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>

2 files changed, 86 insertions, 1 deletions

diff --git a/doc/Makefile.am b/doc/Makefile.am
index dae71be..ff00c18 100644
--- a/doc/Makefile.am
+++ b/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)
diff --git a/doc/zmq_getmsgopt.txt b/doc/zmq_getmsgopt.txt
new file mode 100644
index 0000000..a82c30c
--- /dev/null
+++ b/doc/zmq_getmsgopt.txt
@@ -0,0 +1,85 @@
+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>.