NAME

       IV_SIGNAL_INIT, iv_signal_register, iv_signal_unregister - ivykis signal handling

SYNOPSIS

       #include <iv_signal.h>

       struct iv_signal {
               int             signum;
               unsigned int    flags;
               void            *cookie;
               void            (*handler)(void *);
       };

       void IV_SIGNAL_INIT(struct iv_signal *this);
       int iv_signal_register(struct iv_signal *this);
       void iv_signal_unregister(struct iv_signal *this);

DESCRIPTION

       iv_signal provides a way for ivykis(3) applications to handle POSIX signals, by integrating them with the
       ivykis event loop.

       An ivykis application desiring signal  notification  registers  a  struct  iv_signal  object  by  calling
       iv_signal_register, after having initialised it with IV_SIGNAL_INIT and subsequently having filled in the
       ->signum, ->cookie and ->handler members.

       Once the signal indicated by ->signum is delivered to any thread in the  current  process,  the  callback
       specified  by  ->handler  is  scheduled  to  be called in the thread that the struct iv_signal object was
       registered in, with ->cookie as its sole argument.

       If the same signal arrives again while the callback function is still running, the callback  function  is
       guaranteed to be called again after it returns.

       It  is  permitted  to register multiple struct iv_signal objects for the same signal number.  If all such
       objects are registered with IV_SIGNAL_FLAG_EXCLUSIVE in ->flags unset, then all objects will  have  their
       callback functions called upon arrival of the signal, in no guaranteed order.

       Invoking  callback  functions stops at the first struct iv_signal object with IV_SIGNAL_FLAG_EXCLUSIVE in
       ->flags set, so that if all objects have IV_SIGNAL_FLAG_EXCLUSIVE set, only one callback function will be
       invoked.

       To  deinitialize  a  struct  iv_signal  object,  call  iv_signal_unregister  from  the  same  thread that
       iv_signal_register was called from on that object.

       It is permitted to unregister a struct iv_signal object from any ivykis callback function in  the  thread
       it was registered in, including from a callback function triggered by this object, and it is permitted to
       free the memory corresponding to an unregistered object from its own callback function.

       It is guaranteed that signals delivered to child processes that were created by fork(2) but that have not
       yet called execve(2) will not cause iv_signal callbacks to be invoked in the parent process.

       Internally, iv_signal is implemented using iv_event_raw(3).

SEE ALSO

       ivykis(3), iv_event_raw(3), sigaction(2)