[PATCH v8 11/11] lib: sbi: Fix missing '\0' when buffer szie equal 1

[Xiang W]

在 2023-07-06星期四的 11:08 +0530，Anup Patel写道：
> On Wed, Jul 5, 2023 at 8:08 PM Xiang W <wxjstz at 126.com> wrote:
> > 
> > Fix special case: sbi_snprintf(out, out_len, ...) when out_len equal
> > 1, The previous code will not fill the buffer with any char.
> 
> I would rather do something like below in printc(...)
> 
> diff --git a/lib/sbi/sbi_console.c b/lib/sbi/sbi_console.c
> index 168dffd..e0ecb41 100644
> --- a/lib/sbi/sbi_console.c
> +++ b/lib/sbi/sbi_console.c
> @@ -138,10 +138,10 @@ static void printc(char **out, u32 *out_len, char ch)
>       * The *printf entry point functions have enforced that (*out) can
>       * only be null when out_len is non-null and its value is zero.
>       */
> -    if (!out_len || *out_len > 1) {
> +    if (!out_len || *out_len)
>          *(*out)++ = ch;
> +    if (!out_len || *out_len > 1)
>          **out = '\0';
> -    }

When *out_len is equal to 1, that is, when there is not enough buffer to drop
the formatted string, a string without '\0' will be generated.

And when there is a problem with the format in sbi_snprintf, it may not entry
printc at all. e.g:
	sbi_printf(out,out_len,"%f",3.14)

Regards,
Xiang W

> 
>      if (out_len && *out_len > 0)
>          --(*out_len);
> 
> Regards,
> Anup
> 
> > 
> > Signed-off-by: Xiang W <wxjstz at 126.com>
> > ---
> >  lib/sbi/sbi_console.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/lib/sbi/sbi_console.c b/lib/sbi/sbi_console.c
> > index 00feec8..0703d4a 100644
> > --- a/lib/sbi/sbi_console.c
> > +++ b/lib/sbi/sbi_console.c
> > @@ -271,6 +271,10 @@ static int print(char **out, u32 *out_len, const char *format, va_list args)
> >                 out_len = &console_tbuf_len;
> >         }
> > 
> > +       /* handle special case: *out_len == 1*/
> > +       if (out)
> > +               **out = '\0';
> > +
> >         for (; *format != 0; ++format) {
> >                 width = flags = 0;
> >                 if (use_tbuf)
> > --
> > 2.40.1
> >