You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
107 lines
4.1 KiB
107 lines
4.1 KiB
/*
|
|
* Copyright (C) 2019 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.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <sys/stat.h>
|
|
#include <sys/types.h>
|
|
|
|
#include <type_traits>
|
|
#include <vector>
|
|
|
|
#include <android-base/collections.h>
|
|
#include <android-base/macros.h>
|
|
#include <android-base/unique_fd.h>
|
|
|
|
namespace android {
|
|
namespace base {
|
|
|
|
#if !defined(_WIN32)
|
|
|
|
// Helpers for sending and receiving file descriptors across Unix domain sockets.
|
|
//
|
|
// The cmsg(3) API is very hard to get right, with multiple landmines that can
|
|
// lead to death. Almost all of the uses of cmsg in Android make at least one of
|
|
// the following mistakes:
|
|
//
|
|
// - not aligning the cmsg buffer
|
|
// - leaking fds if more fds are received than expected
|
|
// - blindly dereferencing CMSG_DATA without checking the header
|
|
// - using CMSG_SPACE instead of CMSG_LEN for .cmsg_len
|
|
// - using CMSG_LEN instead of CMSG_SPACE for .msg_controllen
|
|
// - using a length specified in number of fds instead of bytes
|
|
//
|
|
// These functions wrap the hard-to-use cmsg API with an easier to use abstraction.
|
|
|
|
// Send file descriptors across a Unix domain socket.
|
|
//
|
|
// Note that the write can return short if the socket type is SOCK_STREAM. When
|
|
// this happens, file descriptors are still sent to the other end, but with
|
|
// truncated data. For this reason, using SOCK_SEQPACKET or SOCK_DGRAM is recommended.
|
|
ssize_t SendFileDescriptorVector(borrowed_fd sock, const void* data, size_t len,
|
|
const std::vector<int>& fds);
|
|
|
|
// Receive file descriptors from a Unix domain socket.
|
|
//
|
|
// If more FDs (or bytes, for datagram sockets) are received than expected,
|
|
// -1 is returned with errno set to EMSGSIZE, and all received FDs are thrown away.
|
|
ssize_t ReceiveFileDescriptorVector(borrowed_fd sock, void* data, size_t len, size_t max_fds,
|
|
std::vector<android::base::unique_fd>* fds);
|
|
|
|
// Helper for SendFileDescriptorVector that constructs a std::vector for you, e.g.:
|
|
// SendFileDescriptors(sock, "foo", 3, std::move(fd1), std::move(fd2))
|
|
template <typename... Args>
|
|
ssize_t SendFileDescriptors(borrowed_fd sock, const void* data, size_t len, Args&&... sent_fds) {
|
|
// Do not allow implicit conversion to int: people might try to do something along the lines of:
|
|
// SendFileDescriptors(..., std::move(a_unique_fd))
|
|
// and be surprised when the unique_fd isn't closed afterwards.
|
|
AssertType<int>(std::forward<Args>(sent_fds)...);
|
|
std::vector<int> fds;
|
|
Append(fds, std::forward<Args>(sent_fds)...);
|
|
return SendFileDescriptorVector(sock, data, len, fds);
|
|
}
|
|
|
|
// Helper for ReceiveFileDescriptorVector that receives an exact number of file descriptors.
|
|
// If more file descriptors are received than requested, -1 is returned with errno set to EMSGSIZE.
|
|
// If fewer file descriptors are received than requested, -1 is returned with errno set to ENOMSG.
|
|
// In both cases, all arguments are cleared and any received FDs are thrown away.
|
|
template <typename... Args>
|
|
ssize_t ReceiveFileDescriptors(borrowed_fd sock, void* data, size_t len, Args&&... received_fds) {
|
|
std::vector<unique_fd*> fds;
|
|
Append(fds, std::forward<Args>(received_fds)...);
|
|
|
|
std::vector<unique_fd> result;
|
|
ssize_t rc = ReceiveFileDescriptorVector(sock, data, len, fds.size(), &result);
|
|
if (rc == -1 || result.size() != fds.size()) {
|
|
int err = rc == -1 ? errno : ENOMSG;
|
|
for (unique_fd* fd : fds) {
|
|
fd->reset();
|
|
}
|
|
errno = err;
|
|
return -1;
|
|
}
|
|
|
|
for (size_t i = 0; i < fds.size(); ++i) {
|
|
*fds[i] = std::move(result[i]);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
#endif
|
|
|
|
} // namespace base
|
|
} // namespace android
|