include/grub/file.h

/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2002,2007  Free Software Foundation, Inc.
 *
 *  GRUB 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef GRUB_FILE_HEADER
#define GRUB_FILE_HEADER	1

#include <grub/types.h>
#include <grub/err.h>
#include <grub/device.h>
#include <grub/fs.h>

/* File description.  */
struct grub_file
{
  /* The underlying device.  */
  grub_device_t device;

  /* The underlying filesystem.  */
  grub_fs_t fs;

  /* The current offset.  */
  grub_off_t offset;

  /* The file size.  */
  grub_off_t size;

  /* If file is not easily seekable. Should be set by underlying layer.  */
  int not_easily_seekable;

  /* Filesystem-specific data.  */
  void *data;

  /* This is called when a sector is read. Used only for a disk device.  */
  void NESTED_FUNC_ATTR (*read_hook) (grub_disk_addr_t sector,
		     unsigned offset, unsigned length);
};
typedef struct grub_file *grub_file_t;

/* Filters with lower ID are executed first.  */
typedef enum grub_file_filter_id
  {
    GRUB_FILE_FILTER_GZIO,
    GRUB_FILE_FILTER_XZIO,
    GRUB_FILE_FILTER_LZOPIO,
    GRUB_FILE_FILTER_MAX,
    GRUB_FILE_FILTER_COMPRESSION_FIRST = GRUB_FILE_FILTER_GZIO,
    GRUB_FILE_FILTER_COMPRESSION_LAST = GRUB_FILE_FILTER_LZOPIO,
  } grub_file_filter_id_t;

typedef grub_file_t (*grub_file_filter_t) (grub_file_t in);

extern grub_file_filter_t EXPORT_VAR(grub_file_filters_all)[GRUB_FILE_FILTER_MAX];
extern grub_file_filter_t EXPORT_VAR(grub_file_filters_enabled)[GRUB_FILE_FILTER_MAX];

static inline void
grub_file_filter_register (grub_file_filter_id_t id, grub_file_filter_t filter)
{
  grub_file_filters_all[id] = filter;
  grub_file_filters_enabled[id] = filter;
};

static inline void
grub_file_filter_unregister (grub_file_filter_id_t id)
{
  grub_file_filters_all[id] = 0;
  grub_file_filters_enabled[id] = 0;
};

static inline void
grub_file_filter_disable (grub_file_filter_id_t id)
{
  grub_file_filters_enabled[id] = 0;
};

static inline void
grub_file_filter_disable_compression (void)
{
  grub_file_filter_id_t id;

  for (id = GRUB_FILE_FILTER_COMPRESSION_FIRST;
       id <= GRUB_FILE_FILTER_COMPRESSION_LAST; id++)
    grub_file_filters_enabled[id] = 0;
};

/* Get a device name from NAME.  */
char *EXPORT_FUNC(grub_file_get_device_name) (const char *name);

grub_file_t EXPORT_FUNC(grub_file_open) (const char *name);
grub_ssize_t EXPORT_FUNC(grub_file_read) (grub_file_t file, void *buf,
					  grub_size_t len);
grub_off_t EXPORT_FUNC(grub_file_seek) (grub_file_t file, grub_off_t offset);
grub_err_t EXPORT_FUNC(grub_file_close) (grub_file_t file);

/* Return value of grub_file_size() in case file size is unknown. */
#define GRUB_FILE_SIZE_UNKNOWN	 0xffffffffffffffffULL

static inline grub_off_t
grub_file_size (const grub_file_t file)
{
  return file->size;
}

static inline grub_off_t
grub_file_tell (const grub_file_t file)
{
  return file->offset;
}

static inline int
grub_file_seekable (const grub_file_t file)
{
  return !file->not_easily_seekable;
}

#endif /* ! GRUB_FILE_HEADER */