Import who from sbase

Makefile

@@ -48,7 +48,8 @@ SRC = \
 	umount.c            \
 	unshare.c           \
 	uptime.c            \
-	watch.c
+	watch.c             \
+	who.c
 
 MAN1 = \
 	chvt.1              \

who.1

@@ -0,0 +1,27 @@
+.TH WHO 1 sbase\-VERSION
+.SH NAME
+who \- print who has logged on
+.SH SYNOPSIS
+.B who
+.RB [ -m ]
+
+.SH DESCRIPTION
+.B who
+prints a list of who has logged on, their controlling tty, and the
+time at which they logged on.
+.SH OPTIONS
+.TP
+.B \-m
+only show users on current tty
+.TP
+.B \-l
+also print LOGIN processes
+
+.SH BUGS
+.B who
+relies on the utmp file to be updated responsibly. This
+doesn't always happen, which can cause who to print completely
+bogus data.
+
+.SH SEE ALSO
+.IR utmp (5)

who.c

@@ -0,0 +1,63 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <time.h>
+#include <utmp.h>
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: who [-ml]\n");
+}
+
+int
+main(int argc, char **argv)
+{
+	struct utmp usr;
+	FILE *ufp;
+	char timebuf[sizeof "yyyy-mm-dd hh:mm"];
+	char *tty, *ttmp;
+	int mflag = 0, lflag = 0;
+	time_t t;
+
+	ARGBEGIN {
+	case 'm':
+		mflag = 1;
+		tty = ttyname(STDIN_FILENO);
+		if (!tty)
+			eprintf("who: stdin:");
+		if ((ttmp = strrchr(tty, '/')))
+			tty = ttmp+1;
+		break;
+	case 'l':
+		lflag = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc > 0)
+		usage();
+
+	if (!(ufp = fopen("/var/run/utmp", "r")))
+		eprintf("who: '%s':", "/var/run/utmp");
+
+	while(fread(&usr, sizeof(usr), 1, ufp) == 1) {
+		if (!*usr.ut_name || !*usr.ut_line ||
+		    usr.ut_line[0] == '~')
+			continue;
+		if (mflag && strcmp(usr.ut_line, tty))
+			continue;
+		if (strcmp(usr.ut_name, "LOGIN") == lflag)
+			continue;
+		t = usr.ut_time;
+		strftime(timebuf, sizeof timebuf, "%Y-%m-%d %H:%M", localtime(&t));
+		printf("%-8s %-12s %-16s\n", usr.ut_name, usr.ut_line, timebuf);
+	}
+	fclose(ufp);
+	return EXIT_SUCCESS;
+}
+