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/* Licensed under LGPLv2.1+ - see LICENSE file for details */
#ifndef CCAN_IO_PLAN_H
#define CCAN_IO_PLAN_H
struct io_conn;
/**
* union io_plan_union - type for struct io_plan read/write fns.
*/
union io_plan_union {
char *cp;
void *vp;
const void *const_vp;
size_t s;
char c[sizeof(size_t)];
};
/**
* struct io_plan_arg - scratch space for struct io_plan read/write fns.
*/
struct io_plan_arg {
union io_plan_union u1, u2;
};
enum io_direction {
IO_IN,
IO_OUT
};
/**
* io_plan_arg - get a conn's io_plan_arg for a given direction.
* @conn: the connection.
* @dir: IO_IN or IO_OUT.
*
* This is how an io helper gets scratch space to store into; you must call
* io_set_plan() when you've initialized it.
*
* Example:
* #include <ccan/io/io_plan.h>
*
* // Simple helper to read a single char.
* static int do_readchar(int fd, struct io_plan_arg *arg)
* {
* return read(fd, arg->u1.cp, 1) <= 0 ? -1 : 1;
* }
*
* static struct io_plan *io_read_char_(struct io_conn *conn, char *in,
* struct io_plan *(*next)(struct io_conn*,void*),
* void *next_arg)
* {
* struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
*
* // Store information we need in the plan unions u1 and u2.
* arg->u1.cp = in;
*
* return io_set_plan(conn, IO_IN, do_readchar, next, next_arg);
* }
*/
struct io_plan_arg *io_plan_arg(struct io_conn *conn, enum io_direction dir);
/**
* io_set_plan - set a conn's io_plan.
* @conn: the connection.
* @dir: IO_IN or IO_OUT.
* @io: the IO function to call when the fd is ready.
* @next: the next callback when @io returns 1.
* @next_arg: the argument to @next.
*
* If @conn has debug set, the io function will be called immediately,
* so it's important that this be the last thing in your function!
*
* See also:
* io_get_plan_arg()
*/
struct io_plan *io_set_plan(struct io_conn *conn, enum io_direction dir,
int (*io)(int fd, struct io_plan_arg *arg),
struct io_plan *(*next)(struct io_conn *, void *),
void *next_arg);
#endif /* CCAN_IO_PLAN_H */
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