gl/tests/test-dup2.c

   1 /* Test duplicating file descriptors.
   2    Copyright (C) 2009-2012 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
  19 #include <config.h>
  20
  21 #include <unistd.h>
  22
  23 #include "signature.h"
  24 SIGNATURE_CHECK (dup2, int, (int, int));
  25
  26 #include <errno.h>
  27 #include <fcntl.h>
  28
  29 #include "binary-io.h"
  30
  31 #if GNULIB_TEST_CLOEXEC
  32 # include "cloexec.h"
  33 #endif
  34
  35 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  36 /* Get declarations of the native Windows API functions.  */
  37 # define WIN32_LEAN_AND_MEAN
  38 # include <windows.h>
  39 /* Get _get_osfhandle.  */
  40 # include "msvc-nothrow.h"
  41 #endif
  42
  43 #include "macros.h"
  44
  45 /* Return non-zero if FD is open.  */
  46 static int
  47 is_open (int fd)
  48 {
  49 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  50   /* On native Windows, the initial state of unassigned standard file
  51      descriptors is that they are open but point to an
  52      INVALID_HANDLE_VALUE, and there is no fcntl.  */
  53   return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
  54 #else
  55 # ifndef F_GETFL
  56 #  error Please port fcntl to your platform
  57 # endif
  58   return 0 <= fcntl (fd, F_GETFL);
  59 #endif
  60 }
  61
  62 #if GNULIB_TEST_CLOEXEC
  63 /* Return non-zero if FD is open and inheritable across exec/spawn.  */
  64 static int
  65 is_inheritable (int fd)
  66 {
  67 # if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  68   /* On native Windows, the initial state of unassigned standard file
  69      descriptors is that they are open but point to an
  70      INVALID_HANDLE_VALUE, and there is no fcntl.  */
  71   HANDLE h = (HANDLE) _get_osfhandle (fd);
  72   DWORD flags;
  73   if (h == INVALID_HANDLE_VALUE || GetHandleInformation (h, &flags) == 0)
  74     return 0;
  75   return (flags & HANDLE_FLAG_INHERIT) != 0;
  76 # else
  77 #  ifndef F_GETFD
  78 #   error Please port fcntl to your platform
  79 #  endif
  80   int i = fcntl (fd, F_GETFD);
  81   return 0 <= i && (i & FD_CLOEXEC) == 0;
  82 # endif
  83 }
  84 #endif /* GNULIB_TEST_CLOEXEC */
  85
  86 #if !O_BINARY
  87 # define setmode(f,m) zero ()
  88 static int zero (void) { return 0; }
  89 #endif
  90
  91 /* Return non-zero if FD is open in the given MODE, which is either
  92    O_TEXT or O_BINARY.  */
  93 static int
  94 is_mode (int fd, int mode)
  95 {
  96   int value = setmode (fd, O_BINARY);
  97   setmode (fd, value);
  98   return mode == value;
  99 }
 100
 101 int
 102 main (void)
 103 {
 104   const char *file = "test-dup2.tmp";
 105   char buffer[1];
 106   int fd = open (file, O_CREAT | O_TRUNC | O_RDWR, 0600);
 107
 108   /* Assume std descriptors were provided by invoker.  */
 109   ASSERT (STDERR_FILENO < fd);
 110   ASSERT (is_open (fd));
 111   /* Ignore any other fd's leaked into this process.  */
 112   close (fd + 1);
 113   close (fd + 2);
 114   ASSERT (!is_open (fd + 1));
 115   ASSERT (!is_open (fd + 2));
 116
 117   /* Assigning to self must be a no-op.  */
 118   ASSERT (dup2 (fd, fd) == fd);
 119   ASSERT (is_open (fd));
 120
 121   /* The source must be valid.  */
 122   errno = 0;
 123   ASSERT (dup2 (-1, fd) == -1);
 124   ASSERT (errno == EBADF);
 125   errno = 0;
 126   ASSERT (dup2 (99, fd) == -1);
 127   ASSERT (errno == EBADF);
 128   errno = 0;
 129   ASSERT (dup2 (AT_FDCWD, fd) == -1);
 130   ASSERT (errno == EBADF);
 131   ASSERT (is_open (fd));
 132
 133   /* If the source is not open, then the destination is unaffected.  */
 134   errno = 0;
 135   ASSERT (dup2 (fd + 1, fd + 1) == -1);
 136   ASSERT (errno == EBADF);
 137   ASSERT (!is_open (fd + 1));
 138   errno = 0;
 139   ASSERT (dup2 (fd + 1, fd) == -1);
 140   ASSERT (errno == EBADF);
 141   ASSERT (is_open (fd));
 142
 143   /* The destination must be valid.  */
 144   errno = 0;
 145   ASSERT (dup2 (fd, -2) == -1);
 146   ASSERT (errno == EBADF);
 147   errno = 0;
 148   ASSERT (dup2 (fd, 10000000) == -1);
 149   ASSERT (errno == EBADF);
 150
 151   /* Using dup2 can skip fds.  */
 152   ASSERT (dup2 (fd, fd + 2) == fd + 2);
 153   ASSERT (is_open (fd));
 154   ASSERT (!is_open (fd + 1));
 155   ASSERT (is_open (fd + 2));
 156
 157   /* Verify that dup2 closes the previous occupant of a fd.  */
 158   ASSERT (open ("/dev/null", O_WRONLY, 0600) == fd + 1);
 159   ASSERT (dup2 (fd + 1, fd) == fd);
 160   ASSERT (close (fd + 1) == 0);
 161   ASSERT (write (fd, "1", 1) == 1);
 162   ASSERT (dup2 (fd + 2, fd) == fd);
 163   ASSERT (lseek (fd, 0, SEEK_END) == 0);
 164   ASSERT (write (fd + 2, "2", 1) == 1);
 165   ASSERT (lseek (fd, 0, SEEK_SET) == 0);
 166   ASSERT (read (fd, buffer, 1) == 1);
 167   ASSERT (*buffer == '2');
 168
 169 #if GNULIB_TEST_CLOEXEC
 170   /* Any new fd created by dup2 must not be cloexec.  */
 171   ASSERT (close (fd + 2) == 0);
 172   ASSERT (dup_cloexec (fd) == fd + 1);
 173   ASSERT (!is_inheritable (fd + 1));
 174   ASSERT (dup2 (fd + 1, fd + 1) == fd + 1);
 175   ASSERT (!is_inheritable (fd + 1));
 176   ASSERT (dup2 (fd + 1, fd + 2) == fd + 2);
 177   ASSERT (!is_inheritable (fd + 1));
 178   ASSERT (is_inheritable (fd + 2));
 179   errno = 0;
 180   ASSERT (dup2 (fd + 1, -1) == -1);
 181   ASSERT (errno == EBADF);
 182   ASSERT (!is_inheritable (fd + 1));
 183 #endif
 184
 185   /* On systems that distinguish between text and binary mode, dup2
 186      reuses the mode of the source.  */
 187   setmode (fd, O_BINARY);
 188   ASSERT (is_mode (fd, O_BINARY));
 189   ASSERT (dup2 (fd, fd + 1) == fd + 1);
 190   ASSERT (is_mode (fd + 1, O_BINARY));
 191   setmode (fd, O_TEXT);
 192   ASSERT (is_mode (fd, O_TEXT));
 193   ASSERT (dup2 (fd, fd + 1) == fd + 1);
 194   ASSERT (is_mode (fd + 1, O_TEXT));
 195
 196   /* Clean up.  */
 197   ASSERT (close (fd + 2) == 0);
 198   ASSERT (close (fd + 1) == 0);
 199   ASSERT (close (fd) == 0);
 200   ASSERT (unlink (file) == 0);
 201
 202   return 0;
 203 }