[PATCH 1/2] readline_simple: return -1 if getc fails

[Gaël PORTAY]

Hi Lucas,

On Tue, Aug 08, 2017 at 09:51:54AM +0200, Lucas Stach wrote:
> Am Montag, den 07.08.2017, 18:10 -0400 schrieb Gaël PORTAY:
> > The getc function may return an errno code if an error happens.
> > 
> > This patch prevents readline from printing a non printable character and
> > from looping to infinity and beyong.
> > 
> > Signed-off-by: Gaël PORTAY <gael.portay at savoirfairelinux.com>
> > ---
> >  lib/readline_simple.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/lib/readline_simple.c b/lib/readline_simple.c
> > index c4d3d240e..1283c9602 100644
> > --- a/lib/readline_simple.c
> > +++ b/lib/readline_simple.c
> > @@ -58,6 +58,8 @@ int readline (const char *prompt, char *line, int len)
> >  
> >  	for (;;) {
> >  		c = getchar();
> > +		if (c < 0)
> > +			return (-1);
> 
> I don't like made up error codes. Is there any reason why we couldn't
> just pass through the negative error code from getchar?
> 

The thing here is that getchar() may return an error, and that error is not
tested. This causes readline to print the character 0xea (-EINVAL) which is not
printable.

Maybe another solutions would be to print the errno string and continue; or to
return the number of characters already read.

Regards,
Gaël