refactor(misc1): move preserve_exit() to related functions in main.c

src/nvim/main.c

@@ -696,6 +696,50 @@ void getout(int exitval)
   os_exit(exitval);
 }
 
+/// Preserve files and exit.
+/// @note IObuff must contain a message.
+/// @note This may be called from deadly_signal() in a signal handler, avoid
+///       unsafe functions, such as allocating memory.
+void preserve_exit(void)
+  FUNC_ATTR_NORETURN
+{
+  // 'true' when we are sure to exit, e.g., after a deadly signal
+  static bool really_exiting = false;
+
+  // Prevent repeated calls into this method.
+  if (really_exiting) {
+    if (input_global_fd() >= 0) {
+      // normalize stream (#2598)
+      stream_set_blocking(input_global_fd(), true);
+    }
+    exit(2);
+  }
+
+  really_exiting = true;
+  // Ignore SIGHUP while we are already exiting. #9274
+  signal_reject_deadly();
+  mch_errmsg(IObuff);
+  mch_errmsg("\n");
+  ui_flush();
+
+  ml_close_notmod();                // close all not-modified buffers
+
+  FOR_ALL_BUFFERS(buf) {
+    if (buf->b_ml.ml_mfp != NULL && buf->b_ml.ml_mfp->mf_fname != NULL) {
+      mch_errmsg("Vim: preserving files...\r\n");
+      ui_flush();
+      ml_sync_all(false, false, true);  // preserve all swap files
+      break;
+    }
+  }
+
+  ml_close_all(false);              // close all memfiles, without deleting
+
+  mch_errmsg("Vim: Finished.\r\n");
+
+  getout(1);
+}
+
 /// Gets the integer value of a numeric command line argument if given,
 /// such as '-o10'.
 ///