Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 48383c80 authored by Josh Gao's avatar Josh Gao
Browse files

tombstoned: don't create tombstones for failed dumps. 

Instead of creating tombstone FDs in place and passing them out to
crash_dump directly, create them as O_TMPFILEs and link them into place
when crash_dump reports success, to avoid creating empty tombstones
in cases like an aborting thread racing with another thread that
manages to cleanly exit_group before the dump finishes.

Bug: http://b/77729983
Test: debuggerd_test
Test: adb shell 'for x in `seq 0 50`; do crasher; done'
Change-Id: I31ce4fd4a524abf8bde57152450209483d9d0ba9
parent 22dc27b9

debuggerd/tombstoned/tombstoned.cpp

+47 −28
Original line number Original line Diff line number Diff line
@@ -61,10 +61,10 @@ enum CrashStatus { 
struct Crash {

struct Crash {

  ~Crash() { event_free(crash_event); }

  ~Crash() { event_free(crash_event); }





  unique_fd crash_fd;

  unique_fd crash_tombstone_fd;

  unique_fd crash_socket_fd;

  pid_t crash_pid;

  pid_t crash_pid;

  event* crash_event = nullptr;

  event* crash_event = nullptr;

  std::string crash_path;





  DebuggerdDumpType crash_type;

  DebuggerdDumpType crash_type;

};

};
@@ -109,24 +109,27 @@ class CrashQueue { 
    return &queue;

    return &queue;

  }

  }





  std::pair<unique_fd, std::string> get_output() {

  unique_fd get_output() {

    unique_fd result;

    unique_fd result(openat(dir_fd_, ".", O_WRONLY | O_APPEND | O_TMPFILE | O_CLOEXEC, 0640));

    std::string file_name = StringPrintf("%s%02d", file_name_prefix_.c_str(), next_artifact_);



    // Unlink and create the file, instead of using O_TRUNC, to avoid two processes

    // interleaving their output in case we ever get into that situation.

    if (unlinkat(dir_fd_, file_name.c_str(), 0) != 0 && errno != ENOENT) {

      PLOG(FATAL) << "failed to unlink tombstone at " << dir_path_ << "/" << file_name;

    }



    result.reset(openat(dir_fd_, file_name.c_str(),

                        O_CREAT | O_EXCL | O_WRONLY | O_APPEND | O_CLOEXEC, 0640));

    if (result == -1) {

    if (result == -1) {

      PLOG(FATAL) << "failed to create tombstone at " << dir_path_ << "/" << file_name;

      // We might not have O_TMPFILE. Try creating and unlinking instead.

      result.reset(

          openat(dir_fd_, ".temporary", O_WRONLY | O_APPEND | O_CREAT | O_TRUNC | O_CLOEXEC, 0640));

      if (result == -1) {

        PLOG(FATAL) << "failed to create temporary tombstone in " << dir_path_;

      }

      if (unlinkat(dir_fd_, ".temporary", 0) != 0) {

        PLOG(FATAL) << "failed to unlink temporary tombstone";

      }

    }

    return result;

  }

  }





  std::string get_next_artifact_path() {

    std::string file_name =

        StringPrintf("%s/%s%02d", dir_path_.c_str(), file_name_prefix_.c_str(), next_artifact_);

    next_artifact_ = (next_artifact_ + 1) % max_artifacts_;

    next_artifact_ = (next_artifact_ + 1) % max_artifacts_;

    return {std::move(result), dir_path_ + "/" + file_name};

    return file_name;

  }

  }





  bool maybe_enqueue_crash(Crash* crash) {

  bool maybe_enqueue_crash(Crash* crash) {
@@ -203,14 +206,17 @@ static void crash_completed_cb(evutil_socket_t sockfd, short ev, void* arg); 




static void perform_request(Crash* crash) {

static void perform_request(Crash* crash) {

  unique_fd output_fd;

  unique_fd output_fd;

  if (!intercept_manager->GetIntercept(crash->crash_pid, crash->crash_type, &output_fd)) {

  bool intercepted =

    std::tie(output_fd, crash->crash_path) = CrashQueue::for_crash(crash)->get_output();

      intercept_manager->GetIntercept(crash->crash_pid, crash->crash_type, &output_fd);

  if (!intercepted) {

    output_fd = CrashQueue::for_crash(crash)->get_output();

    crash->crash_tombstone_fd.reset(dup(output_fd.get()));

  }

  }





  TombstonedCrashPacket response = {

  TombstonedCrashPacket response = {

    .packet_type = CrashPacketType::kPerformDump

    .packet_type = CrashPacketType::kPerformDump

  };

  };

  ssize_t rc = send_fd(crash->crash_fd, &response, sizeof(response), std::move(output_fd));

  ssize_t rc = send_fd(crash->crash_socket_fd, &response, sizeof(response), std::move(output_fd));

  if (rc == -1) {

  if (rc == -1) {

    PLOG(WARNING) << "failed to send response to CrashRequest";

    PLOG(WARNING) << "failed to send response to CrashRequest";

    goto fail;

    goto fail;
@@ -222,7 +228,7 @@ static void perform_request(Crash* crash) { 
    struct timeval timeout = { 10, 0 };

    struct timeval timeout = { 10, 0 };





    event_base* base = event_get_base(crash->crash_event);

    event_base* base = event_get_base(crash->crash_event);

    event_assign(crash->crash_event, base, crash->crash_fd, EV_TIMEOUT | EV_READ,

    event_assign(crash->crash_event, base, crash->crash_socket_fd, EV_TIMEOUT | EV_READ,

                 crash_completed_cb, crash);

                 crash_completed_cb, crash);

    event_add(crash->crash_event, &timeout);

    event_add(crash->crash_event, &timeout);

  }

  }
@@ -243,7 +249,7 @@ static void crash_accept_cb(evconnlistener* listener, evutil_socket_t sockfd, so 
  // and only native crashes on the native socket.

  // and only native crashes on the native socket.

  struct timeval timeout = { 1, 0 };

  struct timeval timeout = { 1, 0 };

  event* crash_event = event_new(base, sockfd, EV_TIMEOUT | EV_READ, crash_request_cb, crash);

  event* crash_event = event_new(base, sockfd, EV_TIMEOUT | EV_READ, crash_request_cb, crash);

  crash->crash_fd.reset(sockfd);

  crash->crash_socket_fd.reset(sockfd);

  crash->crash_event = crash_event;

  crash->crash_event = crash_event;

  event_add(crash_event, &timeout);

  event_add(crash_event, &timeout);

}

}
@@ -342,14 +348,27 @@ static void crash_completed_cb(evutil_socket_t sockfd, short ev, void* arg) { 
    goto fail;

    goto fail;

  }

  }





  if (!crash->crash_path.empty()) {

  if (crash->crash_tombstone_fd != -1) {

    std::string fd_path = StringPrintf("/proc/self/fd/%d", crash->crash_tombstone_fd.get());

    std::string tombstone_path = CrashQueue::for_crash(crash)->get_next_artifact_path();

    int rc = unlink(tombstone_path.c_str());

    if (rc != 0) {

      PLOG(ERROR) << "failed to unlink tombstone at " << tombstone_path;

      goto fail;

    }



    rc = linkat(AT_FDCWD, fd_path.c_str(), AT_FDCWD, tombstone_path.c_str(), AT_SYMLINK_FOLLOW);

    if (rc != 0) {

      PLOG(ERROR) << "failed to link tombstone";

    } else {

      if (crash->crash_type == kDebuggerdJavaBacktrace) {

      if (crash->crash_type == kDebuggerdJavaBacktrace) {

      LOG(ERROR) << "Traces for pid " << crash->crash_pid << " written to: " << crash->crash_path;

        LOG(ERROR) << "Traces for pid " << crash->crash_pid << " written to: " << tombstone_path;

      } else {

      } else {

        // NOTE: Several tools parse this log message to figure out where the

        // NOTE: Several tools parse this log message to figure out where the

        // tombstone associated with a given native crash was written. Any changes

        // tombstone associated with a given native crash was written. Any changes

        // to this message must be carefully considered.

        // to this message must be carefully considered.

      LOG(ERROR) << "Tombstone written to: " << crash->crash_path;

        LOG(ERROR) << "Tombstone written to: " << tombstone_path;

      }

    }

    }

  }

  }