apps/fat/file.c

   1 /*
   2     fat - A FAT* CDI driver
   3     Copyright (C) 2008  Janosch Gräf <janosch.graef@gmx.net>
   4
   5     This program is free software: you can redistribute it and/or modify
   6     it under the terms of the GNU Lesser 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     This program 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 Lesser General Public License for more details.
  14
  15     You should have received a copy of the GNU Lesser General Public License
  16     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #include <stdint.h>
  20
  21 #include "fat_cdi.h"
  22 #include "cluster.h"
  23
  24 #include "cdi/fs.h"
  25
  26 /**
  27  * Reads from file
  28  *  @param stream CDI FS stream
  29  *  @param start Offset in flie
  30  *  @param size How many bytes to read
  31  *  @param buffer Buffer to store data in
  32  *  @return How many bytes read
  33  */
  34 size_t fat_fs_file_read(struct cdi_fs_stream *stream,uint64_t start,size_t size,void *buffer) {
  35   debug("fat_fs_file_read(0x%x,0x%x,0x%x,0x%x)\n",stream,start,size,buffer);
  36   struct fat_fs_res *res = (struct fat_fs_res*)stream->res;
  37
  38   if (start>res->filesize) return 0;
  39   if (start+size>res->filesize) size = res->filesize-start;
  40
  41   fat_cluster_read(res->fs,res->clusters,start,size,buffer);
  42   return size;
  43 }
  44
  45 /**
  46  * Writes to file
  47  *  @param stream CDI FS stream
  48  *  @param start Offset in flie
  49  *  @param size How many bytes to write
  50  *  @param buffer Data to write to file
  51  *  @return How many bytes read
  52  */
  53 size_t fat_fs_file_write(struct cdi_fs_stream *stream,uint64_t start,size_t size,const void *buffer) {
  54   debug("fat_fs_file_write(0x%x,0x%x,0x%x,0x%x)\n",stream,start,size,buffer);
  55   struct fat_fs_res *res = (struct fat_fs_res*)stream->res;
  56
  57   if (stream->fs->read_only) return 0;
  58
  59   if (start+size>res->filesize) {
  60     /// @todo
  61     //fat_fs_file_truncate(stream,start+size);
  62     return 0;
  63   }
  64
  65   fat_cluster_write(res->fs,res->clusters,start,size,buffer);
  66   return size;
  67 }
  68