lib/dup2.c

   1 /* Duplicate an open file descriptor to a specified file descriptor.
   2
   3    Copyright (C) 1999, 2004-2007, 2009-2018 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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 General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* written by Paul Eggert */
  19
  20 #include <config.h>
  21
  22 /* Specification.  */
  23 #include <unistd.h>
  24
  25 #include <errno.h>
  26 #include <fcntl.h>
  27
  28 #if HAVE_DUP2
  29
  30 # undef dup2
  31
  32 # if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  33
  34 /* Get declarations of the native Windows API functions.  */
  35 #  define WIN32_LEAN_AND_MEAN
  36 #  include <windows.h>
  37
  38 #  if HAVE_MSVC_INVALID_PARAMETER_HANDLER
  39 #   include "msvc-inval.h"
  40 #  endif
  41
  42 /* Get _get_osfhandle.  */
  43 #  if GNULIB_MSVC_NOTHROW
  44 #   include "msvc-nothrow.h"
  45 #  else
  46 #   include <io.h>
  47 #  endif
  48
  49 #  if HAVE_MSVC_INVALID_PARAMETER_HANDLER
  50 static int
  51 dup2_nothrow (int fd, int desired_fd)
  52 {
  53   int result;
  54
  55   TRY_MSVC_INVAL
  56     {
  57       result = dup2 (fd, desired_fd);
  58     }
  59   CATCH_MSVC_INVAL
  60     {
  61       errno = EBADF;
  62       result = -1;
  63     }
  64   DONE_MSVC_INVAL;
  65
  66   return result;
  67 }
  68 #  else
  69 #   define dup2_nothrow dup2
  70 #  endif
  71
  72 static int
  73 ms_windows_dup2 (int fd, int desired_fd)
  74 {
  75   int result;
  76
  77   /* If fd is closed, mingw hangs on dup2 (fd, fd).  If fd is open,
  78      dup2 (fd, fd) returns 0, but all further attempts to use fd in
  79      future dup2 calls will hang.  */
  80   if (fd == desired_fd)
  81     {
  82       if ((HANDLE) _get_osfhandle (fd) == INVALID_HANDLE_VALUE)
  83         {
  84           errno = EBADF;
  85           return -1;
  86         }
  87       return fd;
  88     }
  89
  90   /* Wine 1.0.1 return 0 when desired_fd is negative but not -1:
  91      https://bugs.winehq.org/show_bug.cgi?id=21289 */
  92   if (desired_fd < 0)
  93     {
  94       errno = EBADF;
  95       return -1;
  96     }
  97
  98   result = dup2_nothrow (fd, desired_fd);
  99
 100   if (result == 0)
 101     result = desired_fd;
 102
 103   return result;
 104 }
 105
 106 #  define dup2 ms_windows_dup2
 107
 108 # elif defined __KLIBC__
 109
 110 #  include <InnoTekLIBC/backend.h>
 111
 112 static int
 113 klibc_dup2dirfd (int fd, int desired_fd)
 114 {
 115   int tempfd;
 116   int dupfd;
 117
 118   tempfd = open ("NUL", O_RDONLY);
 119   if (tempfd == -1)
 120     return -1;
 121
 122   if (tempfd == desired_fd)
 123     {
 124       close (tempfd);
 125
 126       char path[_MAX_PATH];
 127       if (__libc_Back_ioFHToPath (fd, path, sizeof (path)))
 128         return -1;
 129
 130       return open(path, O_RDONLY);
 131     }
 132
 133   dupfd = klibc_dup2dirfd (fd, desired_fd);
 134
 135   close (tempfd);
 136
 137   return dupfd;
 138 }
 139
 140 static int
 141 klibc_dup2 (int fd, int desired_fd)
 142 {
 143   int dupfd;
 144   struct stat sbuf;
 145
 146   dupfd = dup2 (fd, desired_fd);
 147   if (dupfd == -1 && errno == ENOTSUP \
 148       && !fstat (fd, &sbuf) && S_ISDIR (sbuf.st_mode))
 149     {
 150       close (desired_fd);
 151
 152       return klibc_dup2dirfd (fd, desired_fd);
 153     }
 154
 155   return dupfd;
 156 }
 157
 158 #  define dup2 klibc_dup2
 159 # endif
 160
 161 int
 162 rpl_dup2 (int fd, int desired_fd)
 163 {
 164   int result;
 165
 166 # ifdef F_GETFL
 167   /* On Linux kernels 2.6.26-2.6.29, dup2 (fd, fd) returns -EBADF.
 168      On Cygwin 1.5.x, dup2 (1, 1) returns 0.
 169      On Cygwin 1.7.17, dup2 (1, -1) dumps core.
 170      On Cygwin 1.7.25, dup2 (1, 256) can dump core.
 171      On Haiku, dup2 (fd, fd) mistakenly clears FD_CLOEXEC.  */
 172 #  if HAVE_SETDTABLESIZE
 173   setdtablesize (desired_fd + 1);
 174 #  endif
 175   if (desired_fd < 0)
 176     fd = desired_fd;
 177   if (fd == desired_fd)
 178     return fcntl (fd, F_GETFL) == -1 ? -1 : fd;
 179 # endif
 180
 181   result = dup2 (fd, desired_fd);
 182
 183   /* Correct an errno value on FreeBSD 6.1 and Cygwin 1.5.x.  */
 184   if (result == -1 && errno == EMFILE)
 185     errno = EBADF;
 186 # if REPLACE_FCHDIR
 187   if (fd != desired_fd && result != -1)
 188     result = _gl_register_dup (fd, result);
 189 # endif
 190   return result;
 191 }
 192
 193 #else /* !HAVE_DUP2 */
 194
 195 /* On older platforms, dup2 did not exist.  */
 196
 197 # ifndef F_DUPFD
 198 static int
 199 dupfd (int fd, int desired_fd)
 200 {
 201   int duplicated_fd = dup (fd);
 202   if (duplicated_fd < 0 || duplicated_fd == desired_fd)
 203     return duplicated_fd;
 204   else
 205     {
 206       int r = dupfd (fd, desired_fd);
 207       int e = errno;
 208       close (duplicated_fd);
 209       errno = e;
 210       return r;
 211     }
 212 }
 213 # endif
 214
 215 int
 216 dup2 (int fd, int desired_fd)
 217 {
 218   int result = fcntl (fd, F_GETFL) < 0 ? -1 : fd;
 219   if (result == -1 || fd == desired_fd)
 220     return result;
 221   close (desired_fd);
 222 # ifdef F_DUPFD
 223   result = fcntl (fd, F_DUPFD, desired_fd);
 224 #  if REPLACE_FCHDIR
 225   if (0 <= result)
 226     result = _gl_register_dup (fd, result);
 227 #  endif
 228 # else
 229   result = dupfd (fd, desired_fd);
 230 # endif
 231   if (result == -1 && (errno == EMFILE || errno == EINVAL))
 232     errno = EBADF;
 233   return result;
 234 }
 235 #endif /* !HAVE_DUP2 */