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 #define DEFAULT_FLAGS (DTF_HIDEW | DTF_NODUP)
  53
  54 /*
  55  * Open a directory given its path.
  56  */
  57 DIR *
  58 opendir(const char *name)
  59 {
  60         return (__opendir2(name, DEFAULT_FLAGS));
  61 }
  62
  63 /*
  64  * Open a directory given a descriptor representing it.
  65  */
  66 DIR *
  67 fdopendir(int fd)
  68 {
  69         return (__fdopendir2(fd, DEFAULT_FLAGS));
  70 }
  71
  72 DIR *
  73 __opendir2(const char *name, int flags)
  74 {
  75         int fd;
  76         struct stat statb;
  77         DIR *dirp;
  78         int saved_errno;
  79
  80         /*
  81          * stat() before _open() because opening of special files may be
  82          * harmful.
  83          */
  84         if (stat(name, &statb) != 0)
  85                 return (NULL);
  86         if (!S_ISDIR(statb.st_mode)) {
  87                 errno = ENOTDIR;
  88                 return (NULL);
  89         }
  90
  91         if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1)
  92                 return (NULL);
  93         dirp = __fdopendir2(fd, flags);
  94         if (dirp == NULL) {
  95                 saved_errno = errno;
  96                 _close(fd);
  97                 errno = saved_errno;
  98         }
  99
 100         return (dirp);
 101 }
 102
 103 DIR *
 104 __fdopendir2(int fd, int flags)
 105 {
 106         DIR *dirp;
 107         int incr;
 108         int saved_errno;
 109         struct stat statb;
 110         off_t off;
 111
 112         dirp = NULL;
 113
 114         if (_fstat(fd, &statb) != 0)
 115                 goto fail;
 116         if (!S_ISDIR(statb.st_mode)) {
 117                 errno = ENOTDIR;
 118                 goto fail;
 119         }
 120         if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
 121             (dirp = malloc(sizeof(DIR))) == NULL)
 122                 goto fail;
 123
 124         /*
 125          * Use the system page size if that is a multiple of DIRBLKSIZ.
 126          * Hopefully this can be a big win someday by allowing page
 127          * trades to user space to be done by _getdirentries().
 128          */
 129         incr = getpagesize();
 130         if ((incr % DIRBLKSIZ) != 0)
 131                 incr = DIRBLKSIZ;
 132
 133         dirp->dd_len = incr;
 134         dirp->dd_buf = malloc(dirp->dd_len);
 135         if (dirp->dd_buf == NULL)
 136                 goto fail;
 137         flags &= ~DTF_REWIND;
 138
 139         dirp->dd_loc = 0;
 140         dirp->dd_fd = fd;
 141         dirp->dd_flags = flags;
 142         dirp->dd_lock = NULL;
 143
 144         /*
 145          * Set up seek point for rewinddir.
 146          */
 147         dirp->dd_seek = 0;
 148         dirp->dd_rewind = telldir(dirp);
 149
 150         /*
 151          * The file offset of the fd passed to fdopendir() determines the
 152          * initial entry returned by readdir().  Save this offset so that
 153          * telldir() right after fdopendir() returns a value pointing to this
 154          * initial entry.
 155          * We don't have to worry about misaligned file offsets.  The kernel
 156          * deals with these.
 157          */
 158         if ((dirp->dd_seek = lseek(fd, 0, SEEK_CUR)) < 0)
 159                 goto fail;
 160
 161         return (dirp);
 162
 163 fail:
 164         saved_errno = errno;
 165         if (dirp != NULL) {
 166                 _reclaim_telldir(dirp);
 167                 free(dirp->dd_buf);
 168         }
 169         free(dirp);
 170         errno = saved_errno;
 171         return (NULL);
 172 }