		ok = brl_lock(fsp->dev, fsp->inode, fsp->fnum,
			      lock_pid, sys_getpid(), conn->cnum, 
			      offset, count, 
			      lock_type);

		if (ok && lp_posix_locking(SNUM(conn))) {

			/*
			 * Try and get a POSIX lock on this range.
			 * Note that this is ok if it is a read lock
			 * overlapping on a different fd. JRA.
			 */

			ok = set_posix_lock(fsp, offset, count, lock_type);

			if (!ok) {
				/*
				 * We failed to map - we must now remove the brl
				 * lock entry.
				 */
				(void)brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
								lock_pid, sys_getpid(), conn->cnum, 
								offset, count);
			}
		}
	}

	if (!ok) {
		*eclass = ERRDOS;
		*ecode = ERRlock;
		return False;
	}
	return True; /* Got lock */
}

/****************************************************************************
 Utility function called by unlocking requests.
****************************************************************************/

BOOL do_unlock(files_struct *fsp,connection_struct *conn, uint16 lock_pid,
               SMB_BIG_UINT count,SMB_BIG_UINT offset, 
	       int *eclass,uint32 *ecode)
{
	BOOL ok = False;
	
	if (!lp_locking(SNUM(conn)))
		return(True);
	
	if (!OPEN_FSP(fsp) || !fsp->can_lock || (fsp->conn != conn)) {
		*eclass = ERRDOS;
		*ecode = ERRbadfid;
		return False;
	}
	
	DEBUG(10,("do_unlock: unlock start=%.0f len=%.0f requested for file %s\n",
		  (double)offset, (double)count, fsp->fsp_name ));

	/*
	 * Remove the existing lock record from the tdb lockdb
	 * before looking at POSIX locks. If this record doesn't
	 * match then don't bother looking to remove POSIX locks.
	 */

	ok = brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
			lock_pid, sys_getpid(), conn->cnum, offset, count);
   
	if (!ok) {
		DEBUG(10,("do_unlock: returning ERRlock.\n" ));
		*eclass = ERRDOS;
		*ecode = ERRnotlocked;
		return False;
	}

	if (!lp_posix_locking(SNUM(conn)))
		return True;

	(void)release_posix_lock(fsp, offset, count);

	return True; /* Did unlock */
}

/****************************************************************************
 Remove any locks on this fd. Called from file_close().
****************************************************************************/

void locking_close_file(files_struct *fsp)
{
	pid_t pid = sys_getpid();

	if (!lp_locking(SNUM(fsp->conn)))
		return;

	/*
	 * Just release all the brl locks, no need to release individually.
	 */

	brl_close(fsp->dev, fsp->inode, pid, fsp->conn->cnum, fsp->fnum);

	if(lp_posix_locking(SNUM(fsp->conn))) {

	 	/* 
		 * Release all the POSIX locks.
		 */
		posix_locking_close_file(fsp);

	}
}

/****************************************************************************
 Delete a record if it is for a dead process, if check_self is true, then
 delete any records belonging to this pid also (there shouldn't be any).
 This function is only called on locking startup and shutdown.
****************************************************************************/

static int delete_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
{
	struct locking_data *data;
	share_mode_entry *shares;
	int i, del_count=0;
	pid_t mypid = sys_getpid();
	BOOL check_self = *(BOOL *)state;

	tdb_chainlock(tdb, kbuf);

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));

	for (i=0;i<data->num_share_mode_entries;) {

		if (check_self && (shares[i].pid == mypid)) {
			DEBUG(0,("locking : delete_fn. LOGIC ERROR ! Shutting down and a record for my pid (%u) exists !\n",
					(unsigned int)shares[i].pid ));
		} else if (!process_exists(shares[i].pid)) {
			DEBUG(0,("locking : delete_fn. LOGIC ERROR ! Entry for pid %u and it no longer exists !\n",
					(unsigned int)shares[i].pid ));
		} else {
			/* Process exists, leave this record alone. */
			i++;
			continue;
		}

		data->num_share_mode_entries--;
		memmove(&shares[i], &shares[i+1],
		dbuf.dsize - (sizeof(*data) + (i+1)*sizeof(*shares)));
		del_count++;

	}

	/* the record has shrunk a bit */
	dbuf.dsize -= del_count * sizeof(*shares);

	/* store it back in the database */
	if (data->num_share_mode_entries == 0)
		tdb_delete(ttdb, kbuf);
	else
		tdb_store(ttdb, kbuf, dbuf, TDB_REPLACE);

	tdb_chainunlock(tdb, kbuf);
	return 0;
}

/****************************************************************************
 Initialise the locking functions.
****************************************************************************/

static int open_read_only;

BOOL locking_init(int read_only)
{
	BOOL check_self = False;

	brl_init(read_only);

	if (tdb)
		return True;

	tdb = tdb_open_log(lock_path("locking.tdb"), 
		       0, TDB_CLEAR_IF_FIRST, 
		       read_only?O_RDONLY:O_RDWR|O_CREAT,
		       0644);

	if (!tdb) {
		DEBUG(0,("ERROR: Failed to initialise locking database\n"));
		return False;
	}
	
	if (!posix_locking_init(read_only))
		return False;

	/* delete any dead locks */
	if (!read_only)
		tdb_traverse(tdb, delete_fn, &check_self);

	open_read_only = read_only;

	return True;
}

/*******************************************************************
 Deinitialize the share_mode management.
******************************************************************/

BOOL locking_end(void)
{
	BOOL check_self = True;

	brl_shutdown(open_read_only);
	if (tdb) {

		/* delete any dead locks */

		if (!open_read_only)
			tdb_traverse(tdb, delete_fn, &check_self);

		if (tdb_close(tdb) != 0)
			return False;
	}

	return True;
}

/*******************************************************************
 form a static locking key for a dev/inode pair 
******************************************************************/
static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
{
	static struct locking_key key;
	TDB_DATA kbuf;

	memset(&key, '\0', sizeof(key));
	key.dev = dev;
	key.inode = inode;
	kbuf.dptr = (char *)&key;
	kbuf.dsize = sizeof(key);
	return kbuf;
}
static TDB_DATA locking_key_fsp(files_struct *fsp)
{
	return locking_key(fsp->dev, fsp->inode);
}

/*******************************************************************
 Lock a hash bucket entry.
******************************************************************/
BOOL lock_share_entry(connection_struct *conn,
		      SMB_DEV_T dev, SMB_INO_T inode)
{
	return tdb_chainlock(tdb, locking_key(dev, inode)) == 0;
}

/*******************************************************************
 Unlock a hash bucket entry.
******************************************************************/
void unlock_share_entry(connection_struct *conn,
			SMB_DEV_T dev, SMB_INO_T inode)
{
	tdb_chainunlock(tdb, locking_key(dev, inode));
}


/*******************************************************************
 Lock a hash bucket entry. use a fsp for convenience
******************************************************************/
BOOL lock_share_entry_fsp(files_struct *fsp)
{
	return tdb_chainlock(tdb, locking_key(fsp->dev, fsp->inode)) == 0;
}

/*******************************************************************
 Unlock a hash bucket entry.
******************************************************************/
void unlock_share_entry_fsp(files_struct *fsp)
{
	tdb_chainunlock(tdb, locking_key(fsp->dev, fsp->inode));
}

/*******************************************************************
 Get all share mode entries for a dev/inode pair.
********************************************************************/
int get_share_modes(connection_struct *conn, 
		    SMB_DEV_T dev, SMB_INO_T inode, 
		    share_mode_entry **shares)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	int ret;

	*shares = NULL;

	dbuf = tdb_fetch(tdb, locking_key(dev, inode));
	if (!dbuf.dptr) return 0;

	data = (struct locking_data *)dbuf.dptr;
	ret = data->num_share_mode_entries;
	if(ret)
		*shares = (share_mode_entry *)memdup(dbuf.dptr + sizeof(*data), ret * sizeof(**shares));
	free(dbuf.dptr);

	if (! *shares) return 0;

	return ret;
}

/*******************************************************************
 Del the share mode of a file for this process. Return the number
 of entries left, and a memdup'ed copy of the entry deleted.
********************************************************************/

size_t del_share_mode(files_struct *fsp, share_mode_entry **ppse)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	int i, del_count=0;
	share_mode_entry *shares;
	pid_t pid = sys_getpid();
	size_t count;

	*ppse = NULL;

	/* read in the existing share modes */
	dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
	if (!dbuf.dptr) return 0;

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));

	/* find any with our pid and delete it by overwriting with the rest of the data 
	   from the record */
	for (i=0;i<data->num_share_mode_entries;) {
		if (shares[i].pid == pid &&
		    memcmp(&shares[i].time, 
			   &fsp->open_time,sizeof(struct timeval)) == 0) {
			*ppse = memdup(&shares[i], sizeof(*shares));
			data->num_share_mode_entries--;
			memmove(&shares[i], &shares[i+1], 
				dbuf.dsize - (sizeof(*data) + (i+1)*sizeof(*shares)));
			del_count++;
		} else {
			i++;
		}
	}

	/* the record has shrunk a bit */
	dbuf.dsize -= del_count * sizeof(*shares);

	count = data->num_share_mode_entries;

	/* store it back in the database */
	if (data->num_share_mode_entries == 0) {
		tdb_delete(tdb, locking_key_fsp(fsp));
	} else {
		tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
	}

	free(dbuf.dptr);
	return count;
}

/*******************************************************************
fill a share mode entry
********************************************************************/
static void fill_share_mode(char *p, files_struct *fsp, uint16 port, uint16 op_type)
{
	share_mode_entry *e = (share_mode_entry *)p;
	e->pid = sys_getpid();
	e->share_mode = fsp->share_mode;
	e->op_port = port;
	e->op_type = op_type;
	memcpy((char *)&e->time, (char *)&fsp->open_time, sizeof(struct timeval));
}

/*******************************************************************
 Set the share mode of a file. Return False on fail, True on success.
********************************************************************/
BOOL set_share_mode(files_struct *fsp, uint16 port, uint16 op_type)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	char *p=NULL;
	int size;
		
	/* read in the existing share modes if any */
	dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
	if (!dbuf.dptr) {
		/* we'll need to create a new record */
		pstring fname;

		pstrcpy(fname, fsp->conn->connectpath);
		pstrcat(fname, "/");
		pstrcat(fname, fsp->fsp_name);

		size = sizeof(*data) + sizeof(share_mode_entry) + strlen(fname) + 1;
		p = (char *)malloc(size);
		data = (struct locking_data *)p;
		data->num_share_mode_entries = 1;
		pstrcpy(p + sizeof(*data) + sizeof(share_mode_entry), fname);
		fill_share_mode(p + sizeof(*data), fsp, port, op_type);
		dbuf.dptr = p;
		dbuf.dsize = size;
		tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
		free(p);
		return True;
	}

	/* we're adding to an existing entry - this is a bit fiddly */
	data = (struct locking_data *)dbuf.dptr;

	data->num_share_mode_entries++;
	size = dbuf.dsize + sizeof(share_mode_entry);
	p = malloc(size);
	memcpy(p, dbuf.dptr, sizeof(*data));
	fill_share_mode(p + sizeof(*data), fsp, port, op_type);
	memcpy(p + sizeof(*data) + sizeof(share_mode_entry), dbuf.dptr + sizeof(*data),
	       dbuf.dsize - sizeof(*data));
	free(dbuf.dptr);
	dbuf.dptr = p;
	dbuf.dsize = size;
	tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
	free(p);
	return True;
}


/*******************************************************************
a generic in-place modification call for share mode entries
********************************************************************/
static BOOL mod_share_mode(files_struct *fsp,
			   void (*mod_fn)(share_mode_entry *, SMB_DEV_T, SMB_INO_T, void *),
			   void *param)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	int i;
	share_mode_entry *shares;
	pid_t pid = sys_getpid();
	int need_store=0;

	/* read in the existing share modes */
	dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
	if (!dbuf.dptr) return False;

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));

	/* find any with our pid and call the supplied function */
	for (i=0;i<data->num_share_mode_entries;i++) {
		if (pid == shares[i].pid && 
		    shares[i].share_mode == fsp->share_mode &&
		    memcmp(&shares[i].time, 
			   &fsp->open_time,sizeof(struct timeval)) == 0) {
			mod_fn(&shares[i], fsp->dev, fsp->inode, param);
			need_store=1;
		}
	}

	/* if the mod fn was called then store it back */
	if (need_store) {
		if (data->num_share_mode_entries == 0) {
			tdb_delete(tdb, locking_key_fsp(fsp));
		} else {
			tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
		}
	}

	free(dbuf.dptr);
	return need_store;
}


/*******************************************************************
 Static function that actually does the work for the generic function
 below.
********************************************************************/
static void remove_share_oplock_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode, 
                                   void *param)
{
	DEBUG(10,("remove_share_oplock_fn: removing oplock info for entry dev=%x ino=%.0f\n",
		  (unsigned int)dev, (double)inode ));
	/* Delete the oplock info. */
	entry->op_port = 0;
	entry->op_type = NO_OPLOCK;
}

/*******************************************************************
 Remove an oplock port and mode entry from a share mode.
********************************************************************/
BOOL remove_share_oplock(files_struct *fsp)
{
	return mod_share_mode(fsp, remove_share_oplock_fn, NULL);
}

/*******************************************************************
 Static function that actually does the work for the generic function
 below.
********************************************************************/
static void downgrade_share_oplock_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode, 
                                   void *param)
{
	DEBUG(10,("downgrade_share_oplock_fn: downgrading oplock info for entry dev=%x ino=%.0f\n",
		  (unsigned int)dev, (double)inode ));
	entry->op_type = LEVEL_II_OPLOCK;
}

/*******************************************************************
 Downgrade a oplock type from exclusive to level II.
********************************************************************/
BOOL downgrade_share_oplock(files_struct *fsp)
{
	return mod_share_mode(fsp, downgrade_share_oplock_fn, NULL);
}

/*******************************************************************
 Get/Set the delete on close flag in a set of share modes.
 Return False on fail, True on success.
********************************************************************/

BOOL modify_delete_flag( SMB_DEV_T dev, SMB_INO_T inode, BOOL delete_on_close)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	int i;
	share_mode_entry *shares;

	/* read in the existing share modes */
	dbuf = tdb_fetch(tdb, locking_key(dev, inode));
	if (!dbuf.dptr) return False;

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));

	/* Set/Unset the delete on close element. */
	for (i=0;i<data->num_share_mode_entries;i++,shares++) {
		shares->share_mode = (delete_on_close ?
                            (shares->share_mode | DELETE_ON_CLOSE_FLAG) :
                            (shares->share_mode & ~DELETE_ON_CLOSE_FLAG) );
	}

	/* store it back */
	if (data->num_share_mode_entries) {
		if (tdb_store(tdb, locking_key(dev,inode), dbuf, TDB_REPLACE)==-1)
			return False;
	}

	free(dbuf.dptr);
	return True;
}


/****************************************************************************
traverse the whole database with this function, calling traverse_callback
on each share mode
****************************************************************************/
static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, 
                       void* state)
{
	struct locking_data *data;
	share_mode_entry *shares;
	char *name;
	int i;

	SHAREMODE_FN(traverse_callback) = (SHAREMODE_FN_CAST())state;

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));
	name = dbuf.dptr + sizeof(*data) + data->num_share_mode_entries*sizeof(*shares);

	for (i=0;i<data->num_share_mode_entries;i++) {
		traverse_callback(&shares[i], name);
	}
	return 0;
}

/*******************************************************************
 Call the specified function on each entry under management by the
 share mode system.
********************************************************************/
int share_mode_forall(SHAREMODE_FN(fn))
{
	if (!tdb) return 0;
	return tdb_traverse(tdb, traverse_fn, (void*)fn);
}