// Copyright (c) Microsoft Corporation.  All rights reserved.
// Copyright (c) Lysann Tranvouez.  All rights reserved.

#pragma once
#ifndef MACH_DETOURS_H
#define MACH_DETOURS_H

#ifdef __cplusplus
extern "C" {
#endif

#include <mach/error.h>
#include <mach/mach_types.h>

typedef void* detour_func_t;

#define	detour_err_in_progress	(err_local | 1)
#define	detour_err_wrong_thread	(err_local | 2)
#define	detour_err_too_small	(err_local | 3)
#define	detour_err_too_large	(err_local | 4)

/// Begin a new transaction on the current thread
///
/// @note This will mark all trampoline regions as writable and not executable. Until the transaction is committed or
///       aborted, no thread can execute the trampoline code. If any threads might be doing that, consider using
///       detour_transaction_begin_managed instead, to ensure all threads are suspended.
mach_error_t detour_transaction_begin();

/// Begin a new transaction on the current thread and immediately manage all (other) threads
/// @see `detour_transaction_begin`
/// @see `detour_manage_all_threads`
mach_error_t detour_transaction_begin_managed();

/// @note Requires an active transaction started on the current thread. If there is no transaction active at all, the
///       function has no effect.
mach_error_t detour_transaction_abort();

/// @see `detour_transaction_commit_ex`
mach_error_t detour_transaction_commit();

/// @note Requires an active transaction started on the current thread.
mach_error_t detour_transaction_commit_ex(detour_func_t** out_failed_target);


/// Suspends the given thread and marks it as pending. It will be resumed when the transaction is committed or aborted.
/// @note Requires an active transaction started on the current thread.
/// @note Calling this function with the transaction thread has no effect.
mach_error_t detour_manage_thread(thread_t thread);

/// Manages all threads via `detour_manage_thread`
/// @see `detour_manage_thread`
/// @note Requires an active transaction started on the current thread.
mach_error_t detour_manage_all_threads();


/// @see `detour_attach_ex`
mach_error_t detour_attach(detour_func_t* inout_pointer, detour_func_t detour);

/// @note Requires an active transaction started on the current thread.
/// @note After calling this function, the memory page containing the target function (*inout_pointer) is no longer
///       executable, until you call either commit or abort the current transaction. Due to this, you might run into
///       EXC_BAD_ACCESS when hooking into local functions in the same executable as the calling function.
///       You can use detour_attach_and_commit/detour_attach_and_commit_ex instead in this case.<br/>
///       Similarly, no caller can execute the target function (whether local or not), including the transaction thread.
///       Make sure to detour_manage_thread/detour_manage_all_threads in this case.
mach_error_t detour_attach_ex(detour_func_t* inout_pointer, detour_func_t detour, detour_func_t* out_real_trampoline, detour_func_t* out_real_target, detour_func_t* out_real_detour);

/// @note Requires an active transaction started on the current thread.
/// @note After calling this function, the memory page containing the target function (*inout_pointer) is no longer
///       executable, until you call either commit or abort the current transaction. Due to this, you might run into
///       EXC_BAD_ACCESS when hooking into local functions in the same executable as the calling function.
///       You can use detour_detach_and_commit instead in this case.
mach_error_t detour_detach(detour_func_t* inout_pointer, detour_func_t detour);


/// Same as calling `detour_attach(inout_pointer, detour)` and `detour_transaction_commit()`
/// @see `detour_attach`
/// @see `detour_transaction_commit`
mach_error_t detour_attach_and_commit(detour_func_t* inout_pointer, detour_func_t detour);

/// Same as calling `detour_attach_ex(inout_pointer, detour, out_real_trampoline, out_real_target, out_real_detour)` and `detour_transaction_commit()`
/// @see `detour_attach_ex`
/// @see `detour_transaction_commit`
mach_error_t detour_attach_and_commit_ex(detour_func_t* inout_pointer, detour_func_t detour, detour_func_t* out_real_trampoline, detour_func_t* out_real_target, detour_func_t* out_real_detour);

/// Same as calling `detour_detach(inout_pointer, detour)` and `detour_transaction_commit()`
/// @see `detour_detach`
/// @see `detour_transaction_commit`
mach_error_t detour_detach_and_commit(detour_func_t* inout_pointer, detour_func_t detour);


bool detour_set_ignore_too_small(bool value);
bool detour_set_retain_regions(bool value);
void* detour_set_system_region_lower_bound(void* value);
void* detour_set_system_region_upper_bound(void* value);

#ifdef __cplusplus
}
#endif

#endif // MACH_DETOURS_H