arch/all-pc/boot/grub2-aros/grub-core/io/offset.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 2013  Free Software Foundation, Inc.
   4  *
   5  *  GRUB is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  GRUB is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <grub/file.h>
  20 #include <grub/dl.h>
  21
  22 GRUB_MOD_LICENSE ("GPLv3+");
  23
  24 struct grub_offset_file
  25 {
  26   grub_file_t parent;
  27   grub_off_t off;
  28 };
  29
  30 static grub_ssize_t
  31 grub_offset_read (grub_file_t file, char *buf, grub_size_t len)
  32 {
  33   struct grub_offset_file *data = file->data;
  34   if (grub_file_seek (data->parent, data->off + file->offset) == (grub_off_t) -1)
  35     return -1;
  36   return grub_file_read (data->parent, buf, len);
  37 }
  38
  39 static grub_err_t
  40 grub_offset_close (grub_file_t file)
  41 {
  42   struct grub_offset_file *data = file->data;
  43
  44   if (data->parent)
  45     grub_file_close (data->parent);
  46
  47   /* No need to close the same device twice.  */
  48   file->device = 0;
  49
  50   return 0;
  51 }
  52
  53 static struct grub_fs grub_offset_fs = {
  54   .name = "offset",
  55   .dir = 0,
  56   .open = 0,
  57   .read = grub_offset_read,
  58   .close = grub_offset_close,
  59   .label = 0,
  60   .next = 0
  61 };
  62
  63 void
  64 grub_file_offset_close (grub_file_t file)
  65 {
  66   struct grub_offset_file *off_data = file->data;
  67   off_data->parent = NULL;
  68   grub_file_close (file);
  69 }
  70
  71 grub_file_t
  72 grub_file_offset_open (grub_file_t parent, grub_off_t start, grub_off_t size)
  73 {
  74   struct grub_offset_file *off_data;
  75   grub_file_t off_file, last_off_file;
  76   grub_file_filter_id_t filter;
  77
  78   off_file = grub_zalloc (sizeof (*off_file));
  79   off_data = grub_zalloc (sizeof (*off_data));
  80   if (!off_file || !off_data)
  81     {
  82       grub_free (off_file);
  83       grub_free (off_data);
  84       return 0;
  85     }
  86
  87   off_data->off = start;
  88   off_data->parent = parent;
  89
  90   off_file->device = parent->device;
  91   off_file->data = off_data;
  92   off_file->fs = &grub_offset_fs;
  93   off_file->size = size;
  94
  95   last_off_file = NULL;
  96   for (filter = GRUB_FILE_FILTER_COMPRESSION_FIRST;
  97        off_file && filter <= GRUB_FILE_FILTER_COMPRESSION_LAST; filter++)
  98     if (grub_file_filters_enabled[filter])
  99       {
 100         last_off_file = off_file;
 101         off_file = grub_file_filters_enabled[filter] (off_file, parent->name);
 102       }
 103
 104   if (!off_file)
 105     {
 106       off_data->parent = NULL;
 107       grub_file_close (last_off_file);
 108       return 0;
 109     }
 110   return off_file;
 111 }