Experimentally recommit of r38041: specify smaller max length

* vm_dump.c (rb_vm_bugreport): get rid of calling methods in sigsegv
  handler.  based on a patch by charliesome (Charlie Somerville)
  [ruby-core:49573] [Bug #7402]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38329 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1214,6 +1214,12 @@ Fri Nov 30 17:43:50 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* string.c (rb_str_cmp_m): return fixed value, one of -1,0,+1 always.
 
+Fri Nov 30 16:19:14 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm_dump.c (rb_vm_bugreport): get rid of calling methods in sigsegv
+	  handler.  based on a patch by charliesome (Charlie Somerville)
+	  [ruby-core:49573] [Bug #7402]
+
 Fri Nov 30 16:05:44 2012  Eric Hodel  <drbrain@segment7.net>
 
 	* NEWS:  Added RubyGems 2.0.0

test/ruby/test_rubyoptions.rb

@@ -508,6 +508,13 @@ class TestRubyOptions < Test::Unit::TestCase
       )x,
       nil,
       opts)
+
+    bug7402 = '[ruby-core:49573]'
+    status = assert_in_out_err(['-e', 'class Bogus; def to_str; exit true; end; end',
+                                '-e', '$".unshift Bogus.new',
+                                '-e', 'Process.kill :SEGV, $$'],
+                               "", //, /#<Bogus:/)
+    assert_not_predicate(status, :success?, "segv but success #{bug7402}")
   end
 
   def test_DATA

vm_dump.c

@@ -675,14 +675,26 @@ rb_vm_bugreport(void)
     if (vm) {
 	int i;
 	VALUE name;
+	long len;
+	const int max_name_length = 128;
+# define LIMITED_NAME_LENGTH(s) \
+	(((len = RSTRING_LEN(s)) > max_name_length) ? max_name_length : (int)len)
 
 	name = vm->progname;
-	fprintf(stderr, "* Loaded script: %s\n", StringValueCStr(name));
+	fprintf(stderr, "* Loaded script: %s\n",
+		RSTRING_PTR(name));
 	fprintf(stderr, "\n");
 	fprintf(stderr, "* Loaded features:\n\n");
 	for (i=0; i<RARRAY_LEN(vm->loaded_features); i++) {
 	    name = RARRAY_PTR(vm->loaded_features)[i];
-	    fprintf(stderr, " %4d %s\n", i, StringValueCStr(name));
+	    if (RB_TYPE_P(name, T_STRING)) {
+		fprintf(stderr, " %4d %.*s\n", i,
+			LIMITED_NAME_LENGTH(name), RSTRING_PTR(name));
+	    }
+	    else {
+		fprintf(stderr, " %4d #<%s:%p>\n", i,
+			rb_class2name(CLASS_OF(name)), (void *)name);
+	    }
 	}
 	fprintf(stderr, "\n");
     }