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

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)readdir.c   5.4 (Berkeley) 6/18/88";
#endif /* LIBC_SCCS and not lint */

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

/*
 * get next entry in a directory.
 */
struct direct *
readdir(dirp)
        register DIR *dirp;
{
        register struct direct *dp;

        for (;;) {
                if (dirp->dd_loc == 0) {
                        dirp->dd_size = read(dirp->dd_fd, dirp->dd_buf,
                            DIRBLKSIZ);
                        if (dirp->dd_size <= 0)
                                return NULL;
                }
                if (dirp->dd_loc >= dirp->dd_size) {
                        dirp->dd_loc = 0;
                        continue;
                }
                dp = (struct direct *)(dirp->dd_buf + dirp->dd_loc);
                if ((int)dp & 03)       /* bogus pointer check */
                        return NULL;
                if (dp->d_reclen <= 0 ||
                    dp->d_reclen > DIRBLKSIZ + 1 - dirp->dd_loc)
                        return NULL;
                dirp->dd_loc += dp->d_reclen;
                if (dp->d_ino == 0)
                        continue;
                return (dp);
        }
}