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      1 /*	$NetBSD: opendir.c,v 1.4 2003/08/07 09:27:58 agc Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 
     34 #ifdef __weak_alias
     35 #define opendir			_opendir
     36 #endif
     37 
     38 #include <sys/param.h>
     39 #include <sys/mount.h>
     40 #include <sys/stat.h>
     41 
     42 #include <dirent.h>
     43 #include <errno.h>
     44 #include <fcntl.h>
     45 #include <stdlib.h>
     46 #include <string.h>
     47 #include <unistd.h>
     48 
     49 #ifdef __weak_alias
     50 __weak_alias(opendir,_opendir)
     51 #endif
     52 
     53 /*
     54  * Open a directory.
     55  */
     56 DIR *
     57 opendir(name)
     58 	const char *name;
     59 {
     60 	DIR *dirp;
     61 	int fd;
     62 	struct stat sb;
     63 
     64 	if ((fd = open(name, O_RDONLY | O_NONBLOCK)) == -1)
     65 		return (NULL);
     66 	if (fstat(fd, &sb) || !S_ISDIR(sb.st_mode)) {
     67 		errno = ENOTDIR;
     68 		close(fd);
     69 		return (NULL);
     70 	}
     71 	if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
     72 	    (dirp = (DIR *)malloc(sizeof(DIR))) == NULL) {
     73 		close(fd);
     74 		return (NULL);
     75 	}
     76 
     77 	/*
     78 	 * Determine whether this directory is the top of a union stack.
     79 	 * (Never is on a ramdisk)
     80 	 */
     81 	{
     82 		dirp->dd_len = DIRBLKSIZ;
     83 		dirp->dd_buf = malloc((size_t)dirp->dd_len);
     84 		if (dirp->dd_buf == NULL) {
     85 			free(dirp);
     86 			close (fd);
     87 			return (NULL);
     88 		}
     89 		dirp->dd_seek = 0;
     90 	}
     91 
     92 	dirp->dd_loc = 0;
     93 	dirp->dd_fd = fd;
     94 	dirp->dd_flags = DTF_HIDEW;
     95 
     96 	/*
     97 	 * Set up seek point for rewinddir.
     98 	 */
     99 	dirp->dd_rewind = telldir(dirp);
    100 
    101 	return (dirp);
    102 }
    103