/************************************************************
Program:		Socket I/0 functions
File:			sockio.cpp
Author:			Ryan Junee	- ryan@cs.usyd.edu.au
Version:		1.0
Date:			02/09/2001
Revisions:		1.0  02/09/2001 First Version

Defines a couple of socket IO functions.
**************************************************************/

#include "sockio.h"

/**
 * This function reads in a text line from a socket 1 byte at a time.
 * It comes from p79 of Stevens - Unix Network Programming.  It is used
 * because reading from sockets can be more delicate than normal File I/O.
 * @param fd The socket
 * @param vptr The buffer to fill
 * @param maxlen The maximum bytes that can be stored in the buffer
 * @return The number of bytes read.
 */
ssize_t readline(int fd, void *vptr, ssize_t maxlen) {
	ssize_t n, rc;
	char c, *ptr;

	ptr = (char *)vptr;
	for (n = 1; n < maxlen; n++) {
	  again:
		if ((rc = read(fd, &c, 1)) == 1) {
			*ptr++ = c;
			if (c == '\n')
				break;		/* newline is stored, like fgets() */
		} else if (rc == 0) {
			if (n == 1)
				return 0;	/* EOF, no data read */
			else
				break;		/* EOF, some data read */
		} else {
			if (errno == EINTR)
				goto again;
			return - 1;		/* error, errno set by read() */
		}
	}

	*ptr = 0;				/* null terminate like fgets() */
	return n;
}


/**
 * This function writes n bytes of text to the socket.  It comes from p78
 * of Stevens - Unix Network Programming.  It is used because writing to a
 * socket can be a bit more delicate than normal file I/O.
 * @param fd The socket
 * @param vptr The buffer to write
 * @param n The number of bytes to write
 * @return The number of bytes written.
 */
ssize_t writen(int fd, const void *vptr, size_t n) {
	size_t nleft;
	ssize_t nwritten;
	const char *ptr;

	ptr = (char *)vptr;
	nleft = n;
	while (nleft > 0) {
		if ((nwritten = write(fd, ptr, nleft)) <= 0) {
			if (errno == EINTR)
				nwritten = 0;	/* and call write() again */
			else
				return -1;		/* error */
		}
		nleft -= nwritten;
		ptr += nwritten;
	}

	return n;
}