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/*
* Copyright (c) 2012-2018 Zeex
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <stddef.h>
#include <windows.h>
typedef __int64 QWORD;
#define SUBHOOK_CODE_PROTECT_FLAGS PAGE_EXECUTE_READWRITE
int subhook_unprotect(void *address, size_t size) {
DWORD old_flags;
BOOL result = VirtualProtect(address,
size,
SUBHOOK_CODE_PROTECT_FLAGS,
&old_flags);
return !result;
}
void *subhook_alloc_code(void *target_address, size_t size) {
#if defined _M_AMD64 || defined __amd64__
if (target_address != NULL) {
SYSTEM_INFO sys_info;
DWORD page_size;
QWORD offset;
GetSystemInfo(&sys_info);
page_size = sys_info.dwPageSize;
QWORD pivot = (QWORD)target_address & ~((QWORD)page_size - 1);
void *result;
for (offset = page_size; offset <= ((QWORD)1 << 31); offset += page_size) {
result = VirtualAlloc((void *)(pivot - offset),
size,
MEM_COMMIT | MEM_RESERVE,
SUBHOOK_CODE_PROTECT_FLAGS);
if (result != NULL) {
return result;
}
result = VirtualAlloc((void *)(pivot + offset),
size,
MEM_COMMIT | MEM_RESERVE,
SUBHOOK_CODE_PROTECT_FLAGS);
if (result != NULL) {
return result;
}
}
}
#endif
return VirtualAlloc(NULL,
size,
MEM_COMMIT | MEM_RESERVE,
SUBHOOK_CODE_PROTECT_FLAGS);
}
int subhook_free_code(void *address, size_t size) {
(void)size;
if (address == NULL) {
return 0;
}
return !VirtualFree(address, 0, MEM_RELEASE);
}
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