DragonFly On-Line Manual Pages

Search: Section:  

iv_fd_pump(3)             ivykis programmer's manual             iv_fd_pump(3)


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


#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);


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).


ivykis(3), splice(2) ivykis 2012-06-05 iv_fd_pump(3)

Search: Section: