From b235c358341b288f34cee5936a376f71d0cfbf9a Mon Sep 17 00:00:00 2001
From: Filip Gawin <filip.gawin@zoho.com>
Date: Fri, 27 Mar 2020 21:50:52 +0100
Subject: Cleanup patching system

---
 src/core/patcher.cpp | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

(limited to 'src/core/patcher.cpp')

diff --git a/src/core/patcher.cpp b/src/core/patcher.cpp
index 5fdbdf8b..19ca5f07 100644
--- a/src/core/patcher.cpp
+++ b/src/core/patcher.cpp
@@ -1,6 +1,11 @@
 #include "common.h"
 #include "patcher.h"
 
+#include <algorithm>
+#include <vector>
+
+#include <Windows.h>
+
 StaticPatcher *StaticPatcher::ms_head;
 
 StaticPatcher::StaticPatcher(Patcher func)
@@ -20,3 +25,55 @@ StaticPatcher::Apply()
 	}
 	ms_head = nil;
 }
+
+std::vector<uint32> usedAddresses;
+
+static DWORD protect[2];
+static uint32 protect_address;
+static uint32 protect_size;
+
+void
+Protect_internal(uint32 address, uint32 size)
+{
+	protect_address = address;
+	protect_size = size;
+	VirtualProtect((void*)address, size, PAGE_EXECUTE_READWRITE, &protect[0]);
+}
+
+void
+Unprotect_internal(void)
+{
+	VirtualProtect((void*)protect_address, protect_size, protect[0], &protect[1]);
+}
+
+void
+InjectHook_internal(uint32 address, uint32 hook, int type)
+{
+	if(std::any_of(usedAddresses.begin(), usedAddresses.end(),
+	               [address](uint32 value) { return value == address; })) {
+		debug("Used address %#06x twice when injecting hook\n", address);
+	}
+
+	usedAddresses.push_back(address);
+
+
+	switch(type){
+	case PATCH_JUMP:
+		VirtualProtect((void*)address, 5, PAGE_EXECUTE_READWRITE, &protect[0]);
+		*(uint8*)address = 0xE9;
+		break;
+	case PATCH_CALL:
+		VirtualProtect((void*)address, 5, PAGE_EXECUTE_READWRITE, &protect[0]);
+		*(uint8*)address = 0xE8;
+		break;
+	default:
+		VirtualProtect((void*)(address + 1), 4, PAGE_EXECUTE_READWRITE, &protect[0]);
+		break;
+	}
+
+	*(ptrdiff_t*)(address + 1) = hook - address - 5;
+	if(type == PATCH_NOTHING)
+		VirtualProtect((void*)(address + 1), 4, protect[0], &protect[1]);
+	else
+		VirtualProtect((void*)address, 5, protect[0], &protect[1]);
+}
\ No newline at end of file
-- 
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