port/stdio/fgets.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 <stdio.h>
#include <memory.h>
#include <errno.h>
#include <thread.h>
#include <synch.h>
#include <sys/types.h>
#include "stdiom.h"
#include "mse.h"

/* read size-max line from stream, including '\n' */
char *
fgets(char *buf, int size, FILE *iop)
{
    char *ptr = buf;
    int n;
    Uchar *bufend;
    char *p;
    rmutex_t *lk;

    FLOCKFILE(lk, iop);

    _SET_ORIENTATION_BYTE(iop);

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

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

    size--;     /* room for '\0' */
    while (size > 0) {
        /* empty buffer */
        if (iop->_cnt <= 0) {
            if (__filbuf(iop) != EOF) {
                iop->_ptr--;    /* put back the character */
                iop->_cnt++;
            } else if (ptr == buf) {  /* never read anything */
                FUNLOCKFILE(lk);
                return (NULL);
            } else
                break;      /* nothing left to read */
        }
        n = (int)(size < iop->_cnt ? size : iop->_cnt);
        if ((p = memccpy(ptr, (char *)iop->_ptr, '\n',
            (size_t)n)) != NULL)
            n = (int)(p - ptr);
        ptr += n;
        iop->_cnt -= n;
        iop->_ptr += n;
        if (_needsync(iop, bufend))
            _bufsync(iop, bufend);
        if (p != NULL)
            break; /* newline found */
        size -= n;
    }
    FUNLOCKFILE(lk);
    *ptr = '\0';
    return (buf);
}