1 /*
2 * Copyright (C) 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 <algorithm>
18 #include <cerrno>
19 #include <cstdint>
20 #include <cstring>
21
22 #include "android-base/logging.h"
23
24 #include "wifilogd/local_utils.h"
25 #include "wifilogd/os.h"
26
27 namespace android {
28 namespace wifilogd {
29
30 using local_utils::GetMaxVal;
31
32 namespace {
33 constexpr auto kMaxNanoSeconds = 1000 * 1000 * 1000 - 1;
34 }
35
36 constexpr int Os::kInvalidFd;
37
Os()38 Os::Os() : raw_os_(new RawOs()) {}
Os(std::unique_ptr<RawOs> raw_os)39 Os::Os(std::unique_ptr<RawOs> raw_os) : raw_os_(std::move(raw_os)) {}
~Os()40 Os::~Os() {}
41
GetControlSocket(const std::string & socket_name)42 std::tuple<int, Os::Errno> Os::GetControlSocket(
43 const std::string& socket_name) {
44 int sock_fd = raw_os_->GetControlSocket(socket_name.c_str());
45 if (sock_fd < 0) {
46 return {kInvalidFd, errno};
47 } else {
48 return {sock_fd, 0};
49 }
50 }
51
GetTimestamp(clockid_t clock_id) const52 Os::Timestamp Os::GetTimestamp(clockid_t clock_id) const {
53 struct timespec now_timespec;
54 int failed = raw_os_->ClockGettime(clock_id, &now_timespec);
55 if (failed) {
56 LOG(FATAL) << "Unexpected error: " << std::strerror(errno);
57 }
58 CHECK(now_timespec.tv_nsec <= kMaxNanoSeconds);
59
60 Timestamp now_timestamp;
61 now_timestamp.secs = SAFELY_CLAMP(
62 now_timespec.tv_sec, uint32_t, 0,
63 // The upper-bound comes from the source-type on 32-bit platforms,
64 // and the dest-type on 64-bit platforms. Using min(), we can figure out
65 // which type to use for the upper bound, without resorting to macros.
66 std::min(static_cast<uintmax_t>(GetMaxVal(now_timestamp.secs)),
67 static_cast<uintmax_t>(GetMaxVal(now_timespec.tv_sec))));
68 now_timestamp.nsecs =
69 SAFELY_CLAMP(now_timespec.tv_nsec, uint32_t, 0, kMaxNanoSeconds);
70 return now_timestamp;
71 }
72
Nanosleep(uint32_t sleep_time_nsec)73 void Os::Nanosleep(uint32_t sleep_time_nsec) {
74 struct timespec sleep_timespec = {
75 0, // tv_sec
76 SAFELY_CLAMP(sleep_time_nsec, decltype(timespec::tv_nsec), 0, kMaxNanos)};
77
78 int failed = 0;
79 do {
80 struct timespec remaining_timespec;
81 failed = raw_os_->Nanosleep(&sleep_timespec, &remaining_timespec);
82 sleep_timespec = remaining_timespec;
83 } while (failed && errno == EINTR && sleep_timespec.tv_nsec > 0);
84
85 if (failed && errno != EINTR) {
86 // The only other documented errors for the underlying nanosleep() call are
87 // EFAULT and EINVAL. But we always pass valid pointers, and the values in
88 // |sleep_timespec| are always valid.
89 LOG(FATAL) << "Unexpected error: " << std::strerror(errno);
90 }
91 }
92
ReceiveDatagram(int fd,void * buf,size_t buflen)93 std::tuple<size_t, Os::Errno> Os::ReceiveDatagram(int fd, void* buf,
94 size_t buflen) {
95 // recv() takes a size_t, but returns an ssize_t. That means that the largest
96 // successful read that recv() can report is the maximal ssize_t. Passing a
97 // larger |buflen| risks mistakenly reporting a truncated read.
98 CHECK(buflen <= GetMaxVal<ssize_t>());
99
100 const ssize_t res = raw_os_->Recv(fd, buf, buflen, MSG_TRUNC);
101 if (res < 0) {
102 return {0, errno};
103 }
104
105 // Due to the MSG_TRUNC flag, |res| may reasonably be larger than
106 // |buflen|. In such cases, |res| indicates the full size of the datagram,
107 // before being truncated to fit our buffer. Hence, we omit the
108 // buffer-overflow CHECK that exists in Write().
109 return {res, 0};
110 }
111
Write(int fd,const void * buf,size_t buflen)112 std::tuple<size_t, Os::Errno> Os::Write(int fd, const void* buf,
113 size_t buflen) {
114 // write() takes a size_t, but returns an ssize_t. That means that the
115 // largest successful write that write() can report is the maximal ssize_t.
116 // Passing a larger |buflen| risks mistakenly reporting a truncated write.
117 CHECK(buflen <= GetMaxVal<ssize_t>());
118
119 const ssize_t res = raw_os_->Write(fd, buf, buflen);
120 if (res < 0) {
121 return {0, errno};
122 }
123
124 CHECK(res <=
125 SAFELY_CLAMP(buflen, ssize_t, 0,
126 GetMaxVal<ssize_t>())); // Abort on buffer overflow.
127
128 // Note that |res| may be less than buflen. However, a) a short write is
129 // not an error, and b) |errno| may be stale, as |errno| is only guaranteed to
130 // be set if an error occurred. Hence, we return Errno of 0 unconditionally.
131 // See http://yarchive.net/comp/linux/write_error_return.html
132 return {res, 0};
133 }
134
135 } // namespace wifilogd
136 } // namespace android
137