/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   read/write to a files_struct
   Copyright (C) Andrew Tridgell 1992-1998
   
   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.
*/

#include "includes.h"

static BOOL setup_write_cache(files_struct *, SMB_OFF_T);

/****************************************************************************
seek a file. Try to avoid the seek if possible
****************************************************************************/

SMB_OFF_T seek_file(files_struct *fsp,SMB_OFF_T pos)
{
  SMB_OFF_T offset = 0;
  SMB_OFF_T seek_ret;

  if (fsp->print_file && lp_postscript(fsp->conn->service))
    offset = 3;

  seek_ret = fsp->conn->vfs_ops.lseek(fsp,fsp->fd,pos+offset,SEEK_SET);

  /*
   * We want to maintain the fiction that we can seek
   * on a fifo for file system purposes. This allows 
   * people to set up UNIX fifo's that feed data to Windows
   * applications. JRA.
   */

  if((seek_ret == -1) && (errno == ESPIPE)) {
    seek_ret = pos+offset;
    errno = 0;
  }

  if((seek_ret == -1) || (seek_ret != pos+offset)) {
    DEBUG(0,("seek_file: sys_lseek failed. Error was %s\n", strerror(errno) ));
    fsp->pos = -1;
    return -1;
  }

  fsp->pos = seek_ret - offset;

  DEBUG(10,("seek_file: requested pos = %.0f, new pos = %.0f\n",
        (double)(pos+offset), (double)fsp->pos ));

  return(fsp->pos);
}

/****************************************************************************
 Read from write cache if we can.
****************************************************************************/


BOOL read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
{
  write_cache *wcp = fsp->wcp;

  if(!wcp)
    return False;

  if(n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size)
    return False;

  memcpy(data, wcp->data + (pos - wcp->offset), n);

  DO_PROFILE_INC(writecache_read_hits);

  return True;
}

/****************************************************************************
read from a file
****************************************************************************/

ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
{
	ssize_t ret=0,readret;

	/* you can't read from print files */
	if (fsp->print_file)
		return -1;

	/*
	 * Serve from write cache if we can.
	 */

	if(read_from_write_cache(fsp, data, pos, n))
		return n;

	flush_write_cache(fsp, READ_FLUSH);

	if (seek_file(fsp,pos) == -1) {
		DEBUG(3,("read_file: Failed to seek to %.0f\n",(double)pos));
		return(ret);
	}
  
	if (n > 0) {
#ifdef DMF_FIX
		int numretries = 3;
tryagain:
		readret = fsp->conn->vfs_ops.read(fsp,fsp->fd,data,n);
		if (readret == -1) {
			if ((errno == EAGAIN) && numretries) {
				DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
				(void)sleep(10);
				--numretries;
				goto tryagain;
			}
			return -1;
		}
#else /* NO DMF fix. */
		readret = fsp->conn->vfs_ops.read(fsp,fsp->fd,data,n);
		if (readret == -1)
			return -1;
#endif
		if (readret > 0)
			ret += readret;
	}

	return(ret);
}

/* how many write cache buffers have been allocated */
static unsigned int allocated_write_caches;

/****************************************************************************
 *Really* write to a file.
****************************************************************************/

static ssize_t real_write_file(files_struct *fsp,char *data,SMB_OFF_T pos, size_t n)
{
  if ((pos != -1) && (seek_file(fsp,pos) == -1))
    return -1;

  return vfs_write_data(fsp,data,n);
}

/****************************************************************************
write to a file
****************************************************************************/

ssize_t write_file(files_struct *fsp, char *data, SMB_OFF_T pos, size_t n)
{
  write_cache *wcp = fsp->wcp;
  ssize_t total_written = 0;
  int write_path = -1; 

  if (fsp->print_file) {
	  return print_job_write(fsp->print_jobid, data, n);
  }

  if (!fsp->can_write) {
    errno = EPERM;
    return(0);
  }

  if (!fsp->modified) {
    SMB_STRUCT_STAT st;
    fsp->modified = True;

    if (fsp->conn->vfs_ops.fstat(fsp,fsp->fd,&st) == 0) {
      int dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
      fsp->size = st.st_size;
      if (MAP_ARCHIVE(fsp->conn) && !IS_DOS_ARCHIVE(dosmode)) {	
        file_chmod(fsp->conn,fsp->fsp_name,dosmode | aARCH,&st);
      }

      /*
       * If this is the first write and we have an exclusive oplock then setup
       * the write cache.
       */

      if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
        setup_write_cache(fsp, st.st_size);
        wcp = fsp->wcp;
      } 
    }  
  }

#ifdef WITH_PROFILE
  DO_PROFILE_INC(writecache_total_writes);
  if (!fsp->oplock_type) {
    DO_PROFILE_INC(writecache_non_oplock_writes);
  }
#endif

  /*
   * 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.
   */

  release_level_2_oplocks_on_change(fsp);

#ifdef WITH_PROFILE
  if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
    DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
	profile_p->writecache_init_writes,
	profile_p->writecache_abutted_writes,
	profile_p->writecache_total_writes,
	profile_p->writecache_non_oplock_writes,
	profile_p->writecache_allocated_write_caches,
	profile_p->writecache_num_write_caches,
	profile_p->writecache_direct_writes,
	profile_p->writecache_num_perfect_writes,
	profile_p->writecache_read_hits ));

    DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
	profile_p->writecache_flushed_writes[SEEK_FLUSH],
	profile_p->writecache_flushed_writes[READ_FLUSH],
	profile_p->writecache_flushed_writes[WRITE_FLUSH],
	profile_p->writecache_flushed_writes[READRAW_FLUSH],
	profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
	profile_p->writecache_flushed_writes[CLOSE_FLUSH],
	profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
  }
#endif

  if(!wcp) {
    DO_PROFILE_INC(writecache_direct_writes);
    total_written = real_write_file(fsp, data, pos, n);
    if ((total_written != -1) && (pos + total_written > fsp->size))
      fsp->size = pos + total_written;
    return total_written;
  }

  DEBUG(9,("write_file(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
	   fsp->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));

  /* 
   * If we have active cache and it isn't contiguous then we flush.
   * NOTE: There is a small problem with running out of disk ....
   */

  if (wcp->data_size) {

    BOOL cache_flush_needed = False;

    if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
      
      /*
       * Start of write overlaps or abutts the existing data.
       */

      size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);

      memcpy(wcp->data + (pos - wcp->offset), data, data_used);

      /*
       * Update the current buffer size with the new data.
       */

      if(pos + data_used > wcp->offset + wcp->data_size)
        wcp->data_size = pos + data_used - wcp->offset;

      /*
       * Update the file size if changed.
       */

      if (wcp->offset + wcp->data_size > wcp->file_size)
        fsp->size = wcp->file_size = wcp->offset + wcp->data_size;

      /*
       * If we used all the data then
       * return here.
       */

      if(n == data_used)
        return n;
      else
        cache_flush_needed = True;

      /*
       * Move the start of data forward by the amount used,
       * cut down the amount left by the same amount.
       */

      data += data_used;
      pos += data_used;
      n -= data_used;

      DO_PROFILE_INC(writecache_abutted_writes);
      total_written = data_used;

      write_path = 1;

    } else if ((pos < wcp->offset) && (pos + n > wcp->offset) && 
               (pos + n <= wcp->offset + wcp->alloc_size)) {

      /*
       * End of write overlaps the existing data.
       */

      size_t data_used = pos + n - wcp->offset;

      memcpy(wcp->data, data + n - data_used, data_used);

      /*
       * Update the current buffer size with the new data.
       */

      if(pos + n > wcp->offset + wcp->data_size)
        wcp->data_size = pos + n - wcp->offset;

      /*
       * Update the file size if changed.
       */

      if (wcp->offset + wcp->data_size > wcp->file_size)
        fsp->size = wcp->file_size = wcp->offset + wcp->data_size;

      /*
       * We don't need to move the start of data, but we
       * cut down the amount left by the amount used.
       */

      n -= data_used;

      /*
       * We cannot have used all the data here.
       */

      cache_flush_needed = True;

      DO_PROFILE_INC(writecache_abutted_writes);
      total_written = data_used;

      write_path = 2;

    } else if ( (pos >= wcp->file_size) && 
                (wcp->offset + wcp->data_size == wcp->file_size) &&
                (pos > wcp->offset + wcp->data_size) && 
                (pos < wcp->offset + wcp->alloc_size) ) {

      /*
       * Non-contiguous write part of which fits within
       * the cache buffer and is extending the file
       * and the cache contents reflect the current
       * data up to the current end of the file.
       */

      size_t data_used;

      if(pos + n <= wcp->offset + wcp->alloc_size)
        data_used = n;
      else
        data_used = wcp->offset + wcp->alloc_size - pos;

      /*
       * Fill in the non-continuous area with zeros.
       */

      memset(wcp->data + wcp->data_size, '\0',
             pos - (wcp->offset + wcp->data_size) );

      memcpy(wcp->data + (pos - wcp->offset), data, data_used);

      /*
       * Update the current buffer size with the new data.
       */

      if(pos + data_used > wcp->offset + wcp->data_size)
        wcp->data_size = pos + data_used - wcp->offset;

      /*
       * Update the file size if changed.
       */

      if (wcp->offset + wcp->data_size > wcp->file_size)
        fsp->size = wcp->file_size = wcp->offset + wcp->data_size;

      /*
       * If we used all the data then
       * return here.
       */

      if(n == data_used)
        return n;
      else
        cache_flush_needed = True;

      /*
       * Move the start of data forward by the amount used,
       * cut down the amount left by the same amount.
       */

      data += data_used;
      pos += data_used;
      n -= data_used;

      DO_PROFILE_INC(writecache_abutted_writes);
      total_written = data_used;

      write_path = 3;

    } else {

      /*
       * Write is bigger than buffer, or there is no overlap on the
       * low or high ends.
       */

      DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
len = %u\n",fsp->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));

      /*
       * Update the file size if needed.
       */

      if(pos + n > wcp->file_size)
        fsp->size = wcp->file_size = pos + n;

      /*
       * If write would fit in the cache, and is larger than
       * the data already in the cache, flush the cache and
       * preferentially copy the data new data into it. Otherwise
       * just write the data directly.
       */

      if ( n <= wcp->alloc_size && n > wcp->data_size) {
        cache_flush_needed = True;
      } else {
        ssize_t ret = real_write_file(fsp, data, pos, n);

        DO_PROFILE_INC(writecache_direct_writes);
        if (ret == -1)
          return ret;

        if (pos + ret > wcp->file_size)
          fsp->size = wcp->file_size = pos + ret;

        return ret;
      }

      write_path = 4;

    }

    if(wcp->data_size > wcp->file_size)
      fsp->size = wcp->file_size = wcp->data_size;

    if (cache_flush_needed) {
      DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
             write_path, fsp->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
             (double)wcp->offset, (unsigned int)wcp->data_size ));

      flush_write_cache(fsp, WRITE_FLUSH);
    }
  }

  /*
   * If the write request is bigger than the cache
   * size, write it all out.
   */

  if (n > wcp->alloc_size ) {
    ssize_t ret = real_write_file(fsp, data, pos, n);
    if (ret == -1)
      return -1;

    if (pos + ret > wcp->file_size)
      fsp->size = wcp->file_size = pos + n;

    DO_PROFILE_INC(writecache_direct_writes);
    return total_written + n;
  }

  /*
   * If there's any data left, cache it.
   */

  if (n) {
#ifdef WITH_PROFILE
    if (wcp->data_size) {
      DO_PROFILE_INC(writecache_abutted_writes);
    } else {
      DO_PROFILE_INC(writecache_init_writes);
    }
#endif
    memcpy(wcp->data+wcp->data_size, data, n);
    if (wcp->data_size == 0) {
      wcp->offset = pos;
      DO_PROFILE_INC(writecache_num_write_caches);
    }
    wcp->data_size += n;

    /*
     * Update the file size if changed.
     */

    if (wcp->offset + wcp->data_size > wcp->file_size)
      fsp->size = wcp->file_size = wcp->offset + wcp->data_size;
    DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
		(double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));

    total_written += n;
    return total_written; /* .... that's a write :) */
  }
  
  return total_written;
}

/****************************************************************************
 Delete the write cache structure.
****************************************************************************/

void delete_write_cache(files_struct *fsp)
{
  write_cache *wcp;

  if(!fsp)
    return;

  if(!(wcp = fsp->wcp))
    return;

  DO_PROFILE_DEC(writecache_allocated_write_caches);
  allocated_write_caches--;

  SMB_ASSERT(wcp->data_size == 0);

  SAFE_FREE(wcp->data);
  SAFE_FREE(fsp->wcp);

  DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));

}

/****************************************************************************
 Setup the write cache structure.
****************************************************************************/

static BOOL setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
{
  ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
  write_cache *wcp;

  if (allocated_write_caches >= MAX_WRITE_CACHES) 
	return False;

  if(alloc_size == 0 || fsp->wcp)
    return False;

  if((wcp = (write_cache *)malloc(sizeof(write_cache))) == NULL) {
    DEBUG(0,("setup_write_cache: malloc fail.\n"));
    return False;
  }

  wcp->file_size = file_size;
  wcp->offset = 0;
  wcp->alloc_size = alloc_size;
  wcp->data_size = 0;
  if((wcp->data = malloc(wcp->alloc_size)) == NULL) {
    DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
          (unsigned int)wcp->alloc_size ));
    SAFE_FREE(wcp);
    return False;
  }

  memset(wcp->data, '\0', wcp->alloc_size );

  fsp->wcp = wcp;
  DO_PROFILE_INC(writecache_allocated_write_caches);
  allocated_write_caches++;

  DEBUG(10,("setup_write_cache: File %s allocated write cache size %u\n",
		fsp->fsp_name, wcp->alloc_size ));

  return True;
}

/****************************************************************************
 Cope with a size change.
****************************************************************************/

void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
{
  fsp->size = file_size;
  if(fsp->wcp) {
    /* The cache *must* have been flushed before we do this. */
    if (fsp->wcp->data_size != 0) {
      pstring msg;
      slprintf(msg, sizeof(msg)-1, "set_filelen_write_cache: size change \
on file %s with write cache size = %u\n", fsp->fsp_name, fsp->wcp->data_size );
      smb_panic(msg);
    }
    fsp->wcp->file_size = file_size;
  }
}

/*******************************************************************
 Flush a write cache struct to disk.
********************************************************************/

ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
{
  write_cache *wcp = fsp->wcp;
  size_t data_size;
  ssize_t ret;

  if(!wcp || !wcp->data_size)
    return 0;

  data_size = wcp->data_size;
  wcp->data_size = 0;

  DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);

  DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
	   fsp->fd, (double)wcp->offset, (unsigned int)data_size));

#ifdef WITH_PROFILE
  if(data_size == wcp->alloc_size)
    DO_PROFILE_INC(writecache_num_perfect_writes);
#endif

  ret = real_write_file(fsp, wcp->data, wcp->offset, data_size);

  /*
   * Ensure file size if kept up to date if write extends file.
   */

  if ((ret != -1) && (wcp->offset + ret > wcp->file_size))
    wcp->file_size = wcp->offset + ret;

  return ret;
}

/*******************************************************************
sync a file
********************************************************************/

void sync_file(connection_struct *conn, files_struct *fsp)
{
    if(lp_strict_sync(SNUM(conn)) && fsp->fd != -1) {
      flush_write_cache(fsp, SYNC_FLUSH);
      conn->vfs_ops.fsync(fsp,fsp->fd);
    }
}
