/*
 * Copyright 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "ProtoFuzzerRunner.h"

#include <dlfcn.h>
#include <sstream>

#include "utils/InterfaceSpecUtil.h"
#include "vintf/HalManifest.h"
#include "vintf/Version.h"
#include "vintf/VintfObject.h"

using android::vintf::HalManifest;
using android::vintf::Version;

using std::cerr;
using std::cout;
using std::string;
using std::unordered_map;
using std::vector;

namespace android {
namespace vts {
namespace fuzzer {

static string GetVersionString(const CompSpec &comp_spec) {
  stringstream version_major, version_minor;
  version_major << comp_spec.component_type_version_major();
  version_minor << comp_spec.component_type_version_minor();
  return version_major.str() + "." + version_minor.str();
}

static string GetDriverName(const CompSpec &comp_spec) {
  string version_string = GetVersionString(comp_spec);
  string driver_name =
      comp_spec.package() + "@" + version_string + "-vts.driver.so";
  return driver_name;
}

static string GetServiceName(const CompSpec &comp_spec) {
  string hal_name = comp_spec.package();
  string iface_name = comp_spec.component_name();

  auto instance_names =
      ::android::vintf::VintfObject::GetDeviceHalManifest()->getHidlInstances(
          hal_name,
          Version(comp_spec.component_type_version_major(),
                  comp_spec.component_type_version_minor()),
          iface_name);
  if (instance_names.empty()) {
    cerr << "HAL service name not available in VINTF." << endl;
    std::abort();
  }

  // For fuzzing we don't care which instance of the HAL is targeted.
  string service_name = *instance_names.begin();
  cout << "Available HAL instances: " << endl;
  for (const string &instance_name : instance_names) {
    cout << instance_name << endl;
  }
  cout << "Using HAL instance: " << service_name << endl;

  return service_name;
}

static void *Dlopen(string lib_name) {
  // Clear dlerror().
  dlerror();
  void *handle = dlopen(lib_name.c_str(), RTLD_LAZY);
  if (!handle) {
    cerr << __func__ << ": " << dlerror() << endl;
    cerr << __func__ << ": Can't load shared library: " << lib_name << endl;
    std::abort();
  }
  return handle;
}

static void *Dlsym(void *handle, string function_name) {
  const char *error;
  // Clear dlerror().
  dlerror();
  void *function = dlsym(handle, function_name.c_str());
  if ((error = dlerror()) != NULL) {
    cerr << __func__ << ": Can't find: " << function_name << endl;
    cerr << error << endl;
    std::abort();
  }
  return function;
}

static void GetService(DriverBase *hal, string service_name, bool binder_mode) {
  // For fuzzing, only passthrough mode provides coverage.
  // If binder mode is not requested, attempt to open HAL in passthrough mode.
  // If the attempt fails, fall back to binder mode.
  if (!binder_mode) {
    if (!hal->GetService(true, service_name.c_str())) {
      cerr << __func__ << ": Failed to open HAL in passthrough mode. "
           << "Falling back to binder mode." << endl;
    } else {
      cerr << "HAL opened in passthrough mode." << endl;
      return;
    }
  }

  if (!hal->GetService(false, service_name.c_str())) {
    cerr << __func__ << ": Failed to open HAL in binder mode." << endl;
    std::abort();
  } else {
    cerr << "HAL opened in binder mode." << endl;
    return;
  }
}

DriverBase *ProtoFuzzerRunner::LoadInterface(const CompSpec &comp_spec,
                                             uint64_t hidl_service = 0) {
  DriverBase *hal;
  // Clear dlerror().
  dlerror();

  // DriverBase can be constructed with or without an argument.
  // Using different DriverBase constructors requires dlsym'ing different
  // symbols from the driver library.
  string function_name = GetFunctionNamePrefix(comp_spec);
  if (hidl_service) {
    function_name += "with_arg";
    using loader_func = DriverBase *(*)(uint64_t);
    auto hal_loader = (loader_func)Dlsym(driver_handle_, function_name.c_str());
    hal = hal_loader(hidl_service);
  } else {
    using loader_func = DriverBase *(*)();
    auto hal_loader = (loader_func)Dlsym(driver_handle_, function_name.c_str());
    hal = hal_loader();
  }
  return hal;
}

ProtoFuzzerRunner::ProtoFuzzerRunner(const vector<CompSpec> &comp_specs,
                                     const string version_iface) {
  for (const auto &comp_spec : comp_specs) {
    string target_version = GetVersionString(comp_spec);
    if (comp_spec.has_interface() && target_version == version_iface) {
      string name = comp_spec.component_name();
      comp_specs_[name] = comp_spec;
    }
  }
}

void ProtoFuzzerRunner::Init(const string &iface_name, bool binder_mode) {
  const CompSpec *comp_spec = FindCompSpec(iface_name);
  // dlopen VTS driver library.
  string driver_name = GetDriverName(*comp_spec);
  driver_handle_ = Dlopen(driver_name);

  std::shared_ptr<DriverBase> hal{LoadInterface(*comp_spec)};
  string service_name = GetServiceName(*comp_spec);
  cerr << "HAL name: " << comp_spec->package() << endl
       << "Interface name: " << comp_spec->component_name() << endl
       << "Service name: " << service_name << endl;

  // This should only be done for top-level interfaces.
  GetService(hal.get(), service_name, binder_mode);

  // Register this interface as opened by the runner.
  opened_ifaces_[iface_name] = {
      .comp_spec_ = comp_spec, .hal_ = hal,
  };
}

void ProtoFuzzerRunner::Execute(const ExecSpec &exec_spec) {
  for (const auto &func_call : exec_spec.function_call()) {
    Execute(func_call);
  }
}

void ProtoFuzzerRunner::Execute(const FuncCall &func_call) {
  string iface_name = func_call.hidl_interface_name();
  const FuncSpec &func_spec = func_call.api();

  auto iface_desc = opened_ifaces_.find(iface_name);
  if (iface_desc == opened_ifaces_.end()) {
    cerr << "Interface is not open: " << iface_name << endl;
    std::abort();
  }

  FuncSpec result{};
  iface_desc->second.hal_->CallFunction(func_spec, "", &result);

  stats_.RegisterTouch(iface_name, func_spec.name());
  ProcessReturnValue(result);
}

static string StripNamespace(const string &type) {
  size_t idx = type.find_last_of(':');
  if (idx == string::npos) {
    return "";
  }
  return type.substr(idx + 1);
}

void ProtoFuzzerRunner::ProcessReturnValue(const FuncSpec &result) {
  for (const auto &var : result.return_type_hidl()) {
    // If result contains a pointer to an interface, register it in
    // opened_ifaces_ table. That pointer must not be a nullptr.
    if (var.has_hidl_interface_pointer() && var.hidl_interface_pointer() &&
        var.has_predefined_type()) {
      uint64_t hidl_service = var.hidl_interface_pointer();
      string type = var.predefined_type();
      string iface_name = StripNamespace(type);

      const CompSpec *comp_spec = FindCompSpec(iface_name);
      std::shared_ptr<DriverBase> hal{LoadInterface(*comp_spec, hidl_service)};

      // If this interface has not been seen before, record the fact.
      if (opened_ifaces_.find(iface_name) == opened_ifaces_.end()) {
        cerr << "Discovered new interface: " << iface_name << endl;
      }

      // Register this interface as opened by the runner.
      opened_ifaces_[iface_name] = {
          .comp_spec_ = comp_spec, .hal_ = hal,
      };
    }
  }
}

const CompSpec *ProtoFuzzerRunner::FindCompSpec(std::string name) {
  auto comp_spec = comp_specs_.find(name);
  if (comp_spec == comp_specs_.end()) {
    cerr << "VTS spec not found: " << name << endl;
    std::abort();
  }
  return &comp_spec->second;
}

}  // namespace fuzzer
}  // namespace vts
}  // namespace android