first_stage_init: add hook to exec a shell script

If the first stage console is being used, attempt to run /first_stage.sh
immediately before the console is created.

Bug: 154126020
Change-Id: I8b7431e7b8219afea295b120d7ea91751804bda6

init/Android.bp

@@ -41,6 +41,7 @@ init_device_sources = [
     "builtins.cpp",
     "devices.cpp",
     "firmware_handler.cpp",
+    "first_stage_console.cpp",
     "first_stage_init.cpp",
     "first_stage_mount.cpp",
     "fscrypt_init_extensions.cpp",

init/Android.mk

@@ -50,6 +50,7 @@ LOCAL_CPPFLAGS := $(init_cflags)
 LOCAL_SRC_FILES := \
     block_dev_initializer.cpp \
     devices.cpp \
+    first_stage_console.cpp \
     first_stage_init.cpp \
     first_stage_main.cpp \
     first_stage_mount.cpp \

init/first_stage_console.cpp

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "first_stage_console.h"
+
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <termios.h>
+
+#include <string>
+#include <thread>
+
+#include <android-base/chrono_utils.h>
+#include <android-base/file.h>
+#include <android-base/logging.h>
+
+static void RunScript() {
+    LOG(INFO) << "Attempting to run /first_stage.sh...";
+    pid_t pid = fork();
+    if (pid != 0) {
+        int status;
+        waitpid(pid, &status, 0);
+        LOG(INFO) << "/first_stage.sh exited with status " << status;
+        return;
+    }
+    const char* path = "/system/bin/sh";
+    const char* args[] = {path, "/first_stage.sh", nullptr};
+    int rv = execv(path, const_cast<char**>(args));
+    LOG(ERROR) << "unable to execv /first_stage.sh, returned " << rv << " errno " << errno;
+}
+
+namespace android {
+namespace init {
+
+void StartConsole() {
+    if (mknod("/dev/console", S_IFCHR | 0600, makedev(5, 1))) {
+        PLOG(ERROR) << "unable to create /dev/console";
+        return;
+    }
+    pid_t pid = fork();
+    if (pid != 0) {
+        int status;
+        waitpid(pid, &status, 0);
+        LOG(ERROR) << "console shell exited with status " << status;
+        return;
+    }
+    int fd = -1;
+    int tries = 50; // should timeout after 5s
+    // The device driver for console may not be ready yet so retry for a while in case of failure.
+    while (tries--) {
+        fd = open("/dev/console", O_RDWR);
+        if (fd != -1) {
+            break;
+        }
+        std::this_thread::sleep_for(100ms);
+    }
+    if (fd == -1) {
+        LOG(ERROR) << "Could not open /dev/console, errno = " << errno;
+        _exit(127);
+    }
+    ioctl(fd, TIOCSCTTY, 0);
+    dup2(fd, STDIN_FILENO);
+    dup2(fd, STDOUT_FILENO);
+    dup2(fd, STDERR_FILENO);
+    close(fd);
+
+    RunScript();
+    const char* path = "/system/bin/sh";
+    const char* args[] = {path, nullptr};
+    int rv = execv(path, const_cast<char**>(args));
+    LOG(ERROR) << "unable to execv, returned " << rv << " errno " << errno;
+    _exit(127);
+}
+
+bool FirstStageConsole(const std::string& cmdline) {
+    return cmdline.find("androidboot.first_stage_console=1") != std::string::npos;
+}
+
+}  // namespace init
+}  // namespace android

init/first_stage_console.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <string>
+
+namespace android {
+namespace init {
+
+void StartConsole();
+bool FirstStageConsole(const std::string& cmdline);
+
+}  // namespace init
+}  // namespace android

init/first_stage_init.cpp

@@ -24,12 +24,10 @@
 #include <sys/stat.h>
 #include <sys/sysmacros.h>
 #include <sys/types.h>
-#include <sys/wait.h>
 #include <unistd.h>
 
 #include <filesystem>
 #include <string>
-#include <thread>
 #include <vector>
 
 #include <android-base/chrono_utils.h>
@@ -39,6 +37,7 @@
 #include <private/android_filesystem_config.h>
 
 #include "debug_ramdisk.h"
+#include "first_stage_console.h"
 #include "first_stage_mount.h"
 #include "reboot_utils.h"
 #include "switch_root.h"
@@ -94,49 +93,6 @@ void FreeRamdisk(DIR* dir, dev_t dev) {
     }
 }
 
-void StartConsole() {
-    if (mknod("/dev/console", S_IFCHR | 0600, makedev(5, 1))) {
-        PLOG(ERROR) << "unable to create /dev/console";
-        return;
-    }
-    pid_t pid = fork();
-    if (pid != 0) {
-        int status;
-        waitpid(pid, &status, 0);
-        LOG(ERROR) << "console shell exited with status " << status;
-        return;
-    }
-    int fd = -1;
-    int tries = 50; // should timeout after 5s
-    // The device driver for console may not be ready yet so retry for a while in case of failure.
-    while (tries--) {
-        fd = open("/dev/console", O_RDWR);
-        if (fd != -1) {
-            break;
-        }
-        std::this_thread::sleep_for(100ms);
-    }
-    if (fd == -1) {
-        LOG(ERROR) << "Could not open /dev/console, errno = " << errno;
-        _exit(127);
-    }
-    ioctl(fd, TIOCSCTTY, 0);
-    dup2(fd, STDIN_FILENO);
-    dup2(fd, STDOUT_FILENO);
-    dup2(fd, STDERR_FILENO);
-    close(fd);
-
-    const char* path = "/system/bin/sh";
-    const char* args[] = {path, nullptr};
-    int rv = execv(path, const_cast<char**>(args));
-    LOG(ERROR) << "unable to execv, returned " << rv << " errno " << errno;
-    _exit(127);
-}
-
-bool FirstStageConsole(const std::string& cmdline) {
-    return cmdline.find("androidboot.first_stage_console=1") != std::string::npos;
-}
-
 bool ForceNormalBoot(const std::string& cmdline) {
     return cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;
 }