Add zmq_getmsgopt to the API

The new function allows to retrieve options (flags)
from zmq_msg_t.
Signed-off-by: Chuck Remes <cremes@mac.com>
Renamed from zmq_msg_flags to zmq_getmsgopt
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

.gitignore

@@ -32,6 +32,7 @@ tests/test_reqrep_device
 tests/test_reqrep_drop
 tests/test_sub_forward
 tests/test_invalid_rep
+tests/test_msg_flags
 src/platform.hpp*
 src/stamp-h1
 perf/local_lat

doc/Makefile.am

@@ -3,7 +3,7 @@ MAN3 = zmq_bind.3 zmq_close.3 zmq_connect.3 zmq_init.3 \
     zmq_msg_init_data.3 zmq_msg_init_size.3 zmq_msg_move.3 zmq_msg_size.3 \
     zmq_poll.3 zmq_recv.3 zmq_send.3 zmq_setsockopt.3 zmq_socket.3 \
     zmq_strerror.3 zmq_term.3 zmq_version.3 zmq_getsockopt.3 zmq_errno.3 \
-    zmq_sendmsg.3 zmq_recvmsg.3
+    zmq_sendmsg.3 zmq_recvmsg.3 zmq_getmsgopt.3
 MAN7 = zmq.7 zmq_tcp.7 zmq_pgm.7 zmq_epgm.7 zmq_inproc.7 zmq_ipc.7
 
 MAN_DOC = $(MAN1) $(MAN3) $(MAN7)

doc/zmq_getmsgopt.txt

+zmq_getmsgopt(3)
+================
+
+
+NAME
+----
+zmq_getmsgopt - retrieve message option
+
+
+SYNOPSIS
+--------
+*int zmq_getmsgopt (zmq_msg_t '*message', int 'option_name', void '*option_value', size_t '*option_len');*
+
+
+DESCRIPTION
+-----------
+The _zmq_getmsgopt()_ function shall retrieve the value for the option
+specified by the 'option_name' argument for the message pointed to by the
+'message' argument, and store it in the buffer pointed to by the 'option_value'
+argument. The 'option_len' argument is the size in bytes of the buffer pointed
+to by 'option_value'; upon successful completion _zmq_getsockopt()_ shall
+modify the 'option_len' argument to indicate the actual size of the option
+value stored in the buffer.
+
+The following options can be retrieved with the _zmq_getmsgopt()_ function:
+
+*ZMQ_MORE*::
+Indicates that there are more message parts to follow after the 'message'.
+
+RETURN VALUE
+------------
+The _zmq_getmsgopt()_ function shall return zero if successful. Otherwise it
+shall return `-1` and set 'errno' to one of the values defined below.
+
+
+ERRORS
+------
+*EINVAL*::
+The requested option _option_name_ is unknown, or the requested _option_size_ or
+_option_value_ is invalid, or the size of the buffer pointed to by
+_option_value_, as specified by _option_len_, is insufficient for storing the
+option value.
+
+
+EXAMPLE
+-------
+.Receiving a multi-part message
+----
+zmq_msg_t part;
+int more;
+size_t more_size = sizeof (more);
+while (true) {
+    /* Create an empty 0MQ message to hold the message part */
+    int rc = zmq_msg_init (&part);
+    assert (rc == 0);
+    /* Block until a message is available to be received from socket */
+    rc = zmq_recvmsg (socket, &part, 0);
+    assert (rc != -1);
+    rc = getmsgopt (&part, ZMQ_MORE, &more, &more_size);
+    assert (rc == 0);
+    if (more) {
+      fprintf (stderr, "more\n");
+    }
+    else {
+      fprintf (stderr, "end\n");
+      break;
+    }
+    zmq_msg_close (part);
+}
+----
+
+
+SEE ALSO
+--------
+linkzmq:zmq_msg_data[3]
+linkzmq:zmq_msg_init[3]
+linkzmq:zmq_msg_init_size[3]
+linkzmq:zmq_msg_init_data[3]
+linkzmq:zmq_msg_close[3]
+linkzmq:zmq[7]
+
+
+AUTHORS
+-------
+The 0MQ documentation was written by Chuck Remes <cremes@mac.com>.

include/zmq.h

@@ -139,6 +139,8 @@ ZMQ_EXPORT int zmq_msg_move (zmq_msg_t *dest, zmq_msg_t *src);
 ZMQ_EXPORT int zmq_msg_copy (zmq_msg_t *dest, zmq_msg_t *src);
 ZMQ_EXPORT void *zmq_msg_data (zmq_msg_t *msg);
 ZMQ_EXPORT size_t zmq_msg_size (zmq_msg_t *msg);
+ZMQ_EXPORT int zmq_getmsgopt (zmq_msg_t *msg, int option, void *optval,
+    size_t *optvallen);
 
 /******************************************************************************/
 /*  0MQ infrastructure (a.k.a. context) initialisation & termination.         */
@@ -192,6 +194,9 @@ ZMQ_EXPORT int zmq_term (void *context);
 #define ZMQ_SNDTIMEO 28
 #define ZMQ_IPV4ONLY 31
 
+/*  Message options                                                           */
+#define ZMQ_MORE 1
+
 /*  Send/recv options.                                                        */
 #define ZMQ_DONTWAIT 1
 #define ZMQ_SNDMORE 2

src/socket_base.cpp

@@ -485,6 +485,9 @@ int zmq::socket_base_t::send (msg_t *msg_, int flags_)
     if (unlikely (rc != 0))
         return -1;
 
+    //  Clear any user-visible flags that are set on the message.
+    msg_->reset_flags (msg_t::more);
+
     //  At this point we impose the flags on the message.
     if (flags_ & ZMQ_SNDMORE)
         msg_->set_flags (msg_t::more);
@@ -857,15 +860,10 @@ void zmq::socket_base_t::terminated (pipe_t *pipe_)
 void zmq::socket_base_t::extract_flags (msg_t *msg_)
 {
     //  Test whether IDENTITY flag is valid for this socket type.
-    if (unlikely (msg_->flags () & msg_t::identity)) {
+    if (unlikely (msg_->flags () & msg_t::identity))
         zmq_assert (options.recv_identity);
-printf ("identity recvd\n");
-    }
   
-
     //  Remove MORE flag.
     rcvmore = msg_->flags () & msg_t::more ? true : false;
-    if (rcvmore)
-        msg_->reset_flags (msg_t::more);
 }
 

src/zmq.cpp

@@ -340,6 +340,25 @@ size_t zmq_msg_size (zmq_msg_t *msg_)
     return ((zmq::msg_t*) msg_)->size ();
 }
 
+int zmq_getmsgopt (zmq_msg_t *msg_, int option_, void *optval_,
+    size_t *optvallen_)
+{
+    switch (option_) {
+    case ZMQ_MORE:
+        if (*optvallen_ < sizeof (int)) {
+            errno = EINVAL;
+            return -1;
+        }
+        *((int*) optval_) =
+            (((zmq::msg_t*) msg_)->flags () & zmq::msg_t::more) ? 1 : 0;
+        *optvallen_ = sizeof (int);
+        return 0;
+    default:
+        errno = EINVAL;
+        return -1;
+    }
+}
+
 int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
 {
 #if defined ZMQ_POLL_BASED_ON_POLL

tests/Makefile.am

@@ -8,7 +8,8 @@ noinst_PROGRAMS = test_pair_inproc \
                   test_hwm \
                   test_reqrep_device \
                   test_sub_forward \
-                  test_invalid_rep
+                  test_invalid_rep \
+                  test_msg_flags
 
 if !ON_MINGW
 noinst_PROGRAMS += test_shutdown_stress \
@@ -25,6 +26,7 @@ test_hwm_SOURCES = test_hwm.cpp
 test_reqrep_device_SOURCES = test_reqrep_device.cpp
 test_sub_forward_SOURCES = test_sub_forward.cpp
 test_invalid_rep_SOURCES = test_invalid_rep.cpp
+test_msg_flags_SOURCES = test_msg_flags.cpp
 
 if !ON_MINGW
 test_shutdown_stress_SOURCES = test_shutdown_stress.cpp

tests/test_msg_flags.cpp

+/*
+    Copyright (c) 2011 250bpm s.r.o.
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <assert.h>
+#include <string.h>
+
+#include "../include/zmq.h"
+
+int main (int argc, char *argv [])
+{
+    //  Create the infrastructure
+    void *ctx = zmq_init (0);
+    assert (ctx);
+    void *sb = zmq_socket (ctx, ZMQ_XREP);
+    assert (sb);
+    int rc = zmq_bind (sb, "inproc://a");
+    assert (rc == 0);
+    void *sc = zmq_socket (ctx, ZMQ_XREQ);
+    assert (sc);
+    rc = zmq_connect (sc, "inproc://a");
+    assert (rc == 0);
+   
+    //  Send 2-part message.
+    rc = zmq_send (sc, "A", 1, ZMQ_SNDMORE);
+    assert (rc == 1);
+    rc = zmq_send (sc, "B", 1, 0);
+    assert (rc == 1);
+
+    //  Identity comes first.
+    zmq_msg_t msg;
+    rc = zmq_msg_init (&msg);
+    assert (rc == 0);
+    rc = zmq_recvmsg (sb, &msg, 0);
+    assert (rc >= 0);
+    int more;
+    size_t more_size = sizeof (more);
+    rc = zmq_getmsgopt (&msg, ZMQ_MORE, &more, &more_size);
+    assert (rc == 0);
+    assert (more == 1);
+
+    //  Then the first part of the message body.
+    rc = zmq_recvmsg (sb, &msg, 0);
+    assert (rc == 1);
+    more_size = sizeof (more);
+    rc = zmq_getmsgopt (&msg, ZMQ_MORE, &more, &more_size);
+    assert (rc == 0);
+    assert (more == 1);
+
+    //  And finally, the second part of the message body.
+    rc = zmq_recvmsg (sb, &msg, 0);
+    assert (rc == 1);
+    more_size = sizeof (more);
+    rc = zmq_getmsgopt (&msg, ZMQ_MORE, &more, &more_size);
+    assert (rc == 0);
+    assert (more == 0);
+
+    //  Deallocate the infrastructure.
+    rc = zmq_close (sc);
+    assert (rc == 0);
+    rc = zmq_close (sb);
+    assert (rc == 0);
+    rc = zmq_term (ctx);
+    assert (rc == 0);
+    return 0 ;
+}
+