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<!DOCTYPE html>

<head>

<title>memory.hooks — Source.Python v743 documentation</title>

</head><body>

<h3>Navigation</h3>

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accesskey="I">index</a></li>

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>modules</a> |</li>

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<li class="nav-item nav-item-1"><a href="../index.html" >Module code</a> »</li>

<li class="nav-item nav-item-2"><a href="../memory.html" accesskey="U">memory</a> »</li>

<li class="nav-item nav-item-this"><a href="">memory.hooks</a></li>

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</div>

<h1>Source code for memory.hooks</h1><div class="highlight"><pre>

# ../memory/hooks.py

"""Provides memory hooking functionality."""

# =============================================================================

# >> IMPORTS

# =============================================================================

# Python

from contextlib import contextmanager

# Source.Python Imports

# Core

from core import AutoUnload

# Memory

from _memory import HookType

from _memory import set_hooks_disabled

from _memory import get_hooks_disabled

from memory import Function

# =============================================================================

# >> ALL DECLARATION

# =============================================================================

__all__ = ('HookType',

'PostHook',

'PreHook',

'set_hooks_disabled',

'get_hooks_disabled',

'hooks_disabled',

'use_pre_registers',

)

# =============================================================================

# >> CLASSES

# =============================================================================

class _Hook(AutoUnload):

"""Create pre and post hooks that auto unload."""

def __init__(self, function):

"""Verify the given function is a Function object and store it."""

# Is the function to be hooked a Function instance?

if not isinstance(function, Function):

# Raise an error as we can only hook Function instances

raise TypeError(

"'" + type(function).__name__ +

"' object is not a Function instance.")

# Store the function

self.callback = None

self.function = function

def __call__(self, callback):

"""Store the callback and hook it."""

# Store the callback

self.callback = callback

# Hook the callback to the Function

self.function.add_hook(self.hook_type, self.callback)

# Return the callback

return self.callback

@property

def hook_type(self):

"""Raise an error if the inheriting class does not have their own."""

raise NotImplementedError('No hook_type defined for class.')

def _unload_instance(self):

"""Unregister the hook on script unload."""

self.function.remove_hook(self.hook_type, self.callback)

class PreHook(_Hook):

"""Decorator class used to create pre hooks that auto unload."""

hook_type = HookType.PRE</div>

class PostHook(_Hook):

"""Decorator class used to create post hooks that auto unload."""

hook_type = HookType.POST</div>

# =============================================================================

# >> FUNCTIONS

# =============================================================================

@contextmanager

def use_pre_registers(stack_data, value=True):

"""Temporarily set ``StackData.use_pre_registers`` to the given value.

When the context ends, the previous value is restored.

Some functions overwrite CPU registers during their execution with values

from their internal calculations. In a post-hook, you have access to the

modified CPU registers, but in some cases you might want to access the

registers that were saved before the pre-hook was called. In that case you

can use this context manager to get access to the previous state of the

registers. On Windows this is often required when hooking THISCALL

functions, because the this-pointer is saved in the CPU register ``ECX``,

but gets overwritten during the execution of the hooked function. So, in a

post-hook you won't have access to the this-pointer anymore.

Example (CS:S/Windows):

.. code:: python

from entities.hooks import EntityCondition

from entities.hooks import EntityPostHook

from entities.hooks import EntityPreHook

from memory.hooks import use_pre_registers

@EntityPreHook(EntityCondition.is_player, 'drop_weapon')

def pre_on_drop_weapon(stack_data):

print(f'PRE: this = {stack_data[0].address}')

@EntityPostHook(EntityCondition.is_player, 'drop_weapon')

def post_on_drop_weapon(stack_data, ret_val):

print(f'POST FALSE: this = {stack_data[0].address}')

with use_pre_registers(stack_data):

print(f'POST CORRECT: this = {stack_data[0].address}')

Output:

.. code::

PRE: this = 546778280

POST FALSE: this = 16439007

POST CORRECT: this = 546778280

"""

old = stack_data.use_pre_registers

stack_data.use_pre_registers = value

try:

yield

finally:

stack_data.use_pre_registers = old</div>

@contextmanager

def hooks_disabled(disabled=True):

"""Temporarily disable or enable all hook callbacks. By default hooks are

enabled. Thus, this context manager is mainly used to temporarily disable

hook callbacks. If the context ends, the original value is restored. This

can be used e. g. to avoid recursive calls when damaging a player in a

``on_take_damage`` hook or ``player_hurt`` event.

.. note::

This would only disable hooks created with Source.Python. Hooks that

have been created by other server plugins will still be called.

Example:

.. code:: python

from players.entity import Player

from memory.hooks import hooks_disabled

# Get a Player instance of the player with index 1

player = Player(1)

# Damage the player. This would call e. g. on_take_damage hooks

player.take_damage(5)

# To avoid calling the on_take_damage hooks, use the following:

with hooks_disabled()

player.take_damage(5)

"""

old = get_hooks_disabled()

set_hooks_disabled(disabled)

try:

yield

finally:

set_hooks_disabled(old)</div>

</pre></div>

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>index</a></li>

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>modules</a> |</li>

<li class="nav-item nav-item-0"><a href="../../index.html"> Source.Python v743 documentation</a> »</li>

<li class="nav-item nav-item-1"><a href="../index.html" >Module code</a> »</li>

<li class="nav-item nav-item-2"><a href="../memory.html" >memory</a> »</li>

<li class="nav-item nav-item-this"><a href="">memory.hooks</a></li>

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