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Synopsis Environment
Description Diagnostics
Globals Notes
See also Examples |
Synopsis |
#include "ucm.h" int
UcmRecv(sock, msgId, msg, msgLen, flag);
T_SOCKET sock;
char *msgId, *msg;
int msgLen, flag; |
Environment |
Unix, Win32
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Description |
UcmRecv reads the next available message
through the BSD stream type socket sock and places it into the buffer pointed to by
msg. The received message is truncated to msgLen bytes if it is larger than msgLen.
The truncated part of the message is lost and no indication of the truncation is given to
the calling process. By specifying msgLen as -1, the entire message up to the UCM
defined limit of UCM_MAX_MSG bytes (see ucm.h) may be received. One or more
(bitwise inclusive OR-operation) of the following modes may be selected in the parameter flag:
| UF_NOFLAGS |
No special processing / normal case. |
| UF_NOWAIT |
Normally UcmRecv will suspend execution until the next message
comes available or the timeout span specified through UcmCntl
has expired. Setting the UF_NOWAITt flag causes UcmRecv to return immediately with
a return value of -1 and errno set to ENOMSG if no pending messages
exist. |
| UF_TIMEOUT |
This flag causes UcmRecv to return with the UE_NOMSG
error when the time span set with the UC_TIMEOUT UcmCntl
command has elapsed without receiving any message. |
UcmRecv will fail and no message will be received if one or more of the
following is true:
| UE_NOTINIT |
The UCM software has not been initialize (see UcmInit) |
| UE_BADSOCK |
The value of sock is not a valid socket descriptor or the socket is
not open. |
| UE_INTR |
The read process has been interrupted by a signal. |
| UE_NOMSG |
No message is available and UF_NOWAIT is set or UF_TIMEOUT is set and the
timeout span specified via UcmCntl has expired. |
| UE_CONNECT |
The socket has been closed. |
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Diagnostics |
Upon successful completion UcmRecv returns a value
equal to the number of bytes actually placed into msg. Otherwise, UCM_ERROR is
returned and ucmErrno is set to indicate the error.
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Notes |
The header ucm.h defines constants and types, that may
be used to allocate msgId and msg buffers:
| Name |
Description |
| UCM_MAX_MSG |
Constant, maximum message size in the current implementation
(see also Chapter 9, Configuration Limits) |
| UCM_MAX_MSGID |
Constant, maximum message ID size |
| T_UCM_MSG |
Type, message buffer, large enough to hold any UCM
message |
| T_UCM_MSGID |
Type, message ID buffer, large enough to hold any UCM
message ID |
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Globals |
char *ucmProgName; /*
reference */
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See also |
UcmCntl, UcmConnect, UcmOpen
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Examples |
#include
"ucm.h"
T_SOCKET socket;
T_UCM_MSG msg; /* buffer to hold message */
T_UCM_MSGID msgId; /* buffer to hold message ID */
int len; /* size of message received */
...
len = UcmRecv(sock, msgId, msg, -1, UF_NOFLAGS);
printf("UcmRecv returned %d\n", len); |
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