clocksettime2

Clocksettime2 is a time-setting API referenced in some software environments to adjust a clock source within a system. It is commonly described as an enhanced variant of the POSIX clock_settime family, but it is not part of the official POSIX standard. Clocksettime2 may appear in vendor SDKs, embedded operating systems, or specialized libraries where precise time control is required.

The API typically accepts a clock identifier, such as a system realtime clock or a hardware clock, and a time value expressed in a timespec-like structure (seconds and nanoseconds). Depending on the implementation, it may support absolute time setting (jump to a specific timestamp) or relative adjustment (slew or step), controlled by additional flags or parameters.

Return semantics are usually straightforward: on success, the function returns zero; on error, it returns a negative value and sets an error indicator (errno). Common error codes include EPERM for insufficient privileges, EINVAL for unsupported clock IDs or invalid time values, and EOVERFLOW if the requested time is out of range.

Security and safety considerations are important, since altering clock values can affect scheduling, timers, and time-dependent protocols. Such calls typically require appropriate privileges and are used with care in multi-process or virtualized environments. In many systems, clock synchronization daemons or time services (such as NTP or chrony) coordinate time updates rather than exposing raw time-setting calls to generic applications.

See also: clock_settime, timespec, CLOCK_REALTIME, time synchronization, POSIX.