[PATCH] login: Remove utmp backend jump tables [BZ #23518]

[Florian Weimer]

* Florian Weimer:

> There is just one file-based implementation, so this dispatch
> mechanism is unnecessary.  Instead of the vtable pointer
> __libc_utmp_jump_table, use a non-negative file_fd as the indicator
> that the backend is initialized.
>
> 2018-08-15  Florian Weimer  <fweimer@redhat.com>
>
> 	[BZ #23518]
> 	* login/uptmp-private.h (struct ufuncs): Remove definition.
> 	(__libc_utmp_file_functions, __libc_utmp_unknown_functions)
> 	(__libc_utmp_jump_table): Remove declarations.
> 	(__libc_setutent, __libc_getutent_r, __libc_getutid_r)
> 	(__libc_getutline_r, __libc_pututline, __libc_endutent)
> 	(__libc_updwtmp): Declare.
> 	* login/getutent_r.c (__libc_utmp_unknown_functions)
> 	(__libc_utmp_jump_table, setutent_unknown, getutent_r_unknown)
> 	(getutid_r_unknown, getutline_r_unknown, pututline_unknown)
> 	(endutent_unknown): Remove definitions.
> 	(__setutent): Call __libc_setutent.
> 	(__getutent_r): Call __libc_getutent_r.
> 	(__pututline): Call __libc_pututline.
> 	(__endutent): Call __libc_endutent.
> 	* login/getutid_r.c (__getutid_r): Call __libc_getutid_r.
> 	* login/getutline_r.c (__getutline_r): Call __libc_getutline_r.
> 	* login/updwtmp.c (__updwtmp): Call __libc_updwtmp.
> 	* login/utmp_file.c (__libc_utmp_file_functions): Remove definition
> 	(__libc_setutent): Rename from stetutent_file.  Drop static.
> 	(maybe_setutent): New function.
> 	(__libc_getutent_r): Rename from getutent_r_file.  Drop static.
> 	Check for initialization.
> 	(__libc_getutid_r): Rename from getutid_r_file.  Drop static.
> 	Check for initialization.
> 	(__libc_getutline_r): Rename from getutline_r_file.  Drop static.
> 	Check for initialization.
> 	(__libc_pututline): Rename from pututline_file.  Drop static.
> 	Check for initialization.
> 	(__libc_endutent): Rename from endutent_file.  Drop static.  Check
> 	for initialization.
> 	(__libc_updwtmp): Rename from updwtmp_file.  Drop static.
> 	* login/utmpname.c (__utmpname): Call __libc_endutent.
> 	* sysdeps/unix/getlogin_r (__getlogin_r): Call __libc_setutent,
> 	__libc_getutlien_r, __libc_endutent.
> 	* manual/users.texi (Who Logged In, Manipulating the Database):
> 	Adjust.

Ping.  This patch still applies to master:

  <https://sourceware.org/ml/libc-alpha/2018-08/msg00391.html>

Thanks,
Florian