gdb: Frames In Guile
23.3.3.15 Accessing inferior stack frames from Guile.
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When the debugged program stops, GDB is able to analyze its call stack
(
Stack frames Frames.). The '<gdb:frame>' class represents a
frame in the stack. A '<gdb:frame>' object is only valid while its
corresponding frame exists in the inferior's stack. If you try to use
an invalid frame object, GDB will throw a 'gdb:invalid-object' exception
(Guile Exception Handling).
Two '<gdb:frame>' objects can be compared for equality with the
'equal?' function, like:
(gdb) guile (equal? (newest-frame) (selected-frame))
#t
The following frame-related procedures are provided by the '(gdb)'
module:
-- Scheme Procedure: frame? object
Return '#t' if OBJECT is a '<gdb:frame>' object. Otherwise return
'#f'.
-- Scheme Procedure: frame-valid? frame
Returns '#t' if FRAME is valid, '#f' if not. A frame object can
become invalid if the frame it refers to doesn't exist anymore in
the inferior. All '<gdb:frame>' procedures will throw an exception
if the frame is invalid at the time the procedure is called.
-- Scheme Procedure: frame-name frame
Return the function name of FRAME, or '#f' if it can't be obtained.
-- Scheme Procedure: frame-arch frame
Return the '<gdb:architecture>' object corresponding to FRAME's
architecture. Architectures In Guile.
-- Scheme Procedure: frame-type frame
Return the type of FRAME. The value can be one of:
'NORMAL_FRAME'
An ordinary stack frame.
'DUMMY_FRAME'
A fake stack frame that was created by GDB when performing an
inferior function call.
'INLINE_FRAME'
A frame representing an inlined function. The function was
inlined into a 'NORMAL_FRAME' that is older than this one.
'TAILCALL_FRAME'
A frame representing a tail call. Tail Call Frames.
'SIGTRAMP_FRAME'
A signal trampoline frame. This is the frame created by the
OS when it calls into a signal handler.
'ARCH_FRAME'
A fake stack frame representing a cross-architecture call.
'SENTINEL_FRAME'
This is like 'NORMAL_FRAME', but it is only used for the
newest frame.
-- Scheme Procedure: frame-unwind-stop-reason frame
Return an integer representing the reason why it's not possible to
find more frames toward the outermost frame. Use
'unwind-stop-reason-string' to convert the value returned by this
function to a string. The value can be one of:
'FRAME_UNWIND_NO_REASON'
No particular reason (older frames should be available).
'FRAME_UNWIND_NULL_ID'
The previous frame's analyzer returns an invalid result.
'FRAME_UNWIND_OUTERMOST'
This frame is the outermost.
'FRAME_UNWIND_UNAVAILABLE'
Cannot unwind further, because that would require knowing the
values of registers or memory that have not been collected.
'FRAME_UNWIND_INNER_ID'
This frame ID looks like it ought to belong to a NEXT frame,
but we got it for a PREV frame. Normally, this is a sign of
unwinder failure. It could also indicate stack corruption.
'FRAME_UNWIND_SAME_ID'
This frame has the same ID as the previous one. That means
that unwinding further would almost certainly give us another
frame with exactly the same ID, so break the chain. Normally,
this is a sign of unwinder failure. It could also indicate
stack corruption.
'FRAME_UNWIND_NO_SAVED_PC'
The frame unwinder did not find any saved PC, but we needed
one to unwind further.
'FRAME_UNWIND_MEMORY_ERROR'
The frame unwinder caused an error while trying to access
memory.
'FRAME_UNWIND_FIRST_ERROR'
Any stop reason greater or equal to this value indicates some
kind of error. This special value facilitates writing code
that tests for errors in unwinding in a way that will work
correctly even if the list of the other values is modified in
future GDB versions. Using it, you could write:
(define reason (frame-unwind-stop-readon (selected-frame)))
(define reason-str (unwind-stop-reason-string reason))
(if (>= reason FRAME_UNWIND_FIRST_ERROR)
(format #t "An error occured: ~s\n" reason-str))
-- Scheme Procedure: frame-pc frame
Return the frame's resume address.
-- Scheme Procedure: frame-block frame
Return the frame's code block as a '<gdb:block>' object.
Blocks In Guile.
-- Scheme Procedure: frame-function frame
Return the symbol for the function corresponding to this frame as a
'<gdb:symbol>' object, or '#f' if there isn't one. Symbols
In Guile.
-- Scheme Procedure: frame-older frame
Return the frame that called FRAME.
-- Scheme Procedure: frame-newer frame
Return the frame called by FRAME.
-- Scheme Procedure: frame-sal frame
Return the frame's '<gdb:sal>' (symtab and line) object.
Symbol Tables In Guile.
-- Scheme Procedure: frame-read-register frame register
Return the value of REGISTER in FRAME. REGISTER should be a
string, like 'pc'.
-- Scheme Procedure: frame-read-var frame variable [#:block block]
Return the value of VARIABLE in FRAME. If the optional argument
BLOCK is provided, search for the variable from that block;
otherwise start at the frame's current block (which is determined
by the frame's current program counter). The VARIABLE must be
given as a string or a '<gdb:symbol>' object, and BLOCK must be a
'<gdb:block>' object.
-- Scheme Procedure: frame-select frame
Set FRAME to be the selected frame. Examining the Stack
Stack.
-- Scheme Procedure: selected-frame
Return the selected frame object. Selecting a Frame
Selection.
-- Scheme Procedure: newest-frame
Return the newest frame object for the selected thread.
-- Scheme Procedure: unwind-stop-reason-string reason
Return a string explaining the reason why GDB stopped unwinding
frames, as expressed by the given REASON code (an integer, see the
'frame-unwind-stop-reason' procedure above in this section).
Info Catalog
gdb: Objfiles In Guile
gdb: Guile API
gdb: Blocks In Guile