locking.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* 
   Unix SMB/CIFS implementation.
   Locking functions
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1992-2000
   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 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: [e-mail]
   added support for shared memory implementation of share mode locking

   May 1997. Jeremy Allison ([e-mail]). Modified share mode
   locking to deal with multiple share modes per open file.

   September 1997. Jeremy Allison ([e-mail]). Added oplock
   support.

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

   Added POSIX locking support. Jeremy Allison ([e-mail]), Apr. 2000.
*/

#include "includes.h"
uint16 global_smbpid;

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

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

struct locking_data {
        union {
		struct {
			int num_share_mode_entries;
			BOOL delete_on_close;
		} s;
                struct share_mode_entry dummy; /* Needed for alignment. */
        } u;
        /* the following two entries are implicit
           struct share_mode_entry modes[num_share_mode_entries];
           char file_name[];
        */
};

/****************************************************************************
 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.
****************************************************************************/

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

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

	if (strict_locking == Auto) {
		if  (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && (lock_type == READ_LOCK || lock_type == WRITE_LOCK)) {
			DEBUG(10,("is_locked: optimisation - exclusive oplock on file %s\n", fsp->fsp_name ));
			ret = 0;
		} else if ((fsp->oplock_type == LEVEL_II_OPLOCK) &&
			   (lock_type == READ_LOCK)) {
			DEBUG(10,("is_locked: optimisation - level II oplock on file %s\n", fsp->fsp_name ));
			ret = 0;
		} else {
			ret = !brl_locktest(fsp->dev, fsp->inode, fsp->fnum,
				     global_smbpid, procid_self(), conn->cnum, 
				     offset, count, lock_type);
		}
	} else {
		ret = !brl_locktest(fsp->dev, fsp->inode, fsp->fnum,
				global_smbpid, procid_self(), conn->cnum,
				offset, count, lock_type);
	}

	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.
****************************************************************************/

static NTSTATUS do_lock(files_struct *fsp,connection_struct *conn, uint16 lock_pid,
		 SMB_BIG_UINT count,SMB_BIG_UINT offset,enum brl_type lock_type, BOOL *my_lock_ctx)
{
	NTSTATUS status = NT_STATUS_LOCK_NOT_GRANTED;

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

	/* NOTE! 0 byte long ranges ARE allowed and should be stored  */

	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)) {
		status = brl_lock(fsp->dev, fsp->inode, fsp->fnum,
				  lock_pid, procid_self(), conn->cnum, 
				  offset, count, 
				  lock_type, my_lock_ctx);

		if (NT_STATUS_IS_OK(status) && 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.
			 */

			if (!set_posix_lock(fsp, offset, count, lock_type)) {
				if (errno == EACCES || errno == EAGAIN)
					status = NT_STATUS_FILE_LOCK_CONFLICT;
				else
					status = map_nt_error_from_unix(errno);

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

	return status;
}

/****************************************************************************
 Utility function called by locking requests. This is *DISGUSTING*. It also
 appears to be "What Windows Does" (tm). Andrew, ever wonder why Windows 2000
 is so slow on the locking tests...... ? This is the reason. Much though I hate
 it, we need this. JRA.
****************************************************************************/

NTSTATUS do_lock_spin(files_struct *fsp,connection_struct *conn, uint16 lock_pid,
		 SMB_BIG_UINT count,SMB_BIG_UINT offset,enum brl_type lock_type, BOOL *my_lock_ctx)
{
	int j, maxj = lp_lock_spin_count();
	int sleeptime = lp_lock_sleep_time();
	NTSTATUS status, ret;

	if (maxj <= 0)
		maxj = 1;

	ret = NT_STATUS_OK; /* to keep dumb compilers happy */

	for (j = 0; j < maxj; j++) {
		status = do_lock(fsp, conn, lock_pid, count, offset, lock_type, my_lock_ctx);
		if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED) &&
		    !NT_STATUS_EQUAL(status, NT_STATUS_FILE_LOCK_CONFLICT)) {
			return status;
		}
		/* if we do fail then return the first error code we got */
		if (j == 0) {
			ret = status;
			/* Don't spin if we blocked ourselves. */
			if (*my_lock_ctx)
				return ret;
		}
		if (sleeptime)
			sys_usleep(sleeptime);
	}
	return ret;
}

/* Struct passed to brl_unlock. */
struct posix_unlock_data_struct {
	files_struct *fsp;
	SMB_BIG_UINT offset;
	SMB_BIG_UINT count;
};

/****************************************************************************
 Function passed to brl_unlock to allow POSIX unlock to be done first.
****************************************************************************/

static void posix_unlock(void *pre_data)
{
	struct posix_unlock_data_struct *pdata = (struct posix_unlock_data_struct *)pre_data;

	if (lp_posix_locking(SNUM(pdata->fsp->conn)))
		release_posix_lock(pdata->fsp, pdata->offset, pdata->count);
}

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

NTSTATUS do_unlock(files_struct *fsp,connection_struct *conn, uint16 lock_pid,
		   SMB_BIG_UINT count,SMB_BIG_UINT offset)
{
	BOOL ok = False;
	struct posix_unlock_data_struct posix_data;
	
	if (!lp_locking(SNUM(conn)))
		return NT_STATUS_OK;
	
	if (!OPEN_FSP(fsp) || !fsp->can_lock || (fsp->conn != conn)) {
		return NT_STATUS_INVALID_HANDLE;
	}
	
	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.
	 */

	posix_data.fsp = fsp;
	posix_data.offset = offset;
	posix_data.count = count;

	ok = brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
			lock_pid, procid_self(), conn->cnum, offset, count,
			False, posix_unlock, (void *)&posix_data);
   
	if (!ok) {
		DEBUG(10,("do_unlock: returning ERRlock.\n" ));
		return NT_STATUS_RANGE_NOT_LOCKED;
	}
	return NT_STATUS_OK;
}

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

void locking_close_file(files_struct *fsp)
{
	struct process_id pid = procid_self();

	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);

	}
}

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

static int open_read_only;

BOOL locking_init(int read_only)
{
	brl_init(read_only);

	if (tdb)
		return True;

	tdb = tdb_open_log(lock_path("locking.tdb"), 
			SMB_OPEN_DATABASE_TDB_HASH_SIZE, TDB_DEFAULT|(read_only?0x0: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;

	open_read_only = read_only;

	return True;
}

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

BOOL locking_end(void)
{
	BOOL ret = True;

	brl_shutdown(open_read_only);
	if (tdb) {
		if (tdb_close(tdb) != 0)
			ret = False;
	}

	return ret;
}

/*******************************************************************
 Form a static locking key for a dev/inode pair.
******************************************************************/

/* key and data records in the tdb locking database */
struct locking_key {
	SMB_DEV_T dev;
	SMB_INO_T ino;
};

/*******************************************************************
 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.ino = inode;
	kbuf.dptr = (char *)&key;
	kbuf.dsize = sizeof(key);
	return kbuf;
}

/*******************************************************************
 Print out a share mode.
********************************************************************/

char *share_mode_str(int num, struct share_mode_entry *e)
{
	static pstring share_str;

	slprintf(share_str, sizeof(share_str)-1, "share_mode_entry[%d]: %s "
		 "pid = %s, share_access = 0x%x, private_options = 0x%x, "
		 "access_mask = 0x%x, mid = 0x%x, type= 0x%x, file_id = %lu, "
		 "dev = 0x%x, inode = %.0f",
		 num,
		 e->op_type == UNUSED_SHARE_MODE_ENTRY ? "UNUSED" : "",
		 procid_str_static(&e->pid),
		 e->share_access, e->private_options,
		 e->access_mask, e->op_mid, e->op_type, e->share_file_id,
		 (unsigned int)e->dev, (double)e->inode );

	return share_str;
}

/*******************************************************************
 Print out a share mode table.
********************************************************************/

static void print_share_mode_table(struct locking_data *data)
{
	int num_share_modes = data->u.s.num_share_mode_entries;
	struct share_mode_entry *shares =
		(struct share_mode_entry *)(data + 1);
	int i;

	for (i = 0; i < num_share_modes; i++) {
		struct share_mode_entry entry;

		memcpy(&entry, &shares[i], sizeof(struct share_mode_entry));
		DEBUG(10,("print_share_mode_table: %s\n",
			  share_mode_str(i, &entry)));
	}
}

/*******************************************************************
 Get all share mode entries for a dev/inode pair.
********************************************************************/

static BOOL parse_share_modes(TDB_DATA dbuf, struct share_mode_lock *lck)
{
	struct locking_data *data;
	int i;

	if (dbuf.dsize < sizeof(struct locking_data)) {
		DEBUG(0, ("parse_share_modes: buffer too short\n"));
		return False;
	}

	data = (struct locking_data *)dbuf.dptr;

	lck->delete_on_close = data->u.s.delete_on_close;
	lck->num_share_modes = data->u.s.num_share_mode_entries;

	DEBUG(10, ("parse_share_modes: delete_on_close: %d, "
		   "num_share_modes: %d\n", lck->delete_on_close,
		   lck->num_share_modes));

	if ((lck->num_share_modes < 0) || (lck->num_share_modes > 1000000)) {
		DEBUG(0, ("invalid number of share modes: %d\n",
			  lck->num_share_modes));
		return False;
	}

	lck->share_modes = NULL;

	if (lck->num_share_modes != 0) {

		if (dbuf.dsize < (sizeof(struct locking_data) +
				  (lck->num_share_modes *
				   sizeof(struct share_mode_entry)))) {
			DEBUG(0, ("parse_share_modes: buffer too short\n"));
			return False;
		}
				  
		lck->share_modes = talloc_memdup(lck, dbuf.dptr+sizeof(*data),
						 lck->num_share_modes *
						 sizeof(struct share_mode_entry));

		if (lck->share_modes == NULL) {
			DEBUG(0, ("talloc failed\n"));
			return False;
		}
	}

	/* Save off the associated service path and filename. */
	lck->servicepath = talloc_strdup(lck, dbuf.dptr + sizeof(*data) +
				      (lck->num_share_modes *
				      sizeof(struct share_mode_entry)));

	lck->filename = talloc_strdup(lck, dbuf.dptr + sizeof(*data) +
				      (lck->num_share_modes *
				      sizeof(struct share_mode_entry)) +
				      strlen(lck->servicepath) + 1 );

	/*
	 * Ensure that each entry has a real process attached.
	 */

	for (i = 0; i < lck->num_share_modes; i++) {
		struct share_mode_entry *entry_p = &lck->share_modes[i];
		DEBUG(10,("parse_share_modes: %s\n",
			  share_mode_str(i, entry_p) ));
		if (!process_exists(entry_p->pid)) {
			DEBUG(10,("parse_share_modes: deleted %s\n",
				  share_mode_str(i, entry_p) ));
			entry_p->op_type = UNUSED_SHARE_MODE_ENTRY;
			lck->modified = True;
		}
	}

	return True;
}

static TDB_DATA unparse_share_modes(struct share_mode_lock *lck)
{
	TDB_DATA result;
	int num_valid = 0;
	int i;
	struct locking_data *data;
	ssize_t offset;
	ssize_t sp_len;

	result.dptr = NULL;
	result.dsize = 0;

	for (i=0; i<lck->num_share_modes; i++) {
		if (!is_unused_share_mode_entry(&lck->share_modes[i])) {
			num_valid += 1;
		}
	}