From 3c1fed7d650c35b11a452e5005abcfb90f126667 Mon Sep 17 00:00:00 2001
From: "A. Wilcox" <AWilcox@Wilcox-Tech.com>
Date: Sat, 16 Jun 2018 02:26:53 -0500
Subject: [PATCH] w: Use POSIX <utmpx.h> functions where available

<utmp.h> has been deprecated since 2001 in favour of <utmpx.h>.

On glibc systems, utmp is just an alias to utmpx, so there is no
functional change using one over the other.

However, on the musl libc, a library (utmps) can be used to provide
utmpx functionality - but not utmp.  This means that procps either
doesn't work properly (`w` shows nothing under musl with default no-op
implementation), or fails to build (utmps provides utmpx.h but no
utmp.h).

This commit will use utmpx.h where available, which allows `w` to work
correctly with utmps and has no change on glibc systems.
---
 configure.ac |  2 +-
 w.c          | 37 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index f29fc064..ebd94c27 100644
--- a/configure.ac
+++ b/configure.ac
@@ -51,7 +51,7 @@ else
 fi
 # Checks for header files.
 AC_HEADER_MAJOR
-AC_CHECK_HEADERS([arpa/inet.h fcntl.h float.h langinfo.h libintl.h limits.h locale.h netinet/in.h stdint.h stdio_ext.h stdlib.h string.h sys/file.h sys/ioctl.h sys/param.h sys/time.h termios.h unistd.h utmp.h values.h wchar.h wctype.h])
+AC_CHECK_HEADERS([arpa/inet.h fcntl.h float.h langinfo.h libintl.h limits.h locale.h netinet/in.h stdint.h stdio_ext.h stdlib.h string.h sys/file.h sys/ioctl.h sys/param.h sys/time.h termios.h unistd.h utmp.h utmpx.h values.h wchar.h wctype.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_CHECK_HEADER_STDBOOL
diff --git a/w.c b/w.c
index 35710a3a..9d07ac9e 100644
--- a/w.c
+++ b/w.c
@@ -23,6 +23,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#include "config.h"
 #include "c.h"
 #include "fileutils.h"
 #include "nls.h"
@@ -54,14 +55,28 @@
 #include <termios.h>
 #include <time.h>
 #include <unistd.h>
-#include <utmp.h>
+#ifdef HAVE_UTMPX_H
+#	include <utmpx.h>
+#else
+#	include <utmp.h>
+#endif
 #include <arpa/inet.h>
 
 static int ignoreuser = 0;	/* for '-u' */
 static int oldstyle = 0;	/* for '-o' */
 static proc_t **procs;		/* our snapshot of the process table */
 
+#ifdef HAVE_UTMPX_H
+typedef struct utmpx utmp_t;
+#else
 typedef struct utmp utmp_t;
+#endif
+
+#if !defined(UT_HOSTSIZE) || defined(__UT_HOSTSIZE)
+#	define UT_HOSTSIZE __UT_HOSTSIZE
+#	define UT_LINESIZE __UT_LINESIZE
+#	define UT_NAMESIZE __UT_NAMESIZE
+#endif
 
 #ifdef W_SHOWFROM
 # define FROM_STRING "on"
@@ -412,7 +427,11 @@ static void showinfo(utmp_t * u, int formtype, int maxcmd, int from,
 		printf("%-*.*s%-9.8s", userlen + 1, userlen, uname, u->ut_line);
 		if (from)
 			print_from(u, ip_addresses, fromlen);
+#ifdef HAVE_UTMPX_H
+		print_logintime(u->ut_tv.tv_sec, stdout);
+#else
 		print_logintime(u->ut_time, stdout);
+#endif
 		if (*u->ut_line == ':')
 			/* idle unknown for xdm logins */
 			printf(" ?xdm? ");
@@ -604,11 +623,19 @@ int main(int argc, char **argv)
 			printf(_("   IDLE WHAT\n"));
 	}
 
+#ifdef HAVE_UTMPX_H
+	setutxent();
+#else
 	utmpname(UTMP_FILE);
 	setutent();
+#endif
 	if (user) {
 		for (;;) {
+#ifdef HAVE_UTMPX_H
+			u = getutxent();
+#else
 			u = getutent();
+#endif
 			if (unlikely(!u))
 				break;
 			if (u->ut_type != USER_PROCESS)
@@ -619,7 +646,11 @@ int main(int argc, char **argv)
 		}
 	} else {
 		for (;;) {
+#ifdef HAVE_UTMPX_H
+			u = getutxent();
+#else
 			u = getutent();
+#endif
 			if (unlikely(!u))
 				break;
 			if (u->ut_type != USER_PROCESS)
@@ -629,7 +660,11 @@ int main(int argc, char **argv)
 					 fromlen, ip_addresses);
 		}
 	}
+#ifdef HAVE_UTMPX_H
+	endutxent();
+#else
 	endutent();
+#endif
 
 	return EXIT_SUCCESS;
 }