[Boost-users] More problems with boost::asio and async_read

Subject: [Boost-users] More problems with boost::asio and async_read
From: Allan Nielsen (a_at_[hidden])
Date: 2011-08-08 14:33:15

Hi

I posted on this a couple of hours ago with some problems. It turned
out that some of the problems I had might have been due to buggy
hardware.

But there is still some thing I do not understand...

So, now I have reproduced some of of the problems I have with out any
hardware (except from a PC).

Basically I'm trying to read from a input source (in this case stdin)
with a timeout. Due to the design of the existing application where
this have to fit is it not possible to call run on my io_service.

Here is my try so far:

#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/optional.hpp>

using namespace std;

void set_result( boost::optional<boost::system::error_code> * a,
boost::system::error_code b ) {
    if( b == 0)
        a->reset( b );
}

void receive(boost::asio::io_service & io,
boost::asio::posix::stream_descriptor & stream, boost::asio::streambuf
& result){
    boost::optional<boost::system::error_code> timer_result;
    boost::optional<boost::system::error_code> read_result;

    boost::asio::deadline_timer timer( io );
    timer.expires_from_now( boost::posix_time::milliseconds(5000) );
// allow up to 50ms of timeout for every char
    timer.async_wait( boost::bind(&set_result, &timer_result, _1) );

    boost::asio::async_read(
            stream,
            result,
            boost::asio::transfer_at_least(1),
            boost::bind( &set_result, &read_result, _1 ));
    boost::system::error_code ec;

    while(1) {
        io.reset();
        io.poll_one(ec);

        if ( read_result ) {
            timer.cancel();
            return;

        } else if ( timer_result )
            throw std::runtime_error("timeout");
    }
}

void receive(boost::asio::io_service & io,
boost::asio::posix::stream_descriptor & stream, size_t size,
boost::asio::streambuf & result){
    while( result.size() < size )
        receive(io, stream, result);
}

int main(int argc, const char *argv[])
{
    boost::asio::io_service io;
    boost::asio::posix::stream_descriptor in(io, ::dup(STDIN_FILENO));

    for(int i = 0; i < 5; i++){
        std::cout << i << " Type in 4 chareters and press enter" <<
std::endl << std::endl;
        std::cout << "in> ";
        std::cout.flush();
        try {
            boost::asio::streambuf buf;
            receive(io, in, 5, buf);
            std::cout << "out> ";
            std::copy(boost::asio::buffer_cast<const char
*>(buf.data()), boost::asio::buffer_cast<const char *>(buf.data()) +
buf.size(), ostream_iterator<char>(std::cout));

        } catch (const std::exception & e) {
            std::cout << e.what() << endl;
        }
    }

    return 0;
}

At my first look, I thought that it was working, but after playing
more around with the test app, I got some segmentations faults.

I found that something bad happens if I wait for the first query to
timeout, and then enter 5 chars the next.

Here is what valgrind says:

==17848== Memcheck, a memory error detector
==17848== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==17848== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info
==17848== Command: ./ccTalkScan
==17848==
==17848==
0 Type in 4 chareters and press enter

in> ==17848== Invalid read of size 8
==17848==    at 0x546EB4A: ??? (setcontext.S:60)
==17848==    by 0x425847: receive(boost::asio::io_service&,
boost::asio::posix::basic_stream_descriptor<boost::asio::posix::stream_descriptor_service>&,
unsigned long, boost::asio::basic_streambuf<std::allocator<char> >&)
(ccTalkScan.cxx:3
20)
==17848==    by 0x425982: main (ccTalkScan.cxx:334)
==17848==  Address 0x7feffdf68 is not stack'd, malloc'd or (recently) free'd
==17848==
==17848== Invalid read of size 8
==17848==    at 0x546EB52: ??? (setcontext.S:63)
==17848==    by 0x425847: receive(boost::asio::io_service&,
boost::asio::posix::basic_stream_descriptor<boost::asio::posix::stream_descriptor_service>&,
unsigned long, boost::asio::basic_streambuf<std::allocator<char> >&)
(ccTalkScan.cxx:3
20)
==17848==    by 0x425982: main (ccTalkScan.cxx:334)
==17848==  Address 0x7feffdf58 is not stack'd, malloc'd or (recently) free'd
==17848==
==17848== Invalid read of size 8
==17848==    at 0x546EB59: ??? (setcontext.S:64)
==17848==    by 0x425847: receive(boost::asio::io_service&,
boost::asio::posix::basic_stream_descriptor<boost::asio::posix::stream_descriptor_service>&,
unsigned long, boost::asio::basic_streambuf<std::allocator<char> >&)
(ccTalkScan.cxx:320)
==17848==    by 0x425982: main (ccTalkScan.cxx:334)
==17848==  Address 0x7feffdf28 is not stack'd, malloc'd or (recently) free'd
==17848==
==17848== Invalid read of size 8
==17848==    at 0x546EB4A: ??? (setcontext.S:60)
==17848==    by 0x5E4BD2C: (below main) (in /lib64/libc-2.12.2.so)
==17848==  Address 0x7feffdfd8 is not stack'd, malloc'd or (recently) free'd
==17848==
==17848== Invalid read of size 8
==17848==    at 0x546EB52: ??? (setcontext.S:63)
==17848==    by 0x5E4BD2C: (below main) (in /lib64/libc-2.12.2.so)
==17848==  Address 0x7feffdfc8 is not stack'd, malloc'd or (recently) free'd
==17848==
==17848== Invalid read of size 8
==17848==    at 0x546EB59: ??? (setcontext.S:64)
==17848==    by 0x5E4BD2C: (below main) (in /lib64/libc-2.12.2.so)
==17848==  Address 0x7feffdf98 is not stack'd, malloc'd or (recently) free'd
==17848==
timeout
1 Type in 4 chareters and press enter

in> asdf
==17848== Syscall param readv(vector[...]) points to unaddressable byte(s)
==17848==    at 0x5EF7A81: readv (in /lib64/libc-2.12.2.so)
==17848==    by 0x42AF1C:
boost::asio::detail::descriptor_ops::non_blocking_read(int, iovec*,
unsigned long, boost::system::error_code&, unsigned long&)
(descriptor_ops.ipp:153)
==17848==    by 0x4360BF:
boost::asio::detail::descriptor_read_op_base<boost::asio::mutable_buffers_1>::do_perform(boost::asio::detail::reactor_op*)
(descriptor_read_op.hpp:55)
==17848==    by 0x427CE4: boost::asio::detail::reactor_op::perform()
(reactor_op.hpp:40)
==17848==    by 0x429003:
boost::asio::detail::epoll_reactor::run(bool,
boost::asio::detail::op_queue<boost::asio::detail::task_io_service_operation>&)
(epoll_reactor.ipp:286)
==17848==    by 0x429C81:
boost::asio::detail::task_io_service::do_one(boost::asio::detail::scoped_lock<boost::asio::detail::posix_mutex>&,
boost::asio::detail::task_io_service::idle_thread_info*)
(task_io_service.ipp:264)
==17848==    by 0x42986F:
boost::asio::detail::task_io_service::poll_one(boost::system::error_code&)
(task_io_service.ipp:188)
==17848==    by 0x42A0C2:
boost::asio::io_service::poll_one(boost::system::error_code&)
(io_service.ipp:103)
==17848==    by 0x4255E1: receive(boost::asio::io_service&,
boost::asio::posix::basic_stream_descriptor<boost::asio::posix::stream_descriptor_service>&,
boost::asio::basic_streambuf<std::allocator<char> >&)
(ccTalkScan.cxx:307)
==17848==    by 0x425847: receive(boost::asio::io_service&,
boost::asio::posix::basic_stream_descriptor<boost::asio::posix::stream_descriptor_service>&,
unsigned long, boost::asio::basic_streambuf<std::allocator<char> >&)
(ccTalkScan.cxx:320)
==17848==    by 0x425982: main (ccTalkScan.cxx:334)
==17848==  Address 0x65ba4f0 is 0 bytes inside a block of size 512 free'd
==17848==    at 0x4C25C4F: operator delete(void*) (vg_replace_malloc.c:387)
==17848==    by 0x432D07:
__gnu_cxx::new_allocator<char>::deallocate(char*, unsigned long)
(new_allocator.h:95)
==17848==    by 0x4316BF: std::_Vector_base<char, std::allocator<char>
>::_M_deallocate(char*, unsigned long) (stl_vector.h:146)
==17848==    by 0x42FD64: std::_Vector_base<char, std::allocator<char>
>::~_Vector_base() (stl_vector.h:132)
==17848==    by 0x42D6A4: std::vector<char, std::allocator<char>
>::~vector() (stl_vector.h:313)
==17848==    by 0x42B657:
boost::asio::basic_streambuf<std::allocator<char>
>::~basic_streambuf() (basic_streambuf.hpp:114)
==17848==    by 0x425A77: main (ccTalkScan.cxx:336)
==17848==
out> 2 Type in 4 chareters and press enter

in> timeout
3 Type in 4 chareters and press enter

in> timeout
4 Type in 4 chareters and press enter

in> timeout
==17848==
==17848== HEAP SUMMARY:
==17848==     in use at exit: 168 bytes in 3 blocks
==17848==   total heap usage: 65 allocs, 62 frees, 22,246 bytes allocated
==17848==
==17848== LEAK SUMMARY:
==17848==    definitely lost: 0 bytes in 0 blocks
==17848==    indirectly lost: 0 bytes in 0 blocks
==17848==      possibly lost: 0 bytes in 0 blocks
==17848==    still reachable: 168 bytes in 3 blocks
==17848==         suppressed: 0 bytes in 0 blocks
==17848== Rerun with --leak-check=full to see details of leaked memory
==17848==
==17848== For counts of detected and suppressed errors, rerun with: -v
==17848== Use --track-origins=yes to see where uninitialised values come from
==17848== ERROR SUMMARY: 27 errors from 9 contexts (suppressed: 4 from 4)

I have tried different things to fix, but I that I might have mis
understood a thing or two here. So some help would be most
appreciated.

--
Allan W. Nielsen