1  /* Duplicate an open file descriptor.
       2  
       3     Copyright (C) 2011-2023 Free Software Foundation, Inc.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13     GNU Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <config.h>
      19  
      20  /* Specification.  */
      21  #include <unistd.h>
      22  
      23  #include <errno.h>
      24  
      25  #if HAVE_MSVC_INVALID_PARAMETER_HANDLER
      26  # include "msvc-inval.h"
      27  #endif
      28  
      29  #undef dup
      30  
      31  #if defined _WIN32 && !defined __CYGWIN__
      32  # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
      33  static int
      34  dup_nothrow (int fd)
      35  {
      36    int result;
      37  
      38    TRY_MSVC_INVAL
      39      {
      40        result = _dup (fd);
      41      }
      42    CATCH_MSVC_INVAL
      43      {
      44        result = -1;
      45        errno = EBADF;
      46      }
      47    DONE_MSVC_INVAL;
      48  
      49    return result;
      50  }
      51  # else
      52  #  define dup_nothrow _dup
      53  # endif
      54  #elif defined __KLIBC__
      55  # include <fcntl.h>
      56  # include <sys/stat.h>
      57  
      58  # include <InnoTekLIBC/backend.h>
      59  
      60  static int
      61  dup_nothrow (int fd)
      62  {
      63    int dupfd;
      64    struct stat sbuf;
      65  
      66    dupfd = dup (fd);
      67    if (dupfd == -1 && errno == ENOTSUP \
      68        && !fstat (fd, &sbuf) && S_ISDIR (sbuf.st_mode))
      69      {
      70        char path[_MAX_PATH];
      71  
      72        /* Get a path from fd */
      73        if (!__libc_Back_ioFHToPath (fd, path, sizeof (path)))
      74          dupfd = open (path, O_RDONLY);
      75      }
      76  
      77    return dupfd;
      78  }
      79  #else
      80  # define dup_nothrow dup
      81  #endif
      82  
      83  int
      84  rpl_dup (int fd)
      85  {
      86    int result = dup_nothrow (fd);
      87  #if REPLACE_FCHDIR
      88    if (result >= 0)
      89      result = _gl_register_dup (fd, result);
      90  #endif
      91    return result;
      92  }