A small patch from metze to fix builds on some platforms ...

[Samba.git] / source3 / smbd / oplock.c

/* 
   Unix SMB/CIFS implementation.
   oplock processing
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Jeremy Allison 1998 - 2001
   
   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"

/* Oplock ipc UDP socket. */
static int oplock_sock = -1;
uint16 global_oplock_port = 0;

/* Current number of oplocks we have outstanding. */
static int32 exclusive_oplocks_open = 0;
static int32 level_II_oplocks_open = 0;
BOOL global_client_failed_oplock_break = False;
BOOL global_oplock_break = False;

extern int smb_read_error;

static struct kernel_oplocks *koplocks;

static BOOL oplock_break(SMB_DEV_T dev, SMB_INO_T inode, unsigned long file_id, BOOL local);

/****************************************************************************
 Get the number of current exclusive oplocks.
****************************************************************************/

int32 get_number_of_exclusive_open_oplocks(void)
{
  return exclusive_oplocks_open;
}

/****************************************************************************
 Return True if an oplock message is pending.
****************************************************************************/

BOOL oplock_message_waiting(fd_set *fds)
{
        if (koplocks && koplocks->msg_waiting(fds))
                return True;

        if (FD_ISSET(oplock_sock, fds))
                return True;

        return False;
}

/****************************************************************************
 Read an oplock break message from either the oplock UDP fd or the
 kernel (if kernel oplocks are supported).

 If timeout is zero then *fds contains the file descriptors that
 are ready to be read and acted upon. If timeout is non-zero then
 *fds contains the file descriptors to be selected on for read.
 The timeout is in milliseconds

****************************************************************************/

BOOL receive_local_message( char *buffer, int buffer_len, int timeout)
{
        struct sockaddr_in from;
        socklen_t fromlen = sizeof(from);
        int32 msg_len = 0;
        fd_set fds;
        int selrtn = -1;

        FD_ZERO(&fds);
        smb_read_error = 0;

        /*
         * We need to check for kernel oplocks before going into the select
         * here, as the EINTR generated by the linux kernel oplock may have
         * already been eaten. JRA.
         */

        if (koplocks && koplocks->msg_waiting(&fds)) {
                return koplocks->receive_message(&fds, buffer, buffer_len);
        }

        while (timeout > 0 && selrtn == -1) {
                struct timeval to;
                int maxfd = oplock_sock;
                time_t starttime = time(NULL);

                FD_ZERO(&fds);
                maxfd = setup_oplock_select_set(&fds);

                to.tv_sec = timeout / 1000;
                to.tv_usec = (timeout % 1000) * 1000;

                DEBUG(5,("receive_local_message: doing select with timeout of %d ms\n", timeout));

                selrtn = sys_select(maxfd+1,&fds,NULL,NULL,&to);

                if (selrtn == -1 && errno == EINTR) {

                        /* could be a kernel oplock interrupt */
                        if (koplocks && koplocks->msg_waiting(&fds)) {
                                return koplocks->receive_message(&fds, buffer, buffer_len);
                        }

                        /*
                         * Linux 2.0.x seems to have a bug in that
                         * it can return -1, EINTR with a timeout of zero.
                         * Make sure we bail out here with a read timeout
                         * if we got EINTR on a timeout of 1 or less.
                         */

                        if (timeout <= 1) {
                                smb_read_error = READ_TIMEOUT;
                                return False;
                        }

                        /* Not a kernel interrupt - could be a SIGUSR1 message. We must restart. */
                        /* We need to decrement the timeout here. */
                        timeout -= ((time(NULL) - starttime)*1000);
                        if (timeout < 0)
                                timeout = 1;

                        DEBUG(5,("receive_local_message: EINTR : new timeout %d ms\n", timeout));
                        continue;
                }

                /* Check if error */
                if(selrtn == -1) {
                        /* something is wrong. Maybe the socket is dead? */
                        smb_read_error = READ_ERROR;
                        return False;
                }

                /* Did we timeout ? */
                if (selrtn == 0) {
                        smb_read_error = READ_TIMEOUT;
                        return False;
                }
        }

        if (koplocks && koplocks->msg_waiting(&fds)) {
                return koplocks->receive_message(&fds, buffer, buffer_len);
        }

        if (!FD_ISSET(oplock_sock, &fds))
                return False;

        /*
         * From here down we deal with the smbd <--> smbd
         * oplock break protocol only.
         */

        /*
         * Read a loopback udp message.
         */
        msg_len = sys_recvfrom(oplock_sock, &buffer[OPBRK_CMD_HEADER_LEN],
                                                buffer_len - OPBRK_CMD_HEADER_LEN, 0, (struct sockaddr *)&from, &fromlen);

        if(msg_len < 0) {
                DEBUG(0,("receive_local_message. Error in recvfrom. (%s).\n",strerror(errno)));
                return False;
        }

        /* Validate message length. */
        if(msg_len > (buffer_len - OPBRK_CMD_HEADER_LEN)) {
                DEBUG(0,("receive_local_message: invalid msg_len (%d) max can be %d\n", msg_len,
                        buffer_len  - OPBRK_CMD_HEADER_LEN));
                return False;
        }

        /* Validate message from address (must be localhost). */
        if(from.sin_addr.s_addr != htonl(INADDR_LOOPBACK)) {
                DEBUG(0,("receive_local_message: invalid 'from' address \
(was %lx should be 127.0.0.1)\n", (long)from.sin_addr.s_addr));
                return False;
        }

        /* Setup the message header */
        SIVAL(buffer,OPBRK_CMD_LEN_OFFSET,msg_len);
        SSVAL(buffer,OPBRK_CMD_PORT_OFFSET,ntohs(from.sin_port));

        return True;
}

/****************************************************************************
 Attempt to set an oplock on a file. Always succeeds if kernel oplocks are
 disabled (just sets flags). Returns True if oplock set.
****************************************************************************/

BOOL set_file_oplock(files_struct *fsp, int oplock_type)
{
        if (koplocks && !koplocks->set_oplock(fsp, oplock_type))
                return False;

        fsp->oplock_type = oplock_type;
        fsp->sent_oplock_break = NO_BREAK_SENT;
        if (oplock_type == LEVEL_II_OPLOCK)
                level_II_oplocks_open++;
        else
                exclusive_oplocks_open++;

        DEBUG(5,("set_file_oplock: granted oplock on file %s, dev = %x, inode = %.0f, file_id = %lu, \
tv_sec = %x, tv_usec = %x\n",
                 fsp->fsp_name, (unsigned int)fsp->dev, (double)fsp->inode, fsp->file_id,
                 (int)fsp->open_time.tv_sec, (int)fsp->open_time.tv_usec ));

        return True;
}

/****************************************************************************
 Attempt to release an oplock on a file. Decrements oplock count.
****************************************************************************/

void release_file_oplock(files_struct *fsp)
{
        if ((fsp->oplock_type != NO_OPLOCK) && koplocks)
                koplocks->release_oplock(fsp);

        if (fsp->oplock_type == LEVEL_II_OPLOCK)
                level_II_oplocks_open--;
        else if (fsp->oplock_type)
                exclusive_oplocks_open--;
        
        fsp->oplock_type = NO_OPLOCK;
        fsp->sent_oplock_break = NO_BREAK_SENT;
        
        flush_write_cache(fsp, OPLOCK_RELEASE_FLUSH);
}

/****************************************************************************
 Attempt to downgrade an oplock on a file. Doesn't decrement oplock count.
****************************************************************************/

static void downgrade_file_oplock(files_struct *fsp)
{
        if (koplocks)
                koplocks->release_oplock(fsp);
        fsp->oplock_type = LEVEL_II_OPLOCK;
        exclusive_oplocks_open--;
        level_II_oplocks_open++;
        fsp->sent_oplock_break = NO_BREAK_SENT;
}

/****************************************************************************
 Remove a file oplock. Copes with level II and exclusive.
 Locks then unlocks the share mode lock. Client can decide to go directly
 to none even if a "break-to-level II" was sent.
****************************************************************************/

BOOL remove_oplock(files_struct *fsp, BOOL break_to_none)
{
        SMB_DEV_T dev = fsp->dev;
        SMB_INO_T inode = fsp->inode;
        BOOL ret = True;

        /* Remove the oplock flag from the sharemode. */
        if (lock_share_entry_fsp(fsp) == False) {
                DEBUG(0,("remove_oplock: failed to lock share entry for file %s\n",
                         fsp->fsp_name ));
                return False;
        }

        if (fsp->sent_oplock_break == EXCLUSIVE_BREAK_SENT || break_to_none) {
                /*
                 * Deal with a reply when a break-to-none was sent.
                 */

                if(remove_share_oplock(fsp)==False) {
                        DEBUG(0,("remove_oplock: failed to remove share oplock for file %s fnum %d, \
dev = %x, inode = %.0f\n", fsp->fsp_name, fsp->fnum, (unsigned int)dev, (double)inode));
                        ret = False;
                }

                release_file_oplock(fsp);
        } else {
                /*
                 * Deal with a reply when a break-to-level II was sent.
                 */
                if(downgrade_share_oplock(fsp)==False) {
                        DEBUG(0,("remove_oplock: failed to downgrade share oplock for file %s fnum %d, \
dev = %x, inode = %.0f\n", fsp->fsp_name, fsp->fnum, (unsigned int)dev, (double)inode));
                        ret = False;
                }
                
                downgrade_file_oplock(fsp);
        }

        unlock_share_entry_fsp(fsp);
        return ret;
}

/****************************************************************************
 Setup the listening set of file descriptors for an oplock break
 message either from the UDP socket or from the kernel. Returns the maximum
 fd used.
****************************************************************************/

int setup_oplock_select_set( fd_set *fds)
{
        int maxfd = oplock_sock;

        if(oplock_sock == -1)
                return 0;

        FD_SET(oplock_sock,fds);

        if (koplocks && koplocks->notification_fd != -1) {
                FD_SET(koplocks->notification_fd, fds);
                maxfd = MAX(maxfd, koplocks->notification_fd);
        }

        return maxfd;
}

/****************************************************************************
 Process an oplock break message - whether it came from the UDP socket
 or from the kernel.
****************************************************************************/

BOOL process_local_message(char *buffer, int buf_size)
{
        int32 msg_len;
        uint16 from_port;
        char *msg_start;
        pid_t remotepid;
        SMB_DEV_T dev;
        SMB_INO_T inode;
        unsigned long file_id;
        uint16 break_cmd_type;

        msg_len = IVAL(buffer,OPBRK_CMD_LEN_OFFSET);
        from_port = SVAL(buffer,OPBRK_CMD_PORT_OFFSET);

        msg_start = &buffer[OPBRK_CMD_HEADER_LEN];

        DEBUG(5,("process_local_message: Got a message of length %d from port (%d)\n", 
                msg_len, from_port));

        /* 
         * Pull the info out of the requesting packet.
         */

        break_cmd_type = SVAL(msg_start,OPBRK_MESSAGE_CMD_OFFSET);

        switch(break_cmd_type) {
                case KERNEL_OPLOCK_BREAK_CMD:
                        if (!koplocks) {
                                DEBUG(0,("unexpected kernel oplock break!\n"));
                                break;
                        } 
                        if (!koplocks->parse_message(msg_start, msg_len, &inode, &dev, &file_id)) {
                                DEBUG(0,("kernel oplock break parse failure!\n"));
                        }
                        break;

                case OPLOCK_BREAK_CMD:
                case LEVEL_II_OPLOCK_BREAK_CMD:
                case ASYNC_LEVEL_II_OPLOCK_BREAK_CMD:

                        /* Ensure that the msg length is correct. */
                        if(msg_len != OPLOCK_BREAK_MSG_LEN) {
                                DEBUG(0,("process_local_message: incorrect length for OPLOCK_BREAK_CMD (was %d, should be %d).\n",
                                        (int)msg_len, (int)OPLOCK_BREAK_MSG_LEN));
                                return False;
                        }

                        memcpy((char *)&remotepid, msg_start+OPLOCK_BREAK_PID_OFFSET,sizeof(remotepid));
                        memcpy((char *)&inode, msg_start+OPLOCK_BREAK_INODE_OFFSET,sizeof(inode));
                        memcpy((char *)&dev, msg_start+OPLOCK_BREAK_DEV_OFFSET,sizeof(dev));
                        memcpy((char *)&file_id, msg_start+OPLOCK_BREAK_FILEID_OFFSET,sizeof(file_id));

                        DEBUG(5,("process_local_message: (%s) oplock break request from \
pid %d, port %d, dev = %x, inode = %.0f, file_id = %lu\n",
                                (break_cmd_type == OPLOCK_BREAK_CMD) ? "exclusive" : "level II",
                                (int)remotepid, from_port, (unsigned int)dev, (double)inode, file_id));
                        break;

                /* 
                 * Keep this as a debug case - eventually we can remove it.
                 */
                case 0x8001:
                        DEBUG(0,("process_local_message: Received unsolicited break \
reply - dumping info.\n"));

                        if(msg_len != OPLOCK_BREAK_MSG_LEN) {
                                DEBUG(0,("process_local_message: ubr: incorrect length for reply \
(was %d, should be %d).\n", (int)msg_len, (int)OPLOCK_BREAK_MSG_LEN));
                                return False;
                        }

                        memcpy((char *)&inode, msg_start+OPLOCK_BREAK_INODE_OFFSET,sizeof(inode));
                        memcpy((char *)&remotepid, msg_start+OPLOCK_BREAK_PID_OFFSET,sizeof(remotepid));
                        memcpy((char *)&dev, msg_start+OPLOCK_BREAK_DEV_OFFSET,sizeof(dev));
                        memcpy((char *)&file_id, msg_start+OPLOCK_BREAK_FILEID_OFFSET,sizeof(file_id));

                        DEBUG(0,("process_local_message: unsolicited oplock break reply from \
pid %d, port %d, dev = %x, inode = %.0f, file_id = %lu\n",
                                (int)remotepid, from_port, (unsigned int)dev, (double)inode, file_id));

                        return False;

                default:
                        DEBUG(0,("process_local_message: unknown UDP message command code (%x) - ignoring.\n",
                                (unsigned int)SVAL(msg_start,0)));
                        return False;
        }

        /*
         * Now actually process the break request.
         */

        if((exclusive_oplocks_open + level_II_oplocks_open) != 0) {
                if (oplock_break(dev, inode, file_id, False) == False) {
                        DEBUG(0,("process_local_message: oplock break failed.\n"));
                        return False;
                }
        } else {
                /*
                 * If we have no record of any currently open oplocks,
                 * it's not an error, as a close command may have
                 * just been issued on the file that was oplocked.
                 * Just log a message and return success in this case.
                 */
                DEBUG(3,("process_local_message: oplock break requested with no outstanding \
oplocks. Returning success.\n"));
        }

        /* 
         * Do the appropriate reply - none in the kernel or async level II case.
         */

        if(break_cmd_type == OPLOCK_BREAK_CMD || break_cmd_type == LEVEL_II_OPLOCK_BREAK_CMD) {
                struct sockaddr_in toaddr;

                /* Send the message back after OR'ing in the 'REPLY' bit. */
                SSVAL(msg_start,OPBRK_MESSAGE_CMD_OFFSET,break_cmd_type | CMD_REPLY);

                memset((char *)&toaddr,'\0',sizeof(toaddr));
                toaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
                toaddr.sin_port = htons(from_port);
                toaddr.sin_family = AF_INET;

                if(sys_sendto( oplock_sock, msg_start, OPLOCK_BREAK_MSG_LEN, 0,
                                (struct sockaddr *)&toaddr, sizeof(toaddr)) < 0) {
                        DEBUG(0,("process_local_message: sendto process %d failed. Errno was %s\n",
                                (int)remotepid, strerror(errno)));
                        return False;
                }

                DEBUG(5,("process_local_message: oplock break reply sent to \
pid %d, port %d, for file dev = %x, inode = %.0f, file_id = %lu\n",
                        (int)remotepid, from_port, (unsigned int)dev, (double)inode, file_id));
        }

        return True;
}

/****************************************************************************
 Set up an oplock break message.
****************************************************************************/

static void prepare_break_message(char *outbuf, files_struct *fsp, BOOL level2)
{
        memset(outbuf,'\0',smb_size);
        set_message(outbuf,8,0,True);

        SCVAL(outbuf,smb_com,SMBlockingX);
        SSVAL(outbuf,smb_tid,fsp->conn->cnum);
        SSVAL(outbuf,smb_pid,0xFFFF);
        SSVAL(outbuf,smb_uid,0);
        SSVAL(outbuf,smb_mid,0xFFFF);
        SCVAL(outbuf,smb_vwv0,0xFF);
        SSVAL(outbuf,smb_vwv2,fsp->fnum);
        SCVAL(outbuf,smb_vwv3,LOCKING_ANDX_OPLOCK_RELEASE);
        SCVAL(outbuf,smb_vwv3+1,level2 ? OPLOCKLEVEL_II : OPLOCKLEVEL_NONE);
}

/****************************************************************************
 Function to do the waiting before sending a local break.
****************************************************************************/

static void wait_before_sending_break(BOOL local_request)
{
        extern struct timeval smb_last_time;

        if(local_request) {
                struct timeval cur_tv;
                long wait_left = (long)lp_oplock_break_wait_time();

                if (wait_left == 0)
                        return;

                GetTimeOfDay(&cur_tv);

                wait_left -= ((cur_tv.tv_sec - smb_last_time.tv_sec)*1000) +
                ((cur_tv.tv_usec - smb_last_time.tv_usec)/1000);

                if(wait_left > 0) {
                        wait_left = MIN(wait_left, 1000);
                        sys_usleep(wait_left * 1000);
                }
        }
}

/****************************************************************************
 Ensure that we have a valid oplock.
****************************************************************************/

static files_struct *initial_break_processing(SMB_DEV_T dev, SMB_INO_T inode, unsigned long file_id)
{
        files_struct *fsp = NULL;

        if( DEBUGLVL( 3 ) ) {
                dbgtext( "initial_break_processing: called for dev = %x, inode = %.0f file_id = %lu\n",
                        (unsigned int)dev, (double)inode, file_id);
                dbgtext( "Current oplocks_open (exclusive = %d, levelII = %d)\n",
                        exclusive_oplocks_open, level_II_oplocks_open );
        }

        /*
         * We need to search the file open table for the
         * entry containing this dev and inode, and ensure
         * we have an oplock on it.
         */

        fsp = file_find_dif(dev, inode, file_id);

        if(fsp == NULL) {
                /* The file could have been closed in the meantime - return success. */
                if( DEBUGLVL( 3 ) ) {
                        dbgtext( "initial_break_processing: cannot find open file with " );
                        dbgtext( "dev = %x, inode = %.0f file_id = %lu", (unsigned int)dev,
                                (double)inode, file_id);
                        dbgtext( "allowing break to succeed.\n" );
                }
                return NULL;
        }

        /* Ensure we have an oplock on the file */

        /*
         * There is a potential race condition in that an oplock could
         * have been broken due to another udp request, and yet there are
         * still oplock break messages being sent in the udp message
         * queue for this file. So return true if we don't have an oplock,
         * as we may have just freed it.
         */

        if(fsp->oplock_type == NO_OPLOCK) {
                if( DEBUGLVL( 3 ) ) {
                        dbgtext( "initial_break_processing: file %s ", fsp->fsp_name );
                        dbgtext( "(dev = %x, inode = %.0f, file_id = %lu) has no oplock.\n",
                                (unsigned int)dev, (double)inode, fsp->file_id );
                        dbgtext( "Allowing break to succeed regardless.\n" );
                }
                return NULL;
        }

        return fsp;
}

/****************************************************************************
 Process a level II oplock break directly.
****************************************************************************/

BOOL oplock_break_level2(files_struct *fsp, BOOL local_request, int token)
{
        extern uint32 global_client_caps;
        char outbuf[128];
        BOOL got_lock = False;
        SMB_DEV_T dev = fsp->dev;
        SMB_INO_T inode = fsp->inode;

        /*
         * We can have a level II oplock even if the client is not
         * level II oplock aware. In this case just remove the
         * flags and don't send the break-to-none message to
         * the client.
         */

        if (global_client_caps & CAP_LEVEL_II_OPLOCKS) {
                /*
                 * If we are sending an oplock break due to an SMB sent
                 * by our own client we ensure that we wait at leat
                 * lp_oplock_break_wait_time() milliseconds before sending
                 * the packet. Sending the packet sooner can break Win9x
                 * and has reported to cause problems on NT. JRA.
                 */

                wait_before_sending_break(local_request);

                /* Prepare the SMBlockingX message. */

                prepare_break_message( outbuf, fsp, False);
                if (!send_smb(smbd_server_fd(), outbuf))
                        exit_server("oplock_break_level2: send_smb failed.");
        }

        /*
         * Now we must update the shared memory structure to tell
         * everyone else we no longer have a level II oplock on 
         * this open file. If local_request is true then token is
         * the existing lock on the shared memory area.
         */

        if(!local_request && lock_share_entry_fsp(fsp) == False) {
                DEBUG(0,("oplock_break_level2: unable to lock share entry for file %s\n", fsp->fsp_name ));
        } else {
                got_lock = True;
        }

        if(remove_share_oplock(fsp)==False) {
                DEBUG(0,("oplock_break_level2: unable to remove level II oplock for file %s\n", fsp->fsp_name ));
        }

        release_file_oplock(fsp);

        if (!local_request && got_lock)
                unlock_share_entry_fsp(fsp);

        if(level_II_oplocks_open < 0) {
                DEBUG(0,("oplock_break_level2: level_II_oplocks_open < 0 (%d). PANIC ERROR\n",
                        level_II_oplocks_open));
                abort();
        }

        if( DEBUGLVL( 3 ) ) {
                dbgtext( "oplock_break_level2: returning success for " );
                dbgtext( "dev = %x, inode = %.0f, file_id = %lu\n", (unsigned int)dev, (double)inode, fsp->file_id );
                dbgtext( "Current level II oplocks_open = %d\n", level_II_oplocks_open );
        }

        return True;
}

/****************************************************************************
 Process an oplock break directly.
****************************************************************************/

static BOOL oplock_break(SMB_DEV_T dev, SMB_INO_T inode, unsigned long file_id, BOOL local_request)
{
        extern uint32 global_client_caps;
        extern struct current_user current_user;
        char *inbuf = NULL;
        char *outbuf = NULL;
        files_struct *fsp = NULL;
        time_t start_time;
        BOOL shutdown_server = False;
        BOOL oplock_timeout = False;
        connection_struct *saved_user_conn;
        connection_struct *saved_fsp_conn;
        int saved_vuid;
        pstring saved_dir; 
        int timeout = (OPLOCK_BREAK_TIMEOUT * 1000);
        pstring file_name;
        BOOL using_levelII;

        if((fsp = initial_break_processing(dev, inode, file_id)) == NULL)
                return True;

        /*
         * Deal with a level II oplock going break to none separately.
         */

        if (LEVEL_II_OPLOCK_TYPE(fsp->oplock_type))
                return oplock_break_level2(fsp, local_request, -1);

        /* Mark the oplock break as sent - we don't want to send twice! */
        if (fsp->sent_oplock_break) {
                if( DEBUGLVL( 0 ) ) {
                        dbgtext( "oplock_break: ERROR: oplock_break already sent for " );
                        dbgtext( "file %s ", fsp->fsp_name);
                        dbgtext( "(dev = %x, inode = %.0f, file_id = %lu)\n", (unsigned int)dev, (double)inode, fsp->file_id );
                }

                /*
                 * We have to fail the open here as we cannot send another oplock break on
                 * this file whilst we are awaiting a response from the client - neither
                 * can we allow another open to succeed while we are waiting for the client.
                 */
                return False;
        }

        if(global_oplock_break) {
                DEBUG(0,("ABORT : ABORT : recursion in oplock_break !!!!!\n"));
                abort();
        }

        /*
         * Now comes the horrid part. We must send an oplock break to the client,
         * and then process incoming messages until we get a close or oplock release.
         * At this point we know we need a new inbuf/outbuf buffer pair.
         * We cannot use these staticaly as we may recurse into here due to
         * messages crossing on the wire.
         */

        if((inbuf = (char *)malloc(BUFFER_SIZE + LARGE_WRITEX_HDR_SIZE + SAFETY_MARGIN))==NULL) {
                DEBUG(0,("oplock_break: malloc fail for input buffer.\n"));
                return False;
        }

        if((outbuf = (char *)malloc(BUFFER_SIZE + LARGE_WRITEX_HDR_SIZE + SAFETY_MARGIN))==NULL) {
                DEBUG(0,("oplock_break: malloc fail for output buffer.\n"));
                SAFE_FREE(inbuf);
                return False;
        }

        /*
         * If we are sending an oplock break due to an SMB sent
         * by our own client we ensure that we wait at leat
         * lp_oplock_break_wait_time() milliseconds before sending
         * the packet. Sending the packet sooner can break Win9x
         * and has reported to cause problems on NT. JRA.
         */

        wait_before_sending_break(local_request);

        /* Prepare the SMBlockingX message. */

        if ((global_client_caps & CAP_LEVEL_II_OPLOCKS) && 
                        !koplocks && /* NOTE: we force levelII off for kernel oplocks - this will change when it is supported */
                        lp_level2_oplocks(SNUM(fsp->conn))) {
                using_levelII = True;
        } else {
                using_levelII = False;
        }

        prepare_break_message( outbuf, fsp, using_levelII);
        /* Remember if we just sent a break to level II on this file. */
        fsp->sent_oplock_break = using_levelII? LEVEL_II_BREAK_SENT:EXCLUSIVE_BREAK_SENT;

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

        /* We need this in case a readraw crosses on the wire. */
        global_oplock_break = True;
 
        /* Process incoming messages. */

        /*
         * JRA - If we don't get a break from the client in OPLOCK_BREAK_TIMEOUT
         * seconds we should just die....
         */

        start_time = time(NULL);

        /*
         * Save the information we need to re-become the
         * user, then unbecome the user whilst we're doing this.
         */
        saved_user_conn = current_user.conn;
        saved_vuid = current_user.vuid;
        saved_fsp_conn = fsp->conn;
        change_to_root_user();
        vfs_GetWd(saved_fsp_conn,saved_dir);
        /* Save the chain fnum. */
        file_chain_save();

        /*
         * From Charles Hoch <hoch@exemplary.com>. If the break processing
         * code closes the file (as it often does), then the fsp pointer here
         * points to free()'d memory. We *must* revalidate fsp each time
         * around the loop.
         */

        pstrcpy(file_name, fsp->fsp_name);

        while((fsp = initial_break_processing(dev, inode, file_id)) &&
                        OPEN_FSP(fsp) && EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type)) {
                if(receive_smb(smbd_server_fd(),inbuf, timeout) == False) {
                        /*
                         * Die if we got an error.
                         */

                        if (smb_read_error == READ_EOF) {
                                DEBUG( 0, ( "oplock_break: end of file from client\n" ) );
                                shutdown_server = True;
                        } else if (smb_read_error == READ_ERROR) {
                                DEBUG( 0, ("oplock_break: receive_smb error (%s)\n", strerror(errno)) );
                                shutdown_server = True;
                        } else if (smb_read_error == READ_TIMEOUT) {
                                DEBUG( 0, ( "oplock_break: receive_smb timed out after %d seconds.\n", OPLOCK_BREAK_TIMEOUT ) );
                                oplock_timeout = True;
                        }

                        DEBUGADD( 0, ( "oplock_break failed for file %s ", file_name ) );
                        DEBUGADD( 0, ( "(dev = %x, inode = %.0f, file_id = %lu).\n",
                                (unsigned int)dev, (double)inode, file_id));

                        break;
                }

                /*
                 * There are certain SMB requests that we shouldn't allow
                 * to recurse. opens, renames and deletes are the obvious
                 * ones. This is handled in the switch_message() function.
                 * If global_oplock_break is set they will push the packet onto
                 * the pending smb queue and return -1 (no reply).
                 * JRA.
                 */

                process_smb(inbuf, outbuf);

                /*
                 * Die if we go over the time limit.
                 */

                if((time(NULL) - start_time) > OPLOCK_BREAK_TIMEOUT) {
                        if( DEBUGLVL( 0 ) ) {
                                dbgtext( "oplock_break: no break received from client " );
                                dbgtext( "within %d seconds.\n", OPLOCK_BREAK_TIMEOUT );
                                dbgtext( "oplock_break failed for file %s ", fsp->fsp_name );
                                dbgtext( "(dev = %x, inode = %.0f, file_id = %lu).\n",  
                                        (unsigned int)dev, (double)inode, file_id );
                        }
                        oplock_timeout = True;
                        break;
                }
        }

        /*
         * Go back to being the user who requested the oplock
         * break.
         */
        if((saved_user_conn != NULL) && (saved_vuid != UID_FIELD_INVALID) && !change_to_user(saved_user_conn, saved_vuid)) {
                DEBUG( 0, ( "oplock_break: unable to re-become user!" ) );
                DEBUGADD( 0, ( "Shutting down server\n" ) );
                close(oplock_sock);
                exit_server("unable to re-become user");
        }

        /* Including the directory. */
        vfs_ChDir(saved_fsp_conn,saved_dir);

        /* Restore the chain fnum. */
        file_chain_restore();

        /* Free the buffers we've been using to recurse. */
        SAFE_FREE(inbuf);
        SAFE_FREE(outbuf);

        /* We need this in case a readraw crossed on the wire. */
        if(global_oplock_break)
                global_oplock_break = False;

        /*
         * If the client timed out then clear the oplock (or go to level II)
         * and continue. This seems to be what NT does and is better than dropping
         * the connection.
         */

        if(oplock_timeout && (fsp = initial_break_processing(dev, inode, file_id)) &&
                        OPEN_FSP(fsp) && EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type)) {
                DEBUG(0,("oplock_break: client failure in oplock break in file %s\n", fsp->fsp_name));
                remove_oplock(fsp,True);
#if FASCIST_OPLOCK_BACKOFF
                global_client_failed_oplock_break = True; /* Never grant this client an oplock again. */
#endif
        }

        /*
         * If the client had an error we must die.
         */

        if(shutdown_server) {
                DEBUG( 0, ( "oplock_break: client failure in break - " ) );
                DEBUGADD( 0, ( "shutting down this smbd.\n" ) );
                close(oplock_sock);
                exit_server("oplock break failure");
        }

        /* Santity check - remove this later. JRA */
        if(exclusive_oplocks_open < 0) {
                DEBUG(0,("oplock_break: exclusive_oplocks_open < 0 (%d). PANIC ERROR\n", exclusive_oplocks_open));
                abort();
        }

        if( DEBUGLVL( 3 ) ) {
                dbgtext( "oplock_break: returning success for " );
                dbgtext( "dev = %x, inode = %.0f, file_id = %lu\n", (unsigned int)dev, (double)inode, file_id );
                dbgtext( "Current exclusive_oplocks_open = %d\n", exclusive_oplocks_open );
        }

        return True;
}

/****************************************************************************
Send an oplock break message to another smbd process. If the oplock is held 
by the local smbd then call the oplock break function directly.
****************************************************************************/

BOOL request_oplock_break(share_mode_entry *share_entry, BOOL async)
{
        char op_break_msg[OPLOCK_BREAK_MSG_LEN];
        struct sockaddr_in addr_out;
        pid_t pid = sys_getpid();
        time_t start_time;
        int time_left;
        SMB_DEV_T dev = share_entry->dev;
        SMB_INO_T inode = share_entry->inode;
        unsigned long file_id = share_entry->share_file_id;
        uint16 break_cmd_type;

        if(pid == share_entry->pid) {
                /* We are breaking our own oplock, make sure it's us. */
                if(share_entry->op_port != global_oplock_port) {
                        DEBUG(0,("request_oplock_break: corrupt share mode entry - pid = %d, port = %d \
should be %d\n", (int)pid, share_entry->op_port, global_oplock_port));
                        return False;
                }

                DEBUG(5,("request_oplock_break: breaking our own oplock\n"));

#if 1 /* JRA PARANOIA TEST.... */
                {
                        files_struct *fsp = file_find_dif(dev, inode, file_id);
                        if (!fsp) {
                                DEBUG(0,("request_oplock_break: PANIC : breaking our own oplock requested for \
dev = %x, inode = %.0f, file_id = %lu and no fsp found !\n",
            (unsigned int)dev, (double)inode, file_id ));
                                smb_panic("request_oplock_break: no fsp found for our own oplock\n");
                        }
                }
#endif /* END JRA PARANOIA TEST... */

                /* Call oplock break direct. */
                return oplock_break(dev, inode, file_id, True);
        }

        /* We need to send a OPLOCK_BREAK_CMD message to the port in the share mode entry. */

        if (LEVEL_II_OPLOCK_TYPE(share_entry->op_type)) {
                break_cmd_type = async ? ASYNC_LEVEL_II_OPLOCK_BREAK_CMD : LEVEL_II_OPLOCK_BREAK_CMD;
        } else {
                break_cmd_type = OPLOCK_BREAK_CMD;
        }

        SSVAL(op_break_msg,OPBRK_MESSAGE_CMD_OFFSET,break_cmd_type);
        memcpy(op_break_msg+OPLOCK_BREAK_PID_OFFSET,(char *)&pid,sizeof(pid));
        memcpy(op_break_msg+OPLOCK_BREAK_DEV_OFFSET,(char *)&dev,sizeof(dev));
        memcpy(op_break_msg+OPLOCK_BREAK_INODE_OFFSET,(char *)&inode,sizeof(inode));
        memcpy(op_break_msg+OPLOCK_BREAK_FILEID_OFFSET,(char *)&file_id,sizeof(file_id));

        /* Set the address and port. */
        memset((char *)&addr_out,'\0',sizeof(addr_out));
        addr_out.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
        addr_out.sin_port = htons( share_entry->op_port );
        addr_out.sin_family = AF_INET;
   
        if( DEBUGLVL( 3 ) ) {
                dbgtext( "request_oplock_break: sending a %s oplock break message to ", async ? "asynchronous" : "synchronous" );
                dbgtext( "pid %d on port %d ", (int)share_entry->pid, share_entry->op_port );
                dbgtext( "for dev = %x, inode = %.0f, file_id = %lu\n",
            (unsigned int)dev, (double)inode, file_id );
        }

        if(sys_sendto(oplock_sock,op_break_msg,OPLOCK_BREAK_MSG_LEN,0,
                        (struct sockaddr *)&addr_out,sizeof(addr_out)) < 0) {
                if( DEBUGLVL( 0 ) ) {
                        dbgtext( "request_oplock_break: failed when sending a oplock " );
                        dbgtext( "break message to pid %d ", (int)share_entry->pid );
                        dbgtext( "on port %d ", share_entry->op_port );
                        dbgtext( "for dev = %x, inode = %.0f, file_id = %lu\n",
                                (unsigned int)dev, (double)inode, file_id );
                        dbgtext( "Error was %s\n", strerror(errno) );
                }
                return False;
        }

        /*
         * If we just sent a message to a level II oplock share entry in async mode then
         * we are done and may return.
         */

        if (LEVEL_II_OPLOCK_TYPE(share_entry->op_type) && async) {
                DEBUG(3,("request_oplock_break: sent async break message to level II entry.\n"));
                return True;
        }

        /*
         * Now we must await the oplock broken message coming back
         * from the target smbd process. Timeout if it fails to
         * return in (OPLOCK_BREAK_TIMEOUT + OPLOCK_BREAK_TIMEOUT_FUDGEFACTOR) seconds.
         * While we get messages that aren't ours, loop.
         */

        start_time = time(NULL);
        time_left = OPLOCK_BREAK_TIMEOUT+OPLOCK_BREAK_TIMEOUT_FUDGEFACTOR;

        while(time_left >= 0) {
                char op_break_reply[OPBRK_CMD_HEADER_LEN+OPLOCK_BREAK_MSG_LEN];
                uint16 reply_from_port;
                char *reply_msg_start;

                if(receive_local_message(op_break_reply, sizeof(op_break_reply),
                                time_left ? time_left * 1000 : 1) == False) {
                        if(smb_read_error == READ_TIMEOUT) {
                                if( DEBUGLVL( 0 ) ) {
                                        dbgtext( "request_oplock_break: no response received to oplock " );
                                        dbgtext( "break request to pid %d ", (int)share_entry->pid );
                                        dbgtext( "on port %d ", share_entry->op_port );
                                        dbgtext( "for dev = %x, inode = %.0f, file_id = %lu\n",
                                                        (unsigned int)dev, (double)inode, file_id );
                                }

                                /*
                                 * This is a hack to make handling of failing clients more robust.
                                 * If a oplock break response message is not received in the timeout
                                 * period we may assume that the smbd servicing that client holding
                                 * the oplock has died and the client changes were lost anyway, so
                                 * we should continue to try and open the file.
                                 */
                                break;
                        } else {
                                if( DEBUGLVL( 0 ) ) {
                                        dbgtext( "request_oplock_break: error in response received " );
                                        dbgtext( "to oplock break request to pid %d ", (int)share_entry->pid );
                                        dbgtext( "on port %d ", share_entry->op_port );
                                        dbgtext( "for dev = %x, inode = %.0f, file_id = %lu\n",
                                                (unsigned int)dev, (double)inode, file_id );
                                        dbgtext( "Error was (%s).\n", strerror(errno) );
                                }
                        }
                        return False;
                }

                reply_from_port = SVAL(op_break_reply,OPBRK_CMD_PORT_OFFSET);
                reply_msg_start = &op_break_reply[OPBRK_CMD_HEADER_LEN];

                /*
                 * Test to see if this is the reply we are awaiting (ie. the one we sent with the CMD_REPLY flag OR'ed in).
                 */
                if((SVAL(reply_msg_start,OPBRK_MESSAGE_CMD_OFFSET) & CMD_REPLY) &&
                        ((SVAL(reply_msg_start,OPBRK_MESSAGE_CMD_OFFSET) & ~CMD_REPLY) == break_cmd_type) &&
                        (reply_from_port == share_entry->op_port) && 
                        (memcmp(&reply_msg_start[OPLOCK_BREAK_PID_OFFSET], &op_break_msg[OPLOCK_BREAK_PID_OFFSET],
                                OPLOCK_BREAK_MSG_LEN - OPLOCK_BREAK_PID_OFFSET) == 0)) {

                        /*
                         * This is the reply we've been waiting for.
                         */
                        break;
                } else {
                        /*
                         * This is another message - a break request.
                         * Note that both kernel oplock break requests
                         * and UDP inter-smbd oplock break requests will
                         * be processed here.
                         *
                         * Process it to prevent potential deadlock.
                         * Note that the code in switch_message() prevents
                         * us from recursing into here as any SMB requests
                         * we might process that would cause another oplock
                         * break request to be made will be queued.
                         * JRA.
                         */

                        process_local_message(op_break_reply, sizeof(op_break_reply));
                }

                time_left -= (time(NULL) - start_time);
        }

        DEBUG(3,("request_oplock_break: broke oplock.\n"));

        return True;
}

/****************************************************************************
  Attempt to break an oplock on a file (if oplocked).
  Returns True if the file was closed as a result of
  the oplock break, False otherwise.
  Used as a last ditch attempt to free a space in the 
  file table when we have run out.
****************************************************************************/

BOOL attempt_close_oplocked_file(files_struct *fsp)
{
        DEBUG(5,("attempt_close_oplocked_file: checking file %s.\n", fsp->fsp_name));

        if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !fsp->sent_oplock_break && (fsp->fd != -1)) {
                /* Try and break the oplock. */
                if (oplock_break(fsp->dev, fsp->inode, fsp->file_id, True)) {
                        if(file_find_fsp(fsp) == NULL) /* Did the oplock break close the file ? */
                                return True;
                }
        }

        return False;
}

/****************************************************************************
 This function is called on any file modification or lock request. If a file
 is level 2 oplocked then it must tell all other level 2 holders to break to none.
****************************************************************************/

void release_level_2_oplocks_on_change(files_struct *fsp)
{
        share_mode_entry *share_list = NULL;
        pid_t pid = sys_getpid();
        int token = -1;
        int num_share_modes = 0;
        int i;

        /*
         * If this file is level II oplocked then we need
         * to grab the shared memory lock and inform all
         * other files with a level II lock that they need
         * to flush their read caches. We keep the lock over
         * the shared memory area whilst doing this.
         */

        if (!LEVEL_II_OPLOCK_TYPE(fsp->oplock_type))
                return;

        if (lock_share_entry_fsp(fsp) == False) {
                DEBUG(0,("release_level_2_oplocks_on_change: failed to lock share mode entry for file %s.\n", fsp->fsp_name ));
        }

        num_share_modes = get_share_modes(fsp->conn, fsp->dev, fsp->inode, &share_list);

        DEBUG(10,("release_level_2_oplocks_on_change: num_share_modes = %d\n", 
                        num_share_modes ));

        for(i = 0; i < num_share_modes; i++) {
                share_mode_entry *share_entry = &share_list[i];

                /*
                 * As there could have been multiple writes waiting at the lock_share_entry
                 * gate we may not be the first to enter. Hence the state of the op_types
                 * in the share mode entries may be partly NO_OPLOCK and partly LEVEL_II
                 * oplock. It will do no harm to re-send break messages to those smbd's
                 * that are still waiting their turn to remove their LEVEL_II state, and
                 * also no harm to ignore existing NO_OPLOCK states. JRA.
                 */

                DEBUG(10,("release_level_2_oplocks_on_change: share_entry[%i]->op_type == %d\n",
                                i, share_entry->op_type ));

                if (share_entry->op_type == NO_OPLOCK)
                        continue;

                /* Paranoia .... */
                if (EXCLUSIVE_OPLOCK_TYPE(share_entry->op_type)) {
                        DEBUG(0,("release_level_2_oplocks_on_change: PANIC. share mode entry %d is an exlusive oplock !\n", i ));
                        unlock_share_entry(fsp->conn, fsp->dev, fsp->inode);
                        abort();
                }

                /*
                 * Check if this is a file we have open (including the
                 * file we've been called to do write_file on. If so
                 * then break it directly without releasing the lock.
                 */

                if (pid == share_entry->pid) {
                        files_struct *new_fsp = file_find_dif(share_entry->dev, share_entry->inode, share_entry->share_file_id);

                        /* Paranoia check... */
                        if(new_fsp == NULL) {
                                DEBUG(0,("release_level_2_oplocks_on_change: PANIC. share mode entry %d is not a local file !\n", i ));
                                unlock_share_entry(fsp->conn, fsp->dev, fsp->inode);
                                abort();
                        }

                        DEBUG(10,("release_level_2_oplocks_on_change: breaking our own oplock.\n"));

                        oplock_break_level2(new_fsp, True, token);

                } else {

                        /*
                         * This is a remote file and so we send an asynchronous
                         * message.
                         */

                        DEBUG(10,("release_level_2_oplocks_on_change: breaking remote oplock (async).\n"));
                        request_oplock_break(share_entry, True);
                }
        }

        SAFE_FREE(share_list);
        unlock_share_entry_fsp(fsp);

        /* Paranoia check... */
        if (LEVEL_II_OPLOCK_TYPE(fsp->oplock_type)) {
                DEBUG(0,("release_level_2_oplocks_on_change: PANIC. File %s still has a level II oplock.\n", fsp->fsp_name));
                smb_panic("release_level_2_oplocks_on_change");
        }
}

/****************************************************************************
setup oplocks for this process
****************************************************************************/

BOOL init_oplocks(void)
{
        struct sockaddr_in sock_name;
        socklen_t len = sizeof(sock_name);

        DEBUG(3,("open_oplock_ipc: opening loopback UDP socket.\n"));

        /* Open a lookback UDP socket on a random port. */
        oplock_sock = open_socket_in(SOCK_DGRAM, 0, 0, htonl(INADDR_LOOPBACK),False);
        if (oplock_sock == -1) {
                DEBUG(0,("open_oplock_ipc: Failed to get local UDP socket for \
address %lx. Error was %s\n", (long)htonl(INADDR_LOOPBACK), strerror(errno)));
                global_oplock_port = 0;
                return(False);
        }

        /* Find out the transient UDP port we have been allocated. */
        if(getsockname(oplock_sock, (struct sockaddr *)&sock_name, &len)<0) {
                DEBUG(0,("open_oplock_ipc: Failed to get local UDP port. Error was %s\n",
                         strerror(errno)));
                close(oplock_sock);
                oplock_sock = -1;
                global_oplock_port = 0;
                return False;
        }
        global_oplock_port = ntohs(sock_name.sin_port);

        if (lp_kernel_oplocks()) {
#if HAVE_KERNEL_OPLOCKS_IRIX
                koplocks = irix_init_kernel_oplocks();
#elif HAVE_KERNEL_OPLOCKS_LINUX
                koplocks = linux_init_kernel_oplocks();
#endif
        }

        DEBUG(3,("open_oplock ipc: pid = %d, global_oplock_port = %u\n", 
                 (int)sys_getpid(), global_oplock_port));

        return True;
}