t_error.3xti

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3XTI 代码 · 共 87 行

.TH t_error 3xti
.SH Name
t_error \- produces error message 
.SH Syntax 
.B #include <xti.h>
.br
.sp 1
.B int t_error(\fIerrmsg\fB)
.br
.B char \fI*errmsg\fB;
.br
.B extern char \fI*t_errlist[]\fB;
.br
.B extern int \fIt_nerr\fB;
.SH Arguments
.IP \fIerrmsg\fR 10
Is a user-supplied error message that gives context to the error.
.SH Description
The 
.PN t_error()
function produces a message on the standard error
output that describes the last error encountered during a call to a
transport function. 
.NXR "t_error system function"
.NXR "error messages" "transport function"
.PP
The 
.PN t_error()
function prints the user-supplied error message
followed by a colon and a standard error message for the current error
defined in \fBt_errno\fR. If \fBt_errno\fR is [TSYSERR],
.PN t_error()
also prints a standard message for the current value
contained in \fBerrno\fR. 
.PP
To simplify variant formatting of messages, the array of message strings
\fBt_errlist\fR is provided: \fBt_errno\fR can be used as an index in
this table to get the message string without the newline. The
\fIt_nerr\fR is the largest message number provided for in the
\fIt_errlist\fR table. 
.PP
The \fBt_errno\fR variable is set only when an error occurs and is not
cleared on successful calls.
.PP
.TS
tab(@);
lfHB lfHB lfHB
lfR  lfR  lfR .
_
.sp 4p
Parameters@Before Call@After Call
.sp 4p
_
.sp 6p
errmsg@x@/
.sp 6p
_
.TE
.PP
.sp 12p
.SH Examples
If a 
.PN t_connect() 
function fails on transport endpoint \fIfd2\fR
because a bad address was given, the following call may follow
the failure:
.EX
t_error ("t_connect failed on fd"):
.EE
.PP
The diagnostic message to be printed would look like:
.EX
t_connect failed on fd2: Incorrect transport address format
.EE
where "Incorrect transport address format" identifies the specific error
that occurred, and "t_connect failed on fd2" tells the user
which function failed on which transport endpoint.
.SH Return Values
Upon successful completion, a value of 0 is returned. On failure, a
value of \-1 is returned, and \fBt_errno\fR is set to indicate the
error.
.SH Diagnostics
On failure, \fBt_errno\fR is set to the following:
.TP 20
[TNOTSUPPORT]
This function is not supported by the current implementation of XTI.