limit_handles breaks exec() error reporting on POSIX

[tomix86]

Using limit_handles on POSIX platforms causes internal logic for exec() error reporting to break.
The root cause is that foreach_used_handle on POSIX does not account for executor::_pipe_sink, which is needed for error reporting from child to parent.

A minimal reproducer:

#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <boost/process.hpp>
#include <boost/process/extend.hpp>

namespace bp = boost::process;

TEST(BoostProcessTest, limit_handles_breaks_exec_error_handling) {
	{
		std::error_code ec;
		bp::child{bp::exe = "some_nonexistent_path", ec}.wait();
		EXPECT_EQ(std::errc::no_such_file_or_directory, ec);
	}

	{
		std::error_code ec;
		bp::child{bp::exe = "some_nonexistent_path", ec, bp::limit_handles}.wait();
		// EXPECT_EQ(std::errc::no_such_file_or_directory, ec);
		EXPECT_EQ(std::error_code{}, ec); // Boost.Process bug
	}
}

int main(int argc, char** argv) {
	::testing::InitGoogleTest(&argc, argv);
	return RUN_ALL_TESTS();
}

[sfc-gh-hyu]

Got the same error, is there any update on this? Or at least small patch on how to fix this?

[dkl]

Testing with boost-process 1.84.0, this issue still seems to exist. Commit 1a1d677 added executor::get_used_handles(), but it doesn't work, because _pipe_sink is assigned after the on_setup() call, so it's missed and closed anyways.

#include <boost/process/handles.hpp>
#include <boost/process/system.hpp>
int main() {
	// with limit_handles: no exception thrown, but should be
	// without limit_handles: throws exception as expected
	boost::process::system("/does/not/exist", boost::process::limit_handles);
	return 0;
}