Problem: test_large_msg kills my system temporarily

And I'm on a reasonably sized laptop. I think allocating INT_MAX
memory is dangerous in a test case.

Solution: expose this as a context option. I've used ZMQ_MAX_MSGSZ
and documented it and implemented the API. However I don't know how
to get the parent context for a socket, so the code in zmq.cpp is
still unfinished.

doc/zmq_ctx_get.txt

@@ -26,20 +26,30 @@ ZMQ_IO_THREADS: Get number of I/O threads
 The 'ZMQ_IO_THREADS' argument returns the size of the 0MQ thread pool
 for this context.
 
+
 ZMQ_MAX_SOCKETS: Get maximum number of sockets
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_MAX_SOCKETS' argument returns the maximum number of sockets
 allowed for this context.
 
+
+ZMQ_MAX_MSGSZ: Get maximum message size
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The 'ZMQ_MAX_MSGSZ' argument returns the maximum size of a message
+allowed for this context. Default value is INT_MAX.
+
+
 ZMQ_SOCKET_LIMIT: Get largest configurable number of sockets
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_SOCKET_LIMIT' argument returns the largest number of sockets that
 linkzmq:zmq_ctx_set[3] will accept.
 
+
 ZMQ_IPV6: Set IPv6 option
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_IPV6' argument returns the IPv6 option for the context.
 
+
 ZMQ_BLOCKY: Get blocky setting
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_BLOCKY' argument returns 1 if the context will block on terminate,

doc/zmq_ctx_set.txt

@@ -47,6 +47,7 @@ context.
 [horizontal]
 Default value:: 1
 
+
 ZMQ_THREAD_SCHED_POLICY: Set scheduling policy for I/O threads
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_THREAD_SCHED_POLICY' argument sets the scheduling policy for
@@ -58,6 +59,7 @@ This option only applies before creating any sockets on the context.
 [horizontal]
 Default value:: -1
 
+
 ZMQ_THREAD_PRIORITY: Set scheduling priority for I/O threads
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_THREAD_PRIORITY' argument sets scheduling priority for
@@ -69,6 +71,19 @@ This option only applies before creating any sockets on the context.
 [horizontal]
 Default value:: -1
 
+
+ZMQ_MAX_MSGSZ: Set maximum message size
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The 'ZMQ_MAX_MSGSZ' argument sets the maximum allowed size
+of a message sent in the context. You can query the maximal
+allowed value with linkzmq:zmq_ctx_get[3] using the
+'ZMQ_MAX_MSGSZ' option.
+
+[horizontal]
+Default value:: INT_MAX
+Maximum value:: INT_MAX
+
+
 ZMQ_MAX_SOCKETS: Set maximum number of sockets
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_MAX_SOCKETS' argument sets the maximum number of sockets allowed
@@ -78,6 +93,7 @@ linkzmq:zmq_ctx_get[3] using the 'ZMQ_SOCKET_LIMIT' option.
 [horizontal]
 Default value:: 1024
 
+
 ZMQ_IPV6: Set IPv6 option
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_IPV6' argument sets the IPv6 value for all sockets created in

include/zmq.h

@@ -185,13 +185,13 @@ ZMQ_EXPORT void zmq_version (int *major, int *minor, int *patch);
 /*  0MQ infrastructure (a.k.a. context) initialisation & termination.         */
 /******************************************************************************/
 
-/*  New API                                                                   */
 /*  Context options                                                           */
 #define ZMQ_IO_THREADS  1
 #define ZMQ_MAX_SOCKETS 2
 #define ZMQ_SOCKET_LIMIT 3
 #define ZMQ_THREAD_PRIORITY 3
 #define ZMQ_THREAD_SCHED_POLICY 4
+#define ZMQ_MAX_MSGSZ 5
 
 /*  Default for new contexts                                                  */
 #define ZMQ_IO_THREADS_DFLT  1

src/ctx.cpp

@@ -36,6 +36,7 @@
 #endif
 
 #include <limits>
+#include <climits>
 #include <new>
 #include <string.h>
 
@@ -79,6 +80,7 @@ zmq::ctx_t::ctx_t () :
     slot_count (0),
     slots (NULL),
     max_sockets (clipped_maxsocket (ZMQ_MAX_SOCKETS_DFLT)),
+    max_msgsz (INT_MAX),
     io_thread_count (ZMQ_IO_THREADS_DFLT),
     blocky (true),
     ipv6 (false),
@@ -251,13 +253,13 @@ int zmq::ctx_t::set (int option_, int optval_)
     if (option_ == ZMQ_THREAD_PRIORITY && optval_ >= 0) {
         opt_sync.lock();
         thread_priority = optval_;
-        opt_sync.unlock();
+        opt_sync.unlock ();
     }
     else
     if (option_ == ZMQ_THREAD_SCHED_POLICY && optval_ >= 0) {
         opt_sync.lock();
         thread_sched_policy = optval_;
-        opt_sync.unlock();
+        opt_sync.unlock ();
     }
     else
     if (option_ == ZMQ_BLOCKY && optval_ >= 0) {
@@ -265,6 +267,12 @@ int zmq::ctx_t::set (int option_, int optval_)
         blocky = (optval_ != 0);
         opt_sync.unlock ();
     }
+    else
+    if (option_ == ZMQ_MAX_MSGSZ && optval_ >= 0) {
+        opt_sync.lock ();
+        max_msgsz = optval_ < INT_MAX? optval_: INT_MAX;
+        opt_sync.unlock ();
+    }
     else {
         errno = EINVAL;
         rc = -1;
@@ -289,6 +297,9 @@ int zmq::ctx_t::get (int option_)
     else
     if (option_ == ZMQ_BLOCKY)
         rc = blocky;
+    else
+    if (option_ == ZMQ_MAX_MSGSZ)
+        rc = max_msgsz;
     else {
         errno = EINVAL;
         rc = -1;

src/ctx.hpp

@@ -199,6 +199,9 @@ namespace zmq
         //  Maximum number of sockets that can be opened at the same time.
         int max_sockets;
 
+        //  Maximum allowed message size
+        int max_msgsz;
+
         //  Number of I/O threads to launch.
         int io_thread_count;
 

src/socket_base.hpp

@@ -245,7 +245,7 @@ namespace zmq
         void update_pipe_options(int option_);
 
         //  Socket's mailbox object.
-        i_mailbox* mailbox;
+        i_mailbox *mailbox;
 
         //  List of attached pipes.
         typedef array_t <pipe_t, 3> pipes_t;

src/zmq.cpp

@@ -164,12 +164,12 @@ void *zmq_ctx_new (void)
 
 int zmq_ctx_term (void *ctx_)
 {
-    if (!ctx_ || !((zmq::ctx_t*) ctx_)->check_tag ()) {
+    if (!ctx_ || !((zmq::ctx_t *) ctx_)->check_tag ()) {
         errno = EFAULT;
         return -1;
     }
 
-    int rc = ((zmq::ctx_t*) ctx_)->terminate ();
+    int rc = ((zmq::ctx_t *) ctx_)->terminate ();
     int en = errno;
 
     //  Shut down only if termination was not interrupted by a signal.
@@ -193,30 +193,29 @@ int zmq_ctx_term (void *ctx_)
 
 int zmq_ctx_shutdown (void *ctx_)
 {
-    if (!ctx_ || !((zmq::ctx_t*) ctx_)->check_tag ()) {
+    if (!ctx_ || !((zmq::ctx_t *) ctx_)->check_tag ()) {
         errno = EFAULT;
         return -1;
     }
-
-    return ((zmq::ctx_t*) ctx_)->shutdown ();
+    return ((zmq::ctx_t *) ctx_)->shutdown ();
 }
 
 int zmq_ctx_set (void *ctx_, int option_, int optval_)
 {
-    if (!ctx_ || !((zmq::ctx_t*) ctx_)->check_tag ()) {
+    if (!ctx_ || !((zmq::ctx_t *) ctx_)->check_tag ()) {
         errno = EFAULT;
         return -1;
     }
-    return ((zmq::ctx_t*) ctx_)->set (option_, optval_);
+    return ((zmq::ctx_t *) ctx_)->set (option_, optval_);
 }
 
 int zmq_ctx_get (void *ctx_, int option_)
 {
-    if (!ctx_ || !((zmq::ctx_t*) ctx_)->check_tag ()) {
+    if (!ctx_ || !((zmq::ctx_t *) ctx_)->check_tag ()) {
         errno = EFAULT;
         return -1;
     }
-    return ((zmq::ctx_t*) ctx_)->get (option_);
+    return ((zmq::ctx_t *) ctx_)->get (option_);
 }
 
 //  Stable/legacy context API
@@ -247,11 +246,11 @@ int zmq_ctx_destroy (void *ctx_)
 
 void *zmq_socket (void *ctx_, int type_)
 {
-    if (!ctx_ || !((zmq::ctx_t*) ctx_)->check_tag ()) {
+    if (!ctx_ || !((zmq::ctx_t *) ctx_)->check_tag ()) {
         errno = EFAULT;
         return NULL;
     }
-    zmq::ctx_t *ctx = (zmq::ctx_t*) ctx_;
+    zmq::ctx_t *ctx = (zmq::ctx_t *) ctx_;
     zmq::socket_base_t *s = ctx->create_socket (type_);
     return (void *) s;
 }
@@ -366,15 +365,20 @@ int zmq_disconnect (void *s_, const char *addr_)
 
 // Sending functions.
 
-static int
+static inline int
 s_sendmsg (zmq::socket_base_t *s_, zmq_msg_t *msg_, int flags_)
 {
     size_t sz = zmq_msg_size (msg_);
     int rc = s_->send ((zmq::msg_t *) msg_, flags_);
     if (unlikely (rc < 0))
         return -1;
-    // truncate returned size to INT_MAX to avoid overflow to negative values
-    return (int) (sz < INT_MAX ? sz : INT_MAX);
+
+    //  This is what I'd like to do, my C++ fu is too weak -- PH 2016/02/09
+    //  int max_msgsz = s_->parent->get (ZMQ_MAX_MSGSZ);
+    size_t max_msgsz = INT_MAX;
+
+    //  Truncate returned size to INT_MAX to avoid overflow to negative values
+    return (int) (sz < max_msgsz? sz: max_msgsz);
 }
 
 /*  To be deprecated once zmq_msg_send() is stable                           */
@@ -407,7 +411,6 @@ int zmq_send (void *s_, const void *buf_, size_t len_, int flags_)
         errno = err;
         return -1;
     }
-
     //  Note the optimisation here. We don't close the msg object as it is
     //  empty anyway. This may change when implementation of zmq_msg_t changes.
     return rc;
@@ -433,7 +436,6 @@ int zmq_send_const (void *s_, const void *buf_, size_t len_, int flags_)
         errno = err;
         return -1;
     }
-
     //  Note the optimisation here. We don't close the msg object as it is
     //  empty anyway. This may change when implementation of zmq_msg_t changes.
     return rc;
@@ -484,12 +486,13 @@ int zmq_sendiov (void *s_, iovec *a_, size_t count_, int flags_)
 static int
 s_recvmsg (zmq::socket_base_t *s_, zmq_msg_t *msg_, int flags_)
 {
-    int rc = s_->recv ((zmq::msg_t*) msg_, flags_);
+    int rc = s_->recv ((zmq::msg_t *) msg_, flags_);
     if (unlikely (rc < 0))
         return -1;
-    // truncate returned size to INT_MAX to avoid overflow to negative values
+
+    //  Truncate returned size to INT_MAX to avoid overflow to negative values
     size_t sz = zmq_msg_size (msg_);
-    return (int) (sz < INT_MAX ? sz : INT_MAX);
+    return (int) (sz < INT_MAX? sz: INT_MAX);
 }
 
 /*  To be deprecated once zmq_msg_recv() is stable                           */

tests/test_setsockopt.cpp

 #include "testutil.hpp"
 
-void test_setsockopt_tcp_recv_buffer()
+void test_setsockopt_tcp_recv_buffer (void)
 {
     int rc;
-    void *ctx = zmq_ctx_new();
-    void *socket = zmq_socket(ctx, ZMQ_PUSH);
+    void *ctx = zmq_ctx_new ();
+    void *socket = zmq_socket (ctx, ZMQ_PUSH);
 
     int val = 0;
-    size_t placeholder = sizeof(val);
+    size_t placeholder = sizeof (val);
 
-    rc = zmq_getsockopt(socket, ZMQ_TCP_RECV_BUFFER, &val, &placeholder);
-    assert(rc == 0);
-    assert(val == 8192);
+    rc = zmq_getsockopt (socket, ZMQ_RCVBUF, &val, &placeholder);
+    assert (rc == 0);
+    assert (val == 8192);
 
-    rc = zmq_setsockopt(socket, ZMQ_TCP_RECV_BUFFER, &val, sizeof(val));
-    assert(rc == 0);
-    assert(val == 8192);
+    rc = zmq_setsockopt (socket, ZMQ_RCVBUF, &val, sizeof (val));
+    assert (rc == 0);
+    assert (val == 8192);
 
-    rc = zmq_getsockopt(socket, ZMQ_TCP_RECV_BUFFER, &val, &placeholder);
-    assert(rc == 0);
-    assert(val == 8192);
+    rc = zmq_getsockopt (socket, ZMQ_RCVBUF, &val, &placeholder);
+    assert (rc == 0);
+    assert (val == 8192);
 
     val = 16384;
 
-    rc = zmq_setsockopt(socket, ZMQ_TCP_RECV_BUFFER, &val, sizeof(val));
-    assert(rc == 0);
-    assert(val == 16384);
+    rc = zmq_setsockopt (socket, ZMQ_RCVBUF, &val, sizeof (val));
+    assert (rc == 0);
+    assert (val == 16384);
 
-    rc = zmq_getsockopt(socket, ZMQ_TCP_RECV_BUFFER, &val, &placeholder);
-    assert(rc == 0);
-    assert(val == 16384);
+    rc = zmq_getsockopt (socket, ZMQ_RCVBUF, &val, &placeholder);
+    assert (rc == 0);
+    assert (val == 16384);
 
-    zmq_close(socket);
-    zmq_ctx_term(ctx);
+    zmq_close (socket);
+    zmq_ctx_term (ctx);
 }
 
-void test_setsockopt_tcp_send_buffer()
+void test_setsockopt_tcp_send_buffer (void)
 {
     int rc;
-    void *ctx = zmq_ctx_new();
-    void *socket = zmq_socket(ctx, ZMQ_PUSH);
+    void *ctx = zmq_ctx_new ();
+    void *socket = zmq_socket (ctx, ZMQ_PUSH);
 
     int val = 0;
-    size_t placeholder = sizeof(val);
+    size_t placeholder = sizeof (val);
 
-    rc = zmq_getsockopt(socket, ZMQ_TCP_SEND_BUFFER, &val, &placeholder);
-    assert(rc == 0);
-    assert(val == 8192);
+    rc = zmq_getsockopt (socket, ZMQ_SNDBUF, &val, &placeholder);
+    assert (rc == 0);
+    assert (val == 8192);
 
-    rc = zmq_setsockopt(socket, ZMQ_TCP_SEND_BUFFER, &val, sizeof(val));
-    assert(rc == 0);
-    assert(val == 8192);
+    rc = zmq_setsockopt (socket, ZMQ_SNDBUF, &val, sizeof (val));
+    assert (rc == 0);
+    assert (val == 8192);
 
-    rc = zmq_getsockopt(socket, ZMQ_TCP_SEND_BUFFER, &val, &placeholder);
-    assert(rc == 0);
-    assert(val == 8192);
+    rc = zmq_getsockopt (socket, ZMQ_SNDBUF, &val, &placeholder);
+    assert (rc == 0);
+    assert (val == 8192);
 
     val = 16384;
 
-    rc = zmq_setsockopt(socket, ZMQ_TCP_SEND_BUFFER, &val, sizeof(val));
-    assert(rc == 0);
-    assert(val == 16384);
+    rc = zmq_setsockopt (socket, ZMQ_SNDBUF, &val, sizeof (val));
+    assert (rc == 0);
+    assert (val == 16384);
 
-    rc = zmq_getsockopt(socket, ZMQ_TCP_SEND_BUFFER, &val, &placeholder);
-    assert(rc == 0);
-    assert(val == 16384);
+    rc = zmq_getsockopt (socket, ZMQ_SNDBUF, &val, &placeholder);
+    assert (rc == 0);
+    assert (val == 16384);
 
-    zmq_close(socket);
-    zmq_ctx_term(ctx);
+    zmq_close (socket);
+    zmq_ctx_term (ctx);
 }
 
-void test_setsockopt_use_fd()
+void test_setsockopt_use_fd ()
 {
     int rc;
-    void *ctx = zmq_ctx_new();
-    void *socket = zmq_socket(ctx, ZMQ_PUSH);
+    void *ctx = zmq_ctx_new ();
+    void *socket = zmq_socket (ctx, ZMQ_PUSH);
 
     int val = 0;
-    size_t placeholder = sizeof(val);
+    size_t placeholder = sizeof (val);
 
-    rc = zmq_getsockopt(socket, ZMQ_USE_FD, &val, &placeholder);
+    rc = zmq_getsockopt (socket, ZMQ_USE_FD, &val, &placeholder);
     assert(rc == 0);
     assert(val == -1);
 
     val = 3;
 
-    rc = zmq_setsockopt(socket, ZMQ_USE_FD, &val, sizeof(val));
+    rc = zmq_setsockopt (socket, ZMQ_USE_FD, &val, sizeof(val));
     assert(rc == 0);
     assert(val == 3);
 
-    rc = zmq_getsockopt(socket, ZMQ_USE_FD, &val, &placeholder);
+    rc = zmq_getsockopt (socket, ZMQ_USE_FD, &val, &placeholder);
     assert(rc == 0);
     assert(val == 3);
 
-    zmq_close(socket);
-    zmq_ctx_term(ctx);
+    zmq_close (socket);
+    zmq_ctx_term (ctx);
 }
 
-
-int main()
+int main (void)
 {
-    test_setsockopt_tcp_recv_buffer();
-    test_setsockopt_tcp_send_buffer();
-    test_setsockopt_use_fd();
+    test_setsockopt_tcp_recv_buffer ();
+    test_setsockopt_tcp_send_buffer ();
+    test_setsockopt_use_fd ();
 }