util.cpp revision cbe70cb0a8cb0171f3802273050e851a47b090ed 
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 "debuggerd/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
26ssize_t send_fd(int sockfd, const void* data, size_t len, android::base::unique_fd fd) {
27  char cmsg_buf[CMSG_SPACE(sizeof(int))];
28
29  iovec iov = { .iov_base = const_cast<void*>(data), .iov_len = len };
30  msghdr msg = {
31    .msg_iov = &iov, .msg_iovlen = 1, .msg_control = cmsg_buf, .msg_controllen = sizeof(cmsg_buf),
32  };
33  auto cmsg = CMSG_FIRSTHDR(&msg);
34  cmsg->cmsg_level = SOL_SOCKET;
35  cmsg->cmsg_type = SCM_RIGHTS;
36  cmsg->cmsg_len = CMSG_LEN(sizeof(int));
37  *reinterpret_cast<int*>(CMSG_DATA(cmsg)) = fd.get();
38
39  return TEMP_FAILURE_RETRY(sendmsg(sockfd, &msg, 0));
40}
41
42ssize_t recv_fd(int sockfd, void* _Nonnull data, size_t len,
43                android::base::unique_fd* _Nullable out_fd) {
44  char cmsg_buf[CMSG_SPACE(sizeof(int))];
45
46  iovec iov = { .iov_base = const_cast<void*>(data), .iov_len = len };
47  msghdr msg = {
48    .msg_iov = &iov,
49    .msg_iovlen = 1,
50    .msg_control = cmsg_buf,
51    .msg_controllen = sizeof(cmsg_buf),
52    .msg_flags = 0,
53  };
54  auto cmsg = CMSG_FIRSTHDR(&msg);
55  cmsg->cmsg_level = SOL_SOCKET;
56  cmsg->cmsg_type = SCM_RIGHTS;
57  cmsg->cmsg_len = CMSG_LEN(sizeof(int));
58
59  ssize_t result = TEMP_FAILURE_RETRY(recvmsg(sockfd, &msg, 0));
60  if (result == -1) {
61    return -1;
62  }
63
64  android::base::unique_fd fd;
65  bool received_fd = msg.msg_controllen == sizeof(cmsg_buf);
66  if (received_fd) {
67    fd.reset(*reinterpret_cast<int*>(CMSG_DATA(cmsg)));
68  }
69
70  if ((msg.msg_flags & MSG_TRUNC) != 0) {
71    errno = EFBIG;
72    return -1;
73  } else if ((msg.msg_flags & MSG_CTRUNC) != 0) {
74    errno = ERANGE;
75    return -1;
76  }
77
78  if (out_fd) {
79    *out_fd = std::move(fd);
80  } else if (received_fd) {
81    errno = ERANGE;
82    return -1;
83  }
84
85  return result;
86}
87
88bool Pipe(android::base::unique_fd* read, android::base::unique_fd* write) {
89  int pipefds[2];
90  if (pipe(pipefds) != 0) {
91    return false;
92  }
93  read->reset(pipefds[0]);
94  write->reset(pipefds[1]);
95  return true;
96}
97