recovery: Get a proper shell environment in recovery

* Root ADB shell by default
 * Try and get adb_keys from /data
 * Nicer mkshrc
 * Build a reboot command

Change-Id: I80b0e2aa5eb7142eaa9f157709f4e029077d8dfa

Android.bp

@@ -1,4 +1,5 @@
 // Copyright (C) 2018 The Android Open Source Project
+// Copyright (C) 2019 The LineageOS Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -171,6 +172,7 @@ cc_binary {
     ],
 
     static_libs: [
+        "libc++fs",
         "librecovery",
         "librecovery_ui_default",
     ],
@@ -182,6 +184,8 @@ cc_binary {
         "minadbd",
         "mke2fs.conf.recovery",
         "mke2fs.recovery",
+        "mkshrc.recovery",
+        "reboot.recovery",
         "recovery_deps",
         "ueventd.rc.recovery",
     ],

recovery_main.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2018 The Android Open Source Project
+ * Copyright (C) 2019 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,6 +32,7 @@
 #include <unistd.h>
 
 #include <atomic>
+#include <filesystem>
 #include <string>
 #include <thread>
 #include <vector>
@@ -60,6 +62,8 @@
 #include "recovery_utils/logging.h"
 #include "recovery_utils/roots.h"
 
+namespace fs = std::filesystem;
+
 static constexpr const char* COMMAND_FILE = "/cache/recovery/command";
 static constexpr const char* LOCALE_FILE = "/cache/recovery/last_locale";
 
@@ -77,6 +81,9 @@ static std::string get_build_type() {
   return android::base::GetProperty("ro.build.type", "");
 }
 
+static constexpr const char* adb_keys_data = "/data/misc/adb/adb_keys";
+static constexpr const char* adb_keys_root = "/adb_keys";
+
 static void UiLogger(android::base::LogId log_buffer_id, android::base::LogSeverity severity,
                      const char* tag, const char* file, unsigned int line, const char* message) {
   android::base::KernelLogger(log_buffer_id, severity, tag, file, line, message);
@@ -194,6 +201,20 @@ static std::string load_locale_from_cache() {
   return android::base::Trim(content);
 }
 
+static void copy_userdata_files() {
+  if (ensure_path_mounted("/data") == 0) {
+    if (access(adb_keys_root, F_OK) != 0) {
+      if (access(adb_keys_data, R_OK) == 0) {
+        std::error_code ec;  // to invoke the overloaded copy_file() that won't throw.
+        if (!fs::copy_file(adb_keys_data, adb_keys_root, ec)) {
+          PLOG(ERROR) << "Failed to copy adb keys";
+        }
+      }
+    }
+    ensure_path_unmounted("/data");
+  }
+}
+
 // Sets the usb config to 'state'.
 static bool SetUsbConfig(const std::string& state) {
   android::base::SetProperty("sys.usb.config", state);
@@ -338,6 +359,10 @@ int main(int argc, char** argv) {
   // Take action to refresh pmsg contents
   __android_log_pmsg_file_read(LOG_ID_SYSTEM, ANDROID_LOG_INFO, filter, logrotate, &do_rotate);
 
+  // Clear umask for packages that copy files out to /tmp and then over
+  // to /system without properly setting all permissions (eg. gapps).
+  umask(0);
+
   time_t start = time(nullptr);
 
   // redirect_stdio should be called only in non-sideload mode. Otherwise we may have two logger
@@ -480,6 +505,12 @@ int main(int argc, char** argv) {
   std::thread listener_thread(ListenRecoverySocket, ui, std::ref(action));
   listener_thread.detach();
 
+  // Set up adb_keys and enable root before starting ADB.
+  if (IsRoDebuggable() && !fastboot) {
+    copy_userdata_files();
+    android::base::SetProperty("service.adb.root", "1");
+  }
+
   while (true) {
     // We start adbd in recovery for the device with userdebug build or a unlocked bootloader.
     std::string usb_config =