js/src/gdb/mozilla/JSObject.py

   1 # Pretty-printers for SpiderMonkey JSObjects.
   2
   3 import gdb
   4 import mozilla.JSString
   5 import mozilla.prettyprinters as prettyprinters
   6 from mozilla.prettyprinters import ptr_pretty_printer, ref_pretty_printer
   7 from mozilla.Root import deref
   8
   9 prettyprinters.clear_module_printers(__name__)
  10
  11 class JSObjectTypeCache(object):
  12     def __init__(self, value, cache):
  13         # In GDB 7.4.50, with some programs, this first dummy gdb.lookup_type
  14         # call is required to make the second lookup_type call succeed. A GDB
  15         # built from the public sources as of 2012-12-12 did not require the
  16         # dummy lookup.
  17         gdb.lookup_type('js::BaseShape')
  18         baseshape_flags = gdb.lookup_type('js::BaseShape::Flag')
  19         self.flag_DELEGATE = prettyprinters.enum_value(baseshape_flags, 'js::BaseShape::DELEGATE')
  20         self.func_ptr_type = gdb.lookup_type('JSFunction').pointer()
  21
  22 # There should be no need to register this for JSFunction as well, since we
  23 # search for pretty-printers under the names of base classes, and
  24 # JSFunction has JSObject as a base class.
  25
  26 @ptr_pretty_printer('JSObject')
  27 class JSObjectPtrOrRef(prettyprinters.Pointer):
  28     def __init__(self, value, cache):
  29         super(JSObjectPtrOrRef, self).__init__(value, cache)
  30         if not cache.mod_JSObject:
  31             cache.mod_JSObject = JSObjectTypeCache(value, cache)
  32         self.otc = cache.mod_JSObject
  33
  34     def summary(self):
  35         shape = deref(self.value['shape_'])
  36         baseshape = deref(shape['base_'])
  37         otype = deref(self.value['type_'])
  38         class_name = otype['clasp_']['name'].string()
  39         flags = baseshape['flags']
  40         is_delegate = bool(flags & self.otc.flag_DELEGATE)
  41         name = None
  42         if class_name == 'Function':
  43             function = self.value
  44             concrete_type = function.type.strip_typedefs()
  45             if concrete_type.code == gdb.TYPE_CODE_REF:
  46                 function = function.address
  47             function = function.cast(self.otc.func_ptr_type)
  48             atom = deref(function['atom_'])
  49             name = str(atom) if atom else '<unnamed>'
  50         return '[object %s%s]%s' % (class_name,
  51                                     ' ' + name if name else '',
  52                                     ' delegate' if is_delegate else '')
  53
  54 @ref_pretty_printer('JSObject')
  55 def JSObjectRef(value, cache): return JSObjectPtrOrRef(value, cache)