orc-rt/lib/bedrock/NativeDylibManager.cpp

//===- NativeDylibManager.cpp ---------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// NativeDylibManager and related APIs.
//
//===----------------------------------------------------------------------===//

#include "orc-rt/bedrock/NativeDylibManager.h"
#include "orc-rt-internal/bedrock/sys/DynamicLibrary.h"
#include "orc-rt/bedrock/Session.h"

namespace orc_rt {

Expected<std::unique_ptr<NativeDylibManager>>
NativeDylibManager::Create(Session &S, SimpleSymbolTable &ST,
                           const char *InstanceName,
                           SimpleSymbolTable::MutatorFn AddInterface) {

  std::unique_ptr<NativeDylibManager> Instance(new NativeDylibManager(S));

  SimpleSymbolTable NDMST;
  if (auto Err = AddInterface(NDMST))
    return Err;
  std::pair<SymbolNameSpec, const void *> InstanceSym[] = {
      {SymbolNameSpec::c(InstanceName),
       static_cast<const void *>(Instance.get())}};
  if (auto Err = NDMST.addUnique(InstanceSym))
    return std::move(Err);

  if (auto Err = ST.addUnique(std::move(NDMST)))
    return std::move(Err);

  return std::move(Instance);
}

void NativeDylibManager::load(OnLoadCompleteFn &&OnComplete, std::string Path) {
  // Empty path -> global handle; no shutdown callback (RTLD_DEFAULT
  // mustn't be dlclose'd).
  if (Path.empty())
    return OnComplete(sys::globalLookupHandle());

  auto H = sys::loadLibrary(Path);
  if (!H)
    return OnComplete(H.takeError());

  // Capture S by reference, rather than this, so that the callback remains
  // valid even if the NativeDylibManager is destroyed prior to shutdown.
  S.addOnShutdown([&S = this->S, Handle = *H]() {
    if (auto Err = sys::unloadLibrary(Handle))
      S.reportError(std::move(Err));
  });
  OnComplete(std::move(H));
}

void NativeDylibManager::lookup(OnLookupCompleteFn &&OnLookupComplete,
                                void *Handle, SymbolLookupSet Symbols) {
  std::vector<std::string> Names;
  Names.reserve(Symbols.size());
  for (auto &S : Symbols)
    Names.push_back(std::move(S.first));

  auto Addrs = sys::lookupLibrarySymbols(Handle, Names);

  // Convert weak-missing entries (empty optional from lookupLibrarySymbols)
  // to a present zero address. This matches the resolve semantics of
  // llvm::orc::rt_bootstrap::SimpleExecutorDylibManager: an empty optional
  // in the result signals a missing required symbol, while a missing
  // weakly-referenced symbol is reported as a zero address.
  for (size_t I = 0, E = Symbols.size(); I != E; ++I)
    if (!Addrs[I] && Symbols[I].second == WeaklyReferencedSymbol)
      Addrs[I] = nullptr;

  OnLookupComplete(std::move(Addrs));
}

void NativeDylibManager::onDetach(Service::OnCompleteFn OnComplete,
                                  bool ShutdownRequested) {
  // Detach is a noop for now. If/when we add bloom-filter support this will be
  // a good time to update filters.
  OnComplete();
}

void NativeDylibManager::onShutdown(Service::OnCompleteFn OnComplete) {
  // Unloads happen via Session shutdown callbacks registered in load().
  OnComplete();
}

} // namespace orc_rt