lib/dup.c

   1 /* Duplicate an open file descriptor.
   2
   3    Copyright (C) 2011-2024 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 }