Experimental function zmq_recviov doesnt work correctly in a couple of cases

1) VSM - you cannot hand out the 'data' address as it was not allocated on the heap
2) for other messages the 'data' address cannot be handed out either, as it not the address
originally returned by malloc and hence cannot be passed to 'free'.
see msg.cpp
u.lmsg.content = (content_t*) malloc (sizeof (content_t) + size_);
....
u.lmsg.content->data = u.lmsg.content + 1;

So the function is changed to always malloc a data buffer and copy the data into it.
There is a possible optimisation using memmove for the non-VSM case but that is not done yet.

src/zmq.cpp

@@ -478,10 +478,6 @@ int zmq_recv (void *s_, void *buf_, size_t len_, int flags_)
 // The iov_base* buffers of each iovec *a_ filled in by this 
 // function may be freed using free().
 //
-// Implementation note: We assume zmq::msg_t buffer allocated
-// by zmq::recvmsg can be freed by free().
-// We assume it is safe to steal these buffers by simply
-// not closing the zmq::msg_t.
 //
 int zmq_recviov (void *s_, iovec *a_, size_t *count_, int flags_)
 {
@@ -498,8 +494,7 @@ int zmq_recviov (void *s_, iovec *a_, size_t *count_, int flags_)
     *count_ = 0;
 
     for (size_t i = 0; recvmore && i < count; ++i) {
-        // Cheat! We never close any msg
-        // because we want to steal the buffer.
+       
         zmq_msg_t msg;
         int rc = zmq_msg_init (&msg);
         errno_assert (rc == 0);
@@ -513,15 +508,21 @@ int zmq_recviov (void *s_, iovec *a_, size_t *count_, int flags_)
             nread = -1;
             break;
         }
-        ++*count_;
-        ++nread;
 
-        // Cheat: acquire zmq_msg buffer.
-        a_[i].iov_base = static_cast<char *> (zmq_msg_data (&msg));
         a_[i].iov_len = zmq_msg_size (&msg);
-
+        a_[i].iov_base = malloc(a_[i].iov_len);
+        if (!a_[i].iov_base) {
+            errno = ENOMEM;
+            return -1;
+        }
+        memcpy(a_[i].iov_base,static_cast<char *> (zmq_msg_data (&msg)),
+               a_[i].iov_len);
         // Assume zmq_socket ZMQ_RVCMORE is properly set.
         recvmore = ((zmq::msg_t*) (void *) &msg)->flags () & zmq::msg_t::more;
+        rc = zmq_msg_close(&msg);
+        errno_assert (rc == 0);
+        ++*count_;
+        ++nread;
     }
     return nread;
 }

tests/Makefile.am

@@ -20,7 +20,8 @@ noinst_PROGRAMS = test_pair_inproc \
                   test_router_mandatory \
                   test_raw_sock \
                   test_disconnect_inproc \
-                  test_ctx_options
+                  test_ctx_options \
+				  test_iov
 
 if !ON_MINGW
 noinst_PROGRAMS += test_shutdown_stress \

tests/test_iov.cpp

+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    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 "../include/zmq.h"
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#undef NDEBUG
+#include <assert.h>
+
+// XSI vector I/O
+#if defined ZMQ_HAVE_UIO
+#include <sys/uio.h>
+#else
+struct iovec {
+    void *iov_base;
+    size_t iov_len;
+};
+#endif
+
+void do_check(void* sb, void* sc, unsigned int msgsz)
+{
+    int rc;
+    int sum =0;
+    for (int i = 0; i < 10; i++)
+    {
+        zmq_msg_t msg;
+        zmq_msg_init_size(&msg, msgsz);
+        void * data = zmq_msg_data(&msg);
+        memcpy(data,&i, sizeof(int));
+        rc = zmq_msg_send(&msg,sc,i==9 ? 0 :ZMQ_SNDMORE);
+        assert (rc == (int)msgsz);
+        zmq_msg_close(&msg);
+        sum += i;
+    }
+
+    struct iovec ibuffer[32] ;
+    memset(&ibuffer[0], 0, sizeof(ibuffer));
+    
+    size_t count = 10;
+    rc = zmq_recviov(sb,&ibuffer[0],&count,0);
+    assert (rc == 10);
+
+    int rsum=0;
+    for(;count;--count)
+    {
+        int v;
+        memcpy(&v,ibuffer[count-1].iov_base,sizeof(int));
+        rsum += v;
+        assert(ibuffer[count-1].iov_len == msgsz);
+        // free up the memory
+        free(ibuffer[count-1].iov_base);
+    }
+    
+    assert ( sum == rsum );
+
+}
+
+int main (void)
+{
+    void *ctx = zmq_ctx_new ();
+    assert (ctx);
+    int rc;
+   
+    void *sb = zmq_socket (ctx, ZMQ_PULL);
+    assert (sb);
+  
+    rc = zmq_bind (sb, "inproc://a");
+    assert (rc == 0);
+
+    ::sleep(1);
+    void *sc = zmq_socket (ctx, ZMQ_PUSH);
+  
+    rc = zmq_connect (sc, "inproc://a");
+    assert (rc == 0);
+
+
+    // message bigger than vsm max
+    do_check(sb,sc,100);
+
+    // message smaller than vsm max
+    do_check(sb,sc,10);
+
+    rc = zmq_close (sc);
+    assert (rc == 0);
+
+    rc = zmq_close (sb);
+    assert (rc == 0);
+
+    rc = zmq_ctx_term (ctx);
+    assert (rc == 0);
+
+	return 0;
+}