1 /*
2 * Copyright (C) 2017 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 <signal.h>
18 #include <unistd.h>
19
20 #include <string>
21 #include <vector>
22
23 #include <android-base/logging.h>
24 #include <android-base/strings.h>
25 #include <gflags/gflags.h>
26 #include <json/json.h>
27
28 #include <common/libs/fs/shared_fd.h>
29 #include <common/libs/fs/shared_select.h>
30 #include <host/libs/config/cuttlefish_config.h>
31 #include <host/libs/config/logging.h>
32 #include "host/commands/kernel_log_monitor/kernel_log_server.h"
33 #include "host/commands/kernel_log_monitor/utils.h"
34
35 DEFINE_int32(log_pipe_fd, -1,
36 "A file descriptor representing a (UNIX) socket from which to "
37 "read the logs. If -1 is given the socket is created according to "
38 "the instance configuration");
39 DEFINE_string(subscriber_fds, "",
40 "A comma separated list of file descriptors (most likely pipes) to"
41 " send kernel log events to.");
42
SubscribersFromCmdline()43 std::vector<cuttlefish::SharedFD> SubscribersFromCmdline() {
44 // Validate the parameter
45 std::string fd_list = FLAGS_subscriber_fds;
46 for (auto c: fd_list) {
47 if (c != ',' && (c < '0' || c > '9')) {
48 LOG(ERROR) << "Invalid file descriptor list: " << fd_list;
49 std::exit(1);
50 }
51 }
52
53 auto fds = android::base::Split(FLAGS_subscriber_fds, ",");
54 std::vector<cuttlefish::SharedFD> shared_fds;
55 for (auto& fd_str: fds) {
56 auto fd = std::stoi(fd_str);
57 auto shared_fd = cuttlefish::SharedFD::Dup(fd);
58 close(fd);
59 shared_fds.push_back(shared_fd);
60 }
61
62 return shared_fds;
63 }
64
main(int argc,char ** argv)65 int main(int argc, char** argv) {
66 cuttlefish::DefaultSubprocessLogging(argv);
67 google::ParseCommandLineFlags(&argc, &argv, true);
68
69 auto config = cuttlefish::CuttlefishConfig::Get();
70
71 CHECK(config) << "Could not open cuttlefish config";
72
73 auto instance = config->ForDefaultInstance();
74
75 auto subscriber_fds = SubscribersFromCmdline();
76
77 // Disable default handling of SIGPIPE
78 struct sigaction new_action {
79 }, old_action{};
80 new_action.sa_handler = SIG_IGN;
81 sigaction(SIGPIPE, &new_action, &old_action);
82
83 cuttlefish::SharedFD pipe;
84 if (FLAGS_log_pipe_fd < 0) {
85 auto log_name = instance.kernel_log_pipe_name();
86 pipe = cuttlefish::SharedFD::Open(log_name.c_str(), O_RDONLY);
87 } else {
88 pipe = cuttlefish::SharedFD::Dup(FLAGS_log_pipe_fd);
89 close(FLAGS_log_pipe_fd);
90 }
91
92 if (!pipe->IsOpen()) {
93 LOG(ERROR) << "Error opening log pipe: " << pipe->StrError();
94 return 2;
95 }
96
97 monitor::KernelLogServer klog{pipe, instance.PerInstancePath("kernel.log"),
98 config->deprecated_boot_completed()};
99
100 for (auto subscriber_fd: subscriber_fds) {
101 if (subscriber_fd->IsOpen()) {
102 klog.SubscribeToEvents([subscriber_fd](Json::Value message) {
103 if (!monitor::WriteEvent(subscriber_fd, message)) {
104 if (subscriber_fd->GetErrno() != EPIPE) {
105 LOG(ERROR) << "Error while writing to pipe: "
106 << subscriber_fd->StrError();
107 }
108 subscriber_fd->Close();
109 return monitor::SubscriptionAction::CancelSubscription;
110 }
111 return monitor::SubscriptionAction::ContinueSubscription;
112 });
113 } else {
114 LOG(ERROR) << "Subscriber fd isn't valid: " << subscriber_fd->StrError();
115 // Don't return here, we still need to write the logs to a file
116 }
117 }
118
119 for (;;) {
120 cuttlefish::SharedFDSet fd_read;
121 fd_read.Zero();
122
123 klog.BeforeSelect(&fd_read);
124
125 int ret = cuttlefish::Select(&fd_read, nullptr, nullptr, nullptr);
126 if (ret <= 0) continue;
127
128 klog.AfterSelect(fd_read);
129 }
130
131 return 0;
132 }
133