msgutil.9

7号信令功能代码,为开源代码

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.\" @(#) msgutil.9,v 1.1.4.1 2004/01/12 23:33:09 brian Exp
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.so lis.macros
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.\"
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.TH MSGUTIL 9 "2004/01/12 23:33:09" "LiS-2_16_18-8" "Linux STREAMS DDI/DKI"
.SH "NAME"
.B msgutil, lis_msgutil
\- \fISTREAMS\fR message utilities
.SH "SYNOPSIS"
.PP
.B #include <sys/stream.h>
.HP 8
.BI "int " retval " = msgsize(mblk_t *" mp );
.HP 8
.BI "int " retval " = msgdsize(mblk_t *" mp );
.HP 8
.BI "int " retval " = xmsgsize(mblk_t *" mp );
.HP 8
.BI "int " retval " = adjmsg(mblk_t *" mp ", int " len );
.HP 8
.BI "mblk_t *" mp " = copyb(mblk_t *" mp );
.HP 8
.BI "mblk_t *" mp " = copymsg(mblk_t *" mp );
.HP 8
.BI "mblk_t *" mp " = dupb(mblk_t *" mp );
.HP 8
.BI "mblk_t *" mp " = dupmsg(mblk_t *" mp );
.HP 8
.BI "void linkb(mblk_t *" mp );
.HP 8
.BI "mblk_t *" mp " = unlinkb(mblk_t *" mp );
.HP 8
.BI "int " retval " = pullupmsg(mblk_t *" mp ", int " len );
.HP 8
.BI "int " retval " = msgpullup(mblk_t *" mp ", int " len );
.HP 8
.BI "mblk_t *" mp " = rmvb(mblk_t *" mp ", mblk_t *" bp );
.fi
.SH "DESCRIPTION"
This man page describes the STREAMS message utility functions.
.TP
\fBmsgsize\fR
calculates and returns the aggregated sizes of all of the
message blocks in the message block chain pointed to by \fImp\fR (in bytes).
.TP
\fBmsgdsize\fR
calculates and returns the aggregated sizes of all of the
\fBM_DATA\fR blocks in the message block chain pointed to by \fImp\fR (in
bytes).
.TP
\fBxmsgsize\fR
calculates and the returns the aggregated sizes of all of the
blocks in the message block chain which are of the same block type as the
first block in the chain pointed to by \fImp\fR (in bytes).
.PP
\fBmsgsize\fR reads the available space (in contrast to used space) in each
message block for the calculation.
\fBmsgdsize\fR and \fBxmsgsize\fR reads the used space (in contrast to
available space) in each message block for the calculation.
.TP
\fBadjmsg\fR
trims the absolute value of \fIlen\fR bytes from a message.

If \fIlen\fR is positive, \fIlen\fR bytes will be trimmed from the head of the
message.  If \fIlen\fR is greater than the aggregate sizes of the blocks of
the same type at the beginning of \fImp\fR, \fBadjmsg\fR fails.

If \fIlen\fR is negative, \fI-len\fR bytes will be trimmed from the tail of
the message.  If \fI-len\fR is greater than the aggregate sizes of the blocks
of the same type at the end of \fImp\fR, \fBadjmsg\fR fails.
.PP
Any message blocks whose resulting sizes are zero are not removed from the
message, but have their \fIb_rptr\fR set to their \fIb_wptr\fR.
.TP
\fBcopyb\fR
.TP
\fBcopymsg\fR
.TP
\fBdupb\fR
.TP
\fBdupmsg\fR
.PP
.TP
\fBlinkb\fR
.TP
\fBunlinkb\fR
.PP
.TP
\fBpullupmsg\fR
.TP
\fBmsgpullup\fR
.PP
.TP
\fBrmvb\fR
Remove the message block pointed to by \fIbp\fR from the message pointed to by
\fImp\fR.  When successful, it returns a pointer to the modified message, or
\fBNULL\fR if \fIbp\fR was the only block in \fImp\fR.  When \fIbp\fR is not
in message \fImp\fR, \fBrmvb\fR fails and returns \fI(mblk_t *)-1\fR.
.PP
.SH "RETURN VALUES"
\fBmsgsize\fR, \fBmsgdsize\fR and \fBxmsgsize\fR return the aggregated sizes
of the message blocks counted in bytes.  Only positive values will be
returned.  If there are no messages of the particular type, the function
returns zero.

\fBadjmsg\fR returns non-zero on success and zero on failure.
.SH "ERRORS"
\fBmsgsize\fR, \fBmsgdsize\fR and \fBxmsgsize\fR always succeed.
.SH "SEE ALSO"
.BR msgsize (9),
.BR msgdsize (9),
.BR xmsgsize (9),
.BR adjmsg (9),
.BR copyb (9),
.BR copymsg (9),
.BR dupb (9),
.BR dupmsg (9),
.BR linkb (9),
.BR unlinkb (9),
.BR pullupmsg (9),
.BR msgpullup (9),
.BR rmvb (9)

.SH "HISTORY"
UNIX SVR 4 and 4.2 STREAMS
.[
svr4
.]
.[
svr42
.]
.SH "BUGS"
These functions should probably return \fIsize_t\fR instead of \fIint\fR.
.SH "NOTICES"
.\"
.\"
.[
$LIST$
.]
.TA