Re: [Minios-devel] [UNIKRAFT PATCH 1/1] lib/vfscore: Add backspace support to the stdio

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

On 05.09.19 15:09, Felipe Huici wrote:
> Hi Vlad,
>
> Please see a small comment inline.
>
> Thanks,
>
> -- Felipe
>
>      Subject: [Minios-devel] [UNIKRAFT PATCH 1/1] lib/vfscore: Add backspace
>      support to the stdio
>      Date: Thu, 29 Aug 2019 17:05:09 +0000
>      From: Vlad-Andrei BĂDOIU (78692) <vlad_andrei.badoiu@xxxxxxxxxxxxxxx>
>      To: minios-devel@xxxxxxxxxxxxx <minios-devel@xxxxxxxxxxxxx>
>      CC: simon.kuenzer@xxxxxxxxx <simon.kuenzer@xxxxxxxxx>, Vlad-Andrei
>      BĂDOIU (78692) <vlad_andrei.badoiu@xxxxxxxxxxxxxxx>,
>      costin.lupu@xxxxxxxxx <costin.lupu@xxxxxxxxx>
>      
>      This patch adds basic backspace support to the stdio. This patch does
>      not handle the cursor differently for the \t. Removing the last
>      character is done by outputing \b \b to the console.
>      
>      Signed-off-by: Vlad-Andrei Badoiu <vlad_andrei.badoiu@xxxxxxxxxxxxxxx>
>      ---
>        lib/vfscore/stdio.c | 16 +++++++++++++---
>        1 file changed, 13 insertions(+), 3 deletions(-)
>      
>      diff --git a/lib/vfscore/stdio.c b/lib/vfscore/stdio.c
>      index 08335367..f23401ff 100644
>      --- a/lib/vfscore/stdio.c
>      +++ b/lib/vfscore/stdio.c
>      @@ -85,9 +85,19 @@ static int __read_fn(void *dst, void *src __unused,
>      size_t *cnt)
>                 *(buf - 1) = *(buf - 1) == '\r' ?
>                                         '\n' : *(buf - 1);
>        -                /* Echo the input */
>      -          ukplat_coutk(buf - bytes_read, bytes_read);
>      -          bytes_total += bytes_read;
>      +          if (*(buf - 1) == '\177') {
>
> Could you please add a small comment to explain why you're using the 177 code?
Hey,

I just double-checked: \177 is the DELETE control character which 
totally makes sense. I will put a comment while upstreaming. Thanks a lot.
Reviewed-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>

>      +                  /* If this is not the first byte */
>      +                  if (buf - 1 != dst) {
>      +                          ukplat_coutk("\b \b", 3);
>      +                          buf -= 1;
>      +                          bytes_total -= 1;
>      +                  }
>      +                  buf -= 1;
>      +          } else {
>      +                  /* Echo the input */
>      +                  ukplat_coutk(buf - bytes_read, bytes_read);
>      +                  bytes_total += bytes_read;
>      +          }
>                 } while (bytes_total < count && *(buf - 1) != '\n'
>                         && *(buf - 1) != VEOF);
>      --
>      2.20.1
>      
>      
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