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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2013 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/>.
*/
#include <grub/file.h>
#include <grub/dl.h>
GRUB_MOD_LICENSE ("GPLv3+");
struct grub_offset_file
{
grub_file_t parent;
grub_off_t off;
};
static grub_ssize_t
grub_offset_read (grub_file_t file, char *buf, grub_size_t len)
{
struct grub_offset_file *data = file->data;
if (grub_file_seek (data->parent, data->off + file->offset) == (grub_off_t) -1)
return -1;
return grub_file_read (data->parent, buf, len);
}
static grub_err_t
grub_offset_close (grub_file_t file)
{
struct grub_offset_file *data = file->data;
if (data->parent)
grub_file_close (data->parent);
/* No need to close the same device twice. */
file->device = 0;
return 0;
}
static struct grub_fs grub_offset_fs = {
.name = "offset",
.fs_dir = 0,
.fs_open = 0,
.fs_read = grub_offset_read,
.fs_close = grub_offset_close,
.fs_label = 0,
.next = 0
};
void
grub_file_offset_close (grub_file_t file)
{
struct grub_offset_file *off_data = file->data;
off_data->parent = NULL;
grub_file_close (file);
}
grub_file_t
grub_file_offset_open (grub_file_t parent, enum grub_file_type type,
grub_off_t start, grub_off_t size)
{
struct grub_offset_file *off_data;
grub_file_t off_file, last_off_file;
grub_file_filter_id_t filter;
off_file = grub_zalloc (sizeof (*off_file));
off_data = grub_zalloc (sizeof (*off_data));
if (!off_file || !off_data)
{
grub_free (off_file);
grub_free (off_data);
return 0;
}
off_data->off = start;
off_data->parent = parent;
off_file->device = parent->device;
off_file->data = off_data;
off_file->fs = &grub_offset_fs;
off_file->size = size;
last_off_file = NULL;
for (filter = GRUB_FILE_FILTER_COMPRESSION_FIRST;
off_file && filter <= GRUB_FILE_FILTER_COMPRESSION_LAST; filter++)
if (grub_file_filters[filter])
{
last_off_file = off_file;
off_file = grub_file_filters[filter] (off_file, type);
}
if (!off_file)
{
off_data->parent = NULL;
grub_file_close (last_off_file);
return 0;
}
return off_file;
}
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