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