apps/fat/file.c

   1 /*
   2  * fat - A FAT* CDI driver
   3  *
   4  * Copyright (C) 2008 Janosch Gräf
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 3 of the License, or (at your option)
   9  * any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  14  * more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along with
  17  * this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <stdint.h>
  21
  22 #include "fat_cdi.h"
  23 #include "cluster.h"
  24
  25 #include "cdi/fs.h"
  26
  27 /**
  28  * Reads from file
  29  *  @param stream CDI FS stream
  30  *  @param start Offset in flie
  31  *  @param size How many bytes to read
  32  *  @param buffer Buffer to store data in
  33  *  @return How many bytes read
  34  */
  35 size_t fat_fs_file_read(struct cdi_fs_stream *stream,uint64_t start,size_t size,void *buffer) {
  36   debug("fat_fs_file_read(0x%x,0x%x,0x%x,0x%x)\n",stream,start,size,buffer);
  37   struct fat_fs_res *res = (struct fat_fs_res*)stream->res;
  38
  39   if (start>res->filesize) return 0;
  40   if (start+size>res->filesize) size = res->filesize-start;
  41
  42   fat_cluster_read(res->fs,res->clusters,start,size,buffer);
  43   return size;
  44 }