.\"***************************************************************************
-.\" Copyright (c) 2000-2015,2016 Free Software Foundation, Inc. *
+.\" Copyright (c) 2000-2016,2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" copy of this software and associated documentation files (the *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_trace.3x,v 1.14 2016/10/15 17:26:09 tom Exp $
+.\" $Id: curs_trace.3x,v 1.19 2017/11/18 23:47:37 tom Exp $
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
.TH curs_trace 3X ""
.na
.hy 0
.SH NAME
+\fBtrace\fR,
\fB_tracef\fR,
-\fB_tracedump\fR,
\fB_traceattr\fR,
\fB_traceattr2\fR,
-\fB_nc_tracebits\fR,
\fB_tracecchar_t\fR,
\fB_tracecchar_t2\fR,
\fB_tracechar\fR,
\fB_tracechtype\fR,
\fB_tracechtype2\fR,
-\fB_tracemouse\fR,
-\fBtrace\fR \- \fBcurses\fR debugging routines
+\fB_nc_tracebits\fR,
+\fB_tracedump\fR,
+\fB_tracemouse\fR \- \fBcurses\fR debugging routines
.ad
.hy
.SH SYNOPSIS
\fB#include <curses.h>\fR
.sp
+\fBvoid trace(const unsigned int \fP\fIparam\fP\fB);\fR
+.sp
\fBvoid _tracef(const char *\fP\fIformat\fP\fB, ...);\fR
-.br
-\fBvoid _tracedump(const char *\fP\fIlabel\fP\fB, WINDOW *\fP\fIwin\fP\fB);\fR
-.br
+.sp
\fBchar *_traceattr(attr_t \fP\fIattr\fP\fB);\fR
.br
\fBchar *_traceattr2(int \fP\fIbuffer\fP\fB, chtype \fP\fIch\fP\fB);\fR
.br
-\fBchar *_nc_tracebits(void);\fR
-.br
-\fBchar * _tracecchar_t(const cchar_t *\fP\fIstring\fP\fB);\fR
+\fBchar *_tracecchar_t(const cchar_t *\fP\fIstring\fP\fB);\fR
.br
-\fBchar * _tracecchar_t2(int \fP\fIbuffer\fP\fB, const cchar_t *\fP\fIstring\fP\fB);\fR
+\fBchar *_tracecchar_t2(int \fP\fIbuffer\fP\fB, const cchar_t *\fP\fIstring\fP\fB);\fR
.br
\fBchar *_tracechar(int \fP\fIch\fP\fB);\fR
.br
\fBchar *_tracechtype(chtype \fP\fIch\fP\fB);\fR
.br
\fBchar *_tracechtype2(int \fP\fIbuffer\fP\fB, chtype \fP\fIch\fP\fB);\fR
+.sp
+\fBvoid _tracedump(const char *\fP\fIlabel\fP\fB, WINDOW *\fP\fIwin\fP\fB);\fR
.br
-\fBchar *_tracemouse(const MEVENT *\fP\fIevent\fP\fB);\fR
+\fBchar *_nc_tracebits(void);\fR
.br
-\fBvoid trace(const unsigned int \fP\fIparam\fP\fB);\fR
+\fBchar *_tracemouse(const MEVENT *\fP\fIevent\fP\fB);\fR
.SH DESCRIPTION
The \fBtrace\fR routines are used for debugging the ncurses libraries,
as well as applications which use the ncurses libraries.
profile) by defining the symbol \fBTRACE\fR.
Additionally, some functions are only available with the wide-character
configuration of the libraries.
-.PP
+.SS Functions
The principal parts of this interface are
.bP
\fBtrace\fR, which selectively enables different tracing features, and
.bP
\fB_tracef\fR, which writes formatted data to the \fItrace\fR file.
.PP
-Calling \fBtrace\fR with a nonzero parameter opens the file \fBtrace\fR
+Calling \fBtrace\fR with a nonzero parameter creates the file \fBtrace\fR
in the current directory for output.
-The parameter is formed by OR'ing
+If the file already exists, no tracing is done.
+.PP
+The other functions either return a pointer to a string-area
+(allocated by the corresponding function),
+or return no value (such as \fB_tracedump\fP, which implements the
+screen dump for \fBTRACE_UPDATE\fP).
+The caller should not free these
+strings, since the allocation is reused on successive calls.
+To work around the problem of a single string-area per function,
+some use a buffer-number parameter, telling the library to allocate
+additional string-areas.
+.SS Trace Parameter
+The trace parameter is formed by OR'ing
values from the list of \fBTRACE_\fP\fIxxx\fR definitions in \fB<curses.h>\fR.
These include:
.TP 5
.B TRACE_DISABLE
-turn off tracing.
+turn off tracing by passing a zero parameter.
+.IP
+The library flushes the output file,
+but retains an open file-descriptor to the trace file
+so that it can resume tracing later if a nonzero parameter is passed
+to the \fBtrace\fP function.
.TP 5
.B TRACE_TIMES
trace user and system times of updates.
.TP 5
.B TRACE_TPUTS
-trace \fBtputs\fP calls.
+trace \fBtputs\fP(3X) calls.
.TP 5
.B TRACE_UPDATE
trace update actions, old & new screens.
is nonzero.
Some features overlap.
The specific names are used as a guideline.
-.PP
-The other functions either return a pointer to a string-area
-(allocated by the corresponding function),
-or return no value (such as \fB_tracedump\fP, which implements the
-screen dump for \fBTRACE_UPDATE\fP).
-The caller should not free these
-strings, since the allocation is reused on successive calls.
-To work around the problem of a single string-area per function,
-some use a buffer-number parameter, telling the library to allocate
-additional string-areas.
-.PP
+.SS Initialization
These functions check the \fBNCURSES_TRACE\fP environment variable,
to set the tracing feature as if \fBtrace\fP was called:
-.RS
+.RS 4
.PP
.na
+.hy 0
filter,
initscr,
new_prescr,
use_env,
use_extended_names,
use_tioctl
+.hy
.ad
.RE
+.SS Command-line Utilities
+.PP
+The command-line utilities such as \fBtic\fP(1) provide a verbose option
+which extends the set of messages written using the \fBtrace\fP function.
+Both of these (\fB\-v\fP and \fBtrace\fP)
+use the same variable (\fB_nc_tracing\fP),
+which determines the messages which are written.
+.PP
+Because the command-line utilities may call initialization functions
+such as \fBsetupterm\fP, \fBtgetent\fP or \fBuse_extended_names\fP,
+some of their debugging output may be directed to the \fItrace\fP file
+if the \fBNCURSES_TRACE\fP environment variable is set:
+.bP
+messages produced in the utility are written to the standard error.
+.bP
+messages produced by the underlying library are written to \fItrace\fP.
+.PP
+If ncurses is built without tracing, none of the latter are produced,
+and fewer diagnostics are provided by the command-line utilities.
.SH RETURN VALUE
Routines which return a value are designed to be used as parameters
to the \fB_tracef\fR routine.
Some other curses implementations are known to
have similar, undocumented features,
but they are not compatible with ncurses.
+.PP
+A few functions are not provided when symbol versioning is used:
+.RS 4
+.PP
+_nc_tracebits,
+_tracedump,
+_tracemouse
+.RE
.SH SEE ALSO
\fBcurses\fR(3X).
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