PATCH to avoid infinite loop in cplus-dem.c on some EDG names

[scott snyder <snyder at fnal dot gov>]

hi -

The following name, emitted by an EDG-based compiler (kcc 4.0),
causes the demangler to go into an infinite loop when run with
auto demangling.  (Try running test-filter with `--format=auto'.)

__CPR212____ct__Q3_3std141list__tm__128_Q2_3edm41THandle__tm__26_Q2_4emid15EMparticleChunkQ2_3std68allocator__tm__51_Q2_3edmJ37J14const_iteratorFRCQ3_3std18list__tm__7_Z1ZZ2Z8iterator

This makes it difficult to use gdb on binaries containing such names --- 
gdb hangs while reading in the symbol table.

It's getting stuck in the loop in demangle_arm_hp_template(), where we have:

      while (args < e) {
        ...
	switch (*args)
	  {
          ...
          default:
            /* Not handling other HP cfront stuff */
            if (!do_type (work, &args, &arg))
              goto cfront_template_args_done;
	  }
          ...
      }

For this case, args is pointing here:

(gdb) p args
$1 = 0x80564c4 "__7_Z1ZZ2Z8iterator"


But do_type doesn't recognize a type of `_' --- and in that case,
it returns without making any progress, leaving its arguments unchanged.
So we loop here forever.

Here's a simple patch to prevent this --- we simply give up if do_type()
doesn't make any progress.  We still don't correctly demangle the name,
but at least we don't hang forever.

thanks,
sss

2002-02-15  scott snyder  <snyder@fnal.gov>

	* testsuite/demangle-expected: Add test case for infinite loop in
	demangler.
	* cplus-dem.c (demangle_arm_hp_template): Stop trying to demangle
	if do_type() doesn't make any progress --- prevents an infinite
	loop.


Index: cplus-dem.c
===================================================================
RCS file: /cvs/src/src/libiberty/cplus-dem.c,v
retrieving revision 1.29
diff -u -p -c -r1.29 cplus-dem.c
*** cplus-dem.c	2002/02/05 17:53:17	1.29
--- cplus-dem.c	2002/02/15 22:26:35
*************** demangle_arm_hp_template (work, mangled,
*** 2403,2410 ****
              break;
            default:
              /* Not handling other HP cfront stuff */
!             if (!do_type (work, &args, &arg))
!               goto cfront_template_args_done;
  	  }
  	string_appends (declp, &arg);
  	string_append (declp, ",");
--- 2403,2417 ----
              break;
            default:
              /* Not handling other HP cfront stuff */
!             {
!               const char* old_args = args;
!               if (!do_type (work, &args, &arg))
!                 goto cfront_template_args_done;
! 
!               /* Fail if we didn't make any progress: prevent infinite loop. */
!               if (args == old_args)
!                 return;
!             }
  	  }
  	string_appends (declp, &arg);
  	string_append (declp, ",");
Index: testsuite/demangle-expected
===================================================================
RCS file: /cvs/src/src/libiberty/testsuite/demangle-expected,v
retrieving revision 1.7
diff -u -p -c -r1.7 demangle-expected
*** demangle-expected	2002/01/31 02:21:27	1.7
--- demangle-expected	2002/02/15 22:26:43
*************** _Utf58_0_1__1_2147483647__2147483648
*** 2594,2596 ****
--- 2594,2602 ----
  --format=gnu-v3
  St9bad_alloc
  std::bad_alloc
+ # 
+ # This caused an infinite loop.
+ # We still don't demangle this correctly, but at least we don't hang.
+ --format=auto
+ __CPR212____ct__Q3_3std141list__tm__128_Q2_3edm41THandle__tm__26_Q2_4emid15EMparticleChunkQ2_3std68allocator__tm__51_Q2_3edmJ37J14const_iteratorFRCQ3_3std18list__tm__7_Z1ZZ2Z8iterator
+ _Z1ZZ2Z::__CPR212____ct__Q3_3std141list__tm__128_Q2_3edm41THandle__tm__26_Q2_4emid15EMparticleChunkQ2_3std68allocator__tm__51_Q2_3edmJ37J14const_iteratorFRCQ3_3std18list__tm(iterator)