openDexFile函数解析

最新推荐文章于 2022-10-12 10:12:08 发布

zhoushishang

最新推荐文章于 2022-10-12 10:12:08 发布

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本文链接：https://blog.youkuaiyun.com/zhoushishang/article/details/38662919

这篇博客详细介绍了Android系统中DexFile_openDexFileNative函数的工作原理，包括计算dex文件校验和、通过ClassLinker查找或创建OAT文件，以及处理无法打开dex文件的异常情况。

static jint DexFile_openDexFileNative(JNIEnv* env, jclass, jstring javaSourceName, jstring javaOutputName, jint) {
  ScopedUtfChars sourceName(env, javaSourceName);
  if (sourceName.c_str() == NULL) {
    return 0;
  }
  std::string dex_location(sourceName.c_str());
  NullableScopedUtfChars outputName(env, javaOutputName);
  if (env->ExceptionCheck()) {
    return 0;
  }
  ScopedObjectAccess soa(env);

  uint32_t dex_location_checksum;
  if (!DexFile::GetChecksum(dex_location, &dex_location_checksum)) {
    LOG(WARNING) << "Failed to compute checksum: " << dex_location;
    ThrowLocation throw_location = soa.Self()->GetCurrentLocationForThrow();
    soa.Self()->ThrowNewExceptionF(throw_location, "Ljava/io/IOException;",
                                   "Unable to get checksum of dex file: %s", dex_location.c_str());
    return 0;
  }

  ClassLinker* linker = Runtime::Current()->GetClassLinker();
  const DexFile* dex_file;
  if (outputName.c_str() == NULL) {
    dex_file = linker->FindDexFileInOatFileFromDexLocation(dex_location, dex_location_checksum);
  } else {
    std::string oat_location(outputName.c_str());
    dex_file = linker->FindOrCreateOatFileForDexLocation(dex_location, dex_location_checksum, oat_location);
  }
  if (dex_file == NULL) {
    LOG(WARNING) << "Failed to open dex file: " << dex_location;
    ThrowLocation throw_location = soa.Self()->GetCurrentLocationForThrow();
    soa.Self()->ThrowNewExceptionF(throw_location, "Ljava/io/IOException;",
                                   "Unable to open dex file: %s", dex_location.c_str());
    return 0;
  }
  return static_cast<jint>(reinterpret_cast<uintptr_t>(dex_file));
}