NAME

       IV_FD_PUMP_INIT,  iv_fd_pump_init,  iv_fd_pump_destroy,  iv_fd_pump_pump,  iv_fd_pump_is_done - pump data
       between file descriptors

SYNOPSIS

       #include <iv_fd_pump.h>

       struct iv_fd_pump {
               int             from_fd;
               int             to_fd;
               void            *cookie;
               void            (*set_bands)(void *cookie, int pollin, int pollout);
               unsigned int    flags;
       };

       void IV_FD_PUMP_INIT(struct iv_fd_pump *this);
       void iv_fd_pump_init(struct iv_fd_pump *this);
       void iv_fd_pump_destroy(struct iv_fd_pump *this);
       int iv_fd_pump_pump(struct iv_fd_pump *this);
       int iv_fd_pump_is_done(const struct iv_fd_pump *this);

DESCRIPTION

       iv_fd_pump provides a way for moving data between two file descriptors.

       To set up iv_fd_pump for moving data, call IV_FD_PUMP_INIT on a struct iv_fd_pump  object,  fill  in  the
       ->from_fd,  ->to_fd,  ->cookie,  ->set_bands  and  ->flags  members, and then call iv_fd_pump_init on the
       object.

       Conversely, to destroy a struct iv_fd_pump object, call iv_fd_pump_destroy.  There are no restrictions on
       when this function can be called.

       A  call  to  iv_fd_pump_pump  will  attempt to move data from ->from_fd to ->to_fd via an internal buffer
       associated with the struct iv_fd_pump object.

       During calls to iv_fd_pump_init, iv_fd_pump_destroy and iv_fd_pump_pump, the callback function  specified
       by  ->set_bands may be invoked (with ->cookie as its first argument), by which iv_fd_pump indicates under
       which circumstances it wishes for future invocations of iv_fd_pump_pump to be done.

       If the pollin argument to ->set_bands is true, there is space left in the internal buffer  (and  we  have
       not  yet seen an end-of-file condition on input), and so you should call iv_fd_pump_pump again when there
       is a POLLIN condition on ->from_fd.

       If the pollout argument to ->set_bands is true, there is data in the internal buffer that could  not  all
       be transferred to ->to_fd, and so you should call iv_fd_pump_pump again when there is a POLLOUT condition
       on ->to_fd.

       If IV_FD_PUMP_FLAG_RELAY_EOF is set in ->flags, iv_fd_pump_pump will call  shutdown(2)  on  ->to_fd  with
       SHUT_WR as its second argument upon seeing an end-of-file condition on ->from_fd (but only after all data
       from the internal buffer has been drained into ->to_fd first).

       iv_fd_pump_pump will return -1 if there was an error, 0 if we're done pumping data (meaning that an  end-
       of-file condition was seen on the input file descriptor and that all data in the internal buffer has been
       drained into the output file descriptor), or 1 if there is more data left to be pumped.

       iv_fd_pump_is_done will return a true value if iv_fd_pump_pump has previously returned  0,  otherwise  it
       will return false.

       Internally, iv_fd_pump_pump will use splice(2) if it is available, otherwise it will fall back to read(2)
       and write(2).

SEE ALSO

       ivykis(3), splice(2)