iv_fd_pump(3) ivykis programmer's manual iv_fd_pump(3)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 pre‐
viously returned 0, otherwise it will return false.
Internally, iv_fd_pump_pump will use splice(2) if it is available, oth‐
erwise it will fall back to read(2) and write(2).
SEE ALSOivykis(3), splice(2)ivykis 2012-06-05 iv_fd_pump(3)
