| /* |
| * Copyright (C) 2019 The Android Open Source Project |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
| * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| #include <inttypes.h> |
| #include <stdint.h> |
| |
| #include <array> |
| #include <mutex> |
| #include <vector> |
| |
| #include <android/fdsan.h> |
| #include <bionic/fdtrack.h> |
| |
| #include <android-base/no_destructor.h> |
| #include <android-base/thread_annotations.h> |
| #include <async_safe/log.h> |
| #include <bionic/reserved_signals.h> |
| #include <unwindstack/LocalUnwinder.h> |
| |
| struct FdEntry { |
| std::mutex mutex; |
| std::vector<unwindstack::LocalFrameData> backtrace GUARDED_BY(mutex); |
| }; |
| |
| extern "C" void fdtrack_dump(); |
| |
| using fdtrack_callback_t = bool (*)(int fd, const char* const* function_names, |
| const uint64_t* function_offsets, size_t count, void* arg); |
| extern "C" void fdtrack_iterate(fdtrack_callback_t callback, void* arg); |
| |
| static void fd_hook(android_fdtrack_event* event); |
| |
| // Backtraces for the first 4k file descriptors ought to be enough to diagnose an fd leak. |
| static constexpr size_t kFdTableSize = 4096; |
| static constexpr size_t kStackDepth = 10; |
| |
| static bool installed = false; |
| static std::array<FdEntry, kFdTableSize> stack_traces [[clang::no_destroy]]; |
| static unwindstack::LocalUnwinder& Unwinder() { |
| static android::base::NoDestructor<unwindstack::LocalUnwinder> unwinder; |
| return *unwinder.get(); |
| } |
| |
| __attribute__((constructor)) static void ctor() { |
| for (auto& entry : stack_traces) { |
| entry.backtrace.reserve(kStackDepth); |
| } |
| |
| signal(BIONIC_SIGNAL_FDTRACK, [](int) { fdtrack_dump(); }); |
| if (Unwinder().Init()) { |
| android_fdtrack_hook_t expected = nullptr; |
| installed = android_fdtrack_compare_exchange_hook(&expected, &fd_hook); |
| } |
| } |
| |
| __attribute__((destructor)) static void dtor() { |
| if (installed) { |
| android_fdtrack_hook_t expected = &fd_hook; |
| android_fdtrack_compare_exchange_hook(&expected, nullptr); |
| } |
| } |
| |
| FdEntry* GetFdEntry(int fd) { |
| if (fd >= 0 && fd < static_cast<int>(kFdTableSize)) { |
| return &stack_traces[fd]; |
| } |
| return nullptr; |
| } |
| |
| static void fd_hook(android_fdtrack_event* event) { |
| if (event->type == ANDROID_FDTRACK_EVENT_TYPE_CREATE) { |
| if (FdEntry* entry = GetFdEntry(event->fd); entry) { |
| std::lock_guard<std::mutex> lock(entry->mutex); |
| entry->backtrace.clear(); |
| Unwinder().Unwind(&entry->backtrace, kStackDepth); |
| } |
| } else if (event->type == ANDROID_FDTRACK_EVENT_TYPE_CLOSE) { |
| if (FdEntry* entry = GetFdEntry(event->fd); entry) { |
| std::lock_guard<std::mutex> lock(entry->mutex); |
| entry->backtrace.clear(); |
| } |
| } |
| } |
| |
| void fdtrack_iterate(fdtrack_callback_t callback, void* arg) { |
| bool prev = android_fdtrack_set_enabled(false); |
| |
| for (int fd = 0; fd < static_cast<int>(stack_traces.size()); ++fd) { |
| const char* function_names[kStackDepth]; |
| uint64_t function_offsets[kStackDepth]; |
| FdEntry* entry = GetFdEntry(fd); |
| if (!entry) { |
| continue; |
| } |
| |
| if (!entry->mutex.try_lock()) { |
| async_safe_format_log(ANDROID_LOG_WARN, "fdtrack", "fd %d locked, skipping", fd); |
| continue; |
| } |
| |
| if (entry->backtrace.empty()) { |
| entry->mutex.unlock(); |
| continue; |
| } else if (entry->backtrace.size() < 2) { |
| async_safe_format_log(ANDROID_LOG_WARN, "fdtrack", "fd %d missing frames: size = %zu", fd, |
| entry->backtrace.size()); |
| |
| entry->mutex.unlock(); |
| continue; |
| } |
| |
| constexpr size_t frame_skip = 2; |
| for (size_t i = frame_skip; i < entry->backtrace.size(); ++i) { |
| size_t j = i - frame_skip; |
| function_names[j] = entry->backtrace[i].function_name.c_str(); |
| function_offsets[j] = entry->backtrace[i].function_offset; |
| } |
| |
| bool should_continue = |
| callback(fd, function_names, function_offsets, entry->backtrace.size() - frame_skip, arg); |
| |
| entry->mutex.unlock(); |
| |
| if (!should_continue) { |
| break; |
| } |
| } |
| |
| android_fdtrack_set_enabled(prev); |
| } |
| |
| void fdtrack_dump() { |
| if (!installed) { |
| async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack not installed"); |
| } else { |
| async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack dumping..."); |
| } |
| |
| fdtrack_iterate( |
| [](int fd, const char* const* function_names, const uint64_t* function_offsets, size_t count, |
| void*) { |
| uint64_t fdsan_owner = android_fdsan_get_owner_tag(fd); |
| if (fdsan_owner != 0) { |
| async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fd %d: (owner = 0x%" PRIx64 ")", fd, |
| fdsan_owner); |
| } else { |
| async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fd %d: (unowned)", fd); |
| } |
| |
| for (size_t i = 0; i < count; ++i) { |
| async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", " %zu: %s+%" PRIu64, i, |
| function_names[i], function_offsets[i]); |
| } |
| |
| return true; |
| }, |
| nullptr); |
| } |