c/chrono/gmtime

@1@ Converts given time since epoch (a time_t value pointed to by ) into calendar time, expressed in Coordinated Universal Time (UTC) in the format. The result is stored in static storage and a pointer to that static storage is returned. @2@ Same as, except that the function uses user-provided storage for the result. @3@ Same as, except that the function uses user-provided storage for the result and that the following errors are detected at runtime and call the currently installed constraint handler function:
 * or is a null pointer

Return value
@1@ pointer to a static internal tm object on success, or null pointer otherwise. The structure may be shared between, localtime, and ctime and may be overwritten on each invocation. @2-3@ copy of the pointer, or null pointer on error (which may be a runtime constraint violation or a failure to convert the specified time to UTC)