def ReadFile(handle, desired_bytes):
"""Calls kernel32.ReadFile()."""
c_read = wintypes.DWORD()
buff = wintypes.create_string_buffer(desired_bytes + 1)
windll.kernel32.ReadFile(handle, buff, desired_bytes,
wintypes.byref(c_read), None)
# NULL terminate it.
buff[c_read.value] = '\x00'
return wintypes.GetLastError(), buff.value
def PeekNamedPipe(handle):
"""Calls kernel32.PeekNamedPipe(). Simplified version."""
c_avail = wintypes.DWORD()
c_message = wintypes.DWORD()
success = windll.kernel32.PeekNamedPipe(handle, None, 0, None,
wintypes.byref(c_avail),
wintypes.byref(c_message))
if not success:
raise OSError(wintypes.GetLastError())
return c_avail.value
def ReadBytes(self, address, num_bytes):
"""Reads at most num_bytes starting from offset <address>."""
address = int(address)
buf = ctypes.create_string_buffer(num_bytes)
bytesread = ctypes.c_size_t(0)
res = ReadProcessMemory(self.h_process, address, buf, num_bytes,
ctypes.byref(bytesread))
if res == 0:
err = wintypes.GetLastError()
if err == 299:
# Only part of ReadProcessMemory has been done, let's return it.
return buf.raw[:bytesread.value]
raise process_error.ProcessError("Error in ReadProcessMemory: %d" % err)
return buf.raw[:bytesread.value]
def acquire(self):
"""Tries to acquire the singleton.
Returns:
True if there was no previous process, False if this process is a
duplicate and should exit.
"""
if sys.platform == 'win32':
# Create a global mutex. Make the mutex so that it disapear automatically
# when the process dies. The handle is not inherited so task_runner
# doesn't get to keep it alive.
# pylint: disable=undefined-variable
self.handle = wintypes.windll.kernel32.CreateMutexW(
wintypes.c_int(0), wintypes.c_int(-1),
wintypes.create_unicode_buffer(self.key))
last_error = wintypes.GetLastError()
logging.info('[singleton] acquire: %s = %s ; %s', self.key,
self.handle, last_error)
if not self.handle:
return False
# ERROR_ALREADY_EXISTS
if last_error == 183:
self.release()
return bool(self.handle)
else:
self.handle = open(self.key, 'a+b')
try:
fcntl.flock(self.handle, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError:
# There's a small race condition where it could report a previous pid.
logging.exception('Singleton "%s" is held by "%s"', self.key,
self.handle.read())
self.handle.close()
self.handle = None
return False
logging.info('[singleton] acquire: %s = %s', self.key, self.handle)
self.handle.seek(0, os.SEEK_SET)
self.handle.truncate(0)
self.handle.write(str(os.getpid()).encode('utf-8'))
return True
