port/stdio/gets.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1988 AT&T */
/*    All Rights Reserved   */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "lint.h"
#include "file64.h"
#include "mtlib.h"
#include <sys/types.h>
#include <stdio.h>
#include <memory.h>
#include <thread.h>
#include <synch.h>
#include <errno.h>
#include "stdiom.h"
#include "mse.h"

/* read a single line from stdin, replace the '\n' with '\0' */
char *
gets(char *buf)
{
    char *ptr = buf;
    ssize_t n;
    char *p;
    Uchar *bufend;
    rmutex_t *lk;

    FLOCKFILE(lk, stdin);

    _SET_ORIENTATION_BYTE(stdin);

    if (!(stdin->_flag & (_IOREAD | _IORW))) {
        errno = EBADF;
        FUNLOCKFILE(lk);
        return (0);
    }

    if (stdin->_base == NULL) {
        if ((bufend = _findbuf(stdin)) == 0) {
            FUNLOCKFILE(lk);
            return (0);
        }
    }
    else
        bufend = _bufend(stdin);

    for (;;)    /* until get a '\n' */
    {
        if (stdin->_cnt <= 0)   /* empty buffer */
        {
            if (__filbuf(stdin) != EOF) {
                stdin->_ptr--;  /* put back the character */
                stdin->_cnt++;
            } else if (ptr == buf) {  /* never read anything */
                FUNLOCKFILE(lk);
                return (0);
            } else
                break;      /* nothing left to read */
        }
        n = stdin->_cnt;
        if ((p = (char *)memccpy(ptr, (char *)stdin->_ptr, '\n',
            (size_t)n)) != 0)
            n = p - ptr;
        ptr += n;
        stdin->_cnt -= n;
        stdin->_ptr += n;
        if (_needsync(stdin, bufend))
            _bufsync(stdin, bufend);
        if (p != 0) /* found a '\n' */
        {
            ptr--;  /* step back over the '\n' */
            break;
        }
    }
    *ptr = '\0';
    FUNLOCKFILE(lk);
    return (buf);
}