[PATCH 1/3] Filesystem: PR1398: Fix lseek() mechanic

[Chris Johns]

On 8/05/12 1:09 AM, sebastian.huber at embedded-brains.de wrote:
> From: Sebastian Huber<sebastian.huber at embedded-brains.de>
>
> According to POSIX the lseek() function shall not, by itself, extend the
> size of a file.
>
> Remove the size field of rtems_libio_t.  A file has only on size but may
> have multiple open file descriptors.  Thus a file size field in the file
> descriptor may lead to inconsistencies.
>
> New default handlers rtems_filesystem_default_lseek_file() and
> rtems_filesystem_default_lseek_directory().

Looks good. It is nice to have this sorted. Thanks.

Minor formatting issue below.

> ---
>   cpukit/libfs/src/rfs/rtems-rfs-rtems-dir.c         |   39 +-----------
> diff --git a/cpukit/libfs/src/rfs/rtems-rfs-rtems-file.c b/cpukit/libfs/src/rfs/rtems-rfs-rtems-file.c
> index 0a15652..c189269 100644
> --- a/cpukit/libfs/src/rfs/rtems-rfs-rtems-file.c
> +++ b/cpukit/libfs/src/rfs/rtems-rfs-rtems-file.c
> @@ -72,7 +72,6 @@ rtems_rfs_rtems_file_open (rtems_libio_t* iop,
>     if (rtems_rfs_rtems_trace (RTEMS_RFS_RTEMS_DEBUG_FILE_OPEN))
>       printf("rtems-rfs: file-open: handle:%p\n", file);
>
> -  iop->size = rtems_rfs_file_size (file);
>     rtems_rfs_rtems_set_iop_file_handle (iop, file);
>
>     rtems_rfs_rtems_unlock (fs);
> @@ -245,8 +244,6 @@ rtems_rfs_rtems_file_write (rtems_libio_t* iop,
>       }
>     }
>
> -  iop->size = rtems_rfs_file_size (file);
> -
>     rtems_rfs_rtems_unlock (rtems_rfs_file_fs (file));
>
>     return write;
> @@ -282,26 +279,31 @@ rtems_rfs_rtems_file_lseek (rtems_libio_t* iop,
>                               int            whence)
>   {
>     rtems_rfs_file_handle* file = rtems_rfs_rtems_get_iop_file_handle (iop);
> -  rtems_rfs_pos          pos;
> -  int                    rc;
> +  off_t                  old_offset;
> +  off_t                  new_offset;
>
>     if (rtems_rfs_rtems_trace (RTEMS_RFS_RTEMS_DEBUG_FILE_LSEEK))
>       printf("rtems-rfs: file-lseek: handle:%p offset:%" PRIdoff_t "\n", file, offset);
>
>     rtems_rfs_rtems_lock (rtems_rfs_file_fs (file));
>
> -  pos = iop->offset;
> +  old_offset = iop->offset;
> +  new_offset = rtems_filesystem_default_lseek_file (iop, offset, whence);
> +  if (new_offset != -1) {
                            ^ not consistent with the RFS formatting :)
> +    rtems_rfs_pos pos = iop->offset;
> +    int           rc = rtems_rfs_file_seek (file, pos,&pos);
>
> -  rc = rtems_rfs_file_seek (file, pos,&pos);
> -  if (rc)
> -  {
> -    rtems_rfs_rtems_unlock (rtems_rfs_file_fs (file));
> -    return rtems_rfs_rtems_error ("file_lseek: lseek", rc);
> +    if (rc)
> +    {
> +      rtems_rfs_rtems_error ("file_lseek: lseek", rc);
> +      iop->offset = old_offset;
> +      new_offset = -1;
> +    }
>     }
>
>     rtems_rfs_rtems_unlock (rtems_rfs_file_fs (file));
>
> -  return iop->offset;
> +  return new_offset;
>   }
>