'\" t
.\"     Title: xs_getmsgopt
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 06/13/2012
.\"    Manual: Crossroads I/O Manual
.\"    Source: Crossroads I/O 1.2.0
.\"  Language: English
.\"
.TH "XS_GETMSGOPT" "3" "06/13/2012" "Crossroads I/O 1\&.2\&.0" "Crossroads I/O Manual"
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.SH "NAME"
xs_getmsgopt \- retrieve message option
.SH "SYNOPSIS"
.sp
\fBint xs_getmsgopt (xs_msg_t \fR\fB\fI*message\fR\fR\fB, int \fR\fB\fIoption_name\fR\fR\fB, void \fR\fB\fI*option_value\fR\fR\fB, size_t \fR\fB\fI*option_len\fR\fR\fB);\fR
.SH "DESCRIPTION"
.sp
The \fIxs_getmsgopt()\fR function shall retrieve the value for the option specified by the \fIoption_name\fR argument for the message pointed to by the \fImessage\fR argument, and store it in the buffer pointed to by the \fIoption_value\fR argument\&. The \fIoption_len\fR argument is the size in bytes of the buffer pointed to by \fIoption_value\fR; upon successful completion \fIxs_getsockopt()\fR shall modify the \fIoption_len\fR argument to indicate the actual size of the option value stored in the buffer\&.
.sp
The following options can be retrieved with the \fIxs_getmsgopt()\fR function:
.PP
\fBXS_MORE\fR
.RS 4
Indicates that there are more message parts to follow after the
\fImessage\fR\&. The type of this option is int\&. 0 means that this is the last message part of a multipart message\&. 1 means that more message parts will follow\&.
.RE
.SH "RETURN VALUE"
.sp
The \fIxs_getmsgopt()\fR function shall return zero if successful\&. Otherwise it shall return \-1 and set \fIerrno\fR to one of the values defined below\&.
.SH "ERRORS"
.PP
\fBEINVAL\fR
.RS 4
The requested option
\fIoption_name\fR
is unknown, or the requested
\fIoption_size\fR
or
\fIoption_value\fR
is invalid, or the size of the buffer pointed to by
\fIoption_value\fR, as specified by
\fIoption_len\fR, is insufficient for storing the option value\&.
.RE
.SH "EXAMPLE"
.PP
\fBReceiving a multi-part message\fR. 
.sp
.if n \{\
.RS 4
.\}
.nf
xs_msg_t part;
int more;
size_t more_size = sizeof (more);
while (true) {
    /* Create an empty message to hold the message part */
    int rc = xs_msg_init (&part);
    assert (rc == 0);
    /* Block until a message is available to be received from socket */
    rc = xs_recvmsg (socket, &part, 0);
    assert (rc != \-1);
    rc = getmsgopt (&part, XS_MORE, &more, &more_size);
    assert (rc == 0);
    if (more) {
      fprintf (stderr, "more\en");
    }
    else {
      fprintf (stderr, "end\en");
      break;
    }
    xs_msg_close (part);
}
.fi
.if n \{\
.RE
.\}
.sp
.SH "SEE ALSO"
.sp
\fBxs_msg_data\fR(3) \fBxs_msg_init\fR(3) \fBxs_msg_init_size\fR(3) \fBxs_msg_init_data\fR(3) \fBxs_msg_close\fR(3) \fBxs\fR(7)
.SH "AUTHORS"
.sp
This manual page was written by Chuck Remes <\m[blue]\fBcremes@mac\&.com\fR\m[]\&\s-2\u[1]\d\s+2>\&.
.SH "NOTES"
.IP " 1." 4
cremes@mac.com
.RS 4
\%mailto:cremes@mac.com
.RE