/*
* Copyright (C) 2017 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 "netdutils/Syscalls.h"
#include <atomic>
#include <type_traits>
#include <utility>
namespace android {
namespace netdutils {
namespace {
// Retry syscall fn as long as it returns -1 with errno == EINTR
template <typename FnT, typename... Params>
typename std::result_of<FnT(Params...)>::type syscallRetry(FnT fn, Params&&... params) {
auto rv = fn(std::forward<Params>(params)...);
while ((rv == -1) && (errno == EINTR)) {
rv = fn(std::forward<Params>(params)...);
}
return rv;
}
} // namespace
// Production implementation of Syscalls that forwards to libc syscalls.
class RealSyscalls final : public Syscalls {
public:
~RealSyscalls() override = default;
StatusOr<UniqueFd> open(const std::string& pathname, int flags, mode_t mode) const override {
UniqueFd fd(::open(pathname.c_str(), flags, mode));
if (!isWellFormed(fd)) {
return statusFromErrno(errno, "open(\"" + pathname + "\"...) failed");
}
return fd;
}
StatusOr<UniqueFd> socket(int domain, int type, int protocol) const override {
UniqueFd sock(::socket(domain, type, protocol));
if (!isWellFormed(sock)) {
return statusFromErrno(errno, "socket() failed");
}
return sock;
}
Status getsockname(Fd sock, sockaddr* addr, socklen_t* addrlen) const override {
auto rv = ::getsockname(sock.get(), addr, addrlen);
if (rv == -1) {
return statusFromErrno(errno, "getsockname() failed");
}
return status::ok;
}
Status getsockopt(Fd sock, int level, int optname, void* optval,
socklen_t* optlen) const override {
auto rv = ::getsockopt(sock.get(), level, optname, optval, optlen);
if (rv == -1) {
return statusFromErrno(errno, "getsockopt() failed");
}
return status::ok;
}
Status setsockopt(Fd sock, int level, int optname, const void* optval,
socklen_t optlen) const override {
auto rv = ::setsockopt(sock.get(), level, optname, optval, optlen);
if (rv == -1) {
return statusFromErrno(errno, "setsockopt() failed");
}
return status::ok;
}
Status bind(Fd sock, const sockaddr* addr, socklen_t addrlen) const override {
auto rv = ::bind(sock.get(), addr, addrlen);
if (rv == -1) {
return statusFromErrno(errno, "bind() failed");
}
return status::ok;
}
Status connect(Fd sock, const sockaddr* addr, socklen_t addrlen) const override {
auto rv = syscallRetry(::connect, sock.get(), addr, addrlen);
if (rv == -1) {
return statusFromErrno(errno, "connect() failed");
}
return status::ok;
}
StatusOr<ifreq> ioctl(Fd sock, unsigned long request, ifreq* ifr) const override {
auto rv = ::ioctl(sock.get(), request, ifr);
if (rv == -1) {
return statusFromErrno(errno, "ioctl() failed");
}
return *ifr;
}
StatusOr<UniqueFd> eventfd(unsigned int initval, int flags) const override {
UniqueFd fd(::eventfd(initval, flags));
if (!isWellFormed(fd)) {
return statusFromErrno(errno, "eventfd() failed");
}
return fd;
}
StatusOr<int> ppoll(pollfd* fds, nfds_t nfds, double timeout) const override {
timespec ts = {};
ts.tv_sec = timeout;
ts.tv_nsec = (timeout - ts.tv_sec) * 1e9;
auto rv = syscallRetry(::ppoll, fds, nfds, &ts, nullptr);
if (rv == -1) {
return statusFromErrno(errno, "ppoll() failed");
}
return rv;
}
StatusOr<size_t> writev(Fd fd, const std::vector<iovec>& iov) const override {
auto rv = syscallRetry(::writev, fd.get(), iov.data(), iov.size());
if (rv == -1) {
return statusFromErrno(errno, "writev() failed");
}
return rv;
}
StatusOr<size_t> write(Fd fd, const Slice buf) const override {
auto rv = syscallRetry(::write, fd.get(), buf.base(), buf.size());
if (rv == -1) {
return statusFromErrno(errno, "write() failed");
}
return static_cast<size_t>(rv);
}
StatusOr<Slice> read(Fd fd, const Slice buf) const override {
auto rv = syscallRetry(::read, fd.get(), buf.base(), buf.size());
if (rv == -1) {
return statusFromErrno(errno, "read() failed");
}
return Slice(buf.base(), rv);
}
StatusOr<size_t> sendto(Fd sock, const Slice buf, int flags, const sockaddr* dst,
socklen_t dstlen) const override {
auto rv = syscallRetry(::sendto, sock.get(), buf.base(), buf.size(), flags, dst, dstlen);
if (rv == -1) {
return statusFromErrno(errno, "sendto() failed");
}
return static_cast<size_t>(rv);
}
StatusOr<Slice> recvfrom(Fd sock, const Slice dst, int flags, sockaddr* src,
socklen_t* srclen) const override {
auto rv = syscallRetry(::recvfrom, sock.get(), dst.base(), dst.size(), flags, src, srclen);
if (rv == -1) {
return statusFromErrno(errno, "recvfrom() failed");
}
if (rv == 0) {
return status::eof;
}
return take(dst, rv);
}
Status shutdown(Fd fd, int how) const override {
auto rv = ::shutdown(fd.get(), how);
if (rv == -1) {
return statusFromErrno(errno, "shutdown() failed");
}
return status::ok;
}
Status close(Fd fd) const override {
auto rv = ::close(fd.get());
if (rv == -1) {
return statusFromErrno(errno, "close() failed");
}
return status::ok;
}
StatusOr<UniqueFile> fopen(const std::string& path, const std::string& mode) const override {
UniqueFile file(::fopen(path.c_str(), mode.c_str()));
if (file == nullptr) {
return statusFromErrno(errno, "fopen(\"" + path + "\", \"" + mode + "\") failed");
}
return file;
}
StatusOr<pid_t> fork() const override {
pid_t rv = ::fork();
if (rv == -1) {
return statusFromErrno(errno, "fork() failed");
}
return rv;
}
StatusOr<int> vfprintf(FILE* file, const char* format, va_list ap) const override {
auto rv = ::vfprintf(file, format, ap);
if (rv == -1) {
return statusFromErrno(errno, "vfprintf() failed");
}
return rv;
}
StatusOr<int> vfscanf(FILE* file, const char* format, va_list ap) const override {
auto rv = ::vfscanf(file, format, ap);
if (rv == -1) {
return statusFromErrno(errno, "vfscanf() failed");
}
return rv;
}
Status fclose(FILE* file) const override {
auto rv = ::fclose(file);
if (rv == -1) {
return statusFromErrno(errno, "fclose() failed");
}
return status::ok;
}
};
SyscallsHolder::~SyscallsHolder() {
delete &get();
}
Syscalls& SyscallsHolder::get() {
while (true) {
// memory_order_relaxed gives the compiler and hardware more
// freedom. If we get a stale value (this should only happen
// early in the execution of a program) the exchange code below
// will loop until we get the most current value.
auto* syscalls = mSyscalls.load(std::memory_order_relaxed);
// Common case returns existing syscalls
if (syscalls) {
return *syscalls;
}
// This code will execute on first get()
std::unique_ptr<Syscalls> tmp(new RealSyscalls());
Syscalls* expected = nullptr;
bool success = mSyscalls.compare_exchange_strong(expected, tmp.get());
if (success) {
// Ownership was transferred to mSyscalls already, must release()
return *tmp.release();
}
}
}
Syscalls& SyscallsHolder::swap(Syscalls& syscalls) {
return *mSyscalls.exchange(&syscalls);
}
SyscallsHolder sSyscalls;
} // namespace netdutils
} // namespace android