Ilya Nozhkin a2c267e0c9 [lldb] Fix race condition between lldb-vscode and stop hooks executor
The race is between these two pieces of code that are executed in two separate
lldb-vscode threads (the first is in the main thread and another is in the
event-handling thread):

```
// lldb-vscode.cpp
g_vsc.debugger.SetAsync(false);
g_vsc.target.Launch(launch_info, error);
g_vsc.debugger.SetAsync(true);
```

```
// Target.cpp
bool old_async = debugger.GetAsyncExecution();
debugger.SetAsyncExecution(true);
debugger.GetCommandInterpreter().HandleCommands(GetCommands(), exc_ctx,
                                                options, result);
debugger.SetAsyncExecution(old_async);
```

The sequence that leads to the bug is this one:
1. Main thread enables synchronous mode and launches the process.
2. When the process is launched, it generates the first stop event.
3. This stop event is catched by the event-handling thread and DoOnRemoval
   is invoked.
4. Inside DoOnRemoval, this thread runs stop hooks. And before running stop
   hooks, the current synchronization mode is stored into old_async (and
   right now it is equal to "false").
5. The main thread finishes the launch and returns to lldb-vscode, the
   synchronization mode is restored to asynchronous by lldb-vscode.
6. Event-handling thread finishes stop hooks processing and restores the
   synchronization mode according to old_async (i.e. makes the mode synchronous)
7. And now the mode is synchronous while lldb-vscode expects it to be
   asynchronous. Synchronous mode forbids the process to broadcast public stop
   events, so, VS Code just hangs because lldb-vscode doesn't notify it about
   stops.

So, this diff makes the target intercept the first stop event if the process is
launched in the synchronous mode, thus preventing stop hooks execution.

The bug is only present on Windows because other platforms already
intercept this event using their own hijacking listeners.

So, this diff also fixes some problems with lldb-vscode tests on Windows to make
it possible to run the related test. Other tests still can't be enabled because
the debugged program prints something into stdout and LLDB can't intercept this
output and redirect it to lldb-vscode properly.

Reviewed By: jingham

Differential Revision: https://reviews.llvm.org/D119548
2022-02-22 12:53:55 +01:00

360 lines
16 KiB
Python

from lldbsuite.test.lldbtest import *
import os
import vscode
import time
class VSCodeTestCaseBase(TestBase):
NO_DEBUG_INFO_TESTCASE = True
def create_debug_adaptor(self, lldbVSCodeEnv=None):
'''Create the Visual Studio Code debug adaptor'''
self.assertTrue(is_exe(self.lldbVSCodeExec),
'lldb-vscode must exist and be executable')
log_file_path = self.getBuildArtifact('vscode.txt')
self.vscode = vscode.DebugAdaptor(
executable=self.lldbVSCodeExec, init_commands=self.setUpCommands(),
log_file=log_file_path, env=lldbVSCodeEnv)
def build_and_create_debug_adaptor(self, lldbVSCodeEnv=None):
self.build()
self.create_debug_adaptor(lldbVSCodeEnv)
def set_source_breakpoints(self, source_path, lines, condition=None,
hitCondition=None):
'''Sets source breakpoints and returns an array of strings containing
the breakpoint IDs ("1", "2") for each breakpoint that was set.
'''
response = self.vscode.request_setBreakpoints(
source_path, lines, condition=condition, hitCondition=hitCondition)
if response is None:
return []
breakpoints = response['body']['breakpoints']
breakpoint_ids = []
for breakpoint in breakpoints:
breakpoint_ids.append('%i' % (breakpoint['id']))
return breakpoint_ids
def set_function_breakpoints(self, functions, condition=None,
hitCondition=None):
'''Sets breakpoints by function name given an array of function names
and returns an array of strings containing the breakpoint IDs
("1", "2") for each breakpoint that was set.
'''
response = self.vscode.request_setFunctionBreakpoints(
functions, condition=condition, hitCondition=hitCondition)
if response is None:
return []
breakpoints = response['body']['breakpoints']
breakpoint_ids = []
for breakpoint in breakpoints:
breakpoint_ids.append('%i' % (breakpoint['id']))
return breakpoint_ids
def waitUntil(self, condition_callback):
for _ in range(20):
if condition_callback():
return True
time.sleep(0.5)
return False
def verify_breakpoint_hit(self, breakpoint_ids):
'''Wait for the process we are debugging to stop, and verify we hit
any breakpoint location in the "breakpoint_ids" array.
"breakpoint_ids" should be a list of breakpoint ID strings
(["1", "2"]). The return value from self.set_source_breakpoints()
or self.set_function_breakpoints() can be passed to this function'''
stopped_events = self.vscode.wait_for_stopped()
for stopped_event in stopped_events:
if 'body' in stopped_event:
body = stopped_event['body']
if 'reason' not in body:
continue
if body['reason'] != 'breakpoint':
continue
if 'description' not in body:
continue
# Descriptions for breakpoints will be in the form
# "breakpoint 1.1", so look for any description that matches
# ("breakpoint 1.") in the description field as verification
# that one of the breakpoint locations was hit. VSCode doesn't
# allow breakpoints to have multiple locations, but LLDB does.
# So when looking at the description we just want to make sure
# the right breakpoint matches and not worry about the actual
# location.
description = body['description']
for breakpoint_id in breakpoint_ids:
match_desc = 'breakpoint %s.' % (breakpoint_id)
if match_desc in description:
return
self.assertTrue(False, "breakpoint not hit")
def verify_exception_breakpoint_hit(self, filter_label):
'''Wait for the process we are debugging to stop, and verify the stop
reason is 'exception' and that the description matches
'filter_label'
'''
stopped_events = self.vscode.wait_for_stopped()
for stopped_event in stopped_events:
if 'body' in stopped_event:
body = stopped_event['body']
if 'reason' not in body:
continue
if body['reason'] != 'exception':
continue
if 'description' not in body:
continue
description = body['description']
if filter_label == description:
return True
return False
def verify_commands(self, flavor, output, commands):
self.assertTrue(output and len(output) > 0, "expect console output")
lines = output.splitlines()
prefix = '(lldb) '
for cmd in commands:
found = False
for line in lines:
if line.startswith(prefix) and cmd in line:
found = True
break
self.assertTrue(found,
"verify '%s' found in console output for '%s'" % (
cmd, flavor))
def get_dict_value(self, d, key_path):
'''Verify each key in the key_path array is in contained in each
dictionary within "d". Assert if any key isn't in the
corresponding dictionary. This is handy for grabbing values from VS
Code response dictionary like getting
response['body']['stackFrames']
'''
value = d
for key in key_path:
if key in value:
value = value[key]
else:
self.assertTrue(key in value,
'key "%s" from key_path "%s" not in "%s"' % (
key, key_path, d))
return value
def get_stackFrames_and_totalFramesCount(self, threadId=None, startFrame=None,
levels=None, dump=False):
response = self.vscode.request_stackTrace(threadId=threadId,
startFrame=startFrame,
levels=levels,
dump=dump)
if response:
stackFrames = self.get_dict_value(response, ['body', 'stackFrames'])
totalFrames = self.get_dict_value(response, ['body', 'totalFrames'])
self.assertTrue(totalFrames > 0,
'verify totalFrames count is provided by extension that supports '
'async frames loading')
return (stackFrames, totalFrames)
return (None, 0)
def get_stackFrames(self, threadId=None, startFrame=None, levels=None,
dump=False):
(stackFrames, totalFrames) = self.get_stackFrames_and_totalFramesCount(
threadId=threadId,
startFrame=startFrame,
levels=levels,
dump=dump)
return stackFrames
def get_source_and_line(self, threadId=None, frameIndex=0):
stackFrames = self.get_stackFrames(threadId=threadId,
startFrame=frameIndex,
levels=1)
if stackFrames is not None:
stackFrame = stackFrames[0]
['source', 'path']
if 'source' in stackFrame:
source = stackFrame['source']
if 'path' in source:
if 'line' in stackFrame:
return (source['path'], stackFrame['line'])
return ('', 0)
def get_stdout(self, timeout=0.0):
return self.vscode.get_output('stdout', timeout=timeout)
def get_console(self, timeout=0.0):
return self.vscode.get_output('console', timeout=timeout)
def collect_console(self, duration):
return self.vscode.collect_output('console', duration=duration)
def get_local_as_int(self, name, threadId=None):
value = self.vscode.get_local_variable_value(name, threadId=threadId)
if value.startswith('0x'):
return int(value, 16)
elif value.startswith('0'):
return int(value, 8)
else:
return int(value)
def set_local(self, name, value, id=None):
'''Set a top level local variable only.'''
return self.vscode.request_setVariable(1, name, str(value), id=id)
def set_global(self, name, value, id=None):
'''Set a top level global variable only.'''
return self.vscode.request_setVariable(2, name, str(value), id=id)
def stepIn(self, threadId=None, waitForStop=True):
self.vscode.request_stepIn(threadId=threadId)
if waitForStop:
return self.vscode.wait_for_stopped()
return None
def stepOver(self, threadId=None, waitForStop=True):
self.vscode.request_next(threadId=threadId)
if waitForStop:
return self.vscode.wait_for_stopped()
return None
def stepOut(self, threadId=None, waitForStop=True):
self.vscode.request_stepOut(threadId=threadId)
if waitForStop:
return self.vscode.wait_for_stopped()
return None
def continue_to_next_stop(self):
self.vscode.request_continue()
return self.vscode.wait_for_stopped()
def continue_to_breakpoints(self, breakpoint_ids):
self.vscode.request_continue()
self.verify_breakpoint_hit(breakpoint_ids)
def continue_to_exception_breakpoint(self, filter_label):
self.vscode.request_continue()
self.assertTrue(self.verify_exception_breakpoint_hit(filter_label),
'verify we got "%s"' % (filter_label))
def continue_to_exit(self, exitCode=0):
self.vscode.request_continue()
stopped_events = self.vscode.wait_for_stopped()
self.assertEquals(len(stopped_events), 1,
"stopped_events = {}".format(stopped_events))
self.assertEquals(stopped_events[0]['event'], 'exited',
'make sure program ran to completion')
self.assertEquals(stopped_events[0]['body']['exitCode'], exitCode,
'exitCode == %i' % (exitCode))
def attach(self, program=None, pid=None, waitFor=None, trace=None,
initCommands=None, preRunCommands=None, stopCommands=None,
exitCommands=None, attachCommands=None, coreFile=None,
disconnectAutomatically=True, terminateCommands=None,
postRunCommands=None, sourceMap=None):
'''Build the default Makefile target, create the VSCode debug adaptor,
and attach to the process.
'''
# Make sure we disconnect and terminate the VSCode debug adaptor even
# if we throw an exception during the test case.
def cleanup():
if disconnectAutomatically:
self.vscode.request_disconnect(terminateDebuggee=True)
self.vscode.terminate()
# Execute the cleanup function during test case tear down.
self.addTearDownHook(cleanup)
# Initialize and launch the program
self.vscode.request_initialize()
response = self.vscode.request_attach(
program=program, pid=pid, waitFor=waitFor, trace=trace,
initCommands=initCommands, preRunCommands=preRunCommands,
stopCommands=stopCommands, exitCommands=exitCommands,
attachCommands=attachCommands, terminateCommands=terminateCommands,
coreFile=coreFile, postRunCommands=postRunCommands,
sourceMap=sourceMap)
if not (response and response['success']):
self.assertTrue(response['success'],
'attach failed (%s)' % (response['message']))
def launch(self, program=None, args=None, cwd=None, env=None,
stopOnEntry=False, disableASLR=True,
disableSTDIO=False, shellExpandArguments=False,
trace=False, initCommands=None, preRunCommands=None,
stopCommands=None, exitCommands=None, terminateCommands=None,
sourcePath=None, debuggerRoot=None, launchCommands=None,
sourceMap=None, disconnectAutomatically=True, runInTerminal=False,
expectFailure=False, postRunCommands=None):
'''Sending launch request to vscode
'''
# Make sure we disconnect and terminate the VSCode debug adapter,
# if we throw an exception during the test case
def cleanup():
if disconnectAutomatically:
self.vscode.request_disconnect(terminateDebuggee=True)
self.vscode.terminate()
# Execute the cleanup function during test case tear down.
self.addTearDownHook(cleanup)
# Initialize and launch the program
self.vscode.request_initialize()
response = self.vscode.request_launch(
program,
args=args,
cwd=cwd,
env=env,
stopOnEntry=stopOnEntry,
disableASLR=disableASLR,
disableSTDIO=disableSTDIO,
shellExpandArguments=shellExpandArguments,
trace=trace,
initCommands=initCommands,
preRunCommands=preRunCommands,
stopCommands=stopCommands,
exitCommands=exitCommands,
terminateCommands=terminateCommands,
sourcePath=sourcePath,
debuggerRoot=debuggerRoot,
launchCommands=launchCommands,
sourceMap=sourceMap,
runInTerminal=runInTerminal,
expectFailure=expectFailure,
postRunCommands=postRunCommands)
if expectFailure:
return response
if not (response and response['success']):
self.assertTrue(response['success'],
'launch failed (%s)' % (response['message']))
# We need to trigger a request_configurationDone after we've successfully
# attached a runInTerminal process to finish initialization.
if runInTerminal:
self.vscode.request_configurationDone()
return response
def build_and_launch(self, program, args=None, cwd=None, env=None,
stopOnEntry=False, disableASLR=True,
disableSTDIO=False, shellExpandArguments=False,
trace=False, initCommands=None, preRunCommands=None,
stopCommands=None, exitCommands=None,
terminateCommands=None, sourcePath=None,
debuggerRoot=None, runInTerminal=False,
disconnectAutomatically=True, postRunCommands=None,
lldbVSCodeEnv=None):
'''Build the default Makefile target, create the VSCode debug adaptor,
and launch the process.
'''
self.build_and_create_debug_adaptor(lldbVSCodeEnv)
self.assertTrue(os.path.exists(program), 'executable must exist')
return self.launch(program, args, cwd, env, stopOnEntry, disableASLR,
disableSTDIO, shellExpandArguments, trace,
initCommands, preRunCommands, stopCommands, exitCommands,
terminateCommands, sourcePath, debuggerRoot, runInTerminal=runInTerminal,
disconnectAutomatically=disconnectAutomatically,
postRunCommands=postRunCommands)