安卓11 linker加载so

    public static void loadLibrary(String libname) {//参数1传输调用者的类，参数2传入将要加载的soname        Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname);    }

//这个函数存在重载    void loadLibrary0(Class<?> fromClass, String libname) {        ClassLoader classLoader = ClassLoader.getClassLoader(fromClass);        loadLibrary0(classLoader, fromClass, libname);    } private synchronized void loadLibrary0(ClassLoader loader, Class<?> callerClass, String libname) {    //so库的名字不含有分割字符        if (libname.indexOf((int)File.separatorChar) != -1) {            throw new UnsatisfiedLinkError(    "Directory separator should not appear in library name: " + libname);        }        String libraryName = libname;    //前方调用的类的classloader不为空，并且不是 BootClassLoade    //这个实现的也就是应用程序的so加载        if (loader != null && !(loader instanceof BootClassLoader)) {      //1.1.1使用用ClassLoader的findLibrary()方法获取so库的path            String filename = loader.findLibrary(libraryName);      //这个地方还不知道什么意思            if (filename == null &&                    (loader.getClass() == PathClassLoader.class ||                     loader.getClass() == DelegateLastClassLoader.class)) {                filename = System.mapLibraryName(libraryName);            }            if (filename == null) {                throw new UnsatisfiedLinkError(loader + " couldn't find "" +                                               System.mapLibraryName(libraryName) + """);            }            String error = nativeLoad(filename, loader);            if (error != null) {                throw new UnsatisfiedLinkError(error);            }            return;        }        getLibPaths();        String filename = System.mapLibraryName(libraryName);        String error = nativeLoad(filename, loader, callerClass);        if (error != null) {            throw new UnsatisfiedLinkError(error);        }    }

     @Override        public String findLibrary(String name) {            return pathList.findLibrary(name);        }

public String findLibrary(String libraryName) {  String fileName = System.mapLibraryName(libraryName);  for (NativeLibraryElement element : nativeLibraryPathElements) {      String path = element.findNativeLibrary(fileName);      if (path != null) {          return path;      }  }  return null;}

//获得nativelibrarythis.nativeLibraryPathElements = makePathElements(getAllNativeLibraryDirectories());private List<File> getAllNativeLibraryDirectories() {   List<File> allNativeLibraryDirectories = new ArrayList<>(nativeLibraryDirectories);    allNativeLibraryDirectories.addAll(systemNativeLibraryDirectories);   return allNativeLibraryDirectories;}//可以知道通过 systemNativeLibraryDirectoriesthis.systemNativeLibraryDirectories =splitPaths(System.getProperty("java.library.path"), true);

  public static String getProperty(String key) {      checkKey(key);      SecurityManager sm = getSecurityManager();      if (sm != null) {          sm.checkPropertyAccess(key);      }      //相当于从props.getProperty()里面拿到的值      return props.getProperty(key);  }

props = initProperties();

private static Properties initProperties() {    Properties p = new PropertiesWithNonOverrideableDefaults(unchangeableProps);    setDefaultChangeableProperties(p);    return p;}

  private static native String[] specialProperties();

static jobjectArray System_specialProperties(JNIEnv* env, jclass ignored) {****代码省略    //从"LD_LIBRARY_PATH获取    const char* library_path = getenv("LD_LIBRARY_PATH");#if defined(__ANDROID__)    //如果为空就调用android_get_LD_LIBRARY_PATH    if (library_path == NULL) {        android_get_LD_LIBRARY_PATH(path, sizeof(path));        library_path = path;    }#endif    if (library_path == NULL) {        library_path = "";    }    char* java_path = malloc(strlen("java.library.path=") + strlen(library_path) + 1);    strcpy(java_path, "java.library.path=");    strcat(java_path, library_path);    jstring java_path_str = (*env)->NewStringUTF(env, java_path);    free((void*)java_path);    if ((*env)->ExceptionCheck(env)) {        return NULL;    }    (*env)->SetObjectArrayElement(env, result, 3, java_path_str);    if ((*env)->ExceptionCheck(env)) {        return NULL;    }    return result;}

void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {//从get_default_library_paths()来的  const auto& default_ld_paths = g_default_namespace.get_default_library_paths();  size_t required_size = 0;  for (const auto& path : default_ld_paths) {    required_size += path.size() + 1;  }  if (buffer_size < required_size) {    async_safe_fatal("android_get_LD_LIBRARY_PATH failed, buffer too small: "                     "buffer len %zu, required len %zu", buffer_size, required_size);  }  char* end = buffer;  //从这个地方给buff赋值  for (size_t i = 0; i < default_ld_paths.size(); ++i) {    if (i > 0) *end++ = ':';    end = stpcpy(end, default_ld_paths[i].c_str());  }}

//AddressSanitizer (ASan) 是一种基于编译器的快速检测工具，用于检测原生代码中的内存错误。  auto default_ld_paths = is_asan ? kAsanDefaultLdPaths : kDefaultLdPaths;static const char* const kDefaultLdPaths[] = {kSystemLibDir,kOdmLibDir,kVendorLibDir,nullptr};static const char* const kAsanDefaultLdPaths[] = {  kAsanSystemLibDir,  kSystemLibDir,  kAsanOdmLibDir,  kOdmLibDir,  kAsanVendorLibDir,  kVendorLibDir,  nullptr};```#if defined(__LP64__)static const char* const kSystemLibDir        = "/system/lib64";static const char* const kOdmLibDir           = "/odm/lib64";static const char* const kVendorLibDir        = "/vendor/lib64";static const char* const kAsanSystemLibDir    = "/data/asan/system/lib64";static const char* const kAsanOdmLibDir       = "/data/asan/odm/lib64";static const char* const kAsanVendorLibDir    = "/data/asan/vendor/lib64";#elsestatic const char* const kSystemLibDir        = "/system/lib";static const char* const kOdmLibDir           = "/odm/lib";static const char* const kVendorLibDir        = "/vendor/lib";static const char* const kAsanSystemLibDir    = "/data/asan/system/lib";static const char* const kAsanOdmLibDir       = "/data/asan/odm/lib";static const char* const kAsanVendorLibDir    = "/data/asan/vendor/lib";#endif```

  private List<File> getAllNativeLibraryDirectories() {      List<File> allNativeLibraryDirectories = new ArrayList<>(nativeLibraryDirectories);      allNativeLibraryDirectories.addAll(systemNativeLibraryDirectories);      return allNativeLibraryDirectories;  }

JNIEXPORT jstring JVM_NativeLoad(JNIEnv* env,                                 jstring javaFilename,                                 jobject javaLoader,                                 jclass caller) {  ScopedUtfChars filename(env, javaFilename);  if (filename.c_str() == nullptr) {    return nullptr;  }  std::string error_msg;  {    art::JavaVMExt* vm = art::Runtime::Current()->GetJavaVM();  //从java虚拟机去加载so    bool success = vm->LoadNativeLibrary(env,                                         filename.c_str(),                                         javaLoader,                                         caller,                                         &error_msg);    if (success) {      return nullptr;    }  }  // Don't let a pending exception from JNI_OnLoad cause a CheckJNI issue with NewStringUTF.  env->ExceptionClear();  return env->NewStringUTF(error_msg.c_str());}

static void* dlopen_ext(const char* filename,                        int flags,                        const android_dlextinfo* extinfo,                        const void* caller_addr) {  ScopedPthreadMutexLocker locker(&g_dl_mutex);  g_linker_logger.ResetState();  void* result = do_dlopen(filename, flags, extinfo, caller_addr);  if (result == nullptr) {    __bionic_format_dlerror("dlopen failed", linker_get_error_buffer());    return nullptr;  }  return result;}

void* do_dlopen(const char* name, int flags,                const android_dlextinfo* extinfo,                const void* caller_addr) {  std::string trace_prefix = std::string("dlopen: ") + (name == nullptr ? "(nullptr)" : name);  ScopedTrace trace(trace_prefix.c_str());  ScopedTrace loading_trace((trace_prefix + " - loading and linking").c_str());  soinfo* const caller = find_containing_library(caller_addr);  android_namespace_t* ns = get_caller_namespace(caller);  LD_LOG(kLogDlopen,         "dlopen(name="%s", flags=0x%x, extinfo=%s, caller="%s", caller_ns=%s@%p, targetSdkVersion=%i) ...",         name,         flags,         android_dlextinfo_to_string(extinfo).c_str(),         caller == nullptr ? "(null)" : caller->get_realpath(),         ns == nullptr ? "(null)" : ns->get_name(),         ns,         get_application_target_sdk_version());  auto purge_guard = android::base::make_scope_guard([&]() { purge_unused_memory(); });  auto failure_guard = android::base::make_scope_guard(      [&]() { LD_LOG(kLogDlopen, "... dlopen failed: %s", linker_get_error_buffer()); });  if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NODELETE|RTLD_NOLOAD)) != 0) {    DL_OPEN_ERR("invalid flags to dlopen: %x", flags);    return nullptr;  }  if (extinfo != nullptr) {    if ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0) {      DL_OPEN_ERR("invalid extended flags to android_dlopen_ext: 0x%" PRIx64, extinfo->flags);      return nullptr;    }    if ((extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) == 0 &&        (extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET) != 0) {      DL_OPEN_ERR("invalid extended flag combination (ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET without "          "ANDROID_DLEXT_USE_LIBRARY_FD): 0x%" PRIx64, extinfo->flags);      return nullptr;    }    if ((extinfo->flags & ANDROID_DLEXT_USE_NAMESPACE) != 0) {      if (extinfo->library_namespace == nullptr) {        DL_OPEN_ERR("ANDROID_DLEXT_USE_NAMESPACE is set but extinfo->library_namespace is null");        return nullptr;      }      ns = extinfo->library_namespace;    }  }  // Workaround for dlopen(/system/lib/<soname>) when .so is in /apex. http://b/121248172  // The workaround works only when targetSdkVersion < Q.  std::string name_to_apex;  if (translateSystemPathToApexPath(name, &name_to_apex)) {    const char* new_name = name_to_apex.c_str();    LD_LOG(kLogDlopen, "dlopen considering translation from %s to APEX path %s",           name,           new_name);    // Some APEXs could be optionally disabled. Only translate the path    // when the old file is absent and the new file exists.    // TODO(b/124218500): Re-enable it once app compat issue is resolved    /*    if (file_exists(name)) {      LD_LOG(kLogDlopen, "dlopen %s exists, not translating", name);    } else    */    if (!file_exists(new_name)) {      LD_LOG(kLogDlopen, "dlopen %s does not exist, not translating",             new_name);    } else {      LD_LOG(kLogDlopen, "dlopen translation accepted: using %s", new_name);      name = new_name;    }  }  // End Workaround for dlopen(/system/lib/<soname>) when .so is in /apex.  std::string asan_name_holder;  const char* translated_name = name;  if (g_is_asan && translated_name != nullptr && translated_name[0] == '/') {    char original_path[PATH_MAX];    if (realpath(name, original_path) != nullptr) {      asan_name_holder = std::string(kAsanLibDirPrefix) + original_path;      if (file_exists(asan_name_holder.c_str())) {        soinfo* si = nullptr;        if (find_loaded_library_by_realpath(ns, original_path, true, &si)) {          PRINT("linker_asan dlopen NOT translating "%s" -> "%s": library already loaded", name,                asan_name_holder.c_str());        } else {          PRINT("linker_asan dlopen translating "%s" -> "%s"", name, translated_name);          translated_name = asan_name_holder.c_str();        }      }    }  }  ProtectedDataGuard guard;  soinfo* si = find_library(ns, translated_name, flags, extinfo, caller);  loading_trace.End();  if (si != nullptr) {    void* handle = si->to_handle();    LD_LOG(kLogDlopen,           "... dlopen calling constructors: realpath="%s", soname="%s", handle=%p",           si->get_realpath(), si->get_soname(), handle);    si->call_constructors();    failure_guard.Disable();    LD_LOG(kLogDlopen,           "... dlopen successful: realpath="%s", soname="%s", handle=%p",           si->get_realpath(), si->get_soname(), handle);    return handle;  }  return nullptr;}int do_dladdr(const void* addr, Dl_info* info) {  // Determine if this address can be found in any library currently mapped.  soinfo* si = find_containing_library(addr);  if (si == nullptr) {    return 0;  }  memset(info, 0, sizeof(Dl_info));  info->dli_fname = si->get_realpath();  // Address at which the shared object is loaded.  info->dli_fbase = reinterpret_cast<void*>(si->base);  // Determine if any symbol in the library contains the specified address.  ElfW(Sym)* sym = si->find_symbol_by_address(addr);  if (sym != nullptr) {    info->dli_sname = si->get_string(sym->st_name);    info->dli_saddr = reinterpret_cast<void*>(si->resolve_symbol_address(sym));  }  return 1;}static soinfo* soinfo_from_handle(void* handle) {  if ((reinterpret_cast<uintptr_t>(handle) & 1) != 0) {    auto it = g_soinfo_handles_map.find(reinterpret_cast<uintptr_t>(handle));    if (it == g_soinfo_handles_map.end()) {      return nullptr;    } else {      return it->second;    }  }  return static_cast<soinfo*>(handle);}

void soinfo::call_constructors() {  if (constructors_called || g_is_ldd) {    return;  }  if (!is_main_executable() && preinit_array_ != nullptr) {    // The GNU dynamic linker silently ignores these, but we warn the developer.    PRINT(""%s": ignoring DT_PREINIT_ARRAY in shared library!", get_realpath());  }  get_children().for_each([] (soinfo* si) {    si->call_constructors();  });  if (!is_linker()) {    bionic_trace_begin((std::string("calling constructors: ") + get_realpath()).c_str());  }  // DT_INIT should be called before DT_INIT_ARRAY if both are present.  call_function("DT_INIT", init_func_, get_realpath());  call_array("DT_INIT_ARRAY", init_array_, init_array_count_, false, get_realpath());  if (!is_linker()) {    bionic_trace_end();  }}

static void call_array(const char* array_name __unused,                       F* functions,                       size_t count,                       bool reverse,                       const char* realpath) {  if (functions == nullptr) {    return;  }  TRACE("[ Calling %s (size %zd) @ %p for '%s' ]", array_name, count, functions, realpath);  int begin = reverse ? (count - 1) : 0;  int end = reverse ? -1 : count;  int step = reverse ? -1 : 1;  for (int i = begin; i != end; i += step) {    TRACE("[ %s[%d] == %p ]", array_name, i, functions[i]);    call_function("function", functions[i], realpath);  }  TRACE("[ Done calling %s for '%s' ]", array_name, realpath);}