bool CDetour::CreateDetour()
{
if (!gameconf->GetMemSig(signame, &detour_address))
{
g_pSM->LogError(myself, "Could not locate %s - Disabling detour", signame);
return false;
}
if (!detour_address)
{
g_pSM->LogError(myself, "Sigscan for %s failed - Disabling detour to prevent crashes", signame);
return false;
}
detour_restore.bytes = copy_bytes((unsigned char *)detour_address, NULL, OP_JMP_SIZE+1);
/* First, save restore bits */
for (size_t i=0; i<detour_restore.bytes; i++)
{
detour_restore.patch[i] = ((unsigned char *)detour_address)[i];
}
JitWriter wr;
JitWriter *jit = ≀
jit_uint32_t CodeSize = 0;
wr.outbase = NULL;
wr.outptr = NULL;
jit_rewind:
/* Patch old bytes in */
if (wr.outbase != NULL)
{
copy_bytes((unsigned char *)detour_address, (unsigned char*)wr.outptr, detour_restore.bytes);
}
wr.outptr += detour_restore.bytes;
/* Return to the original function */
jitoffs_t call = IA32_Jump_Imm32(jit, 0);
IA32_Write_Jump32_Abs(jit, call, (unsigned char *)detour_address + detour_restore.bytes);
if (wr.outbase == NULL)
{
CodeSize = wr.get_outputpos();
wr.outbase = (jitcode_t)spengine->AllocatePageMemory(CodeSize);
spengine->SetReadWrite(wr.outbase);
wr.outptr = wr.outbase;
detour_trampoline = wr.outbase;
goto jit_rewind;
}
spengine->SetReadExecute(wr.outbase);
*trampoline = detour_trampoline;
return true;
}
// this was pretty much copied verbatim from pRED's CBaseServer code. Too much I didn't
// understand in this area .... yet
bool CDetour::StartDetour() {
if (!DetourAddress) {
Msg ("Detour for %s failed - no valid pointer was provided.\n", FunctionDetoured);
return false;
}
orig_bytes.size_stored = copy_bytes((mem_t *)DetourAddress, NULL, OP_JMP_SIZE+1);
for ( size_t i=0; i < orig_bytes.size_stored; i++ )
orig_bytes.bytes_from_memory[i] = ((mem_t *)DetourAddress)[i];
JitWriter wr;
JitWriter *jit = ≀
jit_uint32_t CodeSize = 0;
wr.outbase = NULL;
wr.outptr = NULL;
jit_rewind:
/* Patch old bytes in */
if (wr.outbase != NULL)
copy_bytes((mem_t *)DetourAddress, (mem_t *)wr.outptr, orig_bytes.size_stored);
wr.outptr += orig_bytes.size_stored;
/* Return to the original function */
jitoffs_t call = IA32_Jump_Imm32(jit, 0);
IA32_Write_Jump32_Abs(jit, call, (mem_t *)DetourAddress + orig_bytes.size_stored);
if (wr.outbase == NULL)
{
CodeSize = wr.get_outputpos();
wr.outbase = (jitcode_t)KE_AllocCode(g_pCodeCache, CodeSize);
wr.outptr = wr.outbase;
TrampolineAddress = wr.outbase;
goto jit_rewind;
}
*TrampolineFunc = TrampolineAddress;
return true;
}
