RFA: Patch to fix severe recursion in d_count_templates_scopes (PR 89394)

[Nick Clifton]

Hi Ian,

  Attached is a proposed patch to fix PR 89394, which contains an
  artificial mangled name that triggers excessive recursion in
  d_count_templates_scopes.  The patch uses the same recursion limit
  that is already in place for d_print_comp, which I hope will be
  acceptable.

  There is one frag in the patch which is not directly related to this
  recursion problem however.  It extends the check in
  cplus_demangle_fill_name so that names with a negative length are
  rejected.  I had originally thought that the excessive recursion was
  due to a negative length string, although further investigation proved
  this guess to be wrong.  I felt that leaving the check in however
  would still be a good idea.

  Tested with no regressions with an x86_64-linux-gnu toolchain, as well
  as against the testcase in PR 89394.

  OK to apply ?

Cheers
  Nick

libiberty/ChangeLog
2019-03-21  Nick Clifton  <nickc@redhat.com>

	PR 89394
	* cp-demangle.c (cplus_demangle_fill_name): Reject negative
	lengths.
	(d_count_templates_scopes): Replace num_templates and num_scopes
	parameters with a struct d_print_info pointer parameter.  Adjust
	body of the function accordingly.  Add recursion counter and check
	that the recursion limit is not reached.
	(d_print_init): Pass dpi parameter to d_count_templates_scopes.
	Reset recursion counter afterwards, unless the recursion limit was
	reached.

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