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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# Pretty-printers for SpiderMonkey JSObjects.
import re
import gdb
import mozilla.prettyprinters as prettyprinters
from mozilla.CellHeader import get_header_ptr
from mozilla.jsval import JSValue
from mozilla.prettyprinters import ptr_pretty_printer, ref_pretty_printer
prettyprinters.clear_module_printers(__name__)
class JSObjectTypeCache(object):
def __init__(self):
object_flag = gdb.lookup_type("js::ObjectFlag")
self.objectflag_IsUsedAsPrototype = prettyprinters.enum_value(
object_flag, "js::ObjectFlag::IsUsedAsPrototype"
)
self.value_ptr_t = gdb.lookup_type("JS::Value").pointer()
self.func_ptr_t = gdb.lookup_type("JSFunction").pointer()
self.class_NON_NATIVE = gdb.parse_and_eval("JSClass::NON_NATIVE")
self.BaseShape_ptr_t = gdb.lookup_type("js::BaseShape").pointer()
self.Shape_ptr_t = gdb.lookup_type("js::Shape").pointer()
self.JSClass_ptr_t = gdb.lookup_type("JSClass").pointer()
self.JSScript_ptr_t = gdb.lookup_type("JSScript").pointer()
self.JSFunction_AtomSlot = gdb.parse_and_eval("JSFunction::AtomSlot")
self.JSFunction_NativeJitInfoOrInterpretedScriptSlot = gdb.parse_and_eval(
"JSFunction::NativeJitInfoOrInterpretedScriptSlot"
)
# There should be no need to register this for JSFunction as well, since we
# search for pretty-printers under the names of base classes, and
# JSFunction has JSObject as a base class.
gdb_string_regexp = re.compile(r'(?:0x[0-9a-z]+ )?(?:<.*> )?"(.*)"', re.I)
@ptr_pretty_printer("JSObject")
class JSObjectPtrOrRef(prettyprinters.Pointer):
def __init__(self, value, cache):
super(JSObjectPtrOrRef, self).__init__(value, cache)
if not cache.mod_JSObject:
cache.mod_JSObject = JSObjectTypeCache()
self.otc = cache.mod_JSObject
def summary(self):
shape = get_header_ptr(self.value, self.otc.Shape_ptr_t)
baseshape = get_header_ptr(shape, self.otc.BaseShape_ptr_t)
classp = get_header_ptr(baseshape, self.otc.JSClass_ptr_t)
non_native = classp["flags"] & self.otc.class_NON_NATIVE
# Use GDB to format the class name, but then strip off the address
# and the quotes.
class_name = str(classp["name"])
m = gdb_string_regexp.match(class_name)
if m:
class_name = m.group(1)
if non_native:
return "[object {}]".format(class_name)
else:
flags = shape["objectFlags_"]["flags_"]
used_as_prototype = bool(flags & self.otc.objectflag_IsUsedAsPrototype)
name = None
if class_name == "Function":
function = self.value
concrete_type = function.type.strip_typedefs()
if concrete_type.code == gdb.TYPE_CODE_REF:
function = function.address
name = get_function_name(function, self.cache)
return "[object {}{}]{}".format(
class_name,
" " + name if name else "",
" used_as_prototype" if used_as_prototype else "",
)
def get_function_name(function, cache):
if not cache.mod_JSObject:
cache.mod_JSObject = JSObjectTypeCache()
otc = cache.mod_JSObject
function = function.cast(otc.func_ptr_t)
fixed_slots = (function + 1).cast(otc.value_ptr_t)
atom_value = JSValue(fixed_slots[otc.JSFunction_AtomSlot], cache)
if atom_value.is_undefined():
return "<unnamed>"
return str(atom_value.get_string())
def get_function_script(function, cache):
if not cache.mod_JSObject:
cache.mod_JSObject = JSObjectTypeCache()
otc = cache.mod_JSObject
function = function.cast(otc.func_ptr_t)
fixed_slots = (function + 1).cast(otc.value_ptr_t)
slot = otc.JSFunction_NativeJitInfoOrInterpretedScriptSlot
script_value = JSValue(fixed_slots[slot], cache)
if script_value.is_undefined():
return 0
return script_value.get_private()
@ref_pretty_printer("JSObject")
def JSObjectRef(value, cache):
return JSObjectPtrOrRef(value, cache)