lib/mknod.c

   1 /* Create a device inode.
   2    Copyright (C) 2009-2025 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation, either version 3 of the
   7    License, or (at your option) any later version.
   8
   9    This file 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
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* written by Eric Blake */
  18
  19 #include <config.h>
  20
  21 #include <sys/stat.h>
  22
  23 #include <errno.h>
  24 #include <string.h>
  25
  26 #if !HAVE_MKNOD
  27 /* Mingw lacks mknod; always fail with ENOSYS.  */
  28
  29 int
  30 mknod (_GL_UNUSED char const *name, _GL_UNUSED mode_t mode,
  31        _GL_UNUSED dev_t dev)
  32 {
  33   errno = ENOSYS;
  34   return -1;
  35 }
  36
  37 #else /* HAVE_MKNOD */
  38
  39 # undef mknod
  40
  41 /* Create a file system node FILE, with access permissions and file
  42    type in MODE, and device type in DEV.  Usually, non-root
  43    applications can only create named fifos (mode includes S_IFIFO),
  44    with DEV set to 0.  Also work around trailing slash bugs.  */
  45
  46 int
  47 rpl_mknod (char const *name, mode_t mode, dev_t dev)
  48 {
  49 # if MKFIFO_TRAILING_SLASH_BUG
  50   /* Trailing slash only makes sense for directories.  Of course,
  51      using mknod to create a directory is not very portable, so it may
  52      still fail later on.  */
  53   if (!S_ISDIR (mode))
  54     {
  55       size_t len = strlen (name);
  56       if (len && name[len - 1] == '/')
  57         {
  58           struct stat st;
  59           if (stat (name, &st) == 0 || errno == EOVERFLOW)
  60             errno = EEXIST;
  61           return -1;
  62         }
  63     }
  64 # endif
  65 # if MKNOD_FIFO_BUG
  66   /* POSIX requires mknod to create fifos for non-privileged
  67      processes, but BSD implementations fail with EPERM.  */
  68   if (S_ISFIFO (mode) && dev == 0)
  69     return mkfifo (name, mode & ~S_IFIFO);
  70 # endif
  71   return mknod (name, mode, dev);
  72 }
  73
  74 #endif /* HAVE_MKNOD */