[RFA 3/3] Special case NULL when using printf's %s format

[Pedro Alves]

On 02/15/2018 08:50 PM, Tom Tromey wrote:
> This changes the printf command's %s and %ls formats to special-case
> NULL, and print "(null)" for these.  This is PR cli/14977.  This
> behavior seems a bit friendlier; I was undecided on whether other
> invalid pointers should be handled specially somehow, so for the time
> being I've left those out.

A question here is what to do on targets that actually map things at
address zero.  IIRC, some ARM chips do that.  For such ports, I think you'd
want to be able to read/print that memory.  I thought we had a gdbarch hook
for that, but I'm not finding it right now.  Maybe I was thinking of
has_section_at_zero in dwarf2read.c.

Thanks,
Pedro Alves