111 lines
2.7 KiB
C
111 lines
2.7 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2013 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <grub/file.h>
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#include <grub/dl.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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struct grub_offset_file
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{
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grub_file_t parent;
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grub_off_t off;
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};
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static grub_ssize_t
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grub_offset_read (grub_file_t file, char *buf, grub_size_t len)
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{
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struct grub_offset_file *data = file->data;
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if (grub_file_seek (data->parent, data->off + file->offset) == (grub_off_t) -1)
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return -1;
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return grub_file_read (data->parent, buf, len);
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}
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static grub_err_t
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grub_offset_close (grub_file_t file)
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{
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struct grub_offset_file *data = file->data;
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if (data->parent)
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grub_file_close (data->parent);
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/* No need to close the same device twice. */
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file->device = 0;
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return 0;
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}
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static struct grub_fs grub_offset_fs = {
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.name = "offset",
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.dir = 0,
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.open = 0,
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.read = grub_offset_read,
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.close = grub_offset_close,
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.label = 0,
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.next = 0
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};
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void
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grub_file_offset_close (grub_file_t file)
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{
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struct grub_offset_file *off_data = file->data;
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off_data->parent = NULL;
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grub_file_close (file);
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}
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grub_file_t
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grub_file_offset_open (grub_file_t parent, grub_off_t start, grub_off_t size)
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{
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struct grub_offset_file *off_data;
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grub_file_t off_file, last_off_file;
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grub_file_filter_id_t filter;
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off_file = grub_zalloc (sizeof (*off_file));
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off_data = grub_zalloc (sizeof (*off_data));
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if (!off_file || !off_data)
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{
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grub_free (off_file);
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grub_free (off_data);
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return 0;
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}
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off_data->off = start;
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off_data->parent = parent;
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off_file->device = parent->device;
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off_file->data = off_data;
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off_file->fs = &grub_offset_fs;
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off_file->size = size;
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last_off_file = NULL;
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for (filter = GRUB_FILE_FILTER_COMPRESSION_FIRST;
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off_file && filter <= GRUB_FILE_FILTER_COMPRESSION_LAST; filter++)
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if (grub_file_filters_enabled[filter])
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{
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last_off_file = off_file;
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off_file = grub_file_filters_enabled[filter] (off_file, parent->name);
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}
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if (!off_file)
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{
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off_data->parent = NULL;
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grub_file_close (last_off_file);
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return 0;
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}
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return off_file;
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}
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