Add lastlog(8)

At the moment this does not work with ubase login(1).  We should
add support to login(1) to write the lastlog entries.

Minor modifications by sin.

LICENSE

@@ -8,6 +8,7 @@ MIT/X Consortium License
 © 2014 Carlos J. Torres <vlaadbrain@gmail.com>
 © 2014 Hiltjo Posthuma <hiltjo@codemadness.org>
 © 2014 Laslo Hunhold <dev@frign.de>
+© 2014 Roberto E. Vargas Caballero <k0ga@shike2.com>
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),

Makefile

@@ -33,6 +33,7 @@ LIB = \
 	util/tty.o
 
 SRC = \
+	lastlog.c           \
 	chvt.c              \
 	clear.c             \
 	ctrlaltdel.c        \
@@ -115,6 +116,7 @@ MAN8 = \
 	hwclock.8           \
 	insmod.8            \
 	killall5.8          \
+	lastlog.8           \
 	lsmod.8             \
 	lsusb.8             \
 	mkswap.8            \

lastlog.8

@@ -0,0 +1,11 @@
+.TH LASTLOG 8 ubase-VERSION
+.SH NAME
+\fBlastlog\fR - Show last login of users
+.SH SYPNOSIS
+\fBlastlog\fI [user ...]
+.SH DESCRIPTION
+\fBlastlog\fR Show time, tty, and host (if it was a remote
+connection) of last login of users. If some user names are passed
+as parameter then information about last login of these users is
+shown, otherwise is shown for all the users in /etc/passwd in the
+order they appear in it.

lastlog.c

@@ -0,0 +1,75 @@
+/* See LICENSE file for copyright and license details. */
+#include <paths.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <utmp.h>
+
+#define PASSWD   "/etc/passwd"
+
+static FILE *last;
+
+static void
+lastlog(char *user)
+{
+	struct passwd *pwd;
+	struct lastlog ll;
+	time_t lltime;
+
+	if ((pwd = getpwnam(user)) == NULL) {
+		fprintf(stderr, "unknown user: %s\n", user);
+		return;
+	}
+
+	fseek(last, pwd->pw_uid * sizeof(struct lastlog), 0);
+	fread(&ll, sizeof(struct lastlog), 1, last);
+
+	if (ferror(last)) {
+		perror("error reading lastlog");
+		exit(EXIT_FAILURE);
+	}
+
+	/* on glibc `ll_time' can be an int32_t with compat32
+	 * avoid compiler warning when calling ctime() */
+	lltime = ll.ll_time;
+	printf("%-8.8s %-8.8s %-16.16s %s",
+	       user, ll.ll_line, ll.ll_host, ctime(&lltime));
+}
+
+int
+main(int argc, char **argv)
+{
+	FILE *fp;
+	char line[512], *p;
+
+	if ((last = fopen(_PATH_LASTLOG, "r")) == NULL) {
+	    perror(_PATH_LASTLOG);
+	    exit(EXIT_FAILURE);
+	}
+
+	if (argc > 1) {
+		while (*++argv)
+			lastlog(*argv);
+	} else {
+		if ((fp = fopen(PASSWD, "r")) == NULL) {
+			perror(PASSWD);
+			exit(EXIT_FAILURE);
+		}
+		while ((fgets(line, sizeof(line), fp)) != NULL) {
+			if ((p = strchr(line, ':')) == NULL) {
+				fputs("incorrect password file", stderr);
+				exit(-1);
+			}
+			*p = '\0';
+			lastlog(line);
+		}
+		if (fclose(fp))
+			perror(PASSWD);
+	}
+
+	fclose(last);
+
+	return EXIT_SUCCESS;
+}