# Copyright 2011 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""GDB support for Chrome types.
Add this to your gdb by amending your ~/.gdbinit as follows:
python
import sys
sys.path.insert(1, "/path/to/tools/gdb/")
import gdb_chrome
end
Use
(gdb) p /r any_variable
to print |any_variable| without using any printers.
To interactively type Python for development of the printers:
(gdb) python foo = gdb.parse_and_eval('bar')
to put the C++ value 'bar' in the current scope into a Python variable 'foo'.
Then you can interact with that variable:
(gdb) python print foo['impl_']
"""
import datetime
import gdb
import gdb.printing
import os
import re
import sys
sys.path.insert(
1, os.path.join(os.path.dirname(os.path.abspath(__file__)), 'util'))
import class_methods
sys.path.insert(
1,
os.path.join(
os.path.dirname(os.path.abspath(__file__)), '..', '..', 'third_party',
'blink', 'tools', 'gdb'))
try:
import blink
finally:
sys.path.pop(1)
# When debugging this module, set the below variable to True, and then use
# (gdb) python del sys.modules['gdb_chrome']
# (gdb) python import gdb_chrome
# to reload.
_DEBUGGING = False
pp_set = gdb.printing.RegexpCollectionPrettyPrinter("chromium")
def typed_ptr(ptr):
"""Prints a pointer along with its exact type.
By default, gdb would print just the address, which takes more
steps to interpret.
"""
# Returning this as a cast expression surrounded by parentheses
# makes it easier to cut+paste inside of gdb.
return '((%s)%s)' % (ptr.dynamic_type, ptr)
def yield_fields(val):
"""Use this in a printer's children() method to print an object's fields.
e.g.
def children():
for result in yield_fields(self.val):
yield result
"""
try:
fields = val.type.target().fields()
except:
fields = val.type.fields()
for field in fields:
if field.is_base_class:
yield (field.name, val.cast(gdb.lookup_type(field.name)))
else:
yield (field.name, val[field.name])
class Printer(object):
def __init__(self, val):
self.val = val
class StringPrinter(Printer):
def display_hint(self):
return 'string'
class String16Printer(StringPrinter):
def to_string(self):
return blink.ustring_to_string(self.val['_M_dataplus']['_M_p'])
pp_set.add_printer('string16',
'^string16|std::basic_string<(unsigned short|char16_t).*>$',
String16Printer)
class GURLPrinter(StringPrinter):
def to_string(self):
return self.val['spec_']
pp_set.add_printer('GURL', '^GURL$', GURLPrinter)
class FilePathPrinter(StringPrinter):
def to_string(self):
return self.val['path_']['_M_dataplus']['_M_p']
pp_set.add_printer('FilePath', '^FilePath$', FilePathPrinter)
class SmartPtrPrinter(Printer):
def to_string(self):
return '%s%s' % (self.typename, typed_ptr(self.ptr()))
class ScopedPtrPrinter(SmartPtrPrinter):
typename = 'scoped_ptr'
def ptr(self):
return self.val['impl_']['data_']['ptr']
pp_set.add_printer('scoped_ptr', '^scoped_ptr<.*>$', ScopedPtrPrinter)
class ScopedRefPtrPrinter(SmartPtrPrinter):
typename = 'scoped_refptr'
def ptr(self):
return self.val['ptr_']
pp_set.add_printer('scoped_refptr', '^scoped_refptr<.*>$', ScopedRefPtrPrinter)
class LinkedPtrPrinter(SmartPtrPrinter):
typename = 'linked_ptr'
def ptr(self):
return self.val['value_']
pp_set.add_printer('linked_ptr', '^linked_ptr<.*>$', LinkedPtrPrinter)
class WeakPtrPrinter(SmartPtrPrinter):
typename = 'base::WeakPtr'
def ptr(self):
# Check that the pointer is valid. The invalidated flag is stored at
# val.ref_.flag_.ptr_->invalidated_.flag_.__a_.__a_value. This is a gdb
# implementation of base::WeakReference::IsValid(). This is necessary
# because calling gdb.parse_and_eval('(*(%s*)(%s)).ref_.IsValid()' %
# (self.val.type, self.val.address))) does not work in all cases.
ptr = self.val['ref_']['flag_']['ptr_']
if (ptr and
not ptr.dereference()['invalidated_']['flag_']['__a_']['__a_value']):
return self.val['ptr_']
return gdb.Value(0).cast(self.val['ptr_'].type)
pp_set.add_printer('base::WeakPtr', '^base::WeakPtr<.*>$', WeakPtrPrinter)
class CallbackPrinter(Printer):
"""Callbacks provide no usable information so reduce the space they take."""
def to_string(self):
return '...'
pp_set.add_printer('base::OnceCallback', '^base::OnceCallback<.*>$',
CallbackPrinter)
pp_set.add_printer('base::RepeatingCallback', '^base::RepeatingCallback<.*>$',
CallbackPrinter)
class LocationPrinter(Printer):
def to_string(self):
return '%s()@%s:%s' % (self.val['function_name_'].string(),
self.val['file_name_'].string(),
self.val['line_number_'])
pp_set.add_printer('base::Location', '^base::Location$', LocationPrinter)
class PendingTaskPrinter(Printer):
def to_string(self):
return 'From %s' % (self.val['posted_from'],)
def children(self):
for result in yield_fields(self.val):
if result[0] not in ('task', 'posted_from'):
yield result
pp_set.add_printer('base::PendingTask', '^base::PendingTask$',
PendingTaskPrinter)
class LockPrinter(Printer):
def to_string(self):
try:
if self.val['owned_by_thread_']:
return 'Locked by thread %s' % self.val['owning_thread_id_']
else:
return 'Unlocked'
except gdb.error:
return 'Unknown state'
pp_set.add_printer('base::Lock', '^base::Lock$', LockPrinter)
class AbslOptionalPrinter(Printer):
def to_string(self):
if self.val['engaged_']:
return "%s: %s" % (str(self.val.type.tag), self.val['data_'])
else:
return "%s: is empty" % str(self.val.type.tag)
pp_set.add_printer('absl::optional', '^absl::optional<.*>$',
AbslOptionalPrinter)
class ClampedNumericPrinter(Printer):
type_re = r'^base::internal::ClampedNumeric<(.*)>$'
def to_string(self):
m = type_re.search(self.val.type)
if m is None:
return self.val['value']
return '(%s) %s' % (m.group(1), self.val['value_'])
pp_set.add_printer('base::internal::ClampedNumeric',
'^base::internal::ClampedNumeric<.*>$',
ClampedNumericPrinter)
class TimeDeltaPrinter(object):
def __init__(self, val):
self._timedelta = datetime.timedelta(
microseconds=int(val['delta_']['value_']))
def timedelta(self):
return self._timedelta
def to_string(self):
return str(self._timedelta)
pp_set.add_printer('base::TimeDelta', '^base::TimeDelta$', TimeDeltaPrinter)
class TimeTicksPrinter(TimeDeltaPrinter):
def __init__(self, val):
self._timedelta = datetime.timedelta(microseconds=int(val['us_']['value_']))
pp_set.add_printer('base::TimeTicks', '^base::TimeTicks$', TimeTicksPrinter)
class TimePrinter(object):
def __init__(self, val):
timet_offset = gdb.parse_and_eval('base::Time::kTimeTToMicrosecondsOffset')
self._datetime = (
datetime.datetime.fromtimestamp(0) + datetime.timedelta(
microseconds=int(val['us_']['value_']) - int(timet_offset)))
def datetime(self):
return self._datetime
def to_string(self):
return str(self._datetime)
pp_set.add_printer('base::Time', '^base::Time$', TimePrinter)
class FlatTreePrinter(object):
def __init__(self, val):
self.val = val
def to_string(self):
# It would be nice to match the output of std::map which is a little
# nicer than printing the vector of pairs. But iterating over it in
# Python is much more complicated and this output is reasonable.
# (Without this printer, a flat_map will output 7 lines of internal
# template goop before the vector contents.)
return 'base::flat_tree with ' + str(self.val['body_'])
pp_set.add_printer('base::flat_map', '^base::flat_map<.*>$', FlatTreePrinter)
pp_set.add_printer('base::flat_set', '^base::flat_set<.*>$', FlatTreePrinter)
pp_set.add_printer('base::flat_tree', '^base::internal::flat_tree<.*>$',
FlatTreePrinter)
class ValuePrinter(object):
def __init__(self, val):
self.val = val
def get_type(self):
return self.val['type_']
def to_string(self):
typestr = str(self.get_type())
# Trim prefix to just get the emum short name.
typestr = typestr[typestr.rfind(':') + 1:]
if typestr == 'NONE':
return 'base::Value of type NONE'
if typestr == 'BOOLEAN':
valuestr = self.val['bool_value_']
if typestr == 'INTEGER':
valuestr = self.val['int_value_']
if typestr == 'DOUBLE':
valuestr = self.val['double_value_']
if typestr == 'STRING':
valuestr = self.val['string_value_']
if typestr == 'BINARY':
valuestr = self.val['binary_value_']
if typestr == 'DICTIONARY':
valuestr = self.val['dict_']
if typestr == 'LIST':
valuestr = self.val['list_']
return "base::Value of type %s = %s" % (typestr, str(valuestr))
pp_set.add_printer('base::Value', '^base::Value$', ValuePrinter)
pp_set.add_printer('base::ListValue', '^base::ListValue$', ValuePrinter)
pp_set.add_printer('base::DictionaryValue', '^base::DictionaryValue$',
ValuePrinter)
class IpcMessagePrinter(Printer):
def header(self):
return self.val['header_'].cast(
gdb.lookup_type('IPC::Message::Header').pointer())
def to_string(self):
message_type = self.header()['type']
return '%s of kind %s line %s' % (self.val.dynamic_type,
(message_type >> 16).cast(
gdb.lookup_type('IPCMessageStart')),
message_type & 0xffff)
def children(self):
yield ('header_', self.header().dereference())
yield ('capacity_after_header_', self.val['capacity_after_header_'])
for field in self.val.type.fields():
if field.is_base_class:
continue
yield (field.name, self.val[field.name])
pp_set.add_printer('IPC::Message', '^IPC::Message$', IpcMessagePrinter)
class SiteInstanceImplPrinter(object):
def __init__(self, val):
self.val = val.cast(val.dynamic_type)
def to_string(self):
return 'SiteInstanceImpl@%s for %s' % (self.val.address, self.val['site_'])
def children(self):
yield ('id_', self.val['id_'])
yield ('has_site_', self.val['has_site_'])
if self.val['browsing_instance_']['ptr_']:
yield ('browsing_instance_', self.val['browsing_instance_']['ptr_'])
if self.val['process_']:
yield ('process_', typed_ptr(self.val['process_']))
pp_set.add_printer('content::SiteInstanceImpl', '^content::SiteInstanceImpl$',
SiteInstanceImplPrinter)
class RenderProcessHostImplPrinter(object):
def __init__(self, val):
self.val = val.cast(val.dynamic_type)
def to_string(self):
pid = ''
try:
child_process_launcher_ptr = (
self.val['child_process_launcher_']['impl_']['data_']['ptr'])
if child_process_launcher_ptr:
context = (child_process_launcher_ptr['context_']['ptr_'])
if context:
pid = ' PID %s' % str(context['process_']['process_'])
except gdb.error:
# The definition of the Context type may not be available.
# b/8242773
pass
return 'RenderProcessHostImpl@%s%s' % (self.val.address, pid)
def children(self):
yield ('id_', self.val['id_'])
yield ('listeners_', self.val['listeners_']['data_'])
yield ('worker_ref_count_', self.val['worker_ref_count_'])
yield ('fast_shutdown_started_', self.val['fast_shutdown_started_'])
yield ('deleting_soon_', self.val['deleting_soon_'])
yield ('pending_views_', self.val['pending_views_'])
yield ('visible_widgets_', self.val['visible_widgets_'])
yield ('backgrounded_', self.val['backgrounded_'])
yield ('widget_helper_', self.val['widget_helper_'])
yield ('is_initialized_', self.val['is_initialized_'])
yield ('browser_context_', typed_ptr(self.val['browser_context_']))
yield ('sudden_termination_allowed_',
self.val['sudden_termination_allowed_'])
yield ('ignore_input_events_', self.val['ignore_input_events_'])
yield ('is_guest_', self.val['is_guest_'])
pp_set.add_printer('content::RenderProcessHostImpl',
'^content::RenderProcessHostImpl$',
RenderProcessHostImplPrinter)
class AtomicPrinter(Printer):
typename = 'atomic'
def to_string(self):
return self.val['__a_']['__a_value']
pp_set.add_printer('std::__Cr::__atomic', '^std::__Cr::(__)?atomic<.*>$',
AtomicPrinter)
gdb.printing.register_pretty_printer(gdb, pp_set, replace=_DEBUGGING)
"""Implementations of inlined libc++ std container functions."""
def gdb_running_under_rr():
try:
# rr defines the when command to return the current event number.
gdb.execute('when')
# If there was no error executing the command, we are running under rr.
return True
except gdb.error:
return False
def find_nearest_frame_matching(frame, predicate):
while frame and not predicate(frame):
frame = frame.older()
return frame
class ReverseCallback(gdb.Command):
"""Find when the currently running callback was created."""
def __init__(self):
super(ReverseCallback, self).__init__("reverse-callback", gdb.COMMAND_USER)
def invoke(self, arg, from_tty):
if not gdb_running_under_rr():
raise gdb.error('reverse-callback requires debugging under rr: ' +
'https://rr-project.org/')
# Find the stack frame which extracts the bind state from the task.
bind_state_frame = find_nearest_frame_matching(
gdb.selected_frame(), lambda frame: frame.function() and re.match(
'^base::internal::Invoker<.*>' +
r'::RunOnce\(base::internal::BindStateBase\*\)$',
frame.function().name))
if bind_state_frame is None:
raise Exception(
'base::internal::Invoker frame not found; are you in a callback?')
bind_state_frame.select()
# Disable all existing breakpoints.
was_enabled = []
for breakpoint in gdb.breakpoints():
was_enabled.append(breakpoint.enabled)
breakpoint.enabled = False
# Break on the initialization of the BindState.
storage_address = gdb.parse_and_eval('storage')
watchpoint = gdb.Breakpoint('*' + str(storage_address), gdb.BP_WATCHPOINT)
# Find the construction.
gdb.execute('reverse-continue')
# Restore breakpoints
watchpoint.delete()
for breakpoint, enabled in zip(gdb.breakpoints(), was_enabled):
breakpoint.enabled = enabled
# Find the stack frame which created the BindState.
def in_bindstate(frame):
return frame.function() and frame.function().name.startswith(
'base::internal::BindState<')
creation_frame = find_nearest_frame_matching(
find_nearest_frame_matching(gdb.selected_frame(), in_bindstate),
lambda frame: not in_bindstate(frame))
# The callback creates the bindstate, step up once more to get the creator
# of the callback.
creation_frame.older().select()
ReverseCallback()
@class_methods.Class('std::__1::vector', template_types=['T'])
class LibcppVector(object):
@class_methods.member_function('T&', 'operator[]', ['int'])
def element(obj, i):
return obj['__begin_'][i]
@class_methods.member_function('size_t', 'size', [])
def size(obj):
return obj['__end_'] - obj['__begin_']
@class_methods.Class('std::__1::unique_ptr', template_types=['T'])
class LibcppUniquePtr(object):
@class_methods.member_function('T*', 'get', [])
def get(obj):
return obj['__ptr_']['__value_']
@class_methods.member_function('T*', 'operator->', [])
def arrow(obj):
return obj['__ptr_']['__value_']
@class_methods.member_function('T&', 'operator*', [])
def dereference(obj):
return obj['__ptr_']['__value_'].dereference()
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