curs_trace 3x

curs_trace(3x)                                                  curs_trace(3x)


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


       #include <curses.h>

       void trace(const unsigned int 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);


       The  trace  routines  are  used for debugging the ncurses libraries, as
       well as applications which use the ncurses libraries.  These  functions
       are  normally available only with the debugging library e.g., libncurs-
       es_g.a, but may be compiled into any model (shared, static, profile) by
       defining  the  symbol  TRACE.   Additionally,  some  functions are only
       available with the wide-character configuration of the libraries.


       The principal parts of this interface are

       o   trace, which selectively enables different tracing features, and

       o   _tracef, which writes formatted data to the trace file.

       Calling trace with a nonzero parameter creates the file  trace  in  the
       current  directory  for output.  If the file already exists, no tracing
       is done.

       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  func-
       tion,  some use a buffer-number parameter, telling the library to allo-
       cate additional string-areas.

Trace Parameter

       The trace parameter is  formed  by  OR'ing  values  from  the  list  of
       TRACE_xxx definitions in <curses.h>.  These include:

            turn off tracing by passing a zero parameter.

            The  library flushes the output file, but retains an open file-de-
            scriptor to the trace file so that it can resume tracing later  if
            a nonzero parameter is passed to the trace function.

            trace user and system times of updates.

            trace tputs(3x) calls.

            trace update actions, old & new screens.

            trace cursor movement and scrolling.

            trace all character outputs.

            trace  all  update  actions.   The old and new screen contents are
            written to the trace file for each refresh.

            trace all curses calls.  The parameters for each call are  traced,
            as well as return values.

            trace virtual character puts, i.e., calls to addch.

            trace low-level input processing, including timeouts.

            trace state of TTY control bits.

            trace internal/nested calls.

            trace per-character calls.

            trace read/write of terminfo/termcap data.

            trace changes to video attributes and colors.

            maximum trace level, enables all of the separate trace features.

       Some  tracing  features  are  enabled  whenever  the trace parameter is
       nonzero.  Some features overlap.  The specific  names  are  used  as  a


       These  functions  check  the NCURSES_TRACE environment variable, to set
       the tracing feature as if 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 trace function.
       Both of these (-v and trace) use the same variable (_nc_tracing), which
       determines the messages which are written.

       Because  the  command-line  utilities may call initialization functions
       such as setupterm, tgetent or use_extended_names, some of their  debug-
       ging  output may be directed to the trace file if the NCURSES_TRACE en-
       vironment variable is set:

       o   messages produced in the utility are written to the standard error.

       o   messages produced by the underlying library are written to trace.

       If ncurses is built without tracing, none of the latter  are  produced,
       and fewer diagnostics are provided by the command-line utilities.


       Routines  which return a value are designed to be used as parameters to
       the _tracef routine.


       These functions are not part of the XSI interface.  Some  other  curses
       implementations  are  known to have similar, undocumented features, but
       they are not compatible with ncurses.

       A few functions are not provided when symbol versioning is used:

           _nc_tracebits, _tracedump, _tracemouse