tests/test-cloexec.c

   1 /* Test duplicating non-inheritable 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
  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 __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 # include "msvc-nothrow.h"
  33 #endif
  34
  35 #include "binary-io.h"
  36 #include "macros.h"
  37
  38 /* Return non-zero if FD is open and inheritable across exec/spawn.  */
  39 static int
  40 is_inheritable (int fd)
  41 {
  42 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  43   /* On native Windows, the initial state of unassigned standard file
  44      descriptors is that they are open but point to an
  45      INVALID_HANDLE_VALUE, and there is no fcntl.  */
  46   HANDLE h = (HANDLE) _get_osfhandle (fd);
  47   DWORD flags;
  48   if (h == INVALID_HANDLE_VALUE || GetHandleInformation (h, &flags) == 0)
  49     return 0;
  50   return (flags & HANDLE_FLAG_INHERIT) != 0;
  51 #else
  52 # ifndef F_GETFD
  53 #  error Please port fcntl to your platform
  54 # endif
  55   int i = fcntl (fd, F_GETFD);
  56   return 0 <= i && (i & FD_CLOEXEC) == 0;
  57 #endif
  58 }
  59
  60 #if !O_BINARY
  61 # define setmode(f,m) zero ()
  62 static int zero (void) { return 0; }
  63 #endif
  64
  65 /* Return non-zero if FD is open in the given MODE, which is either
  66    O_TEXT or O_BINARY.  */
  67 static int
  68 is_mode (int fd, int mode)
  69 {
  70   int value = setmode (fd, O_BINARY);
  71   setmode (fd, value);
  72   return mode == value;
  73 }
  74
  75 int
  76 main (void)
  77 {
  78   const char *file = "test-cloexec.tmp";
  79   int fd = creat (file, 0600);
  80   int fd2;
  81   int bad_fd = getdtablesize ();
  82
  83   /* Assume std descriptors were provided by invoker.  */
  84   ASSERT (STDERR_FILENO < fd);
  85   ASSERT (is_inheritable (fd));
  86
  87   /* Normal use of set_cloexec_flag.  */
  88   ASSERT (set_cloexec_flag (fd, true) == 0);
  89 #if !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)
  90   ASSERT (!is_inheritable (fd));
  91 #endif
  92   ASSERT (set_cloexec_flag (fd, false) == 0);
  93   ASSERT (is_inheritable (fd));
  94
  95   /* Normal use of dup_cloexec.  */
  96   fd2 = dup_cloexec (fd);
  97   ASSERT (fd < fd2);
  98   ASSERT (!is_inheritable (fd2));
  99   ASSERT (close (fd) == 0);
 100   ASSERT (dup_cloexec (fd2) == fd);
 101   ASSERT (!is_inheritable (fd));
 102   ASSERT (close (fd2) == 0);
 103
 104   /* On systems that distinguish between text and binary mode,
 105      dup_cloexec reuses the mode of the source.  */
 106   setmode (fd, O_BINARY);
 107   ASSERT (is_mode (fd, O_BINARY));
 108   fd2 = dup_cloexec (fd);
 109   ASSERT (fd < fd2);
 110   ASSERT (is_mode (fd2, O_BINARY));
 111   ASSERT (close (fd2) == 0);
 112   setmode (fd, O_TEXT);
 113   ASSERT (is_mode (fd, O_TEXT));
 114   fd2 = dup_cloexec (fd);
 115   ASSERT (fd < fd2);
 116   ASSERT (is_mode (fd2, O_TEXT));
 117   ASSERT (close (fd2) == 0);
 118
 119   /* Test error handling.  */
 120   errno = 0;
 121   ASSERT (set_cloexec_flag (-1, false) == -1);
 122   ASSERT (errno == EBADF);
 123   errno = 0;
 124   ASSERT (set_cloexec_flag (bad_fd, false) == -1);
 125   ASSERT (errno == EBADF);
 126   errno = 0;
 127   ASSERT (set_cloexec_flag (fd2, false) == -1);
 128   ASSERT (errno == EBADF);
 129   errno = 0;
 130   ASSERT (dup_cloexec (-1) == -1);
 131   ASSERT (errno == EBADF);
 132   errno = 0;
 133   ASSERT (dup_cloexec (bad_fd) == -1);
 134   ASSERT (errno == EBADF);
 135   errno = 0;
 136   ASSERT (dup_cloexec (fd2) == -1);
 137   ASSERT (errno == EBADF);
 138
 139   /* Clean up.  */
 140   ASSERT (close (fd) == 0);
 141   ASSERT (unlink (file) == 0);
 142
 143   return 0;
 144 }