Assume getutent(3) exists (remove dead code)

Recently, we removed support for 'struct utmpx'.  We did it because utmp
and utmpx are identical, and while POSIX specifies utmpx (and not utmp),
GNU/Linux documentation seems to favor utmp.  Also, this project
defaulted to utmp, so changing to utmpx would be more dangerous than
keeping old defaults, even if it's supposed to be the same.

Now, I just found more code that didn't make much sense: lib/utent.c
provides definitions for getutent(3) and friends in case the system
doesn't provide them, but we don't provide prototypes for those
definitions, so code using the functions would have never compiled.

Let's just remove these definitions as dead code.

Fixes: 3be7b9d75a ("Remove traces of utmpx")
Fixes: 170b76cdd1 ("Disable utmpx permanently")
Cc: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

configure.ac

@@ -47,7 +47,7 @@ AC_CHECK_HEADER([shadow.h],,[AC_MSG_ERROR([You need a libc with shadow.h])])
 
 AC_CHECK_FUNCS(arc4random_buf futimes \
 	getentropy getrandom getspnam getusershell \
-	getutent initgroups lckpwdf lutimes \
+	initgroups lckpwdf lutimes \
 	setgroups updwtmp updwtmpx innetgr \
 	getspnam_r \
 	memset_explicit explicit_bzero)

lib/Makefile.am

@@ -66,8 +66,7 @@ libshadow_la_SOURCES = \
 	shadowio.c \
 	shadowio.h \
 	shadowmem.c \
-	spawn.c \
+	spawn.c
-	utent.c
 
 if WITH_TCB
 libshadow_la_SOURCES += tcbfuncs.c tcbfuncs.h

lib/utent.c

@@ -1,70 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 1993 - 1994, Julianne Frances Haugh
- * SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
- * SPDX-FileCopyrightText: 2005       , Tomasz Kłoczko
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-#include <config.h>
-
-#ifndef	HAVE_GETUTENT
-
-#include "defines.h"
-#include <stdio.h>
-#include <fcntl.h>
-#include <utmp.h>
-
-#ifndef	lint
-static char rcsid[] = "$Id$";
-#endif
-
-static int utmp_fd = -1;
-static struct utmp utmp_buf;
-
-/*
- * setutent - open or rewind the utmp file
- */
-
-void setutent (void)
-{
-	if (utmp_fd == -1)
-		if ((utmp_fd = open (_UTMP_FILE, O_RDWR)) == -1)
-			utmp_fd = open (_UTMP_FILE, O_RDONLY);
-
-	if (utmp_fd != -1)
-		lseek (utmp_fd, (off_t) 0L, SEEK_SET);
-}
-
-/*
- * endutent - close the utmp file
- */
-
-void endutent (void)
-{
-	if (utmp_fd != -1)
-		close (utmp_fd);
-
-	utmp_fd = -1;
-}
-
-/*
- * getutent - get the next record from the utmp file
- */
-
-struct utmp *getutent (void)
-{
-	if (utmp_fd == -1)
-		setutent ();
-
-	if (utmp_fd == -1)
-		return 0;
-
-	if (read (utmp_fd, &utmp_buf, sizeof utmp_buf) != sizeof utmp_buf)
-		return 0;
-
-	return &utmp_buf;
-}
-#else
-extern int ISO_C_forbids_an_empty_translation_unit;
-#endif

po/POTFILES.in

@@ -28,7 +28,6 @@ lib/shadowio.c
 lib/shadowmem.c
 lib/spawn.c
 lib/tcbfuncs.c
-lib/utent.c
 libmisc/addgrps.c
 libmisc/age.c
 libmisc/audit_help.c