_msg_info

Information about a message

Synopsis:

#include <sys/neutrino.h>

struct _msg_info {        /* _msg_info    _server_info */
    uint32_t  nd;         /*  client      server */
    uint32_t  srcnd;      /*  server      n/a */
    pid_t     pid;        /*  client      server */
    int32_t   tid;        /*  thread      n/a */
    int32_t   chid;       /*  server      server */
    int32_t   scoid;      /*  server      server */
    int32_t   coid;       /*  client      client */
    int32_t   msglen;     /*  msg         n/a */
    int32_t   srcmsglen;  /*  thread      n/a */
    int32_t   dstmsglen;  /*  thread      n/a */
    int16_t   priority;   /*  thread      n/a */
    int16_t   flags;      /*  n/a         client */
    uint32_t  reserved;
};

Description:

The _msg_info structure contains information about a message. The members include:

nd

The node descriptor of the client machine as viewed by the server. See “Node descriptors,” below.

srcnd

The node descriptor of the server, as viewed by the client.

pid

The process ID of the sending thread.

tid

The thread ID of the sending thread.

chid

The channel ID that the message was received on.

scoid

The server connection ID. This is a unique server-side client process identifier, corresponding to a particular process ID on a particular node.

coid

The client connection ID.

msglen

The number of bytes received.

srcmsglen

The length of the source message, in bytes, as sent by MsgSend*(). This may be greater than the value in msglen. This member is valid only if you set _NTO_CHF_SENDER_LEN in the flags argument to ChannelCreate() for the channel that received the message.

dstmsglen

The length of the client's reply buffer, in bytes, as passed to MsgSend*(). This member is valid only if you set _NTO_CHF_REPLY_LEN in the flags argument to ChannelCreate() for the channel that received the message.

priority

The priority of the sending thread.

flags

Flags that provide information about the sender and message:

• _NTO_MI_ENDIAN_BIG — the sending machine is big endian.
• _NTO_MI_ENDIAN_DIFF — the sending machine has a different endian-ness from the receiving machine.
• _NTO_MI_NET_CRED_DIRTY — used internally.
• _NTO_MI_UNBLOCK_REQ — the client has an unblock pending (i.e. a timeout on the send occurred or a signal was delivered and _NTO_CHF_UNBLOCK is set on the channel).

---

The msglen and srcmsglen members are valid only until the next call to MsgRead*() or MsgWrite*().

---

If msglen is less than srcmsglen and is also less than the receive buffer size, the message is a network transaction that requires more reading of data with MsgRead*().

Node descriptors

The nd (node descriptor) is a temporary numeric description of a remote node; ND_LOCAL_NODE (or 0) is the descriptor for the local node. For more information, see the Qnet Networking chapter of the System Architecture guide.

Classification:

QNX Neutrino

See also:

MsgInfo(), MsgReceive(), MsgReceivev(), ND_NODE_CMP(), netmgr_ndtostr(), netmgr_remote_nd(), netmgr_strtond()

Message Passing chapter of Getting Started with QNX Neutrino