[PATCH] make gcore dump read-only sections not from files

[Michael Snyder]

Roland McGrath wrote:

> This works well enough.  However, I think that making the determination
> based on the kernel-supplied indication of anonymous vs file-backed may
> make more sense.  (Linux 2.6's behavior may be changing in this regard,
> and using that as a determining factor rather than just permission
> bits.)  That would require changing the to_find_memory_regions interface
> as I described earlier.  Can you comment on that?

I guess you mean this?

 > Note that this patch makes gcore dump more regions than the Linux kernel
 > does even with my change to its behavior.  In particular, read-only 
mmap'd
 > portions of files are dumped by gcore but not by the kernel.  This is a
 > real common issue in practice, as your average GNU/Linux process nowadays
 > has the large locale-archive file mapped in, and some processes may be
 > mapping huge files in read-only.  An alternative change would be to 
change
 > the to_find_memory_regions callback interface to add a flag argument 
saying
 > whether the memory region came from a file.  Then gcore_create_callback
 > could simply test !write && !anonymous and be wholly consistent with the
 > kernel core dumping (assuming my change to it), and the infrun.c 
change is
 > not required

Sounds reasonable -- is it portable?  A portable testcase for the
testsuite would make the change fairly easy to evaluate / approve.