code: 9ferno

ref: 44ce0097b612a1fefd754065bdf8d9d2e5ef60c8
dir: /man/1/deb/

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.TH DEB 1
.SH NAME
deb \- graphical Limbo debugger
.SH SYNOPSIS
.B wm/deb
.RB [ -f
.IR file ]
.RB [ -p
.IR pid ]
.SH DESCRIPTION
.B Wm/deb
displays two windows, the main debugging window and
a stack window for browsing the data values of the thread
currently being debugged.
.PP
Debugging is performed using the facilities of the
.B prog
device bound to the local
.B /prog
directory (see
.IR prog (3)).
Debugging of code running on a remote machine can be performed by
binding the remote
.B /prog
directory in place of the local one. (See
.IR bind (1)).
.PP
In order to display source code and set breakpoints accurately, an up to date
symbol file
.RB ( .sbl )
must be available as well as the limbo source file
.RB ( .b ).
.SS "Main window"
The main window is comprised of a menu bar, an icon bar and three text panels.
One panel, labelled
.IR Threads ,
lists the process IDs (PIDs) of the threads being debugged.
Another panel, labelled
.IR Break ,
lists the set of breakpoints, each given a unique number.
The third and largest panel displays the source code of the thread being debugged.
.PP
Breakpoint positions are shown by red text in the source code display.
Clicking on a breakpoint number in the
.I Break
panel results in the source code panel being scrolled or updated to show
the breakpoint.
Breakpoints are toggled by clicking on the statement or sub-expression in the source
code window and clicking the breakpoint
button on the icon bar.
A breakpoint can be hit by any of the threads being debugged -
breakpoints are set on source code, not on individual threads.
.PP
Clicking on a PID in the
.I Threads
panel results in the source code panel being scrolled or updated to highlight
where in the code the thread is blocked, broken or halted on a breakpoint.
.PP
A running thread can be halted by clicking the stop button on the icon bar.
A thread will also halt when it hits a breakpoint.
Once a thread is halted (not blocked or broken) its execution can be advanced
a step at a time by means of the
buttons on the icon bar.
The thread can be stepped one operation at a time or a statement at a time.
Normally when single stepping, function calls are stepped into.
Stepping commands allow for stepping over function calls, whereby the function is still
called but its whole execution is treated as a single step.
Stepping out of a function is also provided, whereby execution continues unabated
until returning from the function.
Execution of the halted thread can be continued, running until it terminates, breaks
or hits another breakpoint.
.PP
Any of the threads being debugged can be killed or detached from the debugger
using buttons on the icon bar.
Detaching a halted thread resumes its execution.
.PP
The main window provides a set of menus for viewing source files, attaching to
other threads, setting debugger options and searching for text in the source code window.
.SS "Stack Window"
The stack window is used to inspect the values of local and global variables and function
arguments.
Items are displayed in a hierarchical manner.
Any item that contains other items, such as a variable of an ADT type, can be expanded
to show the values of the sub-items.
The sub-items are displayed by clicking on the expand button on the left of the
containing item, they can be hidden by pressing the button again.
The sub-item list is displayed indented from its container as a visual cue to their
association.
.PP
The stack window shows the full stack trace of the current thread.
The stack trace is displayed as a list of frames, the current frame displayed
at the top of the window.
Each frame is given by the function name and source location of the code being
executed in the frame.
Each frame has the following sub-items:
.TP 10
.B locals
Local variables declared in the function of the frame.
.TP
.B args
The arguments passed to the frame function.
.TP
.B module
The module global variables in the implementation module
of the frame function.
.PP
Clicking on the name of a variable or function argument highlights the declaration of
that name in the source panel of the main debug window.
Clicking on the function name of a stack frame causes the main window source panel to
display the current statement of the frame.
.PP
The debugger has a stack button which simply brings
that window to the front of the display.
.PP
The options menu has a layout configuration which
allows the user to have a horizontal scroll bar or to wrap long
lines (the default); and an option to strip carriage return characters that precede newlines (for the benefit of those using Windows' editors).
The state of the options is saved in the file
.BI /usr/ username /lib/deb
if that file can be created. The debugger attempts to read
this file on startup to set the user's preferred options.
.SH OPTIONS
.TP 10
.BI -f " file"
Specifies a source file
.RB ( .b )
to load.
The associated executable file
.RB ( .dis )
is not launched until the continue
.RI ( "run to breakpoint" )
button is pressed.
This option takes precedence over the
.B -p
option.
.TP
.BI -p " pid"
Attach to the already running thread given by
.IR pid .
.SH PLUMBING
.B wm/deb
plumbs the address of text selected using
button 3 in the source display panel, as
.B text
of the form
.IP
.IB "file-name" : "line-number"
.SH FILES
.BI /prog/ n /*
.br
.BI /usr/ username /lib/deb
.SH SOURCE
.B /appl/wm/deb.b
.br
.B /appl/wm/debdata.b
.br
.B /appl/wm/debsrc.b
.SH "SEE ALSO"
.IR limbo (1),
.IR prog (3)
.SH BUGS
Displaying large arrays in the Stack window can use excessive amounts of
memory.
.PP
When setting breakpoints there is no visual cue for the selected statement or operation until
the breakpoint is actually set.
.PP
It is only possible to debug modules executed by the interpreter.
Code that has been JITed, the compilation execution method, yields
stack information that does not correspond to information in the symbol
.RB ( .sbl )
file.