tests/test-dup-safer.c

   1 /* Test that dup_safer leaves standard fds alone.
   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 "unistd--.h"
  22
  23 #include <fcntl.h>
  24 #include <errno.h>
  25 #include <stdbool.h>
  26 #include <stdio.h>
  27 #include <unistd.h>
  28
  29 #include "binary-io.h"
  30 #include "cloexec.h"
  31
  32 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  33 /* Get declarations of the native Windows API functions.  */
  34 # define WIN32_LEAN_AND_MEAN
  35 # include <windows.h>
  36 /* Get _get_osfhandle.  */
  37 # include "msvc-nothrow.h"
  38 #endif
  39
  40 #if !O_BINARY
  41 # define setmode(f,m) zero ()
  42 static int zero (void) { return 0; }
  43 #endif
  44
  45 /* This test intentionally closes stderr.  So, we arrange to have fd 10
  46    (outside the range of interesting fd's during the test) set up to
  47    duplicate the original stderr.  */
  48
  49 #define BACKUP_STDERR_FILENO 10
  50 #define ASSERT_STREAM myerr
  51 #include "macros.h"
  52
  53 static FILE *myerr;
  54
  55 /* Return true if FD is open.  */
  56 static bool
  57 is_open (int fd)
  58 {
  59 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  60   /* On native Windows, the initial state of unassigned standard file
  61      descriptors is that they are open but point to an
  62      INVALID_HANDLE_VALUE, and there is no fcntl.  */
  63   return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
  64 #else
  65 # ifndef F_GETFL
  66 #  error Please port fcntl to your platform
  67 # endif
  68   return 0 <= fcntl (fd, F_GETFL);
  69 #endif
  70 }
  71
  72 /* Return true if FD is open and inheritable across exec/spawn.  */
  73 static bool
  74 is_inheritable (int fd)
  75 {
  76 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  77   /* On native Windows, the initial state of unassigned standard file
  78      descriptors is that they are open but point to an
  79      INVALID_HANDLE_VALUE, and there is no fcntl.  */
  80   HANDLE h = (HANDLE) _get_osfhandle (fd);
  81   DWORD flags;
  82   if (h == INVALID_HANDLE_VALUE || GetHandleInformation (h, &flags) == 0)
  83     return 0;
  84   return (flags & HANDLE_FLAG_INHERIT) != 0;
  85 #else
  86 # ifndef F_GETFD
  87 #  error Please port fcntl to your platform
  88 # endif
  89   int i = fcntl (fd, F_GETFD);
  90   return 0 <= i && (i & FD_CLOEXEC) == 0;
  91 #endif
  92 }
  93
  94 /* Return true if FD is open in the given MODE, which is either
  95    O_TEXT or O_BINARY.  */
  96 static bool
  97 is_mode (int fd, int mode)
  98 {
  99   int value = setmode (fd, O_BINARY);
 100   setmode (fd, value);
 101   return mode == value;
 102 }
 103
 104 #define witness "test-dup-safer.txt"
 105
 106 int
 107 main (void)
 108 {
 109   int i;
 110   int fd;
 111   int bad_fd = getdtablesize ();
 112
 113   /* We close fd 2 later, so save it in fd 10.  */
 114   if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
 115       || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
 116     return 2;
 117
 118   /* Create file for later checks.  */
 119   fd = creat (witness, 0600);
 120   ASSERT (STDERR_FILENO < fd);
 121
 122   /* Four iterations, with progressively more standard descriptors
 123      closed.  */
 124   for (i = -1; i <= STDERR_FILENO; i++)
 125     {
 126       if (0 <= i)
 127         ASSERT (close (i) == 0);
 128
 129       /* Detect errors.  */
 130       errno = 0;
 131       ASSERT (dup (-1) == -1);
 132       ASSERT (errno == EBADF);
 133       errno = 0;
 134       ASSERT (dup (bad_fd) == -1);
 135       ASSERT (errno == EBADF);
 136       close (fd + 1);
 137       errno = 0;
 138       ASSERT (dup (fd + 1) == -1);
 139       ASSERT (errno == EBADF);
 140
 141       /* Preserve text vs. binary.  */
 142       setmode (fd, O_BINARY);
 143       ASSERT (dup (fd) == fd + 1);
 144       ASSERT (is_open (fd + 1));
 145       ASSERT (is_inheritable (fd + 1));
 146       ASSERT (is_mode (fd + 1, O_BINARY));
 147
 148       ASSERT (close (fd + 1) == 0);
 149       setmode (fd, O_TEXT);
 150       ASSERT (dup (fd) == fd + 1);
 151       ASSERT (is_open (fd + 1));
 152       ASSERT (is_inheritable (fd + 1));
 153       ASSERT (is_mode (fd + 1, O_TEXT));
 154
 155       /* Create cloexec copy.  */
 156       ASSERT (close (fd + 1) == 0);
 157       ASSERT (fd_safer_flag (dup_cloexec (fd), O_CLOEXEC) == fd + 1);
 158       ASSERT (set_cloexec_flag (fd + 1, true) == 0);
 159       ASSERT (is_open (fd + 1));
 160       ASSERT (!is_inheritable (fd + 1));
 161       ASSERT (close (fd) == 0);
 162
 163       /* dup always creates inheritable copies.  Also, check that
 164          earliest slot past std fds is used.  */
 165       ASSERT (dup (fd + 1) == fd);
 166       ASSERT (is_open (fd));
 167       ASSERT (is_inheritable (fd));
 168       ASSERT (close (fd + 1) == 0);
 169     }
 170
 171   /* Cleanup.  */
 172   ASSERT (close (fd) == 0);
 173   ASSERT (unlink (witness) == 0);
 174
 175   return 0;
 176 }