/*
  file.c  -  file handling

  Copyright (C)         Lumiera.org
    2008,               Christian Thaeter <ct@pipapo.org>

  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 "lib/mutex.h"
#include "lib/safeclib.h"

#include "backend/file.h"
#include "backend/filehandlecache.h"
#include "backend/filedescriptor.h"

#include <limits.h>
#include <unistd.h>

NOBUG_DEFINE_FLAG_PARENT (file, file_all);

LUMIERA_ERROR_DEFINE(FILE_CHANGED, "File changed unexpected");


LumieraFile
lumiera_file_init (LumieraFile self, const char* name, int flags)
{
  TRACE (file);
  if (!(self->descriptor = lumiera_filedescriptor_acquire (name, flags)))
    return NULL;
  self->name = lumiera_strndup (name, PATH_MAX);

  return self;
}

LumieraFile
lumiera_file_destroy (LumieraFile self)
{
  TRACE (file);
  lumiera_filedescriptor_release (self->descriptor);
  lumiera_free (self->name);
  return self;
}


LumieraFile
lumiera_file_new (const char* name, int flags)
{
  TRACE (file);
  LumieraFile self = lumiera_malloc (sizeof (lumiera_file));
  return lumiera_file_init (self, name, flags);
}

void
lumiera_file_delete (LumieraFile self)
{
  TRACE (file);
  lumiera_free (lumiera_file_destroy (self));
}


int
lumiera_file_handle_acquire (LumieraFile self)
{
  TRACE (file);
  REQUIRE (self);
  REQUIRE (self->descriptor);
  REQUIRE (lumiera_fhcache);

  LUMIERA_MUTEX_SECTION (file, &self->descriptor->lock)
    {
      if (!self->descriptor->handle)
        /* no handle yet, get a new one */
        lumiera_filehandlecache_handle_acquire (lumiera_fhcache, self->descriptor);
      else
        lumiera_filehandlecache_checkout (lumiera_fhcache, self->descriptor->handle);

      if (self->descriptor->handle->fd == -1)
        {
          int fd;
          fd = open (self->name, self->descriptor->flags & LUMIERA_FILE_MASK);
          if (fd == -1)
            {
              LUMIERA_ERROR_SET (file, ERRNO);
            }
          else
            {
              struct stat st;
              if (fstat (fd, &st) == -1)
                {
                  close (fd);
                  LUMIERA_ERROR_SET (file, ERRNO);
                }
              else if (self->descriptor->stat.st_dev != st.st_dev || self->descriptor->stat.st_ino != st.st_ino)
                {
                  close (fd);
                  /* Woops this is not the file we expected to use */
                  LUMIERA_ERROR_SET (file, FILE_CHANGED);
                }
            }
          self->descriptor->handle->fd = fd;
        }
    }

  return self->descriptor->handle->fd;
}


void
lumiera_file_handle_release (LumieraFile self)
{
  TRACE (file);

  LUMIERA_MUTEX_SECTION (file, &self->descriptor->lock)
    {
      lumiera_filehandlecache_checkin (lumiera_fhcache, self->descriptor->handle);
    }
}