usr/src/lib/libc/gen/seekdir.c

/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)seekdir.c 4.7 11/14/82";

#include <sys/param.h>
#include <dir.h>

/*
 * seek to an entry in a directory.
 * Only values returned by ``telldir'' should be passed to seekdir.
 */
void
seekdir(dirp, loc)
        register DIR *dirp;
        long loc;
{
        long curloc, base, offset;
        struct direct *dp;

        curloc = telldir(dirp);
        if (loc == curloc)
                return;
        base = loc & ~(DIRBLKSIZ - 1);
        offset = loc & (DIRBLKSIZ - 1);
        if (dirp->dd_loc != 0 && (curloc & ~(DIRBLKSIZ - 1)) == base) {
                dirp->dd_loc = offset;
                return;
        }
        lseek(dirp->dd_fd, base, 0);
        dirp->dd_loc = 0;
        while (dirp->dd_loc < offset) {
                dp = readdir(dirp);
                if (dp == NULL)
                        return;
        }
}