port/gen/readdir.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   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

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

/*
 * readdir -- C library extension routine
 */

#include    <sys/feature_tests.h>

#if !defined(_LP64)
#pragma weak _readdir64 = readdir64
#endif
#pragma weak _readdir = readdir

#include "lint.h"
#include <dirent.h>
#include <limits.h>
#include <errno.h>
#include "libc.h"

#ifdef _LP64

dirent_t *
readdir(DIR *dirp)
{
    dirent_t *dp;   /* -> directory data */
    int saveloc = 0;

    if (dirp->dd_size != 0) {
        dp = (dirent_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc];
        saveloc = dirp->dd_loc;     /* save for possible EOF */
        dirp->dd_loc += (int)dp->d_reclen;
    }
    if (dirp->dd_loc >= dirp->dd_size)
        dirp->dd_loc = dirp->dd_size = 0;

    if (dirp->dd_size == 0 &&   /* refill buffer */
        (dirp->dd_size = getdents(dirp->dd_fd,
        (dirent_t *)(uintptr_t)dirp->dd_buf, DIRBUF)) <= 0) {
        if (dirp->dd_size == 0)     /* This means EOF */
            dirp->dd_loc = saveloc; /* so save for telldir */
        return (NULL);      /* error or EOF */
    }

    return ((dirent_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc]);
}

#else   /* _LP64 */

/*
 * Welcome to the complicated world of large files on a small system.
 */

dirent64_t *
readdir64(DIR *dirp)
{
    dirent64_t *dp64;   /* -> directory data */
    int saveloc = 0;

    if (dirp->dd_size != 0) {
        dp64 = (dirent64_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc];
        /* was converted by readdir and needs to be reversed */
        if (dp64->d_ino == (ino64_t)-1) {
            dirent_t *dp32;

            dp32 = (dirent_t *)(&dp64->d_off);
            dp64->d_ino = (ino64_t)dp32->d_ino;
            dp64->d_off = (off64_t)dp32->d_off;
            dp64->d_reclen = (unsigned short)(dp32->d_reclen +
                ((char *)&dp64->d_off - (char *)dp64));
        }
        saveloc = dirp->dd_loc;     /* save for possible EOF */
        dirp->dd_loc += (int)dp64->d_reclen;
    }
    if (dirp->dd_loc >= dirp->dd_size)
        dirp->dd_loc = dirp->dd_size = 0;

    if (dirp->dd_size == 0 &&   /* refill buffer */
        (dirp->dd_size = getdents64(dirp->dd_fd,
        (dirent64_t *)(uintptr_t)dirp->dd_buf, DIRBUF)) <= 0) {
        if (dirp->dd_size == 0)     /* This means EOF */
            dirp->dd_loc = saveloc; /* so save for telldir */
        return (NULL);      /* error or EOF */
    }

    dp64 = (dirent64_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc];
    return (dp64);
}

/*
 * readdir now does translation of dirent64 entries into dirent entries.
 * We rely on the fact that dirents are smaller than dirent64s and we
 * reuse the space accordingly.
 */
dirent_t *
readdir(DIR *dirp)
{
    dirent64_t *dp64;   /* -> directory data */
    dirent_t *dp32;     /* -> directory data */

    if ((dp64 = readdir64(dirp)) == NULL)
        return (NULL);

    /*
     * Make sure that the offset fits in 32 bits.
     */
    if (((off_t)dp64->d_off != dp64->d_off &&
        (uint64_t)dp64->d_off > (uint64_t)UINT32_MAX) ||
        dp64->d_ino > SIZE_MAX) {
        errno = EOVERFLOW;
        return (NULL);
    }

    dp32 = (dirent_t *)(&dp64->d_off);
    dp32->d_off = (off_t)dp64->d_off;
    dp32->d_ino = (ino_t)dp64->d_ino;
    dp32->d_reclen = (unsigned short)(dp64->d_reclen -
        ((char *)&dp64->d_off - (char *)dp64));
    dp64->d_ino = (ino64_t)-1;  /* flag as converted for readdir64 */
    /* d_name d_reclen should not move */
    return (dp32);
}
#endif  /* _LP64 */