lib/dup2.c

   1 /* Duplicate an open file descriptor to a specified file descriptor.
   2
   3    Copyright (C) 1999, 2004-2007, 2009-2015 Free Software Foundation,
   4    Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 /* written by Paul Eggert */
  20
  21 #include <config.h>
  22
  23 /* Specification.  */
  24 #include <unistd.h>
  25
  26 #include <errno.h>
  27 #include <fcntl.h>
  28
  29 #if HAVE_DUP2
  30
  31 # undef dup2
  32
  33 # if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  34
  35 /* Get declarations of the native Windows API functions.  */
  36 #  define WIN32_LEAN_AND_MEAN
  37 #  include <windows.h>
  38
  39 #  include "msvc-inval.h"
  40
  41 /* Get _get_osfhandle.  */
  42 #  include "msvc-nothrow.h"
  43
  44 static int
  45 ms_windows_dup2 (int fd, int desired_fd)
  46 {
  47   int result;
  48
  49   /* If fd is closed, mingw hangs on dup2 (fd, fd).  If fd is open,
  50      dup2 (fd, fd) returns 0, but all further attempts to use fd in
  51      future dup2 calls will hang.  */
  52   if (fd == desired_fd)
  53     {
  54       if ((HANDLE) _get_osfhandle (fd) == INVALID_HANDLE_VALUE)
  55         {
  56           errno = EBADF;
  57           return -1;
  58         }
  59       return fd;
  60     }
  61
  62   /* Wine 1.0.1 return 0 when desired_fd is negative but not -1:
  63      http://bugs.winehq.org/show_bug.cgi?id=21289 */
  64   if (desired_fd < 0)
  65     {
  66       errno = EBADF;
  67       return -1;
  68     }
  69
  70   TRY_MSVC_INVAL
  71     {
  72       result = dup2 (fd, desired_fd);
  73     }
  74   CATCH_MSVC_INVAL
  75     {
  76       errno = EBADF;
  77       result = -1;
  78     }
  79   DONE_MSVC_INVAL;
  80
  81   if (result == 0)
  82     result = desired_fd;
  83
  84   return result;
  85 }
  86
  87 #  define dup2 ms_windows_dup2
  88
  89 # endif
  90
  91 int
  92 rpl_dup2 (int fd, int desired_fd)
  93 {
  94   int result;
  95
  96 # ifdef F_GETFL
  97   /* On Linux kernels 2.6.26-2.6.29, dup2 (fd, fd) returns -EBADF.
  98      On Cygwin 1.5.x, dup2 (1, 1) returns 0.
  99      On Cygwin 1.7.17, dup2 (1, -1) dumps core.
 100      On Cygwin 1.7.25, dup2 (1, 256) can dump core.
 101      On Haiku, dup2 (fd, fd) mistakenly clears FD_CLOEXEC.  */
 102 #  if HAVE_SETDTABLESIZE
 103   setdtablesize (desired_fd + 1);
 104 #  endif
 105   if (desired_fd < 0)
 106     fd = desired_fd;
 107   if (fd == desired_fd)
 108     return fcntl (fd, F_GETFL) == -1 ? -1 : fd;
 109 # endif
 110
 111   result = dup2 (fd, desired_fd);
 112
 113   /* Correct an errno value on FreeBSD 6.1 and Cygwin 1.5.x.  */
 114   if (result == -1 && errno == EMFILE)
 115     errno = EBADF;
 116 # if REPLACE_FCHDIR
 117   if (fd != desired_fd && result != -1)
 118     result = _gl_register_dup (fd, result);
 119 # endif
 120   return result;
 121 }
 122
 123 #else /* !HAVE_DUP2 */
 124
 125 /* On older platforms, dup2 did not exist.  */
 126
 127 # ifndef F_DUPFD
 128 static int
 129 dupfd (int fd, int desired_fd)
 130 {
 131   int duplicated_fd = dup (fd);
 132   if (duplicated_fd < 0 || duplicated_fd == desired_fd)
 133     return duplicated_fd;
 134   else
 135     {
 136       int r = dupfd (fd, desired_fd);
 137       int e = errno;
 138       close (duplicated_fd);
 139       errno = e;
 140       return r;
 141     }
 142 }
 143 # endif
 144
 145 int
 146 dup2 (int fd, int desired_fd)
 147 {
 148   int result = fcntl (fd, F_GETFL) < 0 ? -1 : fd;
 149   if (result == -1 || fd == desired_fd)
 150     return result;
 151   close (desired_fd);
 152 # ifdef F_DUPFD
 153   result = fcntl (fd, F_DUPFD, desired_fd);
 154 #  if REPLACE_FCHDIR
 155   if (0 <= result)
 156     result = _gl_register_dup (fd, result);
 157 #  endif
 158 # else
 159   result = dupfd (fd, desired_fd);
 160 # endif
 161   if (result == -1 && (errno == EMFILE || errno == EINVAL))
 162     errno = EBADF;
 163   return result;
 164 }
 165 #endif /* !HAVE_DUP2 */