ccan/ccan/io/_info

#include <stdio.h>
#include <string.h>
#include "config.h"

/**
 * io - simple library for stateful io handling.
 *
 * io provides a simple mechanism to write I/O servers with multiple
 * connections.  Handling of connections is multiplexed, and function
 * indicate what they want written or read, and what follow-on
 * function to call on success (or failure).
 *
 * Example:
 * // Given tr A-Z a-z outputs tr a-z a-z
 * #include <ccan/io/io.h>
 * #include <ccan/err/err.h>
 * #include <assert.h>
 * #include <stdlib.h>
 * #include <signal.h>
 * #include <sys/types.h>
 * #include <sys/wait.h>
 *
 * struct buffer {
 * 	size_t max, off, rlen;
 * 	char *buf;
 * };
 *
 * struct stdin_buffer {
 * 	struct io_conn *reader, *writer;
 * 	size_t len;
 * 	char inbuf[4096];
 * };
 *
 * // This reads from stdin.
 * static struct io_plan *wake_writer(struct io_conn *, struct stdin_buffer *);
 * // This writes the stdin buffer to the child.
 * static struct io_plan *write_to_child(struct io_conn *c,
 *					 struct stdin_buffer *b);
 * static struct io_plan *read_stdin(struct io_conn *c, struct stdin_buffer *b)
 * {
 * 	assert(c == b->reader);
 * 	b->len = sizeof(b->inbuf);
 * 	return io_read_partial(b->inbuf, &b->len,
 *			       io_next(c, wake_writer, b));
 * }
 *
 * static struct io_plan *wake_writer(struct io_conn *c, struct stdin_buffer *b)
 * {
 * 	assert(c == b->reader);
 * 	io_wake(b->writer, write_to_child, b);
 * 	return io_idle(c);
 * }
 *
 * static void reader_exit(struct io_conn *c, struct stdin_buffer *b)
 * {
 * 	assert(c == b->reader);
 * 	io_wake(b->writer, write_to_child, b);
 * 	b->reader = NULL;
 * }
 *
 * static struct io_plan *wake_reader(struct io_conn *c, struct stdin_buffer *b)
 * {
 * 	assert(c == b->writer);
 * 	io_wake(b->reader, read_stdin, b);
 * 	return io_idle(c);
 * }
 *
 * static struct io_plan *write_to_child(struct io_conn *conn,
 * 				        struct stdin_buffer *b)
 * {
 * 	assert(conn == b->writer);
 * 	if (!b->reader)
 * 		return io_close(conn, NULL);
 * 	return io_write(b->inbuf, b->len, io_next(conn, wake_reader, b));
 * }
 *
 * static struct io_plan *start_writer(struct io_conn *conn,
 * 				       struct stdin_buffer *b)
 * {
 * 	assert(conn == b->writer);
 * 	return io_idle(conn);
 * }
 *
 * static void fail_child_write(struct io_conn *conn, struct stdin_buffer *b)
 * {
 * 	if (b->reader)
 * 		err(1, "Failed writing to child.");
 * }
 *
 * // This reads from the child and saves it into buffer.
 * static struct io_plan *read_from_child(struct io_conn *conn,
 *					  struct buffer *b)
 * {
 * 	b->off += b->rlen;
 *
 * 	if (b->off == b->max) {
 * 		if (b->max == 0)
 * 			b->max = 128;
 * 		else if (b->max >= 1024*1024)
 * 			b->max += 1024*1024;
 * 		else
 * 			b->max *= 2;
 * 		b->buf = realloc(b->buf, b->max);
 * 	}
 *
 * 	b->rlen = b->max - b->off;
 * 	return io_read_partial(b->buf + b->off, &b->rlen,
 *			       io_next(conn, read_from_child, b));
 * }
 *
 * // Feed a program our stdin, gather its stdout, print that at end.
 * int main(int argc, char *argv[])
 * {
 * 	int tochild[2], fromchild[2];
 * 	struct buffer out = { 0, 0, 0, NULL };
 * 	struct stdin_buffer sbuf;
 * 	int status;
 * 	size_t off;
 * 	ssize_t ret;
 *
 * 	if (argc == 1)
 * 		errx(1, "Usage: runner <cmdline>...");
 *
 * 	if (pipe(tochild) != 0 || pipe(fromchild) != 0)
 * 		err(1, "Creating pipes");
 *
 * 	if (!fork()) {
 * 		// Child runs command.
 * 		close(tochild[1]);
 * 		close(fromchild[0]);
 *
 * 		dup2(tochild[0], STDIN_FILENO);
 * 		dup2(fromchild[1], STDOUT_FILENO);
 * 		execvp(argv[1], argv + 1);
 * 		exit(127);
 * 	}
 *
 * 	close(tochild[0]);
 * 	close(fromchild[1]);
 * 	signal(SIGPIPE, SIG_IGN);
 *
 * 	sbuf.reader = io_new_conn(STDIN_FILENO, read_stdin, reader_exit, &sbuf);
 * 	sbuf.writer = io_new_conn(tochild[1], start_writer, fail_child_write,
 * 				  &sbuf);
 * 	if (!sbuf.reader || !sbuf.writer
 * 	    || !io_new_conn(fromchild[0], read_from_child, NULL, &out))
 * 		err(1, "Allocating connections");
 *
 * 	io_loop();
 * 	wait(&status);
 *
 * 	for (off = 0; off < out.off; off += ret) {
 * 		ret = write(STDOUT_FILENO, out.buf+off, out.off-off);
 * 		if (ret < 0)
 * 			err(1, "Writing stdout");
 * 	}
 * 	free(out.buf);
 *
 * 	return WIFEXITED(status) ? WEXITSTATUS(status) : 2;
 * }
 *
 * License: LGPL (v2.1 or any later version)
 * Author: Rusty Russell <rusty@rustcorp.com.au>
 */
int main(int argc, char *argv[])
{
	if (argc != 2)
		return 1;

	if (strcmp(argv[1], "depends") == 0) {
		printf("ccan/time\n");
		printf("ccan/timer\n");
		return 0;
	}

	return 1;
}