core/shell: Mark the internal startup file as persistent

This fixes the following issue:

    $ cat ~/.config/oils/oshrc
    exec 10>out
    echo hello>&10
    cat out
    $ bin/osh
    hello
    oils I/O error (main): Bad file descriptor

Signed-off-by: Andrii Sultanov <[email protected]>

Author: last-genius

core/shell.py

@@ -151,15 +151,18 @@ def SourceStartupFile(
     # Bash also has --login.
 
     try:
-        f, _ = fd_state.Open(rc_path)
+        f, fd = fd_state.Open(rc_path, persistent=True)
     except (IOError, OSError) as e:
         # TODO: Could warn about nonexistent explicit --rcfile?
         if e.errno != ENOENT:
             raise  # Goes to top level.  Handle this better?
         return
 
     arena = parse_ctx.arena
-    rc_line_reader = reader.FileLineReader(f, arena)
+    file_line_reader = reader.FileLineReader(f, arena)
+    rc_line_reader = file_line_reader
+    fd_state.SetCallback(fd, file_line_reader)
+
     rc_c_parser = parse_ctx.MakeOshParser(rc_line_reader)
 
     with alloc.ctx_SourceCode(arena, source.MainFile(rc_path)):