last: optional alternative sysv-like implementation

(by Patricia Muscalu <patricia.muscalu AT axis.com>)

function                                             old     new   delta
last_main                                            448     917    +469
show_entry                                             -     319    +319
packed_usage                                       24216   24268     +52
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 840/0)             Total: 840 bytes

1 files changed, 283 insertions, 0 deletions

diff --git a/miscutils/last_fancy.c b/miscutils/last_fancy.c
new file mode 100644
index 0000000..0ad2b92
--- /dev/null
+++ b/miscutils/last_fancy.c
@@ -0,0 +1,283 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * (sysvinit like) last implementation
+ *
+ * Copyright (C) 2008 by Patricia Muscalu <patricia.muscalu@axis.com>
+ *
+ * Licensed under the GPLv2 or later, see the file LICENSE in this tarball.
+ */
+
+#define HEADER_FORMAT     "%-8.8s %-12.12s %-*.*s %-16.16s %-7.7s %-12.12s\n"
+#define HEADER_LINE       "USER", "TTY", \
+	INET_ADDRSTRLEN, INET_ADDRSTRLEN, "HOST", "LOGIN", "  TIME", ""
+#define HEADER_LINE_WIDE  "USER", "TTY", \
+	INET6_ADDRSTRLEN, INET6_ADDRSTRLEN, "HOST", "LOGIN", "  TIME", ""
+
+enum {
+	NORMAL,
+	LOGGED,
+	DOWN,
+	REBOOT,
+	CRASH,
+	GONE
+};
+
+enum {
+	LAST_OPT_W = (1 << 0),  /* -W wide            */
+	LAST_OPT_f = (1 << 1),  /* -f input file      */
+	LAST_OPT_H = (1 << 2),  /* -H header          */
+};
+
+#define show_wide (option_mask32 & LAST_OPT_W)
+
+static void show_entry(struct utmp *ut, int state, time_t dur_secs)
+{
+	unsigned days, hours, mins;
+	char duration[32];
+	char login_time[17];
+	char logout_time[8];
+	const char *logout_str;
+	const char *duration_str;
+
+	safe_strncpy(login_time, ctime(&(ut->ut_time)), 17);
+	snprintf(logout_time, 8, "- %s", ctime(&dur_secs) + 11);
+
+	dur_secs = MAX(dur_secs - (time_t)ut->ut_tv.tv_sec, (time_t)0);
+	/* unsigned int is easier to divide than time_t (which may be signed long) */
+	mins = dur_secs / 60;
+	days = mins / (24*60);
+	mins = mins % (24*60);
+	hours = mins / 60;
+	mins = mins % 60;
+
+	if (days) {
+		sprintf(duration, "(%u+%02u:%02u)", days, hours, mins);
+	} else {
+		sprintf(duration, " (%02u:%02u)", hours, mins);
+	}
+
+	logout_str = logout_time;
+	duration_str = duration;
+	switch (state) {
+	case NORMAL:
+		break;
+	case LOGGED:
+		logout_str = "  still";
+		duration_str = "logged in";
+		break;
+	case DOWN:
+		logout_str = "- down ";
+		break;
+	case REBOOT:
+		break;
+	case CRASH:
+		logout_str = "- crash";
+		break;
+	case GONE:
+		logout_str = "   gone";
+		duration_str = "- no logout";
+		break;
+	}
+
+	printf(HEADER_FORMAT,
+		   ut->ut_name,
+		   ut->ut_line,
+		   show_wide ? INET6_ADDRSTRLEN : INET_ADDRSTRLEN,
+		   show_wide ? INET6_ADDRSTRLEN : INET_ADDRSTRLEN,
+		   ut->ut_host,
+		   login_time,
+		   logout_str,
+		   duration_str);
+}
+
+static int get_ut_type(struct utmp *ut)
+{
+	if (ut->ut_line[0] == '~') {
+		if (strncmp(ut->ut_user, "shutdown", sizeof("shutdown")-1) == 0) {
+			return SHUTDOWN_TIME;
+		}
+		if (strncmp(ut->ut_user, "reboot", sizeof("reboot")-1) == 0) {
+			return BOOT_TIME;
+		}
+		if (strncmp(ut->ut_user, "runlevel", sizeof("runlevel")-1) == 0) {
+			return RUN_LVL;
+		}
+		return ut->ut_type;
+	}
+
+	if (ut->ut_name[0] == 0) {
+		return DEAD_PROCESS;
+	}
+
+	if ((ut->ut_type != DEAD_PROCESS)
+	 && (strcmp(ut->ut_name, "LOGIN") != 0)
+	 && ut->ut_name[0]
+	 && ut->ut_line[0]
+	) {
+		ut->ut_type = USER_PROCESS;
+	}
+
+	if (strcmp(ut->ut_name, "date") == 0) {
+		if (ut->ut_line[0] == '|') {
+			return OLD_TIME;
+		}
+		if (ut->ut_line[0] == '{') {
+			return NEW_TIME;
+		}
+	}
+	return ut->ut_type;
+}
+
+static int is_runlevel_shutdown(struct utmp *ut)
+{
+	if (((ut->ut_pid & 255) == '0') || ((ut->ut_pid & 255) == '6')) {
+		return 1;
+	}
+
+	return 0;
+}
+
+int last_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int last_main(int argc ATTRIBUTE_UNUSED, char **argv)
+{
+	struct utmp ut;
+	const char *filename = _PATH_WTMP;
+	llist_t *zlist;
+	off_t pos;
+	time_t start_time;
+	time_t boot_time;
+	time_t down_time;
+	int file;
+	unsigned opt;
+	smallint going_down;
+	smallint boot_down;
+
+	opt = getopt32(argv, "Wf:" /* "H" */, &filename);
+#ifdef BUT_UTIL_LINUX_LAST_HAS_NO_SUCH_OPT
+	if (opt & LAST_OPT_H) {
+		/* Print header line */
+		if (opt & LAST_OPT_W) {
+			printf(HEADER_FORMAT, HEADER_LINE_WIDE);
+		} else {
+			printf(HEADER_FORMAT, HEADER_LINE);
+		}
+	}
+#endif
+
+	file = xopen(filename, O_RDONLY);
+	if (full_read(file, &ut, sizeof(ut)) != sizeof(ut)) {
+		struct stat st;
+		fstat(file, &st);
+		start_time = st.st_ctime;
+		goto exit;
+	}
+	start_time = ut.ut_time;
+
+	time(&down_time);
+	going_down = 0;
+	boot_down = NORMAL; /* 0 */
+	zlist = NULL;
+	boot_time = 0;
+	pos = 0;
+	for (;;) {
+		pos -= (off_t)sizeof(ut);
+		/* Bug? What if file changes size?
+		 * What if size is not a multiple of sizeof(ut)? */
+		if (lseek(file, pos, SEEK_END) < 0) {
+			/* Beyond the beginning of the file boundary =>
+			 * the whole file has been read. */
+			break;
+		}
+		if (full_read(file, &ut, sizeof(ut)) != sizeof(ut))
+			break;
+
+		switch (get_ut_type(&ut)) {
+		case SHUTDOWN_TIME:
+			down_time = ut.ut_time;
+			boot_down = DOWN;
+			going_down = 1;
+			break;
+		case RUN_LVL:
+			if (is_runlevel_shutdown(&ut)) {
+				down_time = ut.ut_time;
+				going_down = 1;
+				boot_down = DOWN;
+			}
+			break;
+		case BOOT_TIME:
+			strcpy(ut.ut_line, "system boot");
+			show_entry(&ut, REBOOT, down_time);
+			boot_down = CRASH;
+			going_down = 1;
+			break;
+		case DEAD_PROCESS:
+			if (!ut.ut_line[0]) {
+				break;
+			}
+			/* add_entry */
+			llist_add_to(&zlist, memcpy(xmalloc(sizeof(ut)), &ut, sizeof(ut)));
+			break;
+		case USER_PROCESS: {
+			int show;
+
+			if (!ut.ut_line[0]) {
+				break;
+			}
+			/* find_entry */
+			show = 1;
+			{
+				llist_t *el, *next;
+				for (el = zlist; el; el = next) {
+					struct utmp *up = (struct utmp *)el->data;
+					next = el->link;
+					if (strncmp(up->ut_line, ut.ut_line, UT_LINESIZE) == 0) {
+						if (show) {
+							show_entry(&ut, NORMAL, up->ut_time);
+							show = 0;
+						}
+						llist_unlink(&zlist, el);
+						free(el->data);
+						free(el);
+					}
+				}
+			}
+
+			if (show) {
+				int state = boot_down;
+
+				if (boot_time == 0) {
+					state = LOGGED;
+					/* Check if the process is alive */
+					if ((ut.ut_pid > 0)
+					 && (kill(ut.ut_pid, 0) != 0)
+					 && (errno == ESRCH)) {
+						state = GONE;
+					}
+				}
+				show_entry(&ut, state, boot_time);
+			}
+			/* add_entry */
+			llist_add_to(&zlist, memcpy(xmalloc(sizeof(ut)), &ut, sizeof(ut)));
+			break;
+		}
+		}
+
+		if (going_down) {
+			boot_time = ut.ut_time;
+			llist_free(zlist, free);
+			zlist = NULL;
+			going_down = 0;
+		}
+	}
+
+	if (ENABLE_FEATURE_CLEAN_UP) {
+		llist_free(zlist, free);
+	}
+
+ exit:
+	printf("\nwtmp begins %s", ctime(&start_time));
+
+	if (ENABLE_FEATURE_CLEAN_UP)
+		close(file);
+	fflush_stdout_and_exit(EXIT_SUCCESS);
+}