/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   Files[] structure handling
   Copyright (C) Andrew Tridgell 1998
   
   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.
*/

/******************************************************************************
 *
 * RCS ID
 * $Id: files,v 1.1 1999/05/16 12:00:06 david Exp $
 *
 * HISTORY
 * $Log: files,v $
 * Revision 1.1  1999/05/16 12:00:06  david
 * Initial revision
 *
 *
 *****************************************************************************/

#include "includes.h"

extern int DEBUGLEVEL;

static int real_max_open_files;

#define VALID_FNUM(fnum)   (((fnum) >= 0) && ((fnum) < real_max_open_files))

#define FILE_HANDLE_OFFSET 0x1000

static struct bitmap *file_bmap;

static files_struct *Files;
 
/* a fsp to use when chaining */
static files_struct *chain_fsp = NULL;
/* a fsp to use to save when breaking an oplock. */
static files_struct *oplock_save_chain_fsp = NULL;

/*
 * Indirection for file fd's. Needed as POSIX locking
 * is based on file/process, not fd/process.
 */
static file_fd_struct *FileFd;

static int files_used, fd_ptr_used;

int file_find_name(int fd,char *fname)
{                       
   int error=EBADF;
   files_struct *fsp;

   for (fsp=Files;fsp;fsp=fsp->next)
   {
      if (fsp->fd_ptr->fd == fd)
      {
         strcpy(fname,fsp->fsp_name);
         error=0;
         break;
      }
   }   

   return error;
}

/****************************************************************************
  find first available file slot
****************************************************************************/
files_struct *file_new(void )
{
    int i;
    static int first_file;
    files_struct *fsp, *next;

    /* we want to give out file handles differently on each new
       connection because of a common bug in MS clients where they try to
       reuse a file descriptor from an earlier smb connection. This code
       increases the chance that the errant client will get an error rather
       than causing corruption */
    if (first_file == 0) {
        first_file = (getpid() ^ (int)time(NULL)) % real_max_open_files;
    }

    i = bitmap_find(file_bmap, first_file);
    if (i == -1) {
        /* 
         * Before we give up, go through the open files 
         * and see if there are any files opened with a
         * batch oplock. If so break the oplock and then
         * re-use that entry (if it becomes closed).
         * This may help as NT/95 clients tend to keep
         * files batch oplocked for quite a long time
         * after they have finished with them.
         */
        for (fsp=Files;fsp;fsp=next) {
            next=fsp->next;
            if (attempt_close_oplocked_file(fsp)) {
                return file_new();
            }
        }

        DEBUG(0,("ERROR! Out of file structures\n"));
        return NULL;
    }

    fsp = (files_struct *)malloc(sizeof(*fsp));
    if (!fsp) return NULL;

    ZERO_STRUCTP(fsp);

    first_file = (i+1) % real_max_open_files;

    bitmap_set(file_bmap, i);
    files_used++;

    fsp->fnum = i + FILE_HANDLE_OFFSET;
    string_init(&fsp->fsp_name,"");
    
    DLIST_ADD(Files, fsp);

    DEBUG(5,("allocated file structure %d, fnum = %d (%d used)\n",
         i, fsp->fnum, files_used));

    chain_fsp = fsp;
    
    return fsp;
}



/****************************************************************************
fd support routines - attempt to find an already open file by dev
and inode - increments the ref_count of the returned file_fd_struct *.
****************************************************************************/
file_fd_struct *fd_get_already_open(SMB_STRUCT_STAT *sbuf)
{
    file_fd_struct *fd_ptr;

    if(!sbuf) return NULL;

    for (fd_ptr=FileFd;fd_ptr;fd_ptr=fd_ptr->next) {
        if ((fd_ptr->ref_count > 0) &&
            (sbuf->st_dev == fd_ptr->dev) &&
            (sbuf->st_ino == fd_ptr->inode)) {
            fd_ptr->ref_count++;

            DEBUG(3,("Re-used file_fd_struct dev = %x, inode = %.0f, ref_count = %d\n",
                 (unsigned int)fd_ptr->dev, (double)fd_ptr->inode, 
                 fd_ptr->ref_count));

            return fd_ptr;
        }
    }

    return NULL;
}



/****************************************************************************
fd support routines - attempt to find a empty slot in the FileFd array.
Increments the ref_count of the returned entry.
****************************************************************************/
file_fd_struct *fd_get_new(void)
{
    extern struct current_user current_user;
    file_fd_struct *fd_ptr;

    fd_ptr = (file_fd_struct *)malloc(sizeof(*fd_ptr));
    if (!fd_ptr) {
          DEBUG(0,("ERROR! malloc fail for file_fd struct.\n"));
          return NULL;
    }
    
    ZERO_STRUCTP(fd_ptr);
    
    fd_ptr->dev = (SMB_DEV_T)-1;
    fd_ptr->inode = (SMB_INO_T)-1;
    fd_ptr->fd = -1;
    fd_ptr->fd_readonly = -1;
    fd_ptr->fd_writeonly = -1;
    fd_ptr->real_open_flags = -1;
    fd_add_to_uid_cache(fd_ptr, (uid_t)current_user.uid);
    fd_ptr->ref_count++;

    fd_ptr_used++;

    DLIST_ADD(FileFd, fd_ptr);

    DEBUG(5,("allocated fd_ptr structure (%d used)\n", fd_ptr_used));

    return fd_ptr;
}


/****************************************************************************
close all open files for a connection
****************************************************************************/
void file_close_conn(connection_struct *conn)
{
    files_struct *fsp, *next;
    
    for (fsp=Files;fsp;fsp=next) {
        next = fsp->next;
        if (fsp->conn == conn && fsp->open) {
            if (fsp->is_directory)
                close_directory(fsp,False); 
            else                  
                close_file(fsp,False); 
        }
    }
}

/****************************************************************************
initialise file structures
****************************************************************************/

#define MAX_OPEN_FUDGEFACTOR 10

void file_init(void)
{
        int request_max_open_files = lp_max_open_files();
    int real_lim;

    /*
     * Set the max_open files to be the requested
     * max plus a fudgefactor to allow for the extra
     * fd's we need such as log files etc...
     */
    real_lim = set_maxfiles(request_max_open_files + MAX_OPEN_FUDGEFACTOR);

    real_max_open_files = real_lim - MAX_OPEN_FUDGEFACTOR;

        if(real_max_open_files != request_max_open_files) {
            DEBUG(1,("file_init: Information only: requested %d \
open files, %d are available.\n", request_max_open_files, real_max_open_files));
    }

    file_bmap = bitmap_allocate(real_max_open_files);
    
    if (!file_bmap) {
        exit_server("out of memory in file_init");
    }
    
    /*
     * Ensure that pipe_handle_oppset is set correctly.
     */
    /* set_pipe_handle_offset(real_max_open_files); */
}


/****************************************************************************
close files open by a specified vuid
****************************************************************************/
void file_close_user(int vuid)
{
    files_struct *fsp, *next;

    for (fsp=Files;fsp;fsp=next) {
        next=fsp->next;
        if ((fsp->vuid == vuid) && fsp->open) {
            if(!fsp->is_directory)
                close_file(fsp,False);
            else
                close_directory(fsp,False);
        }
    }
}

/****************************************************************************
close files open by a specified vuid
****************************************************************************/
void file_close_all(void)
{
    files_struct *fsp, *next;

    for (fsp=Files;fsp;fsp=next) {
        next=fsp->next;
        if(!fsp->is_directory)
           close_file(fsp,False);
        else
           close_directory(fsp,False);
    }
}


/****************************************************************************
 Find a fsp given a device, inode and timevalue
 If this is from a kernel oplock break request then tval may be NULL.
****************************************************************************/

files_struct *file_find_dit(SMB_DEV_T dev, SMB_INO_T inode, struct timeval *tval)
{
    int count=0;
    files_struct *fsp;

    for (fsp=Files;fsp;fsp=fsp->next,count++) {
        if (fsp->open && 
            fsp->fd_ptr != NULL &&
            fsp->fd_ptr->dev == dev && 
            fsp->fd_ptr->inode == inode &&
            (tval ? (fsp->open_time.tv_sec == tval->tv_sec) : True ) &&
            (tval ? (fsp->open_time.tv_usec == tval->tv_usec) : True )) {
            if (count > 10) {
                DLIST_PROMOTE(Files, fsp);
            }
            return fsp;
        }
    }

    return NULL;
}

/****************************************************************************
 Find the first fsp given a device and inode.
****************************************************************************/

files_struct *file_find_di_first(SMB_DEV_T dev, SMB_INO_T inode)
{
    files_struct *fsp;

    for (fsp=Files;fsp;fsp=fsp->next) {
        if (fsp->open &&
            fsp->fd_ptr != NULL &&
            fsp->fd_ptr->dev == dev &&
            fsp->fd_ptr->inode == inode )
            return fsp;
    }

    return NULL;
}

/****************************************************************************
 Find the next fsp having the same device and inode.
****************************************************************************/

files_struct *file_find_di_next(files_struct *start_fsp)
{
    files_struct *fsp;

    for (fsp = start_fsp->next;fsp;fsp=fsp->next) {
        if (fsp->open &&
            fsp->fd_ptr != NULL &&
            fsp->fd_ptr->dev == start_fsp->fd_ptr->dev &&
            fsp->fd_ptr->inode == start_fsp->fd_ptr->inode )
            return fsp;
    }

    return NULL;
}

/****************************************************************************
find a fsp that is open for printing
****************************************************************************/
files_struct *file_find_print(void)
{
    files_struct *fsp;

    for (fsp=Files;fsp;fsp=fsp->next) {
        if (fsp->open && fsp->print_file) return fsp;
    } 

    return NULL;
}


/****************************************************************************
sync open files on a connection
****************************************************************************/
void file_sync_all(connection_struct *conn)
{
    files_struct *fsp, *next;

    for (fsp=Files;fsp;fsp=next) {
        next=fsp->next;
        if (fsp->open && (conn == fsp->conn) && (fsp->fd_ptr != NULL)) {
            sync_file(conn,fsp);
        }
    }
}


/****************************************************************************
free up a fd_ptr
****************************************************************************/
void fd_ptr_free(file_fd_struct *fd_ptr)
{
    DLIST_REMOVE(FileFd, fd_ptr);

    fd_ptr_used--;

    DEBUG(5,("freed fd_ptr structure (%d used)\n", fd_ptr_used));

    /* paranoia */
    ZERO_STRUCTP(fd_ptr);

    free(fd_ptr);
}


/****************************************************************************
free up a fsp
****************************************************************************/
void file_free(files_struct *fsp)
{
    DLIST_REMOVE(Files, fsp);

    string_free(&fsp->fsp_name);

    if ((fsp->fd_ptr != NULL) && fsp->fd_ptr->ref_count == 0) {
        fd_ptr_free(fsp->fd_ptr);
    }

    bitmap_clear(file_bmap, fsp->fnum - FILE_HANDLE_OFFSET);
    files_used--;

    DEBUG(5,("freed files structure %d (%d used)\n",
         fsp->fnum, files_used));

    /* this is paranoia, just in case someone tries to reuse the 
       information */
    ZERO_STRUCTP(fsp);

    if (fsp == chain_fsp) chain_fsp = NULL;

    free(fsp);
}


/****************************************************************************
get a fsp from a packet given the offset of a 16 bit fnum
****************************************************************************/
files_struct *file_fsp(char *buf, int where)
{
    int fnum, count=0;
    files_struct *fsp;

    if (chain_fsp) return chain_fsp;

    fnum = SVAL(buf, where);

    for (fsp=Files;fsp;fsp=fsp->next, count++) {
        if (fsp->fnum == fnum) {
            chain_fsp = fsp;
            if (count > 10) {
                DLIST_PROMOTE(Files, fsp);
            }
            return fsp;
        }
    }
    return NULL;
}

/****************************************************************************
 Reset the chained fsp - done at the start of a packet reply
****************************************************************************/

void file_chain_reset(void)
{
    chain_fsp = NULL;
}

/****************************************************************************
Save the chained fsp - done when about to do an oplock break.
****************************************************************************/

void file_chain_save(void)
{
    oplock_save_chain_fsp = chain_fsp;
}

/****************************************************************************
Restore the chained fsp - done after an oplock break.
****************************************************************************/
void file_chain_restore(void)
{
    chain_fsp = oplock_save_chain_fsp;
}
