root/lib/dup2.c

DEFINITIONS

1. dup2_nothrow
2. ms_windows_dup2
3. klibc_dup2dirfd
4. klibc_dup2
5. rpl_dup2

     1 /* Duplicate an open file descriptor to a specified file descriptor.
     2 
     3    Copyright (C) 1999, 2004-2007, 2009-2023 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 /* 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 #undef dup2
    29 
    30 #if defined _WIN32 && ! defined __CYGWIN__
    31 
    32 /* Get declarations of the native Windows API functions.  */
    33 # define WIN32_LEAN_AND_MEAN
    34 # include <windows.h>
    35 
    36 # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
    37 #  include "msvc-inval.h"
    38 # endif
    39 
    40 /* Get _get_osfhandle.  */
    41 # if GNULIB_MSVC_NOTHROW
    42 #  include "msvc-nothrow.h"
    43 # else
    44 #  include <io.h>
    45 # endif
    46 
    47 # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
    48 static int
    49 dup2_nothrow (int fd, int desired_fd)
    50 {
    51   int result;
    52 
    53   TRY_MSVC_INVAL
    54     {
    55       result = _dup2 (fd, desired_fd);
    56     }
    57   CATCH_MSVC_INVAL
    58     {
    59       errno = EBADF;
    60       result = -1;
    61     }
    62   DONE_MSVC_INVAL;
    63 
    64   return result;
    65 }
    66 # else
    67 #  define dup2_nothrow _dup2
    68 # endif
    69 
    70 static int
    71 ms_windows_dup2 (int fd, int desired_fd)
    72 {
    73   int result;
    74 
    75   /* If fd is closed, mingw hangs on dup2 (fd, fd).  If fd is open,
    76      dup2 (fd, fd) returns 0, but all further attempts to use fd in
    77      future dup2 calls will hang.  */
    78   if (fd == desired_fd)
    79     {
    80       if ((HANDLE) _get_osfhandle (fd) == INVALID_HANDLE_VALUE)
    81         {
    82           errno = EBADF;
    83           return -1;
    84         }
    85       return fd;
    86     }
    87 
    88   /* Wine 1.0.1 return 0 when desired_fd is negative but not -1:
    89      https://bugs.winehq.org/show_bug.cgi?id=21289 */
    90   if (desired_fd < 0)
    91     {
    92       errno = EBADF;
    93       return -1;
    94     }
    95 
    96   result = dup2_nothrow (fd, desired_fd);
    97 
    98   if (result == 0)
    99     result = desired_fd;
   100 
   101   return result;
   102 }
   103 
   104 # define dup2 ms_windows_dup2
   105 
   106 #elif defined __KLIBC__
   107 
   108 # include <InnoTekLIBC/backend.h>
   109 
   110 static int
   111 klibc_dup2dirfd (int fd, int desired_fd)
   112 {
   113   int tempfd;
   114   int dupfd;
   115 
   116   tempfd = open ("NUL", O_RDONLY);
   117   if (tempfd == -1)
   118     return -1;
   119 
   120   if (tempfd == desired_fd)
   121     {
   122       close (tempfd);
   123 
   124       char path[_MAX_PATH];
   125       if (__libc_Back_ioFHToPath (fd, path, sizeof (path)))
   126         return -1;
   127 
   128       return open(path, O_RDONLY);
   129     }
   130 
   131   dupfd = klibc_dup2dirfd (fd, desired_fd);
   132 
   133   close (tempfd);
   134 
   135   return dupfd;
   136 }
   137 
   138 static int
   139 klibc_dup2 (int fd, int desired_fd)
   140 {
   141   int dupfd;
   142   struct stat sbuf;
   143 
   144   dupfd = dup2 (fd, desired_fd);
   145   if (dupfd == -1 && errno == ENOTSUP \
   146       && !fstat (fd, &sbuf) && S_ISDIR (sbuf.st_mode))
   147     {
   148       close (desired_fd);
   149 
   150       return klibc_dup2dirfd (fd, desired_fd);
   151     }
   152 
   153   return dupfd;
   154 }
   155 
   156 # define dup2 klibc_dup2
   157 #endif
   158 
   159 int
   160 rpl_dup2 (int fd, int desired_fd)
   161 {
   162   int result;
   163 
   164 #ifdef F_GETFL
   165   /* On Linux kernels 2.6.26-2.6.29, dup2 (fd, fd) returns -EBADF.
   166      On Cygwin 1.5.x, dup2 (1, 1) returns 0.
   167      On Cygwin 1.7.17, dup2 (1, -1) dumps core.
   168      On Cygwin 1.7.25, dup2 (1, 256) can dump core.
   169      On Haiku, dup2 (fd, fd) mistakenly clears FD_CLOEXEC.  */
   170 # if HAVE_SETDTABLESIZE
   171   setdtablesize (desired_fd + 1);
   172 # endif
   173   if (desired_fd < 0)
   174     fd = desired_fd;
   175   if (fd == desired_fd)
   176     return fcntl (fd, F_GETFL) == -1 ? -1 : fd;
   177 #endif
   178 
   179   result = dup2 (fd, desired_fd);
   180 
   181   /* Correct an errno value on FreeBSD 6.1 and Cygwin 1.5.x.  */
   182   if (result == -1 && errno == EMFILE)
   183     errno = EBADF;
   184 #if REPLACE_FCHDIR
   185   if (fd != desired_fd && result != -1)
   186     result = _gl_register_dup (fd, result);
   187 #endif
   188   return result;
   189 }