- The trace routines are used for debugging the ncurses li-
- braries, as well as applications which use the ncurses li-
- braries. These functions are normally available only with
- the debugging library e.g., libncurses_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 cursestrace routines are used for debugging the ncurses libraries,
+ as well as applications which use the ncurses libraries. Some limita-
+ tions apply:
+
+ o Aside from curses_trace, the other functions are normally available
+ only with the debugging library e.g., libncurses_g.a.
+ All of the trace functions may be compiled into any model (shared,
+ static, profile) by defining the symbol TRACE.
+
+ o Additionally, the functions which use cchar_t are only available
+ with the wide-character configuration of the libraries.
+
+
+
The principal parts of this interface are
- otrace, which selectively enables different tracing
- features, and
+ ocurses_trace, which selectively enables different tracing features,
+ and
+
+ o_tracef, which writes formatted data to the trace file.
+
+ The other functions either return a pointer to a string-area (allo-
+ cated 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:
+
+ o If tracing is available, calling curses_trace with a nonzero param-
+ eter 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 already exists, no
+ tracing is done.
+
+ o If tracing is not available, curses_trace returns zero (0).
- o_tracef, which writes formatted data to the trace
- file.
- Calling trace with a nonzero parameter opens the file
- trace in the current directory for output. The parameter
- is formed by OR'ing values from the list of TRACE_xxx def-
- initions in <curses.h>. These include:
+
+ 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.
+ 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 curses_trace function.
TRACE_TIMES
trace user and system times of updates.
TRACE_TPUTS
- trace tputs calls.
+ trace tputs(3x) calls.
TRACE_UPDATE
trace update actions, old & new screens.
@@ -111,13 +146,12 @@
trace all character outputs.
TRACE_ORDINARY
- trace all update actions. The old and new screen
- contents are written to the trace file for each re-
- fresh.
+ 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 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.
@@ -141,40 +175,81 @@
trace changes to video attributes and colors.
TRACE_MAXIMUM
- maximum trace level, enables all of the separate
- trace features.
+ maximum trace level, enables all of the separate trace features.
+
+ Some tracing features are enabled whenever the curses_trace parameter
+ is nonzero. Some features overlap. The specific names are used as a
+ guideline.
+
+
+
+ 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
- Some tracing features are enabled whenever the trace pa-
- rameter is nonzero. Some features overlap. The specific
- names are used as a guideline.
- 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 command-line utilities such as tic(1) provide a verbose option
+ which extends the set of messages written using the curses_trace func-
+ tion. Both of these (-v and curses_trace) use the same variable
+ (_nc_tracing), which determines the messages which are written.
- These functions check the NCURSES_TRACE environment vari-
- able, to set the tracing feature as if trace was called:
+ 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:
- filter, initscr, new_prescr, newterm, nofilter,
- restartterm, ripoffline, setupterm, slk_init, tge-
- tent, use_env, use_extended_names, use_tioctl
+ 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.
+ 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.
+ 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:
+
+ o SVr4 provided traceon and traceoff, to control whether debugging
+ 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.
+
+ o PDCurses provides traceon and traceoff, which (like SVr4) are al-
+ ways 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' inclusion in a header
+ file section labeled "Quasi-standard" hints at the origin.
+
+ o NetBSD does not provide functions for enabling/disabling traces.
+ It uses environment variables CURSES_TRACE_MASK and CURS-
+ ES_TRACE_FILE to determine what is traced, and where the results
+ are written. This is available only when a debug-library 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 conflicted
+ with application names.