UNLOZE/sm-ext-dhooks2
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Fix overriding return value

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The custom return value was lost when calling the original function.
Save and restore our own return value, if we're about to call the original function.
This commit is contained in:
Peace-Maker
2016-12-13 17:45:22 -07:00
parent 6e96e0fb84
commit b18e3284e1
8 changed files with 82 additions and 33 deletions
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DynamicHooks/hook.cpp
+26 -11
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@@ -52,6 +52,7 @@ CHook::CHook(void* pFunc, ICallingConvention* pConvention)
m_pFunc = pFunc;
m_pRegisters = new CRegisters(pConvention->GetRegisters());
m_pCallingConvention = pConvention;
m_LastPreReturnAction = ReturnAction_Ignored;
if (!m_hookHandler.init())
return;
@@ -150,21 +151,35 @@ bool CHook::AreCallbacksRegistered()
return false;
}
bool CHook::HookHandler(HookType_t eHookType)
ReturnAction_t CHook::HookHandler(HookType_t eHookType)
{
bool bOverride = false;
if (eHookType == HOOKTYPE_POST)
{
if (m_LastPreReturnAction == ReturnAction_Override)
m_pCallingConvention->RestoreReturnValue(m_pRegisters);
}
ReturnAction_t returnAction = ReturnAction_Ignored;
HookTypeMap::Result r = m_hookHandler.find(eHookType);
if (!r.found())
return bOverride;
return returnAction;
HookHandlerSet &callbacks = r->value;
for(HookHandlerSet::iterator it=callbacks.iter(); !it.empty(); it.next())
{
bool result = ((HookHandlerFn) *it)(eHookType, this);
if (result)
bOverride = true;
ReturnAction_t result = ((HookHandlerFn) *it)(eHookType, this);
if (result > returnAction)
returnAction = result;
}
return bOverride;
if (eHookType == HOOKTYPE_PRE)
{
m_LastPreReturnAction = returnAction;
if (returnAction == ReturnAction_Override)
m_pCallingConvention->SaveReturnValue(m_pRegisters);
}
return returnAction;
}
void* __cdecl CHook::GetReturnAddress(void* pESP)
@@ -190,9 +205,9 @@ void* CHook::CreateBridge()
// Write a redirect to the post-hook code
Write_ModifyReturnAddress(masm);
// Call the pre-hook handler and jump to label_supercede if true was returned
// Call the pre-hook handler and jump to label_supercede if ReturnAction_Supercede was returned
Write_CallHandler(masm, HOOKTYPE_PRE);
masm.cmpb(r8_al, true);
masm.cmpb(r8_al, ReturnAction_Supercede);
// Restore the previously saved registers, so any changes will be applied
Write_RestoreRegisters(masm);
@@ -202,7 +217,7 @@ void* CHook::CreateBridge()
// Jump to the trampoline
masm.jmp(ExternalAddress(m_pTrampoline));
// This code will be executed if a pre-hook returns true
// This code will be executed if a pre-hook returns ReturnAction_Supercede
masm.bind(&label_supercede);
// Finally, return to the caller
@@ -302,7 +317,7 @@ void* CHook::CreatePostCallback()
void CHook::Write_CallHandler(sp::MacroAssembler& masm, HookType_t type)
{
bool (__cdecl CHook::*HookHandler)(HookType_t) = &CHook::HookHandler;
ReturnAction_t (__cdecl CHook::*HookHandler)(HookType_t) = &CHook::HookHandler;
// Save the registers so that we can access them in our handlers
Write_SaveRegisters(masm);