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Add a check for wtmp records which have invalid values for ut_time. Wtmp

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records with time==0 get "the time of the last valid record", while records
where time goes backwards (compared to the previous record) are skipped.
Also prints a message saying how many records were changed or skipped due
to these checks. Check was inspired by a simpler check in OpenBSD's version.

This is all meant to sidestep problems that Tillman Hodgson noticed with 'ac'
when running sparc64 with 64-bit time_t's.  The real problem is whatever is
creating wtmp records with ut_time==0, of course, but I have not yet figured
out what is doing that.

Reviewed by:	no screams from freebsd-sparc64 or bde
MFC after:	2 weeks
This commit is contained in:
Garance A Drosehn 2004-03-08 20:02:23 +00:00
parent c38a857969
commit e3b218cd7b
1 changed files with 64 additions and 12 deletions
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76
usr.sbin/ac/ac.c
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@ -510,21 +510,65 @@ ac(FILE *fp)
struct utmp_list *lp, *head = NULL;
struct utmp usr;
struct tm *ltm;
time_t secs;
int day = -1;
time_t prev_secs, secs, ut_timecopy;
int day, rfound, tchanged, tskipped;
day = -1;
prev_secs = 1; /* Minimum acceptable date == 1970 */
rfound = tchanged = tskipped = 0;
secs = 0;
while (fread((char *)&usr, sizeof(usr), 1, fp) == 1) {
rfound++;
/*
* The type of utmp.ut_time is not necessary type time_t, as
* it is explicitly defined as type int32_t. Copy the value
* for platforms where sizeof(time_t) != size(int32_t).
*/
ut_timecopy = _time32_to_time(usr.ut_time);
/*
* With sparc64 using 64-bit time_t's, there is some system
* routine which sets ut_time==0 (the high-order word of a
* 64-bit time) instead of a 32-bit time value. For those
* wtmp files, it is "more-accurate" to substitute the most-
* recent time found, instead of throwing away the entire
* record. While it is still just a guess, it is a better
* guess than throwing away a log-off record and therefore
* counting a session as if it continued to the end of the
* month, or the next system-reboot.
*/
if (ut_timecopy == 0 && prev_secs > 1) {
#ifdef DEBUG
if (Debug)
printf("%s - date changed to: %s",
debug_pfx(&usr, &usr), ctime(&prev_secs));
#endif
tchanged++;
usr.ut_time = ut_timecopy = prev_secs;
}
/*
* Skip records where the time goes backwards.
*/
if (ut_timecopy < prev_secs) {
#ifdef DEBUG
if (Debug)
printf("%s - bad date, record skipped\n",
debug_pfx(&usr, &usr));
#endif
tskipped++;
continue; /* Skip this invalid record. */
}
prev_secs = ut_timecopy;
if (!FirstTime)
FirstTime = usr.ut_time;
FirstTime = ut_timecopy;
if (Flags & AC_D) {
time_t t = _int_to_time(usr.ut_time);
ltm = localtime(&t);
ltm = localtime(&ut_timecopy);
if (day >= 0 && day != ltm->tm_yday) {
day = ltm->tm_yday;
/*
* print yesterday's total
*/
secs = usr.ut_time;
secs = ut_timecopy;
secs -= ltm->tm_sec;
secs -= 60 * ltm->tm_min;
secs -= 3600 * ltm->tm_hour;
@ -534,10 +578,10 @@ ac(FILE *fp)
}
switch(*usr.ut_line) {
case '|':
secs = usr.ut_time;
secs = ut_timecopy;
break;
case '{':
secs -= usr.ut_time;
secs -= ut_timecopy;
/*
* adjust time for those logged in
*/
@ -546,7 +590,7 @@ ac(FILE *fp)
break;
case '~': /* reboot or shutdown */
head = log_out(head, &usr);
FirstTime = usr.ut_time; /* shouldn't be needed */
FirstTime = ut_timecopy; /* shouldn't be needed */
break;
default:
/*
@ -575,13 +619,13 @@ ac(FILE *fp)
(void)strcpy(usr.ut_line, "~");
if (Flags & AC_D) {
time_t t = _int_to_time(usr.ut_time);
ltm = localtime(&t);
ut_timecopy = _time32_to_time(usr.ut_time);
ltm = localtime(&ut_timecopy);
if (day >= 0 && day != ltm->tm_yday) {
/*
* print yesterday's total
*/
secs = usr.ut_time;
secs = ut_timecopy;
secs -= ltm->tm_sec;
secs -= 60 * ltm->tm_min;
secs -= 3600 * ltm->tm_hour;
@ -600,6 +644,14 @@ ac(FILE *fp)
show_users(Users);
show("total", Total);
}
if (tskipped > 0)
printf("(Skipped %d of %d records due to invalid time values)\n",
tskipped, rfound);
if (tchanged > 0)
printf("(Changed %d of %d records to have a more likely time value)\n",
tchanged, rfound);
return 0;
}