[PATCH 0/2] some fixes last(1)

[PATCH 0/2] some fixes last(1)

[Ruediger Meier]

From: Ruediger Meier <ruediger.meier@ga-group.nl>

This is pull request #184 on github
https://github.com/karelzak/util-linux/pull/184

Ruediger Meier (2):
  last: fix first (current) runlevel line
  last, fix race when comparing time stamps

 login-utils/last.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

-- 
1.8.4.5

[PATCH 1/2] last: fix first (current) runlevel line

[Ruediger Meier]

From: Ruediger Meier <ruediger.meier@ga-group.nl>

Since 744c7fec lastrch was not set to current time anymore, but we need it.

 # broken:
 $ ./last -x | grep -m 2 runlevel
 runlevel (to lvl 5)   3.11.10-25-deskt Wed Feb 18 13:11 - 01:00 (-16484+-12:-11)
 runlevel (to lvl 5)   3.11.10-25-deskt Thu Jan 22 16:50 - 13:11 (26+20:21)

 # fixed:
 $ ./last -x | grep -m 2 runlevel
 runlevel (to lvl 5)   3.11.10-25-deskt Wed Feb 18 13:11   still running
 runlevel (to lvl 5)   3.11.10-25-deskt Thu Jan 22 16:50 - 13:11 (26+20:21)

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
---
 login-utils/last.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/login-utils/last.c b/login-utils/last.c
index 9682764..4a165c2 100644
--- a/login-utils/last.c
+++ b/login-utils/last.c
@@ -638,7 +638,7 @@ static void process_wtmp_file(const struct last_control *ctl,
 	/*
 	 * Fill in 'lastdate'
 	 */
-	lastdate = lastdown;
+	lastdate = lastrch = lastdown;
 
 	/*
 	 * Install signal handlers
-- 
1.8.4.5

[PATCH 2/2] last, fix race when comparing time stamps

[Ruediger Meier]

From: Ruediger Meier <ruediger.meier@ga-group.nl>

It is just luck if two time() calls happen within the same
second. Introduced in 31d28e09.

Actually I don't like adding another global variable but this
way we avoid bigger refactoring. IMO it's questionable why
lastdate, lastdown, etc. are initialized with current time() at
all. It looks unsafe to print "still running" always when
logout_time = now.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
---
 login-utils/last.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/login-utils/last.c b/login-utils/last.c
index 4a165c2..8d82c10 100644
--- a/login-utils/last.c
+++ b/login-utils/last.c
@@ -138,6 +138,7 @@ static struct last_timefmt timefmts[] = {
 /* Global variables */
 static unsigned int recsdone;	/* Number of records listed */
 static time_t lastdate;		/* Last date we've seen */
+static time_t currentdate;	/* date when we started processing the file */
 
 /* --time-format=option parser */
 static int which_time_format(const char *optarg)
@@ -372,7 +373,7 @@ static void trim_trailing_spaces(char *s)
  */
 static int list(const struct last_control *ctl, struct utmp *p, time_t logout_time, int what)
 {
-	time_t		secs, utmp_time, now;
+	time_t		secs, utmp_time;
 	char		logintime[LAST_TIMESTAMP_LEN];
 	char		logouttime[LAST_TIMESTAMP_LEN];
 	char		length[LAST_TIMESTAMP_LEN];
@@ -428,8 +429,7 @@ static int list(const struct last_control *ctl, struct utmp *p, time_t logout_ti
 	hours = (secs / 3600) % 24;
 	days  = secs / 86400;
 
-	now = time(NULL);
-	if (logout_time == now) {
+	if (logout_time == currentdate) {
 		if (ctl->time_fmt > LAST_TIMEFTM_SHORT_CTIME) {
 			sprintf(logouttime, "  still running");
 			length[0] = 0;
@@ -638,7 +638,7 @@ static void process_wtmp_file(const struct last_control *ctl,
 	/*
 	 * Fill in 'lastdate'
 	 */
-	lastdate = lastrch = lastdown;
+	lastdate = currentdate = lastrch = lastdown;
 
 	/*
 	 * Install signal handlers
-- 
1.8.4.5