Revert "Revert "base: add support for tagged fd closure to unique_fd."" (22666fea) · Commits · e / os / android_system_core

base/Android.bp

+1 −0

Original line number	Diff line number	Diff line
		@@ -135,6 +135,7 @@ cc_test {
		"strings_test.cpp",
		"test_main.cpp",
		"test_utils_test.cpp",
		"unique_fd_test.cpp",
		],
		target: {
		android: {

base/include/android-base/unique_fd.h

+74 −14

Original line number	Diff line number	Diff line
		@@ -42,10 +42,35 @@
		//
		// unique_fd is also known as ScopedFd/ScopedFD/scoped_fd; mentioned here to help
		// you find this class if you're searching for one of those names.

		#if defined(__BIONIC__)
		#include <android/fdsan.h>
		#endif

		namespace android {
		namespace base {

		struct DefaultCloser {
		#if defined(__BIONIC__)
		static void Tag(int fd, void* old_addr, void* new_addr) {
		if (android_fdsan_exchange_owner_tag) {
		uint64_t old_tag = android_fdsan_create_owner_tag(ANDROID_FDSAN_OWNER_TYPE_UNIQUE_FD,
		reinterpret_cast<uint64_t>(old_addr));
		uint64_t new_tag = android_fdsan_create_owner_tag(ANDROID_FDSAN_OWNER_TYPE_UNIQUE_FD,
		reinterpret_cast<uint64_t>(new_addr));
		android_fdsan_exchange_owner_tag(fd, old_tag, new_tag);
		}
		}
		static void Close(int fd, void* addr) {
		if (android_fdsan_close_with_tag) {
		uint64_t tag = android_fdsan_create_owner_tag(ANDROID_FDSAN_OWNER_TYPE_UNIQUE_FD,
		reinterpret_cast<uint64_t>(addr));
		android_fdsan_close_with_tag(fd, tag);
		} else {
		close(fd);
		}
		}
		#else
		static void Close(int fd) {
		// Even if close(2) fails with EINTR, the fd will have been closed.
		// Using TEMP_FAILURE_RETRY will either lead to EBADF or closing someone
		@@ -53,40 +78,75 @@ struct DefaultCloser {
		// http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
		::close(fd);
		}
		#endif
		};

		template <typename Closer>
		class unique_fd_impl final {
		public:
		unique_fd_impl() : value_(-1) {}
		unique_fd_impl() {}

		explicit unique_fd_impl(int value) : value_(value) {}
		explicit unique_fd_impl(int fd) { reset(fd); }
		~unique_fd_impl() { reset(); }

		unique_fd_impl(unique_fd_impl&& other) : value_(other.release()) {}
		unique_fd_impl(unique_fd_impl&& other) { reset(other.release()); }
		unique_fd_impl& operator=(unique_fd_impl&& s) {
		reset(s.release());
		int fd = s.fd_;
		s.fd_ = -1;
		reset(fd, &s);
		return *this;
		}

		void reset(int new_value = -1) {
		if (value_ != -1) {
		Closer::Close(value_);
		}
		value_ = new_value;
		}
		void reset(int new_value = -1) { reset(new_value, nullptr); }

		int get() const { return value_; }
		int get() const { return fd_; }
		operator int() const { return get(); }

		int release() __attribute__((warn_unused_result)) {
		int ret = value_;
		value_ = -1;
		tag(fd_, this, nullptr);
		int ret = fd_;
		fd_ = -1;
		return ret;
		}

		private:
		int value_;
		void reset(int new_value, void* previous_tag) {
		if (fd_ != -1) {
		close(fd_, this);
		}

		fd_ = new_value;
		if (new_value != -1) {
		tag(new_value, previous_tag, this);
		}
		}

		int fd_ = -1;

		// Template magic to use Closer::Tag if available, and do nothing if not.
		// If Closer::Tag exists, this implementation is preferred, because int is a better match.
		// If not, this implementation is SFINAEd away, and the no-op below is the only one that exists.
		template <typename T = Closer>
		static auto tag(int fd, void* old_tag, void* new_tag)
		-> decltype(T::Tag(fd, old_tag, new_tag), void()) {
		T::Tag(fd, old_tag, new_tag);
		}

		template <typename T = Closer>
		static void tag(long, void, void) {
		// No-op.
		}

		// Same as above, to select between Closer::Close(int) and Closer::Close(int, void*).
		template <typename T = Closer>
		static auto close(int fd, void* tag_value) -> decltype(T::Close(fd, tag_value), void()) {
		T::Close(fd, tag_value);
		}

		template <typename T = Closer>
		static auto close(int fd, void*) -> decltype(T::Close(fd), void()) {
		T::Close(fd);
		}

		unique_fd_impl(const unique_fd_impl&);
		void operator=(const unique_fd_impl&);

base/unique_fd_test.cpp

0 → 100644

+54 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2018 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 "android-base/unique_fd.h"

		#include <gtest/gtest.h>

		#include <errno.h>
		#include <fcntl.h>
		#include <unistd.h>

		using android::base::unique_fd;

		TEST(unique_fd, unowned_close) {
		#if defined(__BIONIC__)
		unique_fd fd(open("/dev/null", O_RDONLY));
		EXPECT_DEATH(close(fd.get()), "incorrect tag");
		#endif
		}

		TEST(unique_fd, untag_on_release) {
		unique_fd fd(open("/dev/null", O_RDONLY));
		close(fd.release());
		}

		TEST(unique_fd, move) {
		unique_fd fd(open("/dev/null", O_RDONLY));
		unique_fd fd_moved = std::move(fd);
		ASSERT_EQ(-1, fd.get());
		ASSERT_GT(fd_moved.get(), -1);
		}

		TEST(unique_fd, unowned_close_after_move) {
		#if defined(__BIONIC__)
		unique_fd fd(open("/dev/null", O_RDONLY));
		unique_fd fd_moved = std::move(fd);
		ASSERT_EQ(-1, fd.get());
		ASSERT_GT(fd_moved.get(), -1);
		EXPECT_DEATH(close(fd_moved.get()), "incorrect tag");
		#endif
		}