2 files changed, 241 insertions, 48 deletions

diff --git a/install/Android.bp b/install/Android.bp
index 221ce72a0..ce4244ca4 100644
--- a/install/Android.bp
+++ b/install/Android.bp
@@ -19,6 +19,10 @@ cc_defaults {
         "recovery_defaults",
     ],
 
+    header_libs: [
+        "libminadbd_headers",
+    ],
+
     shared_libs: [
         "libbase",
         "libbootloader_message",
diff --git a/install/adb_install.cpp b/install/adb_install.cpp
index 5296ff608..dc7ee0b32 100644
--- a/install/adb_install.cpp
+++ b/install/adb_install.cpp
@@ -21,97 +21,286 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/epoll.h>
+#include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
+#include <atomic>
+#include <functional>
+#include <map>
+
+#include <android-base/file.h>
 #include <android-base/logging.h>
+#include <android-base/memory.h>
 #include <android-base/properties.h>
+#include <android-base/strings.h>
+#include <android-base/unique_fd.h>
 
 #include "fuse_sideload.h"
 #include "install/install.h"
+#include "minadbd_types.h"
 #include "recovery_ui/ui.h"
 
+using CommandFunction = std::function<bool()>;
+
 static bool SetUsbConfig(const std::string& state) {
   android::base::SetProperty("sys.usb.config", state);
   return android::base::WaitForProperty("sys.usb.state", state);
 }
 
-int apply_from_adb(bool* wipe_cache, RecoveryUI* ui) {
-  // Save the usb state to restore after the sideload operation.
-  std::string usb_state = android::base::GetProperty("sys.usb.state", "none");
-  // Clean up state and stop adbd.
-  if (usb_state != "none" && !SetUsbConfig("none")) {
-    LOG(ERROR) << "Failed to clear USB config";
-    return INSTALL_ERROR;
+// Parses the minadbd command in |message|; returns MinadbdCommands::kError upon errors.
+static MinadbdCommands ParseMinadbdCommands(const std::string& message) {
+  if (!android::base::StartsWith(message, kMinadbdCommandPrefix)) {
+    LOG(ERROR) << "Failed to parse command in message " << message;
+    return MinadbdCommands::kError;
   }
 
-  ui->Print(
-      "\n\nNow send the package you want to apply\n"
-      "to the device with \"adb sideload <filename>\"...\n");
-
-  pid_t child;
-  if ((child = fork()) == 0) {
-    execl("/system/bin/recovery", "recovery", "--adbd", nullptr);
-    _exit(EXIT_FAILURE);
+  auto cmd_code_string = message.substr(strlen(kMinadbdCommandPrefix));
+  auto cmd_code = android::base::get_unaligned<uint32_t>(cmd_code_string.c_str());
+  if (cmd_code >= static_cast<uint32_t>(MinadbdCommands::kError)) {
+    LOG(ERROR) << "Unsupported command code: " << cmd_code;
+    return MinadbdCommands::kError;
   }
 
-  if (!SetUsbConfig("sideload")) {
-    LOG(ERROR) << "Failed to set usb config to sideload";
-    return INSTALL_ERROR;
-  }
+  return static_cast<MinadbdCommands>(cmd_code);
+}
 
-  // How long (in seconds) we wait for the host to start sending us a package, before timing out.
-  static constexpr int ADB_INSTALL_TIMEOUT = 300;
+static bool WriteStatusToFd(MinadbdCommandStatus status, int fd) {
+  char message[kMinadbdMessageSize];
+  memcpy(message, kMinadbdStatusPrefix, strlen(kMinadbdStatusPrefix));
+  android::base::put_unaligned(message + strlen(kMinadbdStatusPrefix), status);
 
-  // FUSE_SIDELOAD_HOST_PATHNAME will start to exist once the host connects and starts serving a
-  // package. Poll for its appearance. (Note that inotify doesn't work with FUSE.)
-  int result = INSTALL_ERROR;
-  int status;
-  bool waited = false;
-  for (int i = 0; i < ADB_INSTALL_TIMEOUT; ++i) {
-    if (waitpid(child, &status, WNOHANG) != 0) {
-      result = INSTALL_ERROR;
-      waited = true;
-      break;
-    }
+  if (!android::base::WriteFully(fd, message, kMinadbdMessageSize)) {
+    PLOG(ERROR) << "Failed to write message " << message;
+    return false;
+  }
+  return true;
+}
 
+// Installs the package from FUSE. Returns true if the installation succeeds, and false otherwise.
+static bool AdbInstallPackageHandler(bool* wipe_cache, RecoveryUI* ui, int* result) {
+  // How long (in seconds) we wait for the package path to be ready. It doesn't need to be too long
+  // because the minadbd service has already issued an install command. FUSE_SIDELOAD_HOST_PATHNAME
+  // will start to exist once the host connects and starts serving a package. Poll for its
+  // appearance. (Note that inotify doesn't work with FUSE.)
+  constexpr int ADB_INSTALL_TIMEOUT = 15;
+  *result = INSTALL_ERROR;
+  for (int i = 0; i < ADB_INSTALL_TIMEOUT; ++i) {
     struct stat st;
     if (stat(FUSE_SIDELOAD_HOST_PATHNAME, &st) != 0) {
       if (errno == ENOENT && i < ADB_INSTALL_TIMEOUT - 1) {
         sleep(1);
         continue;
       } else {
-        ui->Print("\nTimed out waiting for package.\n\n");
-        result = INSTALL_ERROR;
-        kill(child, SIGKILL);
+        ui->Print("\nTimed out waiting for fuse to be ready.\n\n");
         break;
       }
     }
-    result = install_package(FUSE_SIDELOAD_HOST_PATHNAME, wipe_cache, false, 0, ui);
+    *result = install_package(FUSE_SIDELOAD_HOST_PATHNAME, wipe_cache, false, 0, ui);
     break;
   }
 
-  if (!waited) {
-    // Calling stat() on this magic filename signals the minadbd subprocess to shut down.
-    struct stat st;
-    stat(FUSE_SIDELOAD_HOST_EXIT_PATHNAME, &st);
+  // Calling stat() on this magic filename signals the FUSE to exit.
+  struct stat st;
+  stat(FUSE_SIDELOAD_HOST_EXIT_PATHNAME, &st);
+  return *result == INSTALL_SUCCESS;
+}
+
+// Parses and executes the command from minadbd. Returns false if we enter an invalid state so that
+// the caller can kill the minadbd service properly.
+static bool HandleMessageFromMinadbd(
+    int socket_fd, const std::map<MinadbdCommands, CommandFunction>& command_map) {
+  char buffer[kMinadbdMessageSize];
+  if (!android::base::ReadFully(socket_fd, buffer, kMinadbdMessageSize)) {
+    PLOG(ERROR) << "Failed to read message from minadbd";
+    return false;
+  }
+
+  std::string message(buffer, buffer + kMinadbdMessageSize);
+  auto command_type = ParseMinadbdCommands(message);
+  if (command_type == MinadbdCommands::kError) {
+    return false;
+  }
+  if (command_map.find(command_type) == command_map.end()) {
+    LOG(ERROR) << "Unsupported command: "
+               << android::base::get_unaligned<unsigned int>(
+                      message.substr(strlen(kMinadbdCommandPrefix)).c_str());
+    return false;
+  }
+
+  // We have received a valid command, execute the corresponding function.
+  const auto& command_func = command_map.at(command_type);
+  if (!command_func()) {
+    LOG(ERROR) << "Failed to execute command " << static_cast<unsigned int>(command_type);
+    return WriteStatusToFd(MinadbdCommandStatus::kFailure, socket_fd);
+  }
+  return WriteStatusToFd(MinadbdCommandStatus::kSuccess, socket_fd);
+}
+
+// TODO(xunchang) add a wrapper function and kill the minadbd service there.
+static void ListenAndExecuteMinadbdCommands(
+    pid_t minadbd_pid, android::base::unique_fd&& socket_fd,
+    const std::map<MinadbdCommands, CommandFunction>& command_map) {
+  android::base::unique_fd epoll_fd(epoll_create1(O_CLOEXEC));
+  if (epoll_fd == -1) {
+    PLOG(ERROR) << "Failed to create epoll";
+    kill(minadbd_pid, SIGKILL);
+    return;
+  }
+
+  constexpr int EPOLL_MAX_EVENTS = 10;
+  struct epoll_event ev = {};
+  ev.events = EPOLLIN | EPOLLHUP;
+  ev.data.fd = socket_fd.get();
+  struct epoll_event events[EPOLL_MAX_EVENTS];
+  if (epoll_ctl(epoll_fd.get(), EPOLL_CTL_ADD, socket_fd.get(), &ev) == -1) {
+    PLOG(ERROR) << "Failed to add socket fd to epoll";
+    kill(minadbd_pid, SIGKILL);
+    return;
+  }
+
+  // Set the timeout to be 300s when waiting for minadbd commands.
+  constexpr int TIMEOUT_MILLIS = 300 * 1000;
+  while (true) {
+    // Poll for the status change of the socket_fd, and handle the message if the fd is ready to
+    // read.
+    int event_count =
+        TEMP_FAILURE_RETRY(epoll_wait(epoll_fd.get(), events, EPOLL_MAX_EVENTS, TIMEOUT_MILLIS));
+    if (event_count == -1) {
+      PLOG(ERROR) << "Failed to wait for epoll events";
+      kill(minadbd_pid, SIGKILL);
+      return;
+    }
+    if (event_count == 0) {
+      LOG(ERROR) << "Timeout waiting for messages from minadbd";
+      kill(minadbd_pid, SIGKILL);
+      return;
+    }
+
+    for (int n = 0; n < event_count; n++) {
+      if (events[n].events & EPOLLHUP) {
+        LOG(INFO) << "Socket has been closed";
+        kill(minadbd_pid, SIGKILL);
+        return;
+      }
+      if (!HandleMessageFromMinadbd(socket_fd.get(), command_map)) {
+        kill(minadbd_pid, SIGKILL);
+        return;
+      }
+    }
+  }
+}
+
+// Recovery starts minadbd service as a child process, and spawns another thread to listen for the
+// message from minadbd through a socket pair. Here is an example to execute one command from adb
+// host.
+//  a. recovery                    b. listener thread               c. minadbd service
+//
+//  a1. create socket pair
+//  a2. fork minadbd service
+//                                                                c3. wait for the adb commands
+//                                                                    from host
+//                                                                c4. after receiving host commands:
+//                                                                  1) set up pre-condition (i.e.
+//                                                                     start fuse for adb sideload)
+//                                                                  2) issue command through
+//                                                                     socket.
+//                                                                  3) wait for result
+//  a5. start listener thread
+//                               b6. listen for message from
+//                                   minadbd in a loop.
+//                               b7. After receiving a minadbd
+//                                   command from socket
+//                                 1) execute the command function
+//                                 2) send the result back to
+//                                    minadbd
+//  ......
+//                                                                 c8. exit upon receiving the
+//                                                                     result
+// a9.  wait for listener thread
+//      to exit.
+//
+// a10. wait for minadbd to
+//      exit
+//                               b11. exit the listening loop
+//
+static void CreateMinadbdServiceAndExecuteCommands(
+    const std::map<MinadbdCommands, CommandFunction>& command_map) {
+  signal(SIGPIPE, SIG_IGN);
+
+  android::base::unique_fd recovery_socket;
+  android::base::unique_fd minadbd_socket;
+  if (!android::base::Socketpair(AF_UNIX, SOCK_STREAM, 0, &recovery_socket, &minadbd_socket)) {
+    PLOG(ERROR) << "Failed to create socket";
+    return;
+  }
+
+  pid_t child = fork();
+  if (child == -1) {
+    PLOG(ERROR) << "Failed to fork child process";
+    return;
+  }
+  if (child == 0) {
+    recovery_socket.reset();
+    execl("/system/bin/minadbd", "minadbd", "--socket_fd",
+          std::to_string(minadbd_socket.release()).c_str(), nullptr);
+
+    _exit(EXIT_FAILURE);
+  }
+
+  minadbd_socket.reset();
+
+  // We need to call SetUsbConfig() after forking minadbd service. Because the function waits for
+  // the usb state to be updated, which depends on sys.usb.ffs.ready=1 set in the adb daemon.
+  if (!SetUsbConfig("sideload")) {
+    LOG(ERROR) << "Failed to set usb config to sideload";
+    return;
+  }
+
+  std::thread listener_thread(ListenAndExecuteMinadbdCommands, child, std::move(recovery_socket),
+                              std::ref(command_map));
 
-    // TODO: there should be a way to cancel waiting for a package (by pushing some button combo on
-    // the device). For now you just have to 'adb sideload' a file that's not a valid package, like
-    // "/dev/null".
-    waitpid(child, &status, 0);
+  if (listener_thread.joinable()) {
+    listener_thread.join();
   }
 
+  int status;
+  waitpid(child, &status, 0);
   if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
-    if (WEXITSTATUS(status) == 3) {
-      ui->Print("\nYou need adb 1.0.32 or newer to sideload\nto this device.\n\n");
+    if (WEXITSTATUS(status) == MinadbdErrorCode::kMinadbdAdbVersionError) {
+      LOG(ERROR) << "\nYou need adb 1.0.32 or newer to sideload\nto this device.\n";
     } else if (!WIFSIGNALED(status)) {
-      ui->Print("\n(adbd status %d)\n", WEXITSTATUS(status));
+      LOG(ERROR) << "\n(adbd status " << WEXITSTATUS(status) << ")";
     }
   }
 
+  signal(SIGPIPE, SIG_DFL);
+}
+
+int apply_from_adb(bool* wipe_cache, RecoveryUI* ui) {
+  // Save the usb state to restore after the sideload operation.
+  std::string usb_state = android::base::GetProperty("sys.usb.state", "none");
+  // Clean up state and stop adbd.
+  if (usb_state != "none" && !SetUsbConfig("none")) {
+    LOG(ERROR) << "Failed to clear USB config";
+    return INSTALL_ERROR;
+  }
+
+  ui->Print(
+      "\n\nNow send the package you want to apply\n"
+      "to the device with \"adb sideload <filename>\"...\n");
+
+  int install_result = INSTALL_ERROR;
+  std::map<MinadbdCommands, CommandFunction> command_map{
+    { MinadbdCommands::kInstall,
+      std::bind(&AdbInstallPackageHandler, wipe_cache, ui, &install_result) },
+  };
+
+  CreateMinadbdServiceAndExecuteCommands(command_map);
+
   // Clean up before switching to the older state, for example setting the state
   // to none sets sys/class/android_usb/android0/enable to 0.
   if (!SetUsbConfig("none")) {
@@ -124,5 +313,5 @@ int apply_from_adb(bool* wipe_cache, RecoveryUI* ui) {
     }
   }
 
-  return result;
+  return install_result;
 }