base/config_globals_custom.cc

/*
 * Copyright (C) 2020 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 "berberis/base/config_globals.h"

#include <bitset>
#include <cerrno>
#include <cstdint>
#include <cstdlib>  // strtoull
#include <string>

#include "berberis/base/logging.h"
#include "berberis/base/strings.h"

namespace berberis {

namespace {

std::string ToString(ConfigFlag flag) {
  switch (flag) {
    case kVerboseTranslation:
      return "verbose-translation";
    case kAccurateSigsegv:
      return "accurate-sigsegv";
    case kTopByteIgnore:
      return "top-byte-ignore";
    case kDisableRegMap:
      return "disable-reg-map";
    case kEnableDisjointRegionsTranslation:
      return "enable-disjoint-regions-translation";
    case kNumConfigFlags:
      break;
  }
  return "<unknown-config-flag>";
}

std::bitset<kNumConfigFlags> MakeConfigFlagsSet() {
  ConfigStr var("BERBERIS_FLAGS", "ro.berberis.flags");
  std::bitset<kNumConfigFlags> flags_set;
  if (!var.get()) {
    return flags_set;
  }
  auto token_vector = Split(var.get(), ",");
  for (const auto& token : token_vector) {
    bool found = false;
    for (int flag = 0; flag < kNumConfigFlags; flag++) {
      if (token == ToString(ConfigFlag(flag))) {
        flags_set.set(flag);
        found = true;
        break;
      }
    }
    if (!found) {
      ALOGW("Unrecognized config flag '%s' - ignoring", token.c_str());
    }
  }
  return flags_set;
}

uintptr_t ParseAddr(const char* addr_cstr) {
  if (!addr_cstr) {
    return 0;
  }
  char* end_ptr = nullptr;
  errno = 0;
  uintptr_t addr = static_cast<uintptr_t>(strtoull(addr_cstr, &end_ptr, 16));

  // Warning: setting errno on failure is implementation defined. So we also use extra heuristics.
  if (errno != 0 || (*end_ptr != '\n' && *end_ptr != '\0')) {
    ALOGE("Cannot convert \"%s\" to integer: %s\n",
          addr_cstr,
          errno != 0 ? strerror(errno) : "unexpected end of string");
    return 0;
  }
  return addr;
}

}  // namespace

const char* GetTracingConfig() {
  static ConfigStr var("BERBERIS_TRACING", "berberis.tracing");
  return var.get();
}

const char* GetTranslationModeConfig() {
  static ConfigStr var("BERBERIS_MODE", "berberis.mode");
  return var.get();
}

const char* GetProfilingConfig() {
  static ConfigStr var("BERBERIS_PROFILING", "berberis.profiling");
  return var.get();
}

uintptr_t GetEntryPointOverride() {
  static ConfigStr var("BERBERIS_ENTRY_POINT", "berberis.entry_point");
  static uintptr_t entry_point = ParseAddr(var.get());
  return entry_point;
}

bool IsConfigFlagSet(ConfigFlag flag) {
  static auto flags_set = MakeConfigFlagsSet();
  return flags_set.test(flag);
}

}  // namespace berberis