0.9.16.38:
[sbcl.git] / src / code / debug.lisp
index e47ac17..bb78629 100644 (file)
@@ -120,9 +120,14 @@ Inspecting frames:
   SOURCE [n]     displays frame's source form with n levels of enclosing forms.
 
 Stepping:
-  STEP  Selects the CONTINUE restart if one exists and starts
+  START Selects the CONTINUE restart if one exists and starts
         single-stepping. Single stepping affects only code compiled with
         under high DEBUG optimization quality. See User Manual for details.
+  STEP  Steps into the current form.
+  NEXT  Steps over the current form.
+  OUT   Stops stepping temporarily, but resumes it when the topmost frame that
+        was stepped into returns.
+  STOP  Stops single-stepping.
 
 Function and macro commands:
  (SB-DEBUG:ARG n)
@@ -223,17 +228,6 @@ is how many frames to show."
 
 ) ; EVAL-WHEN
 
-;;; This is used in constructing arg lists for debugger printing when
-;;; the arg list is unavailable, some arg is unavailable or unused, etc.
-(defstruct (unprintable-object
-            (:constructor make-unprintable-object (string))
-            (:print-object (lambda (x s)
-                             (print-unreadable-object (x s)
-                               (write-string (unprintable-object-string x)
-                                             s))))
-            (:copier nil))
-  string)
-
 ;;; Extract the function argument values for a debug frame.
 (defun frame-args-as-list (frame)
   (let ((debug-fun (sb!di:frame-debug-fun frame))
@@ -471,28 +465,20 @@ is how many frames to show."
                 (nreverse (mapcar #'cdr *debug-print-variable-alist*))
               (apply fun rest)))))))
 
-;;; the ordinary ANSI case of INVOKE-DEBUGGER, when not suppressed by
-;;; command-line --disable-debugger option
 (defun invoke-debugger (condition)
   #!+sb-doc
   "Enter the debugger."
 
-  (let ((old-hook *debugger-hook*))
-    (when old-hook
-      (let ((*debugger-hook* nil))
-        (funcall old-hook condition old-hook))))
+  ;; call *INVOKE-DEBUGGER-HOOK* first, so that *DEBUGGER-HOOK* is not
+  ;; called when the debugger is disabled
   (let ((old-hook *invoke-debugger-hook*))
     (when old-hook
       (let ((*invoke-debugger-hook* nil))
         (funcall old-hook condition old-hook))))
-
-  ;; Note: CMU CL had (SB-UNIX:UNIX-SIGSETMASK 0) here, to reset the
-  ;; signal state in the case that we wind up in the debugger as a
-  ;; result of something done by a signal handler.  It's not
-  ;; altogether obvious that this is necessary, and indeed SBCL has
-  ;; not been doing it since 0.7.8.5.  But nobody seems altogether
-  ;; convinced yet
-  ;; -- dan 2003.11.11, based on earlier comment of WHN 2002-09-28
+  (let ((old-hook *debugger-hook*))
+    (when old-hook
+      (let ((*debugger-hook* nil))
+        (funcall old-hook condition old-hook))))
 
   ;; We definitely want *PACKAGE* to be of valid type.
   ;;
@@ -515,8 +501,22 @@ reset to ~S."
 
   (funcall-with-debug-io-syntax #'%invoke-debugger condition))
 
-(defun %invoke-debugger (condition)
+(defun %print-debugger-invocation-reason (condition stream)
+  (format stream "~2&")
+  ;; Note: Ordinarily it's only a matter of taste whether to use
+  ;; FORMAT "~<...~:>" or to use PPRINT-LOGICAL-BLOCK directly, but
+  ;; until bug 403 is fixed, PPRINT-LOGICAL-BLOCK (STREAM NIL) is
+  ;; definitely preferred, because the FORMAT alternative was acting odd.
+  (pprint-logical-block (stream nil)
+    (format stream
+            "debugger invoked on a ~S~@[ in thread ~A~]: ~2I~_~A"
+            (type-of condition)
+            #!+sb-thread sb!thread:*current-thread*
+            #!-sb-thread nil
+            condition))
+  (terpri stream))
 
+(defun %invoke-debugger (condition)
   (let ((*debug-condition* condition)
         (*debug-restarts* (compute-restarts condition))
         (*nested-debug-condition* nil))
@@ -526,13 +526,8 @@ reset to ~S."
         ;; when people redirect *ERROR-OUTPUT*, they could reasonably
         ;; expect to see error messages logged there, regardless of what
         ;; the debugger does afterwards.)
-        (format *error-output*
-                "~2&~@<debugger invoked on a ~S~@[ in thread ~A~]: ~
-                    ~2I~_~A~:>~%"
-                (type-of *debug-condition*)
-                #!+sb-thread sb!thread:*current-thread*
-                #!-sb-thread nil
-                *debug-condition*)
+        (unless (typep condition 'step-condition)
+          (%print-debugger-invocation-reason condition *error-output*))
       (error (condition)
         (setf *nested-debug-condition* condition)
         (let ((ndc-type (type-of *nested-debug-condition*)))
@@ -544,12 +539,12 @@ reset to ~S."
                   '*debug-condition*
                   ndc-type
                   '*nested-debug-condition*))
-        (when (typep condition 'cell-error)
+        (when (typep *nested-debug-condition* 'cell-error)
           ;; what we really want to know when it's e.g. an UNBOUND-VARIABLE:
           (format *error-output*
                   "~&(CELL-ERROR-NAME ~S) = ~S~%"
-                  '*debug-condition*
-                  (cell-error-name *debug-condition*)))))
+                  '*nested-debug-condition*
+                  (cell-error-name *nested-debug-condition*)))))
 
     (let ((background-p (sb!thread::debugger-wait-until-foreground-thread
                          *debug-io*)))
@@ -646,19 +641,30 @@ reset to ~S."
                      "Argh! error within --disable-debugger error handling"))
         (failure-quit :recklessly-p t)))))
 
+(defvar *old-debugger-hook* nil)
+
 ;;; halt-on-failures and prompt-on-failures modes, suitable for
 ;;; noninteractive and interactive use respectively
 (defun disable-debugger ()
-  (when (eql *invoke-debugger-hook* nil)
-    (setf *debug-io* *error-output*
-          *invoke-debugger-hook* 'debugger-disabled-hook)))
+  ;; *DEBUG-IO* used to be set here to *ERROR-OUTPUT* which is sort
+  ;; of unexpected but mostly harmless, but then ENABLE-DEBUGGER had
+  ;; to set it to a suitable value again and be very careful,
+  ;; especially if the user has also set it. -- MG 2005-07-15
+  (unless (eq *invoke-debugger-hook* 'debugger-disabled-hook)
+    (setf *old-debugger-hook* *invoke-debugger-hook*
+          *invoke-debugger-hook* 'debugger-disabled-hook))
+  ;; This is not inside the UNLESS to ensure that LDB is disabled
+  ;; regardless of what the old value of *INVOKE-DEBUGGER-HOOK* was.
+  ;; This might matter for example when restoring a core.
+  (sb!alien:alien-funcall (sb!alien:extern-alien "disable_lossage_handler"
+                                                 (function sb!alien:void))))
 
 (defun enable-debugger ()
   (when (eql *invoke-debugger-hook* 'debugger-disabled-hook)
-    (setf *debug-io* *query-io*
-          *invoke-debugger-hook* nil)))
-
-(setf *debug-io* *query-io*)
+    (setf *invoke-debugger-hook* *old-debugger-hook*
+          *old-debugger-hook* nil))
+  (sb!alien:alien-funcall (sb!alien:extern-alien "enable_lossage_handler"
+                                                 (function sb!alien:void))))
 
 (defun show-restarts (restarts s)
   (cond ((null restarts)
@@ -696,6 +702,11 @@ reset to ~S."
 (defvar *debug-loop-fun* #'debug-loop-fun
   "a function taking no parameters that starts the low-level debug loop")
 
+;;; When the debugger is invoked due to a stepper condition, we don't
+;;; want to print the current frame before the first prompt for aesthetic
+;;; reasons.
+(defvar *suppress-frame-print* nil)
+
 ;;; This calls DEBUG-LOOP, performing some simple initializations
 ;;; before doing so. INVOKE-DEBUGGER calls this to actually get into
 ;;; the debugger. SB!KERNEL::ERROR-ERROR calls this in emergencies
@@ -707,7 +718,8 @@ reset to ~S."
         (*read-suppress* nil))
     (unless (typep *debug-condition* 'step-condition)
       (clear-input *debug-io*))
-    (funcall *debug-loop-fun*)))
+    (let ((*suppress-frame-print* (typep *debug-condition* 'step-condition)))
+      (funcall *debug-loop-fun*))))
 \f
 ;;;; DEBUG-LOOP
 
@@ -718,6 +730,14 @@ reset to ~S."
   "When set, avoid calling INVOKE-DEBUGGER recursively when errors occur while
    executing in the debugger.")
 
+(defun debug-read (stream)
+  (declare (type stream stream))
+  (let* ((eof-marker (cons nil nil))
+         (form (read stream nil eof-marker)))
+    (if (eq form eof-marker)
+        (abort)
+        form)))
+
 (defun debug-loop-fun ()
   (let* ((*debug-command-level* (1+ *debug-command-level*))
          (*real-stack-top* (sb!di:top-frame))
@@ -729,41 +749,45 @@ reset to ~S."
                       (princ condition *debug-io*)
                       (/show0 "handling d-c by THROWing DEBUG-LOOP-CATCHER")
                       (throw 'debug-loop-catcher nil))))
-      (terpri *debug-io*)
-      (print-frame-call *current-frame* *debug-io* :verbosity 2)
+      (cond (*suppress-frame-print*
+             (setf *suppress-frame-print* nil))
+            (t
+             (terpri *debug-io*)
+             (print-frame-call *current-frame* *debug-io* :verbosity 2)))
       (loop
-        (catch 'debug-loop-catcher
-          (handler-bind ((error (lambda (condition)
-                                  (when *flush-debug-errors*
-                                    (clear-input *debug-io*)
-                                    (princ condition *debug-io*)
-                                    (format *debug-io*
-                                            "~&error flushed (because ~
+       (catch 'debug-loop-catcher
+         (handler-bind ((error (lambda (condition)
+                                 (when *flush-debug-errors*
+                                   (clear-input *debug-io*)
+                                   (princ condition *debug-io*)
+                                   (format *debug-io*
+                                           "~&error flushed (because ~
                                              ~S is set)"
-                                            '*flush-debug-errors*)
-                                    (/show0 "throwing DEBUG-LOOP-CATCHER")
-                                    (throw 'debug-loop-catcher nil)))))
-            ;; We have to bind LEVEL for the restart function created by
-            ;; WITH-SIMPLE-RESTART.
-            (let ((level *debug-command-level*)
-                  (restart-commands (make-restart-commands)))
-              (with-simple-restart (abort
-                                   "~@<Reduce debugger level (to debug level ~W).~@:>"
-                                    level)
-                (debug-prompt *debug-io*)
-                (force-output *debug-io*)
-                (let* ((exp (read *debug-io*))
-                       (cmd-fun (debug-command-p exp restart-commands)))
-                  (cond ((not cmd-fun)
-                         (debug-eval-print exp))
-                        ((consp cmd-fun)
-                         (format *debug-io*
-                                 "~&Your command, ~S, is ambiguous:~%"
-                                 exp)
-                         (dolist (ele cmd-fun)
-                           (format *debug-io* "   ~A~%" ele)))
-                        (t
-                         (funcall cmd-fun))))))))))))
+                                           '*flush-debug-errors*)
+                                   (/show0 "throwing DEBUG-LOOP-CATCHER")
+                                   (throw 'debug-loop-catcher nil)))))
+           ;; We have to bind LEVEL for the restart function created by
+           ;; WITH-SIMPLE-RESTART.
+           (let ((level *debug-command-level*)
+                 (restart-commands (make-restart-commands)))
+             (flush-standard-output-streams)
+             (debug-prompt *debug-io*)
+             (force-output *debug-io*)
+             (let* ((exp (debug-read *debug-io*))
+                    (cmd-fun (debug-command-p exp restart-commands)))
+               (with-simple-restart (abort
+                                     "~@<Reduce debugger level (to debug level ~W).~@:>"
+                                     level)
+                 (cond ((not cmd-fun)
+                        (debug-eval-print exp))
+                       ((consp cmd-fun)
+                        (format *debug-io*
+                                "~&Your command, ~S, is ambiguous:~%"
+                                exp)
+                        (dolist (ele cmd-fun)
+                          (format *debug-io* "   ~A~%" ele)))
+                       (t
+                        (funcall cmd-fun))))))))))))
 
 (defun debug-eval-print (expr)
   (/noshow "entering DEBUG-EVAL-PRINT" expr)
@@ -1095,8 +1119,8 @@ reset to ~S."
   (let ((num (read-if-available :prompt)))
     (when (eq num :prompt)
       (show-restarts *debug-restarts* *debug-io*)
-      (write-string "restart: ")
-      (force-output)
+      (write-string "restart: " *debug-io*)
+      (force-output *debug-io*)
       (setf num (read *debug-io*)))
     (let ((restart (typecase num
                      (unsigned-byte
@@ -1301,15 +1325,41 @@ reset to ~S."
                                  (svref translations form-num)
                                  context))))
 \f
-;;; step to the next steppable form
-(!def-debug-command "STEP" ()
-  (let ((restart (find-restart 'continue *debug-condition*)))
-    (cond (restart
-           (setf *stepping* t
-                 *step* t)
+
+;;; start single-stepping
+(!def-debug-command "START" ()
+  (if (typep *debug-condition* 'step-condition)
+      (format *debug-io* "~&Already single-stepping.~%")
+      (let ((restart (find-restart 'continue *debug-condition*)))
+        (cond (restart
+               (sb!impl::enable-stepping)
+               (invoke-restart restart))
+              (t
+               (format *debug-io* "~&Non-continuable error, cannot start stepping.~%"))))))
+
+(defmacro def-step-command (command-name restart-name)
+  `(!def-debug-command ,command-name ()
+     (if (typep *debug-condition* 'step-condition)
+         (let ((restart (find-restart ',restart-name *debug-condition*)))
+           (aver restart)
            (invoke-restart restart))
-          (t
-           (format *debug-io* "~&Non-continuable error, cannot step.~%")))))
+         (format *debug-io* "~&Not currently single-stepping. (Use START to activate the single-stepper)~%"))))
+
+(def-step-command "STEP" step-into)
+(def-step-command "NEXT" step-next)
+(def-step-command "STOP" step-continue)
+
+(!def-debug-command-alias "S" "STEP")
+(!def-debug-command-alias "N" "NEXT")
+
+(!def-debug-command "OUT" ()
+  (if (typep *debug-condition* 'step-condition)
+      (if sb!impl::*step-out*
+          (let ((restart (find-restart 'step-out *debug-condition*)))
+            (aver restart)
+            (invoke-restart restart))
+          (format *debug-io* "~&OUT can only be used step out of frames that were originally stepped into with STEP.~%"))
+      (format *debug-io* "~&Not currently single-stepping. (Use START to activate the single-stepper)~%")))
 
 ;;; miscellaneous commands