Merge pull request #2274 from bluca/cloexec

CMakeLists.txt

@@ -101,6 +101,10 @@ if (POLLER STREQUAL "")
     set (CMAKE_REQUIRED_INCLUDES)
     if (HAVE_EPOLL)
         set (POLLER "epoll")
+        check_function_exists (epoll_create1 HAVE_EPOLL_CLOEXEC)
+        if (HAVE_EPOLL_CLOEXEC)
+            set (ZMQ_USE_EPOLL_CLOEXEC 1)
+        endif ()
     endif ()
 endif ()
 
@@ -179,6 +183,9 @@ check_include_files (ifaddrs.h ZMQ_HAVE_IFADDRS)
 check_include_files (windows.h ZMQ_HAVE_WINDOWS)
 check_include_files (sys/uio.h ZMQ_HAVE_UIO)
 check_include_files (sys/eventfd.h ZMQ_HAVE_EVENTFD)
+if (ZMQ_HAVE_EVENTFD)
+  zmq_check_efd_cloexec ()
+endif ()
 
 check_library_exists (ws2_32 fopen "" HAVE_WS2_32) # TODO: Why doesn't something logical like WSAStartup work?
 check_library_exists (ws2 fopen "" HAVE_WS2)

acinclude.m4

@@ -614,6 +614,29 @@ int main (int argc, char *argv [])
     AS_IF([test "x$libzmq_cv_sock_cloexec" = "xyes"], [$1], [$2])
 }])
 
+dnl ################################################################################
+dnl # LIBZMQ_CHECK_EVENTFD_CLOEXEC([action-if-found], [action-if-not-found])          #
+dnl # Check if EFD_CLOEXEC is supported                                           #
+dnl ################################################################################
+AC_DEFUN([LIBZMQ_CHECK_EVENTFD_CLOEXEC], [{
+    AC_CACHE_CHECK([whether EFD_CLOEXEC is supported], [libzmq_cv_efd_cloexec],
+        [AC_TRY_RUN([/* EFD_CLOEXEC test */
+#include <sys/eventfd.h>
+
+int main (int argc, char *argv [])
+{
+    int s = eventfd (0, EFD_CLOEXEC);
+    return (s == -1);
+}
+        ],
+        [libzmq_cv_efd_cloexec="yes"],
+        [libzmq_cv_efd_cloexec="no"],
+        [libzmq_cv_efd_cloexec="not during cross-compile"]
+        )]
+    )
+    AS_IF([test "x$libzmq_cv_efd_cloexec" = "xyes"], [$1], [$2])
+}])
+
 dnl ################################################################################
 dnl # LIBZMQ_CHECK_ATOMIC_INSTRINSICS([action-if-found], [action-if-not-found])    #
 dnl # Check if compiler supoorts __atomic_Xxx intrinsics                           #
@@ -801,6 +824,7 @@ kqueue();
 
 dnl ################################################################################
 dnl # LIBZMQ_CHECK_POLLER_EPOLL_RUN([action-if-found], [action-if-not-found])      #
+dnl # LIBZMQ_CHECK_POLLER_EPOLL_CLOEXEC([action-if-found], [action-if-not-found])  #
 dnl # Checks epoll polling system can actually run #
 dnl # For cross-compile, only requires that epoll can link #
 dnl ################################################################################
@@ -828,6 +852,30 @@ epoll_create(10);
     )
 }])
 
+AC_DEFUN([LIBZMQ_CHECK_POLLER_EPOLL_CLOEXEC], [{
+    AC_RUN_IFELSE([
+        AC_LANG_PROGRAM([
+#include <sys/epoll.h>
+        ],[[
+struct epoll_event t_ev;
+int r;
+r = epoll_create1(EPOLL_CLOEXEC);
+return(r < 0);
+        ]])],
+        [$1],[$2],[
+            AC_LINK_IFELSE([
+                AC_LANG_PROGRAM([
+#include <sys/epoll.h>
+                ],[[
+struct epoll_event t_ev;
+epoll_create1(EPOLL_CLOEXEC);
+                ]])],
+                [$1], [$2]
+            )
+        ]
+    )
+}])
+
 dnl ################################################################################
 dnl # LIBZMQ_CHECK_POLLER_DEVPOLL([action-if-found], [action-if-not-found])        #
 dnl # Checks devpoll polling system                                                #
@@ -938,11 +986,18 @@ AC_DEFUN([LIBZMQ_CHECK_POLLER], [{
                 ])
             ;;
             epoll)
+                LIBZMQ_CHECK_POLLER_EPOLL_CLOEXEC([
+                    AC_MSG_NOTICE([Using 'epoll' polling system with CLOEXEC])
+                    AC_DEFINE(ZMQ_USE_EPOLL, 1, [Use 'epoll' polling system])
+                    AC_DEFINE(ZMQ_USE_EPOLL_CLOEXEC, 1, [Use 'epoll' polling system with CLOEXEC])
+                    poller_found=1
+                    ],[
                     LIBZMQ_CHECK_POLLER_EPOLL([
-                    AC_MSG_NOTICE([Using 'epoll' polling system])
+                        AC_MSG_NOTICE([Using 'epoll' polling system with CLOEXEC])
                         AC_DEFINE(ZMQ_USE_EPOLL, 1, [Use 'epoll' polling system])
                         poller_found=1
                     ])
+                ])
             ;;
             devpoll)
                 LIBZMQ_CHECK_POLLER_DEVPOLL([

builds/cmake/Modules/ZMQSourceRunChecks.cmake

@@ -16,6 +16,21 @@ int main(int argc, char *argv [])
     ZMQ_HAVE_SOCK_CLOEXEC)
 endmacro()
 
+macro(zmq_check_efd_cloexec)
+  message(STATUS "Checking whether EFD_CLOEXEC is supported")
+  check_c_source_runs(
+    "
+#include <sys/eventfd.h>
+
+int main(int argc, char *argv [])
+{
+    int s = eventfd (0, EFD_CLOEXEC);
+    return(s == -1);
+}
+"
+    ZMQ_HAVE_EVENTFD_CLOEXEC)
+endmacro()
+
 # TCP keep-alives Checks.
 
 macro(zmq_check_so_keepalive)

builds/cmake/platform.hpp.in

@@ -3,6 +3,7 @@
 
 #cmakedefine ZMQ_USE_KQUEUE
 #cmakedefine ZMQ_USE_EPOLL
+#cmakedefine ZMQ_USE_EPOLL_CLOEXEC
 #cmakedefine ZMQ_USE_DEVPOLL
 #cmakedefine ZMQ_USE_POLL
 #cmakedefine ZMQ_USE_SELECT
@@ -16,6 +17,7 @@
 #cmakedefine ZMQ_HAVE_UIO
 
 #cmakedefine ZMQ_HAVE_EVENTFD
+#cmakedefine ZMQ_HAVE_EVENTFD_CLOEXEC
 #cmakedefine ZMQ_HAVE_IFADDRS
 
 #cmakedefine ZMQ_HAVE_SO_PEERCRED

configure.ac

@@ -358,8 +358,14 @@ AC_ARG_ENABLE([eventfd],
 
 if test "x$zmq_enable_eventfd" = "xyes"; then
     # Check if we have eventfd.h header file.
-    AC_CHECK_HEADERS(sys/eventfd.h,
-        [AC_DEFINE(ZMQ_HAVE_EVENTFD, 1, [Have eventfd extension])])
+    AC_CHECK_HEADERS(sys/eventfd.h, [
+        AC_DEFINE(ZMQ_HAVE_EVENTFD, 1, [Have eventfd extension])
+        LIBZMQ_CHECK_EVENTFD_CLOEXEC([
+            AC_DEFINE([ZMQ_HAVE_EVENTFD_CLOEXEC],
+               [1],
+               [Whether EFD_CLOEXEC is defined and functioning.])
+            ])
+    ])
 fi
 
 # Conditionally build performance measurement tools

src/epoll.cpp

@@ -48,7 +48,14 @@ zmq::epoll_t::epoll_t (const zmq::ctx_t &ctx_) :
     ctx(ctx_),
     stopping (false)
 {
+#ifdef ZMQ_USE_EPOLL_CLOEXEC
+    //  Setting this option result in sane behaviour when exec() functions
+    //  are used. Old sockets are closed and don't block TCP ports, avoid
+    //  leaks, etc.
+    epoll_fd = epoll_create1 (EPOLL_CLOEXEC);
+#else
     epoll_fd = epoll_create (1);
+#endif
     errno_assert (epoll_fd != -1);
 }
 

src/signaler.cpp

@@ -381,7 +381,14 @@ void zmq::signaler_t::forked ()
 int zmq::signaler_t::make_fdpair (fd_t *r_, fd_t *w_)
 {
 #if defined ZMQ_HAVE_EVENTFD
-    fd_t fd = eventfd (0, 0);
+    int flags = 0;
+#if defined ZMQ_HAVE_EVENTFD_CLOEXEC
+    //  Setting this option result in sane behaviour when exec() functions
+    //  are used. Old sockets are closed and don't block TCP ports, avoid
+    //  leaks, etc.
+    flags |= EFD_CLOEXEC;
+#endif
+    fd_t fd = eventfd (0, flags);
     if (fd == -1) {
         errno_assert (errno == ENFILE || errno == EMFILE);
         *w_ = *r_ = -1;
@@ -637,13 +644,29 @@ int zmq::signaler_t::make_fdpair (fd_t *r_, fd_t *w_)
 #else
     // All other implementations support socketpair()
     int sv [2];
-    int rc = socketpair (AF_UNIX, SOCK_STREAM, 0, sv);
+    int type = SOCK_STREAM;
+    //  Setting this option result in sane behaviour when exec() functions
+    //  are used. Old sockets are closed and don't block TCP ports, avoid
+    //  leaks, etc.
+#if defined ZMQ_HAVE_SOCK_CLOEXEC
+    type |= SOCK_CLOEXEC;
+#endif
+    int rc = socketpair (AF_UNIX, type, 0, sv);
     if (rc == -1) {
         errno_assert (errno == ENFILE || errno == EMFILE);
         *w_ = *r_ = -1;
         return -1;
     }
     else {
+        //  If there's no SOCK_CLOEXEC, let's try the second best option. Note that
+        //  race condition can cause socket not to be closed (if fork happens
+        //  between socket creation and this point).
+#if !defined ZMQ_HAVE_SOCK_CLOEXEC && defined FD_CLOEXEC
+        rc = fcntl (sv [0], F_SETFD, FD_CLOEXEC);
+        errno_assert (rc != -1);
+        rc = fcntl (sv [1], F_SETFD, FD_CLOEXEC);
+        errno_assert (rc != -1);
+#endif
         *w_ = sv [0];
         *r_ = sv [1];
         return 0;

tests/CMakeLists.txt

@@ -84,6 +84,7 @@ if(NOT WIN32)
           test_router_mandatory_hwm
           test_use_fd_ipc
           test_use_fd_tcp
+          test_zmq_poll_fd
   )
   if(HAVE_FORK)
     list(APPEND tests test_fork)