"""
Process
-------
Provides functions, constants and utilities that wrap the Windows
functions associated with process management and interaction. This
module also provides several constants as well, see Microsoft's
documentation for the constant names and their purpose:
* **Process Security and Access Rights** -
https://msdn.microsoft.com/en-us/library/windows/desktop/ms684880
.. note::
Not all constants may be defined
"""
import six
from pywincffi.core import dist
from pywincffi.core.checks import Enums, input_check, error_check
from pywincffi.exceptions import WindowsAPIError, PyWinCFFINotImplementedError
from pywincffi.kernel32.handle import CloseHandle, WaitForSingleObject
RESERVED_PIDS = set([0, 4])
[docs]def pid_exists(pid, wait=0):
"""
Returns True if there's a process associated with ``pid``.
:param int pid:
The id of the process to check for.
:keyword int wait:
An optional keyword that controls how long we tell
:func:`WaitForSingleObject` to wait on the process.
:raises ValidationError:
Raised if there's a problem with the value provided for ``pid``.
"""
input_check("pid", pid, six.integer_types)
# Process IDs which always exist shouldn't need to continue
# further.
if pid in RESERVED_PIDS:
return True
_, library = dist.load()
try:
hProcess = OpenProcess(
library.PROCESS_QUERY_INFORMATION | library.SYNCHRONIZE,
False, pid)
except WindowsAPIError as error:
# If we can't access the process then it must exist
# otherwise there would be nothing to access. We
# reach this bit of code if the pid in question
# is owned by another user or the system and
# the process running this code does not have the
# rights to query the other process's information.
if error.errno == library.ERROR_ACCESS_DENIED:
return True
# Sometimes the PID we're asking about no longer exists
# in the stack anywhere so we'll get ERROR_INVALID_PARAMETER
# so there's not any reason to continue further.
if error.errno == library.ERROR_INVALID_PARAMETER:
return False
raise
try:
process_exit_code = GetExitCodeProcess(hProcess)
# Process may or may not still be running. If process_exit_code
# seem to indicate the process is still alive then run one
# last check to be certain.
if process_exit_code == library.STILL_ACTIVE:
wait_result = WaitForSingleObject(hProcess, wait)
# The process was still running.
if wait_result == library.WAIT_TIMEOUT:
return True
# The process exited while we were waiting
# on it so it no longer exists.
elif wait_result == library.WAIT_OBJECT_0:
return False
elif wait_result == library.WAIT_ABANDONED:
raise PyWinCFFINotImplementedError(
"An unknown error occurred while running "
"pid_exists(%r). It appears that the call to "
"WaitForSingleObject may be been terminated." % pid)
else:
raise PyWinCFFINotImplementedError(
"Unhandled result from "
"WaitForSingleObject(): %r" % wait_result)
return False
finally:
CloseHandle(hProcess)
[docs]def GetExitCodeProcess(hProcess):
"""
Retrieves the exit code of the given process handle. To retrieve
a process handle use :func:`OpenProcess`.
.. warning::
You may want to use :func:`process_exit_code` instead of this
function if you're just checking to see if a process has
exited at all.
.. seealso::
https://msdn.microsoft.com/en-us/library/ms683189
:param handle hProcess:
The handle of the process to retrieve the exit code for
:returns:
Returns the exit code of the requested process if one
can be found.
"""
input_check("hProcess", hProcess, Enums.HANDLE)
ffi, library = dist.load()
lpExitCode = ffi.new("LPDWORD")
code = library.GetExitCodeProcess(hProcess, lpExitCode)
error_check("GetExitCodeProcess", code=code, expected=Enums.NON_ZERO)
return lpExitCode[0]
[docs]def OpenProcess(dwDesiredAccess, bInheritHandle, dwProcessId):
"""
Opens an existing local process object.
.. seealso::
https://msdn.microsoft.com/en-us/library/ms684320
:param int dwDesiredAccess:
The required access to the process object.
:param bool bInheritHandle:
Enables or disable handle inheritance for child processes.
:param int dwProcessId:
The id of the local process to be opened.
:returns:
Returns a handle to the opened process in the form of
a void pointer. This value can be used by other functions
such as :func:`TerminateProcess`
"""
input_check("dwDesiredAccess", dwDesiredAccess, six.integer_types)
input_check("bInheritHandle", bInheritHandle, bool)
input_check("dwProcessId", dwProcessId, six.integer_types)
ffi, library = dist.load()
handle = library.OpenProcess(
ffi.cast("DWORD", dwDesiredAccess),
ffi.cast("BOOL", bInheritHandle),
ffi.cast("DWORD", dwProcessId)
)
error_check("OpenProcess")
return handle
[docs]def GetCurrentProcess():
"""
Returns a handle to the current thread.
.. seealso::
https://msdn.microsoft.com/en-us/library/ms683179
.. note::
Calling :func:`pywincffi.kernel32.handle.CloseHandle` on the handle
produced by this function will produce an exception.
:returns:
The handle to the current process.
"""
_, library = dist.load()
return library.GetCurrentProcess()
[docs]def GetProcessId(Process): # pylint: disable=invalid-name
"""
Returns the pid of the process handle provided in ``Process``.
.. seealso::
https://msdn.microsoft.com/en-us/library/ms683215
:param handle Process:
The handle of the process to re
:return:
Returns an integer which represents the pid of the given
process handle.
"""
input_check("Process", Process, Enums.HANDLE)
_, library = dist.load()
pid = library.GetProcessId(Process)
error_check("GetProcessId")
return pid