1 /* 2 * Copyright 2016, The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "util.h" 18 19 #include <sys/socket.h> 20 21 #include <utility> 22 23 #include <android-base/unique_fd.h> 24 #include <cutils/sockets.h> 25 #include "protocol.h" 26 27 using android::base::unique_fd; 28 29 ssize_t send_fd(int sockfd, const void* data, size_t len, unique_fd fd) { 30 char cmsg_buf[CMSG_SPACE(sizeof(int))]; 31 32 iovec iov = { .iov_base = const_cast<void*>(data), .iov_len = len }; 33 msghdr msg = { 34 .msg_iov = &iov, .msg_iovlen = 1, .msg_control = cmsg_buf, .msg_controllen = sizeof(cmsg_buf), 35 }; 36 auto cmsg = CMSG_FIRSTHDR(&msg); 37 cmsg->cmsg_level = SOL_SOCKET; 38 cmsg->cmsg_type = SCM_RIGHTS; 39 cmsg->cmsg_len = CMSG_LEN(sizeof(int)); 40 *reinterpret_cast<int*>(CMSG_DATA(cmsg)) = fd.get(); 41 42 return TEMP_FAILURE_RETRY(sendmsg(sockfd, &msg, 0)); 43 } 44 45 ssize_t recv_fd(int sockfd, void* _Nonnull data, size_t len, unique_fd* _Nullable out_fd) { 46 char cmsg_buf[CMSG_SPACE(sizeof(int))]; 47 48 iovec iov = { .iov_base = const_cast<void*>(data), .iov_len = len }; 49 msghdr msg = { 50 .msg_iov = &iov, 51 .msg_iovlen = 1, 52 .msg_control = cmsg_buf, 53 .msg_controllen = sizeof(cmsg_buf), 54 .msg_flags = 0, 55 }; 56 auto cmsg = CMSG_FIRSTHDR(&msg); 57 cmsg->cmsg_level = SOL_SOCKET; 58 cmsg->cmsg_type = SCM_RIGHTS; 59 cmsg->cmsg_len = CMSG_LEN(sizeof(int)); 60 61 ssize_t result = TEMP_FAILURE_RETRY(recvmsg(sockfd, &msg, 0)); 62 if (result == -1) { 63 return -1; 64 } 65 66 unique_fd fd; 67 bool received_fd = msg.msg_controllen == sizeof(cmsg_buf); 68 if (received_fd) { 69 fd.reset(*reinterpret_cast<int*>(CMSG_DATA(cmsg))); 70 } 71 72 if ((msg.msg_flags & MSG_TRUNC) != 0) { 73 errno = EFBIG; 74 return -1; 75 } else if ((msg.msg_flags & MSG_CTRUNC) != 0) { 76 errno = ERANGE; 77 return -1; 78 } 79 80 if (out_fd) { 81 *out_fd = std::move(fd); 82 } else if (received_fd) { 83 errno = ERANGE; 84 return -1; 85 } 86 87 return result; 88 } 89 90 bool Pipe(unique_fd* read, unique_fd* write) { 91 int pipefds[2]; 92 if (pipe(pipefds) != 0) { 93 return false; 94 } 95 read->reset(pipefds[0]); 96 write->reset(pipefds[1]); 97 return true; 98 } 99
