Fixup: check if the user has a model directry in the PAM module

Revert the use of pipe to signal from the script that the face model is
not found and do it directly in the module.

howdy/src/compare.py

@@ -140,11 +140,6 @@ def send_to_ui(type, message):
 if len(models) < 1:
  exit(10)
 
-# notify the PAM module so that it issues a message
-sys.stdout.flush()
-print("HAS_MODEL")
-sys.stdout.flush()
-
 # Read config from disk
 config = configparser.ConfigParser()
 config.read(PATH + "/config.ini")

howdy/src/pam/main.cc

@@ -243,9 +243,6 @@ auto identify(pam_handle_t *pamh, int flags, int argc, const char **argv,
  bindtextdomain(GETTEXT_PACKAGE, LOCALEDIR);
  textdomain(GETTEXT_PACKAGE);
 
- // If enabled, send a notice to the user that facial login is being attempted
- bool detection_notice = config.GetBoolean("core", "detection_notice", true);
-
  // Get the username from PAM, needed to match correct face model
  char *username = nullptr;
  if ((pam_res = pam_get_user(pamh, const_cast<const char **>(&username),
@@ -254,46 +251,30 @@ auto identify(pam_handle_t *pamh, int flags, int argc, const char **argv,
  return pam_res;
  }
 
- int conv_pipe[2];
-
- if (pipe (conv_pipe)) {
- syslog(LOG_ERR, "Pipe failed.");
- return PAM_SYSTEM_ERR;
+ // pre-check if this user has face model file
+ auto model_path = std::string("/etc/howdy/models/") + username + ".dat";
+ if (!std::ifstream(model_path)) {
+ return howdy_status(username, CompareError::NO_FACE_MODEL, config,
+ conv_function);
+ } else if (config.GetBoolean("core", "detection_notice", true)) {
+ if ((conv_function(PAM_TEXT_INFO, S("Attempting facial authentication"))) !=
+ PAM_SUCCESS) {
+ syslog(LOG_ERR, "Failed to send detection notice");
+ }
  }
 
- posix_spawn_file_actions_t action;
- posix_spawn_file_actions_init(&action);
- posix_spawn_file_actions_addclose(&action, conv_pipe[0]);
- posix_spawn_file_actions_adddup2(&action, conv_pipe[1], 1);
- posix_spawn_file_actions_addclose(&action, conv_pipe[1]);
-
  const char *const args[] = {PYTHON_EXECUTABLE, // NOLINT
  COMPARE_PROCESS_PATH, username, nullptr};
  pid_t child_pid;
 
  // Start the python subprocess
- if (posix_spawnp(&child_pid, PYTHON_EXECUTABLE, &action, nullptr,
+ if (posix_spawnp(&child_pid, PYTHON_EXECUTABLE, nullptr, nullptr,
  const_cast<char *const *>(args), nullptr) != 0) {
  syslog(LOG_ERR, "Can't spawn the howdy process: %s (%d)", strerror(errno),
  errno);
  return PAM_SYSTEM_ERR;
  }
 
- // show the PAM message from the compare script
- optional_task<void> child_conv([&] {
- char buffer[100];
- while(read(conv_pipe[0], buffer, 100)) {
- if (!strncmp(buffer, "HAS_MODEL", 9) && detection_notice) {
- if ((conv_function(PAM_TEXT_INFO,
- S("Attempting facial authentication"))) !=
- PAM_SUCCESS) {
- syslog(LOG_ERR, "Failed to send detection notice");
- }
- }
- }
- });
- child_conv.activate();
-
  // NOTE: We should replace mutex and condition_variable by atomic wait, but
  // it's too recent (C++20)
  std::mutex mutx;
@@ -370,7 +351,6 @@ auto identify(pam_handle_t *pamh, int flags, int argc, const char **argv,
 
  // The compare process has finished its execution
  child_task.stop(false);
- child_conv.stop(true);
 
  // Get python process status code
  int status = child_task.get();