blocking.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* 
   Unix SMB/CIFS implementation.
   Blocking Locking functions
   Copyright (C) Jeremy Allison 1998-2003
   
   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.
*/

#include "includes.h"

/****************************************************************************
 This is the structure to queue to implement blocking locks.
 notify. It consists of the requesting SMB and the expiry time.
*****************************************************************************/

typedef struct _blocking_lock_record {
	struct _blocking_lock_record *next;
	struct _blocking_lock_record *prev;
	int com_type;
	files_struct *fsp;
	time_t expire_time;
	int lock_num;
	SMB_BIG_UINT offset;
	SMB_BIG_UINT count;
	uint16 lock_pid;
	char *inbuf;
	int length;
} blocking_lock_record;

static blocking_lock_record *blocking_lock_queue;

/****************************************************************************
 Destructor for the above structure.
****************************************************************************/

static void free_blocking_lock_record(blocking_lock_record *blr)
{
	DLIST_REMOVE(blocking_lock_queue, blr);
	SAFE_FREE(blr->inbuf);
	SAFE_FREE(blr);
}

/****************************************************************************
 Get the files_struct given a particular queued SMB.
*****************************************************************************/

static files_struct *get_fsp_from_pkt(char *inbuf)
{
	switch(CVAL(inbuf,smb_com)) {
		case SMBlock:
		case SMBlockread:
			return file_fsp(inbuf,smb_vwv0);
		case SMBlockingX:
			return file_fsp(inbuf,smb_vwv2);
		default:
			DEBUG(0,("get_fsp_from_pkt: PANIC - unknown type on blocking lock queue - exiting.!\n"));
			exit_server("PANIC - unknown type on blocking lock queue");
	}
	return NULL; /* Keep compiler happy. */
}

/****************************************************************************
 Determine if this is a secondary element of a chained SMB.
  **************************************************************************/

static BOOL in_chained_smb(void)
{
	return (chain_size != 0);
}

static void received_unlock_msg(int msg_type, struct process_id src,
				void *buf, size_t len);

/****************************************************************************
 Function to push a blocking lock request onto the lock queue.
****************************************************************************/

BOOL push_blocking_lock_request( char *inbuf, int length, int lock_timeout,
		int lock_num, uint16 lock_pid, SMB_BIG_UINT offset, SMB_BIG_UINT count)
{
	static BOOL set_lock_msg;
	blocking_lock_record *blr, *tmp;
	BOOL my_lock_ctx = False;
	NTSTATUS status;

	if(in_chained_smb() ) {
		DEBUG(0,("push_blocking_lock_request: cannot queue a chained request (currently).\n"));
		return False;
	}

	/*
	 * Now queue an entry on the blocking lock queue. We setup
	 * the expiration time here.
	 */

	if((blr = SMB_MALLOC_P(blocking_lock_record)) == NULL) {
		DEBUG(0,("push_blocking_lock_request: Malloc fail !\n" ));
		return False;
	}

	if((blr->inbuf = (char *)SMB_MALLOC(length)) == NULL) {
		DEBUG(0,("push_blocking_lock_request: Malloc fail (2)!\n" ));
		SAFE_FREE(blr);
		return False;
	}

	blr->com_type = CVAL(inbuf,smb_com);
	blr->fsp = get_fsp_from_pkt(inbuf);
	blr->expire_time = (lock_timeout == -1) ? (time_t)-1 : time(NULL) + (time_t)lock_timeout;
	blr->lock_num = lock_num;
	blr->lock_pid = lock_pid;
	blr->offset = offset;
	blr->count = count;
	memcpy(blr->inbuf, inbuf, length);
	blr->length = length;

	/* Add a pending lock record for this. */
	status = brl_lock(blr->fsp->dev, blr->fsp->inode, blr->fsp->fnum,
			lock_pid, procid_self(), blr->fsp->conn->cnum,
			offset, count, PENDING_LOCK, &my_lock_ctx);

	if (!NT_STATUS_IS_OK(status)) {
		DEBUG(0,("push_blocking_lock_request: failed to add PENDING_LOCK record.\n"));
		free_blocking_lock_record(blr);
		return False;
	}

	DLIST_ADD_END(blocking_lock_queue, blr, tmp);

	/* Ensure we'll receive messages when this is unlocked. */
	if (!set_lock_msg) {
		message_register(MSG_SMB_UNLOCK, received_unlock_msg);
		set_lock_msg = True;
	}

	DEBUG(3,("push_blocking_lock_request: lock request length=%d blocked with expiry time %d (+%d) \
for fnum = %d, name = %s\n", length, (int)blr->expire_time, lock_timeout,
		blr->fsp->fnum, blr->fsp->fsp_name ));

	/* Push the MID of this packet on the signing queue. */
	srv_defer_sign_response(SVAL(inbuf,smb_mid));

	return True;
}

/****************************************************************************
 Return a smd with a given size.
*****************************************************************************/

static void send_blocking_reply(char *outbuf, int outsize)
{
	if(outsize > 4)
		smb_setlen(outbuf,outsize - 4);

	if (!send_smb(smbd_server_fd(),outbuf))
		exit_server("send_blocking_reply: send_smb failed.");
}

/****************************************************************************
 Return a lockingX success SMB.
*****************************************************************************/

static void reply_lockingX_success(blocking_lock_record *blr)
{
	char *outbuf = get_OutBuffer();
	int bufsize = BUFFER_SIZE;
	char *inbuf = blr->inbuf;
	int outsize = 0;

	construct_reply_common(inbuf, outbuf);
	set_message(outbuf,2,0,True);

	/*
	 * As this message is a lockingX call we must handle
	 * any following chained message correctly.
	 * This is normally handled in construct_reply(),
	 * but as that calls switch_message, we can't use
	 * that here and must set up the chain info manually.
	 */

	outsize = chain_reply(inbuf,outbuf,blr->length,bufsize);

	outsize += chain_size;

	send_blocking_reply(outbuf,outsize);
}

/****************************************************************************
 Return a generic lock fail error blocking call.
*****************************************************************************/

static void generic_blocking_lock_error(blocking_lock_record *blr, NTSTATUS status)
{
	char *outbuf = get_OutBuffer();
	char *inbuf = blr->inbuf;
	construct_reply_common(inbuf, outbuf);

	/* whenever a timeout is given w2k maps LOCK_NOT_GRANTED to
	   FILE_LOCK_CONFLICT! (tridge) */
	if (NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
		status = NT_STATUS_FILE_LOCK_CONFLICT;
	}

	ERROR_NT(status);
	if (!send_smb(smbd_server_fd(),outbuf))
		exit_server("generic_blocking_lock_error: send_smb failed.");
}

/****************************************************************************
 Return a lock fail error for a lockingX call. Undo all the locks we have 
 obtained first.
*****************************************************************************/

static void reply_lockingX_error(blocking_lock_record *blr, NTSTATUS status)
{
	char *inbuf = blr->inbuf;
	files_struct *fsp = blr->fsp;
	connection_struct *conn = conn_find(SVAL(inbuf,smb_tid));
	uint16 num_ulocks = SVAL(inbuf,smb_vwv6);
	SMB_BIG_UINT count = (SMB_BIG_UINT)0, offset = (SMB_BIG_UINT) 0;
	uint16 lock_pid;
	unsigned char locktype = CVAL(inbuf,smb_vwv3);
	BOOL large_file_format = (locktype & LOCKING_ANDX_LARGE_FILES);
	char *data;
	int i;

	data = smb_buf(inbuf) + ((large_file_format ? 20 : 10)*num_ulocks);
	
	/* 
	 * Data now points at the beginning of the list
	 * of smb_lkrng structs.
	 */

	/*
	 * Ensure we don't do a remove on the lock that just failed,
	 * as under POSIX rules, if we have a lock already there, we
	 * will delete it (and we shouldn't) .....
	 */
	
	for(i = blr->lock_num - 1; i >= 0; i--) {
		BOOL err;
		
		lock_pid = get_lock_pid( data, i, large_file_format);
		count = get_lock_count( data, i, large_file_format);
		offset = get_lock_offset( data, i, large_file_format, &err);
		
		/*
		 * We know err cannot be set as if it was the lock
		 * request would never have been queued. JRA.
		 */
		
		do_unlock(fsp,conn,lock_pid,count,offset);
	}
	
	generic_blocking_lock_error(blr, status);
}

/****************************************************************************
 Return a lock fail error.
*****************************************************************************/

static void blocking_lock_reply_error(blocking_lock_record *blr, NTSTATUS status)
{
	switch(blr->com_type) {
	case SMBlock:
	case SMBlockread:
		generic_blocking_lock_error(blr, status);
		break;
	case SMBlockingX:
		reply_lockingX_error(blr, status);
		break;
	default:
		DEBUG(0,("blocking_lock_reply_error: PANIC - unknown type on blocking lock queue - exiting.!\n"));
		exit_server("PANIC - unknown type on blocking lock queue");
	}
}

/****************************************************************************
 Attempt to finish off getting all pending blocking locks for a lockread call.
 Returns True if we want to be removed from the list.
*****************************************************************************/

static BOOL process_lockread(blocking_lock_record *blr)
{
	char *outbuf = get_OutBuffer();
	char *inbuf = blr->inbuf;
	ssize_t nread = -1;
	char *data, *p;
	int outsize = 0;
	SMB_BIG_UINT startpos;
	size_t numtoread;
	NTSTATUS status;
	connection_struct *conn = conn_find(SVAL(inbuf,smb_tid));
	files_struct *fsp = blr->fsp;
	BOOL my_lock_ctx = False;

	numtoread = SVAL(inbuf,smb_vwv1);
	startpos = (SMB_BIG_UINT)IVAL(inbuf,smb_vwv2);
	
	numtoread = MIN(BUFFER_SIZE-outsize,numtoread);
	data = smb_buf(outbuf) + 3;
 
	status = do_lock_spin( fsp, conn, SVAL(inbuf,smb_pid), (SMB_BIG_UINT)numtoread, startpos, READ_LOCK, &my_lock_ctx);
	if (NT_STATUS_V(status)) {
		if (!NT_STATUS_EQUAL(status,NT_STATUS_LOCK_NOT_GRANTED) &&
			!NT_STATUS_EQUAL(status,NT_STATUS_FILE_LOCK_CONFLICT)) {
			/*
			 * We have other than a "can't get lock"
			 * error. Send an error.
			 * Return True so we get dequeued.
			 */
			generic_blocking_lock_error(blr, status);
			return True;
		}

		/*
		 * Still waiting for lock....
		 */
		
		DEBUG(10,("process_lockread: failed to get lock for file = %s. Still waiting....\n",
			  fsp->fsp_name));
		return False;
	}

	nread = read_file(fsp,data,startpos,numtoread);

	if (nread < 0) {
		generic_blocking_lock_error(blr,NT_STATUS_ACCESS_DENIED);
		return True;
	}
	
	construct_reply_common(inbuf, outbuf);
	outsize = set_message(outbuf,5,0,True);
	
	outsize += nread;
	SSVAL(outbuf,smb_vwv0,nread);
	SSVAL(outbuf,smb_vwv5,nread+3);
	p = smb_buf(outbuf);
	*p++ = 1;
	SSVAL(p,0,nread); p += 2;