/* $begin common.c */

#include "common.h"


/*********************************************************************
 * The Rio package - robust I/O functions
 **********************************************************************/
/*
 * rio_readn - robustly read n bytes (unbuffered)
 */
/* $begin rio_readn */
ssize_t rio_readn(int fd, void *usrbuf, size_t n) 
{
    size_t nleft = n;
    ssize_t nread;
    char *bufp = usrbuf;

    while (nleft > 0) {
	if ((nread = read(fd, bufp, nleft)) < 0) {
	    if (errno == EINTR) /* interrupted by sig handler return */
		nread = 0;      /* and call read() again */
	    else
		return -1;      /* errno set by read() */ 
	} 
	else if (nread == 0)
	    break;              /* EOF */
	nleft -= nread;
	bufp += nread;
    }
    return (n - nleft);         /* return >= 0 */
}
/* $end rio_readn */

/*
 * rio_writen - robustly write n bytes (unbuffered)
 */
/* $begin rio_writen */
ssize_t rio_writen(int fd, void *usrbuf, size_t n) 
{
    size_t nleft = n;
    ssize_t nwritten;
    char *bufp = usrbuf;

    while (nleft > 0) {
	if ((nwritten = write(fd, bufp, nleft)) <= 0) {
	    if (errno == EINTR)  /* interrupted by sig handler return */
		nwritten = 0;    /* and call write() again */
	    else
		return -1;       /* errorno set by write() */
	}
	nleft -= nwritten;
	bufp += nwritten;
    }
    return n;
}
/* $end rio_writen */


/* 
 * rio_read - This is a wrapper for the Unix read() function that
 *    transfers min(n, rio_cnt) bytes from an internal buffer to a user
 *    buffer, where n is the number of bytes requested by the user and
 *    rio_cnt is the number of unread bytes in the internal buffer. On
 *    entry, rio_read() refills the internal buffer via a call to
 *    read() if the internal buffer is empty.
 */
/* $begin rio_read */
static ssize_t rio_read(rio_t *rp, char *usrbuf, size_t n)
{
    int cnt;

    while (rp->rio_cnt <= 0) {  /* refill if buf is empty */
	rp->rio_cnt = read(rp->rio_fd, rp->rio_buf, 
			   sizeof(rp->rio_buf));
	if (rp->rio_cnt < 0) {
	    if (errno != EINTR) /* interrupted by sig handler return */
		return -1;
	}
	else if (rp->rio_cnt == 0)  /* EOF */
	    return 0;
	else 
	    rp->rio_bufptr = rp->rio_buf; /* reset buffer ptr */
    }

    /* Copy min(n, rp->rio_cnt) bytes from internal buf to user buf */
    cnt = n;          
    if (rp->rio_cnt < n)   
	cnt = rp->rio_cnt;
    memcpy(usrbuf, rp->rio_bufptr, cnt);
    rp->rio_bufptr += cnt;
    rp->rio_cnt -= cnt;
    return cnt;
}
/* $end rio_read */

/*
 * rio_readinitb - Associate a descriptor with a read buffer and reset buffer
 */
/* $begin rio_readinitb */
void rio_readinitb(rio_t *rp, int fd) 
{
    rp->rio_fd = fd;  
    rp->rio_cnt = 0;  
    rp->rio_bufptr = rp->rio_buf;
}
/* $end rio_readinitb */

/*
 * rio_readnb - Robustly read n bytes (buffered)
 */
/* $begin rio_readnb */
ssize_t rio_readnb(rio_t *rp, void *usrbuf, size_t n) 
{
    size_t nleft = n;
    ssize_t nread;
    char *bufp = usrbuf;
    
    while (nleft > 0) {
	if ((nread = rio_read(rp, bufp, nleft)) < 0) {
	    if (errno == EINTR) /* interrupted by sig handler return */
		nread = 0;      /* call read() again */
	    else
		return -1;      /* errno set by read() */ 
	} 
	else if (nread == 0)
	    break;              /* EOF */
	nleft -= nread;
	bufp += nread;
    }
    return (n - nleft);         /* return >= 0 */
}
/* $end rio_readnb */

/* 
 * rio_readlineb - robustly read a text line (buffered)
 */
/* $begin rio_readlineb */
ssize_t rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen) 
{
    int n, rc;
    char c, *bufp = usrbuf;

    for (n = 1; n < maxlen; n++) { 
	if ((rc = rio_read(rp, &c, 1)) == 1) {
	    *bufp++ = c;
	    if (c == '\n')
		break;
	} else if (rc == 0) {
	    if (n == 1)
		return 0; /* EOF, no data read */
	    else
		break;    /* EOF, some data was read */
	} else
	    return -1;	  /* error */
    }
    *bufp = 0;
    return n;
}
/* $end rio_readlineb */

/**********************************
 * Wrappers for robust I/O routines
 **********************************/


/******************************** 
 * Client/server helper functions
 ********************************/
/*
 * open_client_sock - open connection to server at <hostname, port> 
 *   and return a socket descriptor ready for reading and writing.
 *   Returns -1 and sets errno on Unix error. 
 *   Returns -2 and sets h_errno on DNS (gethostbyname) error.
 */
/* $begin open_client_sock */
int open_client_sock(char *hostname, int port) 
{
    int client_sock;
    struct hostent *hp;
    struct sockaddr_in serveraddr;

    if ((client_sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
	return -1; /* check errno for cause of error */

    /* Fill in the server's IP address and port */
    if ((hp = gethostbyname(hostname)) == NULL)
	return -2; /* check h_errno for cause of error */
    bzero((char *) &serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = AF_INET;
    bcopy((char *)hp->h_addr_list[0], 
	  (char *)&serveraddr.sin_addr.s_addr, hp->h_length);
    serveraddr.sin_port = htons(port);

    /* Establish a connection with the server */
    if (connect(client_sock, (SA *) &serveraddr, sizeof(serveraddr)) < 0)
	return -1;
    return client_sock;
}
/* $end open_client_sock */

/*  
 * open_listen_sock - open and return a listening socket on port
 *     Returns -1 and sets errno on Unix error.
 */
/* $begin open_listen_sock */
int open_listen_sock(int port) 
{
    int listen_sock, optval=1;
    struct sockaddr_in serveraddr;
  
    /* Create a socket descriptor */
    if ((listen_sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
	return -1;
 
    /* Eliminates "Address already in use" error from bind. */
    if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 
		   (const void *)&optval , sizeof(int)) < 0)
	return -1;

    /* Listen_sock will be an endpoint for all requests to port
       on any IP address for this host */
    bzero((char *) &serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = AF_INET; 
    serveraddr.sin_addr.s_addr = htonl(INADDR_ANY); 
    serveraddr.sin_port = htons((unsigned short)port); 
    if (bind(listen_sock, (SA *)&serveraddr, sizeof(serveraddr)) < 0)
	return -1;

    /* Make it a listening socket ready to accept connection requests */
    if (listen(listen_sock, LISTENQ) < 0)
	return -1;
    return listen_sock;
}
/* $end open_listen_sock */


/* $end wrapper.c */