# curs_trace

## NAME



           **curses_trace** , **trace** , **_tracef** , **_traceattr** , **_traceattr2** ,
           **_tracecchar_t** , **_tracecchar_t2** , **_tracechar** , **_tracechtype** ,
           **_tracechtype2** , **_nc_tracebits** , **_tracedump** , **_tracemouse** - **curses**
           debugging routines
    


## SYNOPSIS



           **#include <curses.h>**
    
           **unsigned curses_trace(const unsigned** _param_**);**
    
           **void _tracef(const char ***_format_**, ...);**
    
           **char *_traceattr(attr_t** _attr_**);**
           **char *_traceattr2(int** _buffer_**, chtype** _ch_**);**
           **char *_tracecchar_t(const cchar_t ***_string_**);**
           **char *_tracecchar_t2(int** _buffer_**, const cchar_t ***_string_**);**
           **char *_tracechar(int** _ch_**);**
           **char *_tracechtype(chtype** _ch_**);**
           **char *_tracechtype2(int** _buffer_**, chtype** _ch_**);**
    
           **void _tracedump(const char ***_label_**, WINDOW ***_win_**);**
           **char *_nc_tracebits(void);**
           **char *_tracemouse(const MEVENT ***_event_**);**
    
           /* deprecated */
           **void trace(const unsigned int** _param_**);**
    


## DESCRIPTION



           The  _curses_  _trace_ routines are used for debugging the ncurses li‐
           braries, as well as applications which use the ncurses  libraries.
           Some limitations apply:
    
           •   Aside from **curses_trace** , the other functions are normally
               available only with the debugging library e.g., **libncurs‐**
               **es_g.a**.
    
               All of the trace functions may be compiled into any model
               (shared, static, profile) by defining the symbol **TRACE**.
    
           •   Additionally, the functions which use **cchar_t** are only avail‐
               able with the wide-character configuration of the libraries.
    
       **Functions**
           The principal parts of this interface are
    
           •   **curses_trace** , which selectively enables different tracing fea‐
               tures, and
    
           •   **_tracef** , which writes formatted data to the _trace_ file.
    
               The other functions either return a pointer to a string-area
               (allocated by the corresponding function), or return no value
               (such as **_tracedump** , which implements the screen dump for
               **TRACE_UPDATE**).  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.
    
           The **curses_trace** function is always available, whether or not the
           other trace functions are available:
    
           •   If tracing is available, calling **curses_trace** with a nonzero
               parameter updates the trace mask, and returns the previous
               trace mask.
    
               When the trace mask is nonzero, ncurses creates the file
               “trace” in the current directory for output.  If the file al‐
               ready exists, no tracing is done.
    
           •   If tracing is not available, **curses_trace** returns zero (0).
    
       **Trace Parameter**
           The trace parameter is formed by OR'ing values from the list of
           **TRACE_**_xxx_ definitions in **< curses.h>**.  These include:
    
           **TRACE_DISABLE**
                turn off tracing by passing a zero parameter.
    
                The library flushes the output file, but retains an open
                file-descriptor to the trace file so that it can resume trac‐
                ing later if a nonzero parameter is passed to the **curs‐**
                **es_trace** function.
    
           **TRACE_TIMES**
                trace user and system times of updates.
    
           **TRACE_TPUTS**
                trace **tputs**(3X) calls.
    
           **TRACE_UPDATE**
                trace update actions, old & new screens.
    
           **TRACE_MOVE**
                trace cursor movement and scrolling.
    
           **TRACE_CHARPUT**
                trace all character outputs.
    
           **TRACE_ORDINARY**
                trace all update actions.  The old and new screen contents
                are written to the trace file for each refresh.
    
           **TRACE_CALLS**
                trace all curses calls.  The parameters for each call are
                traced, as well as return values.
    
           **TRACE_VIRTPUT**
                trace virtual character puts, i.e., calls to **addch**.
    
           **TRACE_IEVENT**
                trace low-level input processing, including timeouts.
    
           **TRACE_BITS**
                trace state of TTY control bits.
    
           **TRACE_ICALLS**
                trace internal/nested calls.
    
           **TRACE_CCALLS**
                trace per-character calls.
    
           **TRACE_DATABASE**
                trace read/write of terminfo/termcap data.
    
           **TRACE_ATTRS**
                trace changes to video attributes and colors.
    
           **TRACE_MAXIMUM**
                maximum trace level, enables all of the separate trace fea‐
                tures.
    
           Some tracing features are enabled whenever the **curses_trace** para‐
           meter is nonzero.  Some features overlap.  The specific names are
           used as a guideline.
    
       **Initialization**
           These functions check the **NCURSES_TRACE** environment variable, to
           set the tracing feature as if **curses_trace** was called:
    
               filter, initscr, new_prescr, newterm, nofilter, restartterm,
               ripoffline, setupterm, slk_init, tgetent, use_env,
               use_extended_names, use_tioctl
    
       **Command-line Utilities**
           The command-line utilities such as **tic**(1) provide a verbose option
           which  extends  the set of messages written using the **curses_trace**
           function.  Both of these (**-v** and **curses_trace**) use the same  vari‐
           able  (**_nc_tracing**), which determines the messages which are writ‐
           ten.
    
           Because the command-line utilities may call  initialization  func‐
           tions  such  as  **setupterm** , **tgetent** or **use_extended_names** , some of
           their debugging output may be directed to the _trace_  file  if  the
           **NCURSES_TRACE** environment variable is set:
    
           •   messages produced in the utility are written to the standard
               error.
    
           •   messages produced by the underlying library are written to
               _trace_.
    
           If ncurses is built without tracing, none of the latter are pro‐
           duced, and fewer diagnostics are provided by the command-line
           utilities.
    


## RETURN VALUE



           Routines which return a value are designed to be used as parame‐
           ters to the **_tracef** routine.
    


## PORTABILITY



           These functions are not part of the XSI interface.  Some other
           curses implementations are known to have similar features, but
           they are not compatible with ncurses:
    
           •   SVr4 provided **traceon** and **traceoff** , to control whether debug‐
               ging information was written to the “trace” file.  While the
               functions were always available, this feature was only enabled
               if **DEBUG** was defined when building the library.
    
               The SVr4 tracing feature is undocumented.
    
           •   PDCurses provides **traceon** and **traceoff** , which (like SVr4) are
               always available, and enable tracing to the “trace” file only
               when a debug-library is built.
    
               PDCurses has a short description of these functions, with a
               note that they are not present in X/Open Curses, ncurses or
               NetBSD.  It does not mention SVr4, but the functions' inclu‐
               sion in a header file section labeled “Quasi-standard” hints
               at the origin.
    
           •   NetBSD does not provide functions for enabling/disabling
               traces.  It uses environment variables **CURSES_TRACE_MASK** and
               **CURSES_TRACE_FILE** to determine what is traced, and where the
               results are written.  This is available only when a debug-li‐
               brary is built.
    
               The NetBSD tracing feature is undocumented.
    
           A few ncurses functions are not provided when symbol versioning is
           used:
    
               _nc_tracebits, _tracedump, _tracemouse
    
           The original **trace** routine was deprecated because it often con‐
           flicted with application names.
    


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