Re: [PATCH] Add nil check for decoding buffer

[Lukas Fürmetz]

It was definitly a pipe process (cquery (github.com/cquery-project/cquery) via 
lsp-mode).
I have a reproducable workspace, but I cannot share it. The crash happens, when 
stdout is
split exactly between a windows newline, so between \r and \n.

Maybe I have time to debug it again tomorrow. Otherwise, I'll try to reproduce 
the problem
in another way..

> Eli Zaretskii <address@hidden> hat am 11. April 2018 um 19:00 geschrieben:
> 
> 
> > From: Lukas Fürmetz <address@hidden>
> > Date: Tue, 10 Apr 2018 23:44:22 +0200
> > 
> > This patch prevents a emacs crash under Windows for me. Sometimes the
> > buffer is split between \r\n and the \n is carried over, but the
> > decoding_buf is NIL, so "SCHARS (p->decoding_buf)" leads to a SEGFAULT.
> > 
> > Would be nice, if this is backported to emacs-26..
> > 
> > Best regards,
> > Lukas
> > 
> > ---
> >  src/process.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/process.c b/src/process.c
> > index c357a8bdc3..ab2e6ce4da 100644
> > --- a/src/process.c
> > +++ b/src/process.c
> > @@ -5996,7 +5996,7 @@ read_and_dispose_of_process_output (struct 
> > Lisp_Process *p, char *chars,
> > 
> >    if (coding->carryover_bytes > 0)
> >      {
> > -      if (SCHARS (p->decoding_buf) < coding->carryover_bytes)
> > +      if (NILP (p->decoding_buf) || (SCHARS (p->decoding_buf) < 
> > coding->carryover_bytes))
> >     pset_decoding_buf (p, make_uninit_string (coding->carryover_bytes));
> >        memcpy (SDATA (p->decoding_buf), coding->carryover,
> >           coding->carryover_bytes);
> 
> Thanks, but I don't think this is the right fix for the problem.
> Every process object must have an associated decoding_buf, so if some
> process doesn't, it's a bug in that process's creation code.  My
> reading of the code is that all the process types we support have
> decoding_buf defined during creation -- except one: make-pipe-process
> fails to do that.  So the fix should be in make-pipe-process.
> 
> Is the problem reproducible, or do you remember what you did when it
> happened?  I'd like to make sure that indeed some pipe process was
> involved in the crash, because otherwise I don't see how it could
> happen.