loop.poll.c

UNIX环境高级编程第二版（英文版）配书的源代码

#include	"call.h"
#include	<poll.h>

#define	BUFFSIZE	512

/*
 * Copy everything from stdin to "remfd",
 * and everything from "remfd" to stdout.
 */
void
loop(int remfd)
{
	int				bol, n, nread;
	char			c;
	char			buff[BUFFSIZE];
	struct pollfd	fds[2];

	/*
	 * Set stdout unbuffered for printfs in take() and put().
	 */
	setbuf(stdout, NULL);
	fds[0].fd = STDIN_FILENO;	/* user's terminal input */
	fds[0].events = POLLIN;
	fds[1].fd = remfd;			/* input from remote (modem) */
	fds[1].events = POLLIN;

	for ( ; ; ) {
		if (poll(fds, 2, -1) <= 0)
			err_sys("poll error");
		if (fds[0].revents & POLLIN) {	/* data to read on stdin */
			if (read(STDIN_FILENO, &c, 1) != 1)
				err_sys("read error from stdin");
			if (c == escapec && bol) {
				if ((n = doescape(remfd)) < 0)
					break;		/* user wants to terminate */
				else if (n == 0)
					continue;	/* escape seq has been processed */

				/* else char following escape wasn't special, */
				/* so return and echo it below. */
				c = n;
			}
			if (c == '\r' || c == '\n')
				bol = 1;
			else
				bol = 0;
			if (write(remfd, &c, 1) != 1)
				err_sys("write error");
		}
		if (fds[0].revents & POLLHUP)
			break;		/* stdin hangup -> done */
		if (fds[1].revents & POLLIN) {	/* data to read from remote */
			if ((nread = read(remfd, buff, BUFFSIZE)) <= 0)
				break;		/* error or EOF, terminate */
			if (writen(STDOUT_FILENO, buff, nread) != nread)
				err_sys("writen error to stdout");
		}
		if (fds[1].revents & POLLHUP)
			break;		/* modem hangup -> done */
	}
}