'\"
'\" Copyright (c) 1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: SetErrno.3,v 1.9 2007/12/13 15:22:31 dgp Exp $
.so man.macros
.TH Tcl_SetErrno 3 8.3 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_SetErrno, Tcl_GetErrno, Tcl_ErrnoId, Tcl_ErrnoMsg \- manipulate errno to store and retrieve error codes
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
void
\fBTcl_SetErrno\fR(\fIerrorCode\fR)
.sp
int
\fBTcl_GetErrno\fR()
.sp
const char *
\fBTcl_ErrnoId\fR()
.sp
const char *
\fBTcl_ErrnoMsg\fR(\fIerrorCode\fR)
.sp
.SH ARGUMENTS
.AS int errorCode
.AP int errorCode in
A POSIX error code such as \fBENOENT\fR.
.BE

.SH DESCRIPTION
.PP
\fBTcl_SetErrno\fR and \fBTcl_GetErrno\fR provide portable access
to the \fBerrno\fR variable, which is used to record a POSIX error
code after system calls and other operations such as \fBTcl_Gets\fR.
These procedures are necessary because global variable accesses cannot
be made across module boundaries on some platforms.
.PP
\fBTcl_SetErrno\fR sets the \fBerrno\fR variable to the value of the
\fIerrorCode\fR argument
C procedures that wish to return error information to their callers
via \fBerrno\fR should call \fBTcl_SetErrno\fR rather than setting
\fBerrno\fR directly.
.PP
\fBTcl_GetErrno\fR returns the current value of \fBerrno\fR.
Procedures wishing to access \fBerrno\fR should call this procedure
instead of accessing \fBerrno\fR directly.
.PP
\fBTcl_ErrnoId\fR and \fBTcl_ErrnoMsg\fR return string
representations of \fBerrno\fR values.  \fBTcl_ErrnoId\fR
returns a machine-readable textual identifier such as
.QW EACCES
that corresponds to the current value of \fBerrno\fR.
\fBTcl_ErrnoMsg\fR returns a human-readable string such as
.QW "permission denied"
that corresponds to the value of its
\fIerrorCode\fR argument.  The \fIerrorCode\fR argument is
typically the value returned by \fBTcl_GetErrno\fR.
The strings returned by these functions are
statically allocated and the caller must not free or modify them.

.SH KEYWORDS
errno, error code, global variables