port/gen/seekdir.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 (c) 1988, 2011, Oracle and/or its affiliates. All rights reserved.
 */

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

/*
 * seekdir -- C library extension routine
 */

#include    <sys/feature_tests.h>

#if !defined(_LP64)
#pragma weak _seekdir64 = seekdir64
#endif
#pragma weak _seekdir = seekdir

#include "lint.h"
#include "libc.h"
#include <mtlib.h>
#include <dirent.h>
#include <fcntl.h>
#include <unistd.h>

#ifdef _LP64

void
seekdir(DIR *dirp, long loc)
{
    private_DIR *pdirp = (private_DIR *)dirp;
    dirent_t    *dp;
    off_t       off = 0;

    lmutex_lock(&pdirp->d_lock);
    if (lseek(dirp->d_fd, 0, SEEK_CUR) != 0) {
        dp = (dirent_t *)(uintptr_t)&dirp->d_buf[dirp->d_loc];
        off = dp->d_off;
    }
    if (off != loc) {
        dirp->d_loc = 0;
        (void) lseek(dirp->d_fd, loc, SEEK_SET);
        dirp->d_size = 0;

        /*
         * Save seek offset in d_off field, in case telldir
         * follows seekdir with no intervening call to readdir
         */
        ((dirent_t *)(uintptr_t)&dirp->d_buf[0])->d_off = loc;
    }
    lmutex_unlock(&pdirp->d_lock);
}

#else   /* _LP64 */

/*
 * Note: Instead of making this function static, we reduce it to local
 * scope in the mapfile. That allows the linker to prevent it from
 * appearing in the .SUNW_dynsymsort section.
 */
void
seekdir64(DIR *dirp, off64_t loc)
{
    private_DIR *pdirp = (private_DIR *)(uintptr_t)dirp;
    dirent64_t  *dp64;
    off64_t     off = 0;

    lmutex_lock(&pdirp->d_lock);
    if (lseek64(dirp->d_fd, 0, SEEK_CUR) != 0) {
        dp64 = (dirent64_t *)(uintptr_t)&dirp->d_buf[dirp->d_loc];
        /* was converted by readdir and needs to be reversed */
        if (dp64->d_ino == (ino64_t)-1) {
            dirent_t *dp32;

            dp32 = (dirent_t *)((uintptr_t)dp64 + sizeof (ino64_t));
            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));
        }
        off = dp64->d_off;
    }
    if (off != loc) {
        dirp->d_loc = 0;
        (void) lseek64(dirp->d_fd, loc, SEEK_SET);
        dirp->d_size = 0;

        /*
         * Save seek offset in d_off field, in case telldir
         * follows seekdir with no intervening call to readdir
         */
        ((dirent64_t *)(uintptr_t)&dirp->d_buf[0])->d_off = loc;
    }
    lmutex_unlock(&pdirp->d_lock);
}

void
seekdir(DIR *dirp, long loc)
{
    seekdir64(dirp, (off64_t)(uint32_t)loc);
}

#endif  /* _LP64 */