lib/libc/gen/opendir.c

   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  * $FreeBSD: src/lib/libc/gen/opendir.c,v 1.10.2.1 2001/06/04 20:59:48 joerg Exp $
  34  * $DragonFly: src/lib/libc/gen/opendir.c,v 1.6 2005/11/13 00:07:42 swildner Exp $
  35  *
  36  * @(#)opendir.c        8.8 (Berkeley) 5/1/95
  37  */
  38
  39 #include "namespace.h"
  40 #include <sys/param.h>
  41 #include <sys/stat.h>
  42
  43 #include <dirent.h>
  44 #include <errno.h>
  45 #include <fcntl.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49 #include "un-namespace.h"
  50
  51 /*
  52  * Open a directory.
  53  */
  54 DIR *
  55 opendir(const char *name)
  56 {
  57         return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
  58 }
  59
  60 DIR *
  61 __opendir2(const char *name, int flags)
  62 {
  63         DIR *dirp;
  64         int fd;
  65         int incr;
  66         int saved_errno;
  67         struct stat statb;
  68
  69         /*
  70          * stat() before _open() because opening of special files may be
  71          * harmful.  _fstat() after open because the file may have changed.
  72          */
  73         if (stat(name, &statb) != 0)
  74                 return (NULL);
  75         if (!S_ISDIR(statb.st_mode)) {
  76                 errno = ENOTDIR;
  77                 return (NULL);
  78         }
  79         if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1)
  80                 return (NULL);
  81         dirp = NULL;
  82         if (_fstat(fd, &statb) != 0)
  83                 goto fail;
  84         if (!S_ISDIR(statb.st_mode)) {
  85                 errno = ENOTDIR;
  86                 goto fail;
  87         }
  88         if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
  89             (dirp = malloc(sizeof(DIR))) == NULL)
  90                 goto fail;
  91
  92         /*
  93          * Use the system page size if that is a multiple of DIRBLKSIZ.
  94          * Hopefully this can be a big win someday by allowing page
  95          * trades to user space to be done by _getdirentries().
  96          */
  97         incr = getpagesize();
  98         if ((incr % DIRBLKSIZ) != 0)
  99                 incr = DIRBLKSIZ;
 100
 101         dirp->dd_len = incr;
 102         dirp->dd_buf = malloc(dirp->dd_len);
 103         if (dirp->dd_buf == NULL)
 104                 goto fail;
 105         dirp->dd_seek = 0;
 106         flags &= ~DTF_REWIND;
 107
 108         dirp->dd_loc = 0;
 109         dirp->dd_fd = fd;
 110         dirp->dd_flags = flags;
 111         dirp->dd_lock = NULL;
 112
 113         /*
 114          * Set up seek point for rewinddir.
 115          */
 116         dirp->dd_rewind = telldir(dirp);
 117
 118         return (dirp);
 119
 120 fail:
 121         saved_errno = errno;
 122         free(dirp);
 123         _close(fd);
 124         errno = saved_errno;
 125         return (NULL);
 126 }