Re: [PATCH 1/2] Warn when accessing binaries over RSP

[Gary Benson <gbenson at redhat dot com>]

Andrew Burgess wrote:
> * Gary Benson <gbenson@redhat.com> [2015-08-05 16:28:15 +0100]:
> > 
> > diff --git a/gdb/gdb_bfd.c b/gdb/gdb_bfd.c
> > index 1781d80..b511777 100644
> > --- a/gdb/gdb_bfd.c
> > +++ b/gdb/gdb_bfd.c
> > @@ -219,13 +219,38 @@ gdb_bfd_iovec_fileio_open (struct bfd *abfd, void *inferior)
> >    const char *filename = bfd_get_filename (abfd);
> >    int fd, target_errno;
> >    int *stream;
> > +  struct target_ops *ops = find_target_at (process_stratum);
> >  
> >    gdb_assert (is_target_filename (filename));
> > +  filename += strlen (TARGET_SYSROOT_PREFIX);
> > +
> > +  /* GDB provides no indicator of progress during file operations, and
> > +     can appear to have locked up during slow remote transfers, so we
> > +     inform the user what is happening and suggest a way out.  It's
> > +     unpleasant that we need to detect remote targets this way (rather
> > +     than putting the warnings in remote_hostio_open), but it's not
> > +     possible for remote_hostio_open to differentiate between
> > +     accessing inferior binaries (which can be bypassed) and accessing
> > +     things like /proc/ (which is unavoidable).  */
> > +  if (strcmp (ops->to_shortname, "remote") == 0
> > +      || strcmp (ops->to_shortname, "extended-remote") == 0)
> > +    {
> > +      static int warning_issued = 0;
> > +
> > +      printf_unfiltered (_("Reading %s from remote target\n"),
> > +			 filename);
> > +
> > +      if (!warning_issued)
> > +	{
> > +	  warning (_("File transfers from remote targets can be slow.\n"
> > +		     "Use \"set sysroot\" to access files locally"
> > +		     " instead."));
> > +	  warning_issued = 1;
> > +	}
> > +    }
> 
> Altering the behaviour based on to_shortname feels like breaking
> this nice target OO model we have.

Yeah... :-/

> Could the warning not be moved down into target_fileio_open instead?

Not so much target_fileio_open as remote_hostio_open; only remote
targets need the warning.  And originally I thought no, the warning
couldn't go there, because target_fileio_open/remote_hostio_open is
used for various internal things such as /proc/ file reads on Linux
that the user shouldn't see.

...however...

remote_hostio_open *can* differentiate between reading inferior
binaries and reading internal stuff because the internal stuff is
accessed with the INF argument NULL and binaries are accessed with
a non-NULL INF.

So I can do that, if it doesn't seem too hacky.

> Or if that's really not an appropriate place should we add a new
> target method?

I considered that but couldn't think of a good name :-)
target_fileio_warn_if_slow ??
I can do that too.

Cheers,
Gary

-- 
http://gbenson.net/