Ultrix-3.1/src/libc/stdio/gets.c

/**********************************************************************
 *   Copyright (c) Digital Equipment Corporation 1984, 1985, 1986.    *
 *   All Rights Reserved. 					      *
 *   Reference "/usr/src/COPYRIGHT" for applicable restrictions.      *
 **********************************************************************/

/*
 * SCCSID: @(#)gets.c	3.0	4/22/86
 */
/*	(System 5)  gets.c	3.3	*/
/*LINTLIBRARY*/

/*
 * This version reads directly from the buffer rather than looping on getc.
 * Ptr args aren't checked for NULL because the program would be a
 * catastrophic mess anyway.  Better to abort than just to return NULL.
 */
#include <stdio.h>
#include "stdiom.h"

extern int _filbuf();
extern _bufsync();
extern char *memccpy();

char *
gets(ptr)
char *ptr;
{
	char *p, *ptr0 = ptr;
	register int n;

	for ( ; ; ) {
		if (stdin->_cnt <= 0) { /* empty buffer */
			if (_filbuf(stdin) == EOF) {
				if (ptr0 == ptr)
					return (NULL);
				break; /* no more data */
			}
			stdin->_ptr--;
			stdin->_cnt++;
		}
		n = stdin->_cnt;
		if ((p = memccpy(ptr, (char *) stdin->_ptr, '\n', n)) != NULL)
			n = p - ptr;
		ptr += n;
		stdin->_cnt -= n;
		stdin->_ptr += n;
		_BUFSYNC(stdin);
		if (p != NULL) { /* found '\n' in buffer */
			ptr--; /* step back over '\n' */
			break;
		}
	}
	*ptr = '\0';
	return (ptr0);
}