91 lines
3.2 KiB
C++
91 lines
3.2 KiB
C++
/*
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* Copyright (C) 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <dlfcn.h>
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#include <cstdlib>
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#include <iostream>
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#include <string>
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#include <android/dlext.h>
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extern "C" {
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enum {
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ANDROID_NAMESPACE_TYPE_REGULAR = 0,
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ANDROID_NAMESPACE_TYPE_ISOLATED = 1,
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ANDROID_NAMESPACE_TYPE_SHARED = 2,
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};
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extern struct android_namespace_t* android_create_namespace(
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const char* name, const char* ld_library_path, const char* default_library_path,
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uint64_t type, const char* permitted_when_isolated_path,
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struct android_namespace_t* parent);
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} // extern "C"
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static void* load(const std::string& libname);
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int main(int argc, char* argv[]) {
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if (argc < 2) {
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std::cout << "Usage:\n";
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std::cout << " " << argv[0] << " LIBNAME [ARGS...]\n";
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return EXIT_FAILURE;
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}
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const char* libname = argv[1];
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void* handle = load(libname);
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if (handle == nullptr) {
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std::cerr << "Failed to load " << libname << ": " << dlerror() << "\n";
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return EXIT_FAILURE;
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}
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int (*entry)(int argc, char* argv[]) = nullptr;
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entry = reinterpret_cast<decltype(entry)>(dlsym(handle, "android_native_main"));
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if (entry == nullptr) {
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std::cerr << "Failed to find entrypoint `android_native_main`: " << dlerror() << "\n";
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return EXIT_FAILURE;
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}
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return entry(argc - 1, argv + 1);
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}
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// Create a new linker namespace whose search path is set to the directory of the library. Then
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// load it from there. Returns the handle to the loaded library if successful. Returns nullptr
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// if failed.
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void* load(const std::string& libname) {
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// Parent as nullptr means the default namespace
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android_namespace_t* parent = nullptr;
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// The search paths of the new namespace are inherited from the parent namespace.
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const uint64_t type = ANDROID_NAMESPACE_TYPE_SHARED;
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// The directory of the library is appended to the search paths
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const std::string libdir = libname.substr(0, libname.find_last_of("/"));
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const char* ld_library_path = libdir.c_str();
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const char* default_library_path = libdir.c_str();
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android_namespace_t* new_ns = nullptr;
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new_ns = android_create_namespace("microdroid_app", ld_library_path, default_library_path, type,
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/* permitted_when_isolated_path */ nullptr, parent);
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if (new_ns == nullptr) {
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std::cerr << "Failed to create linker namespace: " << dlerror() << "\n";
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return nullptr;
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}
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const android_dlextinfo info = {
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.flags = ANDROID_DLEXT_USE_NAMESPACE,
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.library_namespace = new_ns,
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};
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return android_dlopen_ext(libname.c_str(), RTLD_NOW, &info);
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}
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