kc3-lang/gnulib/lib/opendir-safer.c

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• Hash : 32a72f45
  Author :
  Date : 2023-01-01T01:14:21
  

  maint: run 'make update-copyright'
  

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• lib/opendir-safer.c

• /* Invoke opendir, but avoid some glitches.
  
     Copyright (C) 2009-2023 Free Software Foundation, Inc.
  
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation, either version 3 of the License, or
     (at your option) any later version.
  
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
  
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  
  /* Written by Eric Blake.  */
  
  #include <config.h>
  
  #include "dirent-safer.h"
  
  #include <errno.h>
  #include <fcntl.h>
  #include <unistd.h>
  
  /* Like opendir, but do not clobber stdin, stdout, or stderr.  */
  
  DIR *
  opendir_safer (char const *name)
  {
    DIR *dp = opendir (name);
  
    if (dp)
      {
        int fd = dirfd (dp);
  
        if (0 <= fd && fd <= STDERR_FILENO)
          {
            /* If fdopendir is native (as on Linux), then it is safe to
               assume dirfd(fdopendir(n))==n.  If we are using the
               gnulib module fdopendir, then this guarantee is not met,
               but fdopendir recursively calls opendir_safer up to 3
               times to at least get a safe fd.  If fdopendir is not
               present but dirfd is accurate (as on cygwin 1.5.x), then
               we recurse up to 3 times ourselves.  Finally, if dirfd
               always fails (as on mingw), then we are already safe.  */
            DIR *newdp;
            int e;
  #if HAVE_FDOPENDIR || GNULIB_FDOPENDIR
            int f = fcntl (fd, F_DUPFD_CLOEXEC, STDERR_FILENO + 1);
            if (f < 0)
              {
                e = errno;
                newdp = NULL;
              }
            else
              {
                newdp = fdopendir (f);
                e = errno;
                if (! newdp)
                  close (f);
              }
  #else /* !FDOPENDIR */
            newdp = opendir_safer (name);
            e = errno;
  #endif
            closedir (dp);
            errno = e;
            dp = newdp;
          }
      }
  
    return dp;
  }
  

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