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;;; trap-state.scm: a set of traps
;; Copyright (C) 2010, 2013 Free Software Foundation, Inc.
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
;;; License as published by the Free Software Foundation; either
;;; version 3 of the License, or (at your option) any later version.
;;;
;;; This library is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;; Commentary:
;;;
;;; Code:
(define-module (system vm trap-state)
#:use-module (system base syntax)
#:use-module ((srfi srfi-1) #:select (fold))
#:use-module (system vm vm)
#:use-module (system vm traps)
#:use-module (system vm trace)
#:use-module (system vm program)
#:export (add-trap!
list-traps
trap-enabled?
trap-name
enable-trap!
disable-trap!
delete-trap!
with-default-trap-handler
install-trap-handler!
add-trap-at-procedure-call!
add-trace-at-procedure-call!
add-trap-at-source-location!
add-ephemeral-trap-at-frame-finish!
add-ephemeral-stepping-trap!))
(define %default-trap-handler (make-fluid))
(define (default-trap-handler frame idx trap-name)
(let ((default-handler (fluid-ref %default-trap-handler)))
(if default-handler
(default-handler frame idx trap-name)
(warn "Trap with no handler installed" frame idx trap-name))))
(define-record <trap-wrapper>
index
enabled?
trap
name)
(define-record <trap-state>
(handler default-trap-handler)
(next-idx 0)
(next-ephemeral-idx -1)
(wrappers '()))
(define (trap-wrapper<? t1 t2)
(< (trap-wrapper-index t1) (trap-wrapper-index t2)))
;; The interface that a trap provides to the outside world is that of a
;; procedure, which when called disables the trap, and returns a
;; procedure to enable the trap. Perhaps this is a bit too odd and we
;; should fix this.
(define (enable-trap-wrapper! wrapper)
(if (trap-wrapper-enabled? wrapper)
(error "Trap already enabled" (trap-wrapper-index wrapper))
(let ((trap (trap-wrapper-trap wrapper)))
(set! (trap-wrapper-trap wrapper) (trap))
(set! (trap-wrapper-enabled? wrapper) #t))))
(define (disable-trap-wrapper! wrapper)
(if (not (trap-wrapper-enabled? wrapper))
(error "Trap already disabled" (trap-wrapper-index wrapper))
(let ((trap (trap-wrapper-trap wrapper)))
(set! (trap-wrapper-trap wrapper) (trap))
(set! (trap-wrapper-enabled? wrapper) #f))))
(define (add-trap-wrapper! trap-state wrapper)
(set! (trap-state-wrappers trap-state)
(append (trap-state-wrappers trap-state) (list wrapper)))
(trap-wrapper-index wrapper))
(define (remove-trap-wrapper! trap-state wrapper)
(set! (trap-state-wrappers trap-state)
(delq wrapper (trap-state-wrappers trap-state))))
(define (trap-state->trace-level trap-state)
(fold (lambda (wrapper level)
(if (trap-wrapper-enabled? wrapper)
(1+ level)
level))
0
(trap-state-wrappers trap-state)))
(define (wrapper-at-index trap-state idx)
(let lp ((wrappers (trap-state-wrappers trap-state)))
(cond
((null? wrappers)
(warn "no wrapper found with index in trap-state" idx)
#f)
((eqv? (trap-wrapper-index (car wrappers)) idx)
(car wrappers))
(else
(lp (cdr wrappers))))))
(define (next-index! trap-state)
(let ((idx (trap-state-next-idx trap-state)))
(set! (trap-state-next-idx trap-state) (1+ idx))
idx))
(define (next-ephemeral-index! trap-state)
(let ((idx (trap-state-next-ephemeral-idx trap-state)))
(set! (trap-state-next-ephemeral-idx trap-state) (1- idx))
idx))
(define (handler-for-index trap-state idx)
(lambda (frame)
(let ((wrapper (wrapper-at-index trap-state idx))
(handler (trap-state-handler trap-state)))
(if wrapper
(handler frame
(trap-wrapper-index wrapper)
(trap-wrapper-name wrapper))))))
(define (ephemeral-handler-for-index trap-state idx handler)
(lambda (frame)
(let ((wrapper (wrapper-at-index trap-state idx)))
(if wrapper
(begin
(if (trap-wrapper-enabled? wrapper)
(disable-trap-wrapper! wrapper))
(remove-trap-wrapper! trap-state wrapper)
(handler frame))))))
;;;
;;; Per-thread trap states
;;;
;; FIXME: This should be thread-local -- not something you can inherit
;; from a dynamic state.
(define %trap-state (make-parameter #f))
(define (the-trap-state)
(or (%trap-state)
(let ((ts (make-trap-state)))
(%trap-state ts)
ts)))
;;;
;;; API
;;;
(define* (with-default-trap-handler handler thunk
#:optional (trap-state (the-trap-state)))
(with-fluids ((%default-trap-handler handler))
(dynamic-wind
(lambda ()
;; Don't enable hooks if the handler is #f.
(if handler
(set-vm-trace-level! (trap-state->trace-level trap-state))))
thunk
(lambda ()
(if handler
(set-vm-trace-level! 0))))))
(define* (list-traps #:optional (trap-state (the-trap-state)))
(map trap-wrapper-index (trap-state-wrappers trap-state)))
(define* (trap-name idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
trap-wrapper-name))
(define* (trap-enabled? idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
trap-wrapper-enabled?))
(define* (enable-trap! idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
enable-trap-wrapper!))
(define* (disable-trap! idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
disable-trap-wrapper!))
(define* (delete-trap! idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
(lambda (wrapper)
(if (trap-wrapper-enabled? wrapper)
(disable-trap-wrapper! wrapper))
(remove-trap-wrapper! trap-state wrapper))))
(define* (install-trap-handler! handler #:optional (trap-state (the-trap-state)))
(set! (trap-state-handler trap-state) handler))
(define* (add-trap-at-procedure-call! proc #:optional (trap-state (the-trap-state)))
(let* ((idx (next-index! trap-state))
(trap (trap-at-procedure-call
proc
(handler-for-index trap-state idx))))
(add-trap-wrapper!
trap-state
(make-trap-wrapper
idx #t trap
(format #f "Breakpoint at ~a" proc)))))
(define* (add-trace-at-procedure-call! proc
#:optional (trap-state (the-trap-state)))
(let* ((idx (next-index! trap-state))
(trap (trace-calls-to-procedure
proc
#:prefix (format #f "Trap ~a: " idx))))
(add-trap-wrapper!
trap-state
(make-trap-wrapper
idx #t trap
(format #f "Tracepoint at ~a" proc)))))
(define* (add-trap-at-source-location! file user-line
#:optional (trap-state (the-trap-state)))
(let* ((idx (next-index! trap-state))
(trap (trap-at-source-location file user-line
(handler-for-index trap-state idx))))
(add-trap-wrapper!
trap-state
(make-trap-wrapper
idx #t trap
(format #f "Breakpoint at ~a:~a" file user-line)))))
;; handler := frame -> nothing
(define* (add-ephemeral-trap-at-frame-finish! frame handler
#:optional (trap-state
(the-trap-state)))
(let* ((idx (next-ephemeral-index! trap-state))
(trap (trap-frame-finish
frame
(ephemeral-handler-for-index trap-state idx handler)
(lambda (frame) (delete-trap! idx trap-state)))))
(add-trap-wrapper!
trap-state
(make-trap-wrapper
idx #t trap
(format #f "Return from ~a" frame)))))
(define (source-string source)
(if source
(format #f "~a:~a:~a" (or (source:file source) "unknown file")
(source:line-for-user source) (source:column source))
"unknown source location"))
(define* (add-ephemeral-stepping-trap! frame handler
#:optional (trap-state
(the-trap-state))
#:key (into? #t) (instruction? #f))
(define (wrap-predicate-according-to-into predicate)
(if into?
predicate
(let ((fp (frame-address frame)))
(lambda (f)
(and (<= (frame-address f) fp)
(predicate f))))))
(let* ((source (frame-source frame))
(idx (next-ephemeral-index! trap-state))
(trap (trap-matching-instructions
(wrap-predicate-according-to-into
(if instruction?
(lambda (f) #t)
(lambda (f) (not (equal? (frame-source f) source)))))
(ephemeral-handler-for-index trap-state idx handler))))
(add-trap-wrapper!
trap-state
(make-trap-wrapper
idx #t trap
(if instruction?
(if into?
"Step to different instruction"
(format #f "Step to different instruction in ~a" frame))
(if into?
(format #f "Step into ~a" (source-string source))
(format #f "Step out of ~a" (source-string source))))))))
(define* (add-trap! trap name #:optional (trap-state (the-trap-state)))
(let* ((idx (next-index! trap-state)))
(add-trap-wrapper!
trap-state
(make-trap-wrapper idx #t trap name))))
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