generic-library/libzmq
1
0
Fork 0
mirror of https://github.com/zeromq/libzmq.git synced 2025-11-09 23:57:50 +01:00
Code Issues Projects Releases Wiki Activity

Terminate context in a child process of fork() to replace file descriptors to not interfere with parent process's context

Browse Source
This commit is contained in:
Matt Connolly
2013-08-31 21:17:11 +10:00
parent 0478ee04f4
commit ff2900fd52
10 changed files with 141 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

62
src/signaler.cpp
View File

@@ -86,6 +86,10 @@ zmq::signaler_t::signaler_t ()
// Set both fds to non-blocking mode.
unblock_socket (w);
unblock_socket (r);
#ifdef HAVE_FORK
pid = getpid();
#endif
}
zmq::signaler_t::~signaler_t ()
@@ -117,6 +121,12 @@ zmq::fd_t zmq::signaler_t::get_fd ()
void zmq::signaler_t::send ()
{
#if HAVE_FORK
if (unlikely(pid != getpid())) {
//printf("Child process %d signaler_t::send returning without sending #1\n", getpid());
return; // do not send anything in forked child context
}
#endif
#if defined ZMQ_HAVE_EVENTFD
const uint64_t inc = 1;
ssize_t sz = write (w, &inc, sizeof (inc));
@@ -132,6 +142,13 @@ void zmq::signaler_t::send ()
ssize_t nbytes = ::send (w, &dummy, sizeof (dummy), 0);
if (unlikely (nbytes == -1 && errno == EINTR))
continue;
#if HAVE_FORK
if (unlikely(pid != getpid())) {
//printf("Child process %d signaler_t::send returning without sending #2\n", getpid());
errno = EINTR;
break;
}
#endif
zmq_assert (nbytes == sizeof (dummy));
break;
}
@@ -140,6 +157,17 @@ void zmq::signaler_t::send ()
int zmq::signaler_t::wait (int timeout_)
{
#ifdef HAVE_FORK
if (unlikely(pid != getpid()))
{
// we have forked and the file descriptor is closed. Emulate an interupt
// response.
//printf("Child process %d signaler_t::wait returning simulating interrupt #1\n", getpid());
errno = EINTR;
return -1;
}
#endif
#ifdef ZMQ_SIGNALER_WAIT_BASED_ON_POLL
struct pollfd pfd;
@@ -155,6 +183,16 @@ int zmq::signaler_t::wait (int timeout_)
errno = EAGAIN;
return -1;
}
#ifdef HAVE_FORK
if (unlikely(pid != getpid()))
{
// we have forked and the file descriptor is closed. Emulate an interupt
// response.
//printf("Child process %d signaler_t::wait returning simulating interrupt #2\n", getpid());
errno = EINTR;
return -1;
}
#endif
zmq_assert (rc == 1);
zmq_assert (pfd.revents & POLLIN);
return 0;
@@ -225,6 +263,30 @@ void zmq::signaler_t::recv ()
#endif
}
#ifdef HAVE_FORK
void zmq::signaler_t::forked()
{
int oldr = r;
int oldw = w;
// replace the file descriptors created in the parent with new
// ones, and close the inherited ones
make_fdpair(&r, &w);
#if defined ZMQ_HAVE_EVENTFD
int rc = close (oldr);
errno_assert (rc == 0);
#else
int rc = close (oldw);
errno_assert (rc == 0);
rc = close (oldr);
errno_assert (rc == 0);
#endif
}
#endif
int zmq::signaler_t::make_fdpair (fd_t *r_, fd_t *w_)
{
#if defined ZMQ_HAVE_EVENTFD