reloc_transform_pass.cpp

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// Copyright (c) 2022, _xeroxz
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#include <obf/passes/reloc_transform_pass.hpp>
 
namespace theo::obf {
reloc_transform_pass_t* reloc_transform_pass_t::get() {
  static reloc_transform_pass_t obj;
  return &obj;
}
 
void reloc_transform_pass_t::run(decomp::symbol_t* sym) {
  std::optional<recomp::reloc_t*> reloc;
  if (!(reloc = has_legit_reloc(sym)).has_value())
    return;
 
  spdlog::info("adding transformations to relocation in symbol: {}",
               sym->name());
 
  xed_error_enum_t err;
  xed_decoded_inst_t inst;
  xed_state_t istate{XED_MACHINE_MODE_LONG_64, XED_ADDRESS_WIDTH_64b};
  xed_decoded_inst_zero_set_mode(&inst, &istate);
 
  if ((err = xed_decode(&inst, sym->data().data(), sym->data().size())) !=
      XED_ERROR_NONE) {
    spdlog::error("failed to decode instruction, reason: {} in symbol: {}",
                  xed_error_enum_t2str(err), sym->name());
 
    assert(err == XED_ERROR_NONE);
  }
 
  auto transforms_bytes = transform::generate(&inst, reloc.value(), 3, 6);
  sym->data().insert(sym->data().end(), transforms_bytes.begin(),
                     transforms_bytes.end());
};
 
std::optional<recomp::reloc_t*> reloc_transform_pass_t::has_legit_reloc(
    decomp::symbol_t* sym) {
  auto res =  // see if there are any relocations with offset not equal to
              // zero... relocations with zero mean its a relocation to the next
              // instruction...
      std::find_if(
          sym->relocs().begin(), sym->relocs().end(),
          [&](recomp::reloc_t& reloc) -> bool { return reloc.offset(); });
 
  return res != sym->relocs().end() ? &(*res)
                                    : std::optional<recomp::reloc_t*>();
}
}  // namespace theo::obf