1  /* Test duplicating non-inheritable file descriptors.
       2     Copyright (C) 2009-2023 Free Software Foundation, Inc.
       3  
       4     This program is free software: you can redistribute it and/or modify
       5     it under the terms of the GNU General Public License as published by
       6     the Free Software Foundation, either version 3 of the License, or
       7     (at your option) any later version.
       8  
       9     This program is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      12     GNU General Public License for more details.
      13  
      14     You should have received a copy of the GNU General Public License
      15     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      16  
      17  /* Written by Eric Blake <ebb9@byu.net>, 2009.  */
      18  
      19  #include <config.h>
      20  
      21  #include "cloexec.h"
      22  
      23  #include <errno.h>
      24  #include <fcntl.h>
      25  #include <unistd.h>
      26  
      27  #if defined _WIN32 && ! defined __CYGWIN__
      28  /* Get declarations of the native Windows API functions.  */
      29  # define WIN32_LEAN_AND_MEAN
      30  # include <windows.h>
      31  /* Get _get_osfhandle.  */
      32  # if GNULIB_MSVC_NOTHROW
      33  #  include "msvc-nothrow.h"
      34  # else
      35  #  include <io.h>
      36  # endif
      37  #endif
      38  
      39  #include "binary-io.h"
      40  #include "macros.h"
      41  
      42  /* Return non-zero if FD is open and inheritable across exec/spawn.  */
      43  static int
      44  is_inheritable (int fd)
      45  {
      46  #if defined _WIN32 && ! defined __CYGWIN__
      47    /* On native Windows, the initial state of unassigned standard file
      48       descriptors is that they are open but point to an
      49       INVALID_HANDLE_VALUE, and there is no fcntl.  */
      50    HANDLE h = (HANDLE) _get_osfhandle (fd);
      51    DWORD flags;
      52    if (h == INVALID_HANDLE_VALUE || GetHandleInformation (h, &flags) == 0)
      53      return 0;
      54    return (flags & HANDLE_FLAG_INHERIT) != 0;
      55  #else
      56  # ifndef F_GETFD
      57  #  error Please port fcntl to your platform
      58  # endif
      59    int i = fcntl (fd, F_GETFD);
      60    return 0 <= i && (i & FD_CLOEXEC) == 0;
      61  #endif
      62  }
      63  
      64  #if !O_BINARY
      65  # define set_binary_mode my_set_binary_mode
      66  static int
      67  set_binary_mode (_GL_UNUSED int fd, _GL_UNUSED int mode)
      68  {
      69    return 0;
      70  }
      71  #endif
      72  
      73  /* Return non-zero if FD is open in the given MODE, which is either
      74     O_TEXT or O_BINARY.  */
      75  static int
      76  is_mode (int fd, int mode)
      77  {
      78    int value = set_binary_mode (fd, O_BINARY);
      79    set_binary_mode (fd, value);
      80    return mode == value;
      81  }
      82  
      83  int
      84  main (void)
      85  {
      86    const char *file = "test-cloexec.tmp";
      87    int fd = creat (file, 0600);
      88    int fd2;
      89    int bad_fd = getdtablesize ();
      90  
      91    /* Assume std descriptors were provided by invoker.  */
      92    ASSERT (STDERR_FILENO < fd);
      93    ASSERT (is_inheritable (fd));
      94  
      95    /* Normal use of set_cloexec_flag.  */
      96    ASSERT (set_cloexec_flag (fd, true) == 0);
      97  #if !(defined _WIN32 && ! defined __CYGWIN__)
      98    ASSERT (!is_inheritable (fd));
      99  #endif
     100    ASSERT (set_cloexec_flag (fd, false) == 0);
     101    ASSERT (is_inheritable (fd));
     102  
     103    /* Normal use of dup_cloexec.  */
     104    fd2 = dup_cloexec (fd);
     105    ASSERT (fd < fd2);
     106    ASSERT (!is_inheritable (fd2));
     107    ASSERT (close (fd) == 0);
     108    ASSERT (dup_cloexec (fd2) == fd);
     109    ASSERT (!is_inheritable (fd));
     110    ASSERT (close (fd2) == 0);
     111  
     112    /* On systems that distinguish between text and binary mode,
     113       dup_cloexec reuses the mode of the source.  */
     114    set_binary_mode (fd, O_BINARY);
     115    ASSERT (is_mode (fd, O_BINARY));
     116    fd2 = dup_cloexec (fd);
     117    ASSERT (fd < fd2);
     118    ASSERT (is_mode (fd2, O_BINARY));
     119    ASSERT (close (fd2) == 0);
     120    set_binary_mode (fd, O_TEXT);
     121    ASSERT (is_mode (fd, O_TEXT));
     122    fd2 = dup_cloexec (fd);
     123    ASSERT (fd < fd2);
     124    ASSERT (is_mode (fd2, O_TEXT));
     125    ASSERT (close (fd2) == 0);
     126  
     127    /* Test error handling.  */
     128    errno = 0;
     129    ASSERT (set_cloexec_flag (-1, false) == -1);
     130    ASSERT (errno == EBADF);
     131    errno = 0;
     132    ASSERT (set_cloexec_flag (bad_fd, false) == -1);
     133    ASSERT (errno == EBADF);
     134    errno = 0;
     135    ASSERT (set_cloexec_flag (fd2, false) == -1);
     136    ASSERT (errno == EBADF);
     137    errno = 0;
     138    ASSERT (dup_cloexec (-1) == -1);
     139    ASSERT (errno == EBADF);
     140    errno = 0;
     141    ASSERT (dup_cloexec (bad_fd) == -1);
     142    ASSERT (errno == EBADF);
     143    errno = 0;
     144    ASSERT (dup_cloexec (fd2) == -1);
     145    ASSERT (errno == EBADF);
     146  
     147    /* Clean up.  */
     148    ASSERT (close (fd) == 0);
     149    ASSERT (unlink (file) == 0);
     150  
     151    return 0;
     152  }