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# Copyright (C) 2006 Zack Weinberg <zackw@panix.com>
#
# This program is made available under the GNU GPL version 2.0 or
# greater. See the accompanying file COPYING for details.
#
# This program is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
# PURPOSE.
# Check whether sync_with_stdio(false) run on C++ streams works correctly.
# It causes strange problems (EOF returned too early) on some versions of
# MinGW and OS X. The first test is for the MinGW issue, the second for
# the OS X issue.
#
# In order to check for this issue, we first generate a large input file
# (over 128KB) and then try to read it (using a buffer size over 512
# bytes). If the amount of bytes read does not match the generated input,
# the implementation is broken.
AC_DEFUN([AC_CXX_SYNC_WITH_STDIO_WORKS],
[AC_CACHE_CHECK([whether C++ streams support sync_with_stdio],
ac_cv_cxx_sync_with_stdio_works, [
if test x$cross_compiling = xyes; then
AC_MSG_FAILURE([cannot run test program while cross compiling])
fi
# Note that we can't use AC_RUN_IFELSE for these because we have to
# redirect standard input. Instead, we use AC_LINK_IFELSE to
# generate the binaries and then run them by hand. Hence the manual
# failure-if-cross-compiling above.
AC_RUN_IFELSE([AC_LANG_SOURCE([
/*
* Generates the input file.
*/
#include <cstdlib>
#include <fstream>
int
main(void)
{
std::ofstream ofs("_conftest.dat");
for (int i = 0; i < 50000; i++)
ofs << "0123456789\r\n";
ofs.close();
return EXIT_SUCCESS;
}
])], [], [AC_MSG_FAILURE([could not generate input for test 1])])
AC_LINK_IFELSE([AC_LANG_SOURCE([[
/*
* Reads the input file.
*/
#include <cstdlib>
#include <fstream>
#include <iostream>
int
main(void)
{
std::cin.sync_with_stdio(false);
int length = 0;
while (std::cin.good())
{
char buffer[1024];
(void)std::cin.read(buffer, sizeof(buffer));
length += std::cin.gcount();
}
return length == 600000 ? EXIT_SUCCESS : EXIT_FAILURE;
}
]])],
[if ./conftest$ac_exeext <_conftest.dat; then
:
else
ac_cv_sync_with_stdio_works=no
fi],
[AC_MSG_FAILURE([could not link test program for test 1])])
rm -f _conftest.dat
if test "x$ac_cv_sync_with_stdio_works" != xno; then
# To check for issue 2, we have a writer with a short delay between
# writes, and a reader who has set sync_with_stdio(false).
AC_LINK_IFELSE([AC_LANG_SOURCE([[
#include <cstdlib>
#include <iostream>
#ifdef WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#define sleep(x) Sleep((x) * 1000)
#else
#include <unistd.h>
#endif
int
main(int argc, char * argv[])
{
if (argc != 2)
return EXIT_FAILURE;
if (argv[1][0] == 'R')
{
std::cin.sync_with_stdio(false);
int length = 0;
while (std::cin.good())
{
char buffer@<:@1024@:>@;
(void)std::cin.read(buffer, sizeof(buffer));
length += std::cin.gcount();
}
return length == 82 ? EXIT_SUCCESS : EXIT_FAILURE;
}
else
{
std::cout << "1234567890123456789012345678901234567890" << std::endl;
sleep(1);
std::cout << "1234567890123456789012345678901234567890" << std::endl;
}
return EXIT_SUCCESS;
}
]])],
[if ./conftest$ac_exeext W | ./conftest$ac_exeext R; then
ac_cv_cxx_sync_with_stdio_works=yes
else
ac_cv_cxx_sync_with_stdio_works=no
fi],
[AC_MSG_FAILURE([could not link test program for test 2])])
fi # skip test 2
])
if test $ac_cv_cxx_sync_with_stdio_works = yes; then
AC_DEFINE(SYNC_WITH_STDIO_WORKS, 1,
[Define to 1 if ios::sync_with_stdio(false) works])
fi
])
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