int adjtimex(struct timex *buf);
adjtimex takes a pointer to a timex structure, updates kernel parameters from field values, and returns the same structure with current kernel values. This structure is declared as follows:
struct timex { int mode; /* mode selector */ long offset; /* time offset (usec) */ long frequency; /* frequency offset (scaled ppm) */ long maxerror; /* maximum error (usec) */ long esterror; /* estimated error (usec) */ int status; /* clock command/status */ long time_constant; /* pll time constant */ long precision; /* clock precision (usec) (read only) */ long tolerance; /* clock frequency tolerance (ppm) (read only) */ struct timeval time; /* (read only) */ long tick; /* usecs between clock ticks */ };
The mode field determines which parameters, if any, to set. It may contain a bitwise-or combination of zero or more of the following bits:
#define ADJ_OFFSET 0x0001 /* time offset */ #define ADJ_FREQUENCY 0x0002 /* frequency offset */ #define ADJ_MAXERROR 0x0004 /* maximum time error */ #define ADJ_ESTERROR 0x0008 /* estimated time error */ #define ADJ_STATUS 0x0010 /* clock status */ #define ADJ_TIMECONST 0x0020 /* pll time constant */ #define ADJ_TICK 0x4000 /* tick value */ #define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */
Ordinary users are restricted to a zero value for
mode.
Only the superuser may set any parameters.
#define TIME_OK 0 /* clock synchronized */ #define TIME_INS 1 /* insert leap second */ #define TIME_DEL 2 /* delete leap second */ #define TIME_OOP 3 /* leap second in progress */ #define TIME_BAD 4 /* clock not synchronized */
On failure, adjtimex returns -1 and sets errno.