tests/test-dup3.c

   1 /* Test duplicating file descriptors.
   2    Copyright (C) 2009-2017 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 <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Eric Blake <ebb9@byu.net>, 2009,
  18    and Bruno Haible <bruno@clisp.org>, 2009.  */
  19
  20 #include <config.h>
  21
  22 #include <unistd.h>
  23
  24 #include "signature.h"
  25 SIGNATURE_CHECK (dup3, int, (int, int, int));
  26
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <stdbool.h>
  30
  31 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  32 /* Get declarations of the native Windows API functions.  */
  33 # define WIN32_LEAN_AND_MEAN
  34 # include <windows.h>
  35 /* Get _get_osfhandle.  */
  36 # include "msvc-nothrow.h"
  37 #endif
  38
  39 #include "binary-io.h"
  40 #include "macros.h"
  41
  42 /* Return true if FD is open.  */
  43 static bool
  44 is_open (int fd)
  45 {
  46 #if (defined _WIN32 || 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   return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
  51 #else
  52 # ifndef F_GETFL
  53 #  error Please port fcntl to your platform
  54 # endif
  55   return 0 <= fcntl (fd, F_GETFL);
  56 #endif
  57 }
  58
  59 /* Return true if FD is not inherited to child processes.  */
  60 static bool
  61 is_cloexec (int fd)
  62 {
  63 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  64   HANDLE h = (HANDLE) _get_osfhandle (fd);
  65   DWORD flags;
  66   ASSERT (GetHandleInformation (h, &flags));
  67   return (flags & HANDLE_FLAG_INHERIT) == 0;
  68 #else
  69   int flags;
  70   ASSERT ((flags = fcntl (fd, F_GETFD)) >= 0);
  71   return (flags & FD_CLOEXEC) != 0;
  72 #endif
  73 }
  74
  75 int
  76 main ()
  77 {
  78   int use_cloexec;
  79   int bad_fd = getdtablesize ();
  80
  81 #if O_CLOEXEC
  82   for (use_cloexec = 0; use_cloexec <= 1; use_cloexec++)
  83 #else
  84   use_cloexec = 0;
  85 #endif
  86     {
  87       const char *file = "test-dup3.tmp";
  88       int fd = open (file, O_CREAT | O_TRUNC | O_RDWR, 0600);
  89       int o_flags;
  90       char buffer[1];
  91
  92       o_flags = 0;
  93 #if O_CLOEXEC
  94       if (use_cloexec)
  95         o_flags |= O_CLOEXEC;
  96 #endif
  97
  98       /* Assume std descriptors were provided by invoker.  */
  99       ASSERT (STDERR_FILENO < fd);
 100       ASSERT (is_open (fd));
 101       /* Ignore any other fd's leaked into this process.  */
 102       close (fd + 1);
 103       close (fd + 2);
 104       ASSERT (!is_open (fd + 1));
 105       ASSERT (!is_open (fd + 2));
 106
 107       /* Assigning to self is invalid.  */
 108       errno = 0;
 109       ASSERT (dup3 (fd, fd, o_flags) == -1);
 110       ASSERT (errno == EINVAL);
 111       ASSERT (is_open (fd));
 112
 113       /* If the source is not open, then the destination is unaffected.  */
 114       errno = 0;
 115       ASSERT (dup3 (fd + 1, fd + 2, o_flags) == -1);
 116       ASSERT (errno == EBADF);
 117       ASSERT (!is_open (fd + 2));
 118       errno = 0;
 119       ASSERT (dup3 (fd + 1, fd, o_flags) == -1);
 120       ASSERT (errno == EBADF);
 121       ASSERT (is_open (fd));
 122
 123       /* The destination must be valid.  */
 124       errno = 0;
 125       ASSERT (dup3 (fd, -2, o_flags) == -1);
 126       ASSERT (errno == EBADF);
 127       if (bad_fd > 256)
 128         {
 129           ASSERT (dup3 (fd, 255, 0) == 255);
 130           ASSERT (dup3 (fd, 256, 0) == 256);
 131           ASSERT (close (255) == 0);
 132           ASSERT (close (256) == 0);
 133         }
 134       ASSERT (dup3 (fd, bad_fd - 1, 0) == bad_fd - 1);
 135       ASSERT (close (bad_fd - 1) == 0);
 136       errno = 0;
 137       ASSERT (dup3 (fd, bad_fd, o_flags) == -1);
 138       ASSERT (errno == EBADF);
 139
 140       /* Using dup3 can skip fds.  */
 141       ASSERT (dup3 (fd, fd + 2, o_flags) == fd + 2);
 142       ASSERT (is_open (fd));
 143       ASSERT (!is_open (fd + 1));
 144       ASSERT (is_open (fd + 2));
 145       if (use_cloexec)
 146         ASSERT (is_cloexec (fd + 2));
 147       else
 148         ASSERT (!is_cloexec (fd + 2));
 149
 150       /* Verify that dup3 closes the previous occupant of a fd.  */
 151       ASSERT (open ("/dev/null", O_WRONLY, 0600) == fd + 1);
 152       ASSERT (dup3 (fd + 1, fd, o_flags) == fd);
 153       ASSERT (close (fd + 1) == 0);
 154       ASSERT (write (fd, "1", 1) == 1);
 155       ASSERT (dup3 (fd + 2, fd, o_flags) == fd);
 156       ASSERT (lseek (fd, 0, SEEK_END) == 0);
 157       ASSERT (write (fd + 2, "2", 1) == 1);
 158       ASSERT (lseek (fd, 0, SEEK_SET) == 0);
 159       ASSERT (read (fd, buffer, 1) == 1);
 160       ASSERT (*buffer == '2');
 161
 162       /* Clean up.  */
 163       ASSERT (close (fd + 2) == 0);
 164       ASSERT (close (fd) == 0);
 165       ASSERT (unlink (file) == 0);
 166     }
 167
 168   return 0;
 169 }