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opendir.c revision 1.4 
      1 /*
      2  * Copyright (c) 1983, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 /*static char sccsid[] = "from: @(#)opendir.c	8.2 (Berkeley) 2/12/94";*/
     36 static char rcsid[] = "$Id: opendir.c,v 1.4 1994/09/15 10:48:51 pk Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/param.h>
     40 #include <sys/types.h>
     41 #include <sys/stat.h>
     42 #include <dirent.h>
     43 #include <fcntl.h>
     44 #include <stdlib.h>
     45 #include <unistd.h>
     46 #include <errno.h>
     47 
     48 /*
     49  * open a directory.
     50  */
     51 DIR *
     52 opendir(name)
     53 	const char *name;
     54 {
     55         struct stat statb;
     56 	register DIR *dirp;
     57 	register int fd;
     58 	register int pagesz;
     59 
     60 	if ((fd = open(name, 0)) == -1)
     61 		return NULL;
     62 	if (fstat(fd, &statb) || !S_ISDIR(statb.st_mode)) {
     63 		errno = ENOTDIR;
     64 		close (fd);
     65 		return NULL;
     66 	}
     67 	if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
     68 	    (dirp = (DIR *)malloc(sizeof(DIR))) == NULL) {
     69 		close (fd);
     70 		return NULL;
     71 	}
     72 	/*
     73 	 * If the machine's page size is an exact multiple of DIRBLKSIZ,
     74 	 * use a buffer that is cluster boundary aligned.
     75 	 * Hopefully this can be a big win someday by allowing page trades
     76 	 * to user space to be done by getdirentries()
     77 	 */
     78 	if (((pagesz = getpagesize()) % DIRBLKSIZ) == 0)
     79 		dirp->dd_len = pagesz;
     80 	else
     81 		dirp->dd_len = DIRBLKSIZ;
     82 
     83 	dirp->dd_buf = malloc(dirp->dd_len);
     84 	if (dirp->dd_buf == NULL) {
     85 		close (fd);
     86 		return NULL;
     87 	}
     88 	dirp->dd_fd = fd;
     89 	dirp->dd_loc = 0;
     90 	dirp->dd_seek = 0;
     91 	/*
     92 	 * Set up seek point for rewinddir.
     93 	 */
     94 	dirp->dd_rewind = telldir(dirp);
     95 	return dirp;
     96 }
     97