sysdeps/unix/opendir.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96, 98 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23 #include <dirent.h>
  24 #include <fcntl.h>
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27 #include <unistd.h>
  28 #include <stdio.h>
  29
  30 #include <dirstream.h>
  31
  32 /* Open a directory stream on NAME.  */
  33 DIR *
  34 __opendir (const char *name)
  35 {
  36   DIR *dirp;
  37   struct stat statbuf;
  38   int fd;
  39   size_t allocation;
  40   int save_errno;
  41
  42   if (name[0] == '\0')
  43     {
  44       /* POSIX.1-1990 says an empty name gets ENOENT;
  45          but `open' might like it fine.  */
  46       __set_errno (ENOENT);
  47       return NULL;
  48     }
  49
  50   /* We first have to check whether the name is for a directory.  We
  51      cannot do this after the open() call since the open/close operation
  52      performed on, say, a tape device might have undesirable effects.  */
  53   if (stat (name, &statbuf) < 0)
  54     return NULL;
  55   if (! S_ISDIR (statbuf.st_mode))
  56     {
  57       __set_errno (ENOTDIR);
  58       return NULL;
  59     }
  60
  61   fd = __open (name, O_RDONLY|O_NDELAY);
  62   if (fd < 0)
  63     return NULL;
  64
  65   if (__fcntl (fd, F_SETFD, FD_CLOEXEC) < 0)
  66     goto lose;
  67
  68 #ifdef _STATBUF_ST_BLKSIZE
  69   if (statbuf.st_blksize < sizeof (struct dirent))
  70     allocation = sizeof (struct dirent);
  71   else
  72     allocation = statbuf.st_blksize;
  73 #else
  74   allocation = (BUFSIZ < sizeof (struct dirent)
  75                 ? sizeof (struct dirent) : BUFSIZ);
  76 #endif
  77
  78   dirp = (DIR *) calloc (1, sizeof (DIR) + allocation); /* Zero-fill.  */
  79   if (dirp == NULL)
  80   lose:
  81     {
  82       save_errno = errno;
  83     lose2:
  84       (void) __close (fd);
  85       __set_errno (save_errno);
  86       return NULL;
  87     }
  88   dirp->data = (char *) (dirp + 1);
  89   dirp->allocation = allocation;
  90   dirp->fd = fd;
  91
  92   __libc_lock_init (dirp->lock);
  93
  94   return dirp;
  95 }
  96 weak_alias (__opendir, opendir)