Reimplements users(1) in C++.

This reduces the lines of code by roughly 50% (not counting the COPYRIGHT
header) and makes it more readable by using standard algorithms.

Approved by:	bapt

2 files changed, 26 insertions, 65 deletions

diff --git a/usr.bin/users/Makefile b/usr.bin/users/Makefile
index 3d6524b..29b5983 100644
--- a/usr.bin/users/Makefile
+++ b/usr.bin/users/Makefile
@@ -1,6 +1,7 @@
 #	@(#)Makefile	8.1 (Berkeley) 6/6/93
 # $FreeBSD$
 
-PROG=	users
+WARNS=		3
+PROG_CXX=	users
 
 .include <bsd.prog.mk>
diff --git a/usr.bin/users/users.c b/usr.bin/users/users.cc
index e0d04e7..ef64a9f 100644
--- a/usr.bin/users/users.c
+++ b/usr.bin/users/users.cc
@@ -1,6 +1,6 @@
 /*
- * Copyright (c) 1980, 1987, 1993
- *	The Regents of the University of California.  All rights reserved.
+ * Copyright (c) 2014 Pietro Cerutti <gahr@FreeBSD.org>
+ * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -27,83 +27,43 @@
  * SUCH DAMAGE.
  */
 
-#ifndef lint
-static const char copyright[] =
-"@(#) Copyright (c) 1980, 1987, 1993\n\
-	The Regents of the University of California.  All rights reserved.\n";
-#endif /* not lint */
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
 
-#ifndef lint
-#if 0
-static char sccsid[] = "@(#)users.c	8.1 (Berkeley) 6/6/93";
-#endif
-static const char rcsid[] =
-  "$FreeBSD$";
-#endif /* not lint */
-
-#include <sys/param.h>
-#include <sys/types.h>
-#include <err.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
 #include <utmpx.h>
 
-typedef char namebuf[sizeof(((struct utmpx *)0)->ut_user) + 1];
-typedef int (*scmp)(const void *, const void *);
-
-static void usage(void);
+#include <algorithm>
+#include <iostream>
+#include <iterator>
+#include <string>
+#include <vector>
+using namespace std;
 
 int
-main(int argc, char **argv)
+main(int argc, char **)
 {
-	namebuf *names = NULL;
-	int ncnt = 0;
-	int nmax = 0;
-	int cnt;
 	struct utmpx *ut;
-	int ch;
+	vector<string> names;
 
-	while ((ch = getopt(argc, argv, "")) != -1)
-		switch(ch) {
-		case '?':
-		default:
-			usage();
-		}
-	argc -= optind;
-	argv += optind;
+	if (argc > 1) {
+		cerr << "usage: users" << endl;
+		return (1);
+	}
 
 	setutxent();
 	while ((ut = getutxent()) != NULL) {
 		if (ut->ut_type != USER_PROCESS)
 			continue;
-		if (ncnt >= nmax) {
-			nmax += 32;
-			names = realloc(names, sizeof(*names) * nmax);
-			if (!names) {
-				errx(1, "realloc");
-				/* NOTREACHED */
-			}
-		}
-		strlcpy(names[ncnt], ut->ut_user, sizeof(*names));
-		++ncnt;
+		names.push_back(ut->ut_user);
 	}
 	endutxent();
-	if (ncnt > 0) {
-		qsort(names, ncnt, sizeof(*names), (scmp)strcmp);
-		printf("%s", names[0]);
-		for (cnt = 1; cnt < ncnt; ++cnt)
-			if (strcmp(names[cnt], names[cnt - 1]) != 0)
-				printf(" %s", names[cnt]);
-		printf("\n");
+
+	if (names.size() == 0) {
+		return (0);
 	}
-	exit(0);
-}
 
-static void
-usage(void)
-{
-	fprintf(stderr, "usage: users\n");
-	exit(1);
+	sort(begin(names), end(names));
+	vector<string>::iterator last(unique(begin(names), end(names)));
+	copy(begin(names), last-1, ostream_iterator<string>(cout, " "));
+	cout << *(last-1) << endl;
 }