1 /*
2 * Copyright (C) 2020 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 "first_stage_console.h"
18
19 #include <stdio.h>
20 #include <sys/stat.h>
21 #include <sys/sysmacros.h>
22 #include <sys/types.h>
23 #include <sys/wait.h>
24 #include <termios.h>
25
26 #include <string>
27 #include <thread>
28
29 #include <android-base/chrono_utils.h>
30 #include <android-base/file.h>
31 #include <android-base/logging.h>
32
KernelConsolePresent(const std::string & cmdline)33 static bool KernelConsolePresent(const std::string& cmdline) {
34 size_t pos = 0;
35 while (true) {
36 pos = cmdline.find("console=", pos);
37 if (pos == std::string::npos) return false;
38 if (pos == 0 || cmdline[pos - 1] == ' ') return true;
39 pos++;
40 }
41 }
42
SetupConsole()43 static bool SetupConsole() {
44 if (mknod("/dev/console", S_IFCHR | 0600, makedev(5, 1))) {
45 PLOG(ERROR) << "unable to create /dev/console";
46 return false;
47 }
48 int fd = -1;
49 int tries = 50; // should timeout after 5s
50 // The device driver for console may not be ready yet so retry for a while in case of failure.
51 while (tries--) {
52 fd = open("/dev/console", O_RDWR);
53 if (fd != -1) break;
54 std::this_thread::sleep_for(100ms);
55 }
56 if (fd == -1) {
57 PLOG(ERROR) << "could not open /dev/console";
58 return false;
59 }
60 ioctl(fd, TIOCSCTTY, 0);
61 dup2(fd, STDIN_FILENO);
62 dup2(fd, STDOUT_FILENO);
63 dup2(fd, STDERR_FILENO);
64 close(fd);
65 return true;
66 }
67
RunScript()68 static void RunScript() {
69 LOG(INFO) << "Attempting to run /first_stage.sh...";
70 pid_t pid = fork();
71 if (pid != 0) {
72 int status;
73 waitpid(pid, &status, 0);
74 LOG(INFO) << "/first_stage.sh exited with status " << status;
75 return;
76 }
77 const char* path = "/system/bin/sh";
78 const char* args[] = {path, "/first_stage.sh", nullptr};
79 int rv = execv(path, const_cast<char**>(args));
80 LOG(ERROR) << "unable to execv /first_stage.sh, returned " << rv << " errno " << errno;
81 }
82
83 namespace android {
84 namespace init {
85
StartConsole(const std::string & cmdline)86 void StartConsole(const std::string& cmdline) {
87 bool console = KernelConsolePresent(cmdline);
88 // Use a simple sigchld handler -- first_stage_console doesn't need to track or log zombies
89 const struct sigaction chld_act { .sa_handler = SIG_DFL, .sa_flags = SA_NOCLDWAIT };
90
91 sigaction(SIGCHLD, &chld_act, nullptr);
92 pid_t pid = fork();
93 if (pid != 0) {
94 int status;
95 waitpid(pid, &status, 0);
96 LOG(ERROR) << "console shell exited with status " << status;
97 return;
98 }
99
100 if (console) console = SetupConsole();
101 RunScript();
102 if (console) {
103 const char* path = "/system/bin/sh";
104 const char* args[] = {path, nullptr};
105 int rv = execv(path, const_cast<char**>(args));
106 LOG(ERROR) << "unable to execv, returned " << rv << " errno " << errno;
107 }
108 _exit(127);
109 }
110
FirstStageConsole(const std::string & cmdline,const std::string & bootconfig)111 int FirstStageConsole(const std::string& cmdline, const std::string& bootconfig) {
112 auto pos = bootconfig.find("androidboot.first_stage_console =");
113 if (pos != std::string::npos) {
114 int val = 0;
115 if (sscanf(bootconfig.c_str() + pos, "androidboot.first_stage_console = \"%d\"", &val) !=
116 1) {
117 return FirstStageConsoleParam::DISABLED;
118 }
119 if (val <= FirstStageConsoleParam::MAX_PARAM_VALUE && val >= 0) {
120 return val;
121 }
122 }
123
124 pos = cmdline.find("androidboot.first_stage_console=");
125 if (pos != std::string::npos) {
126 int val = 0;
127 if (sscanf(cmdline.c_str() + pos, "androidboot.first_stage_console=%d", &val) != 1) {
128 return FirstStageConsoleParam::DISABLED;
129 }
130 if (val <= FirstStageConsoleParam::MAX_PARAM_VALUE && val >= 0) {
131 return val;
132 }
133 }
134 return FirstStageConsoleParam::DISABLED;
135 }
136
137 } // namespace init
138 } // namespace android
139