LOGIN_TIMES(3) FreeBSD Library Functions Manual LOGIN_TIMES(3)


parse_lt, in_lt, in_ltm, in_ltms, in_ltsfunctions for parsing and checking login time periods


System Utilities Library (libutil, -lutil)


#include < sys/types.h>
#include < time.h>
#include < login_cap.h>

parse_lt( const char *str);

in_lt( const login_time_t *lt, time_t *ends);

in_ltm( const login_time_t *lt, struct tm *t, time_t *ends);

in_ltms( const login_time_t *lt, struct tm *t, time_t *ends);

in_lts( const login_time_t *lt, time_t *ends);


This set of functions may be used for parsing and checking login and session times against a predefined list of allowed login times as used in login.conf(5).

The format of allowed and disallowed session times specified in the times.allow and times.deny capability fields in a login class are comprised of a prefix which specifies one or more 2- or 3-character day codes, followed by a start and end time in 24 hour format separated by a hyphen. Day codes may be concatenated together to select specific days, or the special mnemonics "Any" and "All" (for any/all days of the week), "Wk" for any day of the week (excluding Saturdays and Sundays) and "Wd" for any weekend day may be used.

For example, the following time period:


is interpreted as Monday, Thursday through Saturday between the hours of 2pm and 10pm.


means Saturday and Sunday, between the hours of 6am through 6pm, and


means any day of the week, between 4am and 4pm.

Note that all time periods reference system local time.

The parse_lt() function converts the ASCII representation of a time period into a structure of type login_time_t. This is defined as:

typedef struct login_time 
  u_short lt_start;   /* Start time */ 
  u_short lt_end;     /* End time */ 
  u_char lt_dow;     /* Days of week */ 
} login_time_t;

The lt_start and lt_end fields contain the number of minutes past midnight at which the described period begins and ends. The lt_dow field is a bit field, containing one bit for each day of the week and one bit unused. A series LTM_* macros may be used for testing bits individually and in combination. If no bits are set in this field - i.e., it contains the value LTM_NONE - then the entire period is assumed invalid. This is used as a convention to mark the termination of an array of login_time_t values. If parse_lt() returns a login_time_t with lt_dow equal to LTM_NONE then a parsing error was encountered.

The remaining functions provide the ability to test a given time_t or struct tm value against a specific time period or array of time periods. The in_ltm() function determines whether the given time described by the struct tm passed as the second parameter falls within the period described by the first parameter. A boolean value is returned, indicating whether or not the time specified falls within the period. If the time does fall within the time period, and the third parameter to the function is not NULL, the time at which the period ends relative to the time passed is returned.

The in_ltms() function is similar to in_ltm() except that the first parameter must be a pointer to an array of login_time_t objects, which is up to LC_MAXTIMES (64) elements in length, and terminated by an element with its lt_dow field set to LTM_NONE.

The in_lt() and in_lts() functions are equivalent to in_ltm() and in_ltms(), respectively, with the second argument set to the current time as returned by localtime(3).


The parse_lt() function returns a filled in structure of type login_time_t containing the parsed time period. If a parsing error occurs, the lt_dow field is set to LTM_NONE (i.e., 0).

The in_ltm() function returns non-zero if the given time falls within the period described by the login_time_t passed as the first parameter.

The in_ltms() function returns the index of the first time period found in which the given time falls, or -1 if none of them apply.

October 20, 2008 FreeBSD