;;;; stuff related to the toplevel read-eval-print loop, plus some ;;;; other miscellaneous functions that we don't have any better place ;;;; for ;;;; This software is part of the SBCL system. See the README file for ;;;; more information. ;;;; ;;;; This software is derived from the CMU CL system, which was ;;;; written at Carnegie Mellon University and released into the ;;;; public domain. The software is in the public domain and is ;;;; provided with absolutely no warranty. See the COPYING and CREDITS ;;;; files for more information. (in-package "SB!IMPL") ;;;; magic specials initialized by GENESIS ;;; FIXME: The DEFVAR here is redundant with the (DECLAIM (SPECIAL ..)) ;;; of all static symbols in early-impl.lisp. (progn (defvar sb!vm::*current-catch-block*) (defvar sb!vm::*current-unwind-protect-block*) (defvar *free-interrupt-context-index*)) ;;; specials initialized by !COLD-INIT ;;; FIXME: These could be converted to DEFVARs. (declaim (special #!+(or x86 x86-64) *pseudo-atomic-bits* *allow-with-interrupts* *interrupts-enabled* *interrupt-pending* *type-system-initialized*)) (defvar *cold-init-complete-p*) ;;; counts of nested errors (with internal errors double-counted) (defvar *maximum-error-depth*) (defvar *current-error-depth*) ;;;; default initfiles (defun sysinit-pathname () (or (let ((sbcl-homedir (sbcl-homedir-pathname))) (when sbcl-homedir (probe-file (merge-pathnames "sbclrc" sbcl-homedir)))) #!+win32 (merge-pathnames "sbcl\\sbclrc" (sb!win32::get-folder-pathname sb!win32::csidl_common_appdata)) #!-win32 "/etc/sbclrc")) (defun userinit-pathname () (merge-pathnames ".sbclrc" (user-homedir-pathname))) (defvar *sysinit-pathname-function* #'sysinit-pathname #!+sb-doc "Designator for a function of zero arguments called to obtain a pathname designator for the default sysinit file, or NIL. If the function returns NIL, no sysinit file is used unless one has been specified on the command-line.") (defvar *userinit-pathname-function* #'userinit-pathname #!+sb-doc "Designator for a function of zero arguments called to obtain a pathname designator or a stream for the default userinit file, or NIL. If the function returns NIL, no userinit file is used unless one has been specified on the command-line.") ;;;; miscellaneous utilities for working with with TOPLEVEL ;;; Execute BODY in a context where any %END-OF-THE-WORLD (thrown e.g. ;;; by QUIT) is caught and any final processing and return codes are ;;; handled appropriately. (defmacro handling-end-of-the-world (&body body) (with-unique-names (caught) `(let ((,caught (catch '%end-of-the-world (/show0 "inside CATCH '%END-OF-THE-WORLD") (unwind-protect (progn ,@body) (call-hooks "exit" *exit-hooks*))))) (/show0 "back from CATCH '%END-OF-THE-WORLD, flushing output") (flush-standard-output-streams) (sb!thread::terminate-session) (/show0 "calling UNIX-EXIT") (sb!unix:unix-exit ,caught)))) ;;;; working with *CURRENT-ERROR-DEPTH* and *MAXIMUM-ERROR-DEPTH* ;;; INFINITE-ERROR-PROTECT is used by ERROR and friends to keep us out ;;; of hyperspace. (defmacro infinite-error-protect (&rest forms) `(unless (infinite-error-protector) (/show0 "back from INFINITE-ERROR-PROTECTOR") (let ((*current-error-depth* (1+ *current-error-depth*))) (/show0 "in INFINITE-ERROR-PROTECT, incremented error depth") ;; arbitrary truncation #!+sb-show (sb!debug:backtrace 8) ,@forms))) ;;; a helper function for INFINITE-ERROR-PROTECT (defun infinite-error-protector () (/show0 "entering INFINITE-ERROR-PROTECTOR, *CURRENT-ERROR-DEPTH*=..") (/hexstr *current-error-depth*) (cond ((not *cold-init-complete-p*) (%primitive print "Argh! error in cold init, halting") (%primitive sb!c:halt)) ((or (not (boundp '*current-error-depth*)) (not (realp *current-error-depth*)) (not (boundp '*maximum-error-depth*)) (not (realp *maximum-error-depth*))) (%primitive print "Argh! corrupted error depth, halting") (%primitive sb!c:halt)) ((> *current-error-depth* *maximum-error-depth*) (/show0 "*MAXIMUM-ERROR-DEPTH*=..") (/hexstr *maximum-error-depth*) (/show0 "in INFINITE-ERROR-PROTECTOR, calling ERROR-ERROR") (error-error "Help! " *current-error-depth* " nested errors. " "SB-KERNEL:*MAXIMUM-ERROR-DEPTH* exceeded.") t) (t (/show0 "returning normally from INFINITE-ERROR-PROTECTOR") nil))) ;;; FIXME: I had a badly broken version of INFINITE-ERROR-PROTECTOR at ;;; one point (shown below), and SBCL cross-compiled it without ;;; warning about FORMS being undefined. Check whether that problem ;;; (missing warning) is repeatable in the final system and if so, fix ;;; it. #| (defun infinite-error-protector () `(cond ((not *cold-init-complete-p*) (%primitive print "Argh! error in cold init, halting") (%primitive sb!c:halt)) ((or (not (boundp '*current-error-depth*)) (not (realp *current-error-depth*)) (not (boundp '*maximum-error-depth*)) (not (realp *maximum-error-depth*))) (%primitive print "Argh! corrupted error depth, halting") (%primitive sb!c:halt)) ((> *current-error-depth* *maximum-error-depth*) (/show0 "in INFINITE-ERROR-PROTECTOR, calling ERROR-ERROR") (error-error "Help! " *current-error-depth* " nested errors. " "SB-KERNEL:*MAXIMUM-ERROR-DEPTH* exceeded.") (progn ,@forms) t) (t (/show0 "in INFINITE-ERROR-PROTECTOR, returning normally") nil))) |# ;;;; miscellaneous external functions (defun sleep (n) #!+sb-doc "This function causes execution to be suspended for N seconds. N may be any non-negative, non-complex number." (when (or (not (realp n)) (minusp n)) (error 'simple-type-error :format-control "invalid argument to SLEEP: ~S" :format-arguments (list n) :datum n :expected-type '(real 0))) #!-win32 (multiple-value-bind (sec nsec) (if (integerp n) (values n 0) (multiple-value-bind (sec frac) (truncate n) (values sec (truncate frac 1e-9)))) (sb!unix:nanosleep sec nsec)) #!+win32 (sb!win32:millisleep (truncate (* n 1000))) nil) ;;;; SCRUB-CONTROL-STACK (defconstant bytes-per-scrub-unit 2048) ;;; Zero the unused portion of the control stack so that old objects ;;; are not kept alive because of uninitialized stack variables. ;;; "To summarize the problem, since not all allocated stack frame ;;; slots are guaranteed to be written by the time you call an another ;;; function or GC, there may be garbage pointers retained in your ;;; dead stack locations. The stack scrubbing only affects the part ;;; of the stack from the SP to the end of the allocated stack." ;;; - ram, on cmucl-imp, Tue, 25 Sep 2001 ;;; So, as an (admittedly lame) workaround, from time to time we call ;;; scrub-control-stack to zero out all the unused portion. This is ;;; supposed to happen when the stack is mostly empty, so that we have ;;; a chance of clearing more of it: callers are currently (2002.07.18) ;;; REPL and SUB-GC (defun scrub-control-stack () (declare (optimize (speed 3) (safety 0)) (values (unsigned-byte 20))) ; FIXME: DECLARE VALUES? #!-stack-grows-downward-not-upward (let* ((csp (sap-int (sb!c::control-stack-pointer-sap))) (initial-offset (logand csp (1- bytes-per-scrub-unit))) (end-of-stack (- (sap-int (sb!di::descriptor-sap sb!vm:*control-stack-end*)) sb!c:*backend-page-bytes*))) (labels ((scrub (ptr offset count) (declare (type system-area-pointer ptr) (type (unsigned-byte 16) offset) (type (unsigned-byte 20) count) (values (unsigned-byte 20))) (cond ((>= (sap-int ptr) end-of-stack) 0) ((= offset bytes-per-scrub-unit) (look (sap+ ptr bytes-per-scrub-unit) 0 count)) (t (setf (sap-ref-word ptr offset) 0) (scrub ptr (+ offset sb!vm:n-word-bytes) count)))) (look (ptr offset count) (declare (type system-area-pointer ptr) (type (unsigned-byte 16) offset) (type (unsigned-byte 20) count) (values (unsigned-byte 20))) (cond ((>= (sap-int ptr) end-of-stack) 0) ((= offset bytes-per-scrub-unit) count) ((zerop (sap-ref-word ptr offset)) (look ptr (+ offset sb!vm:n-word-bytes) count)) (t (scrub ptr offset (+ count sb!vm:n-word-bytes)))))) (declare (type sb!vm::word csp)) (scrub (int-sap (- csp initial-offset)) (* (floor initial-offset sb!vm:n-word-bytes) sb!vm:n-word-bytes) 0))) #!+stack-grows-downward-not-upward (let* ((csp (sap-int (sb!c::control-stack-pointer-sap))) (end-of-stack (+ (sap-int (sb!di::descriptor-sap sb!vm:*control-stack-start*)) sb!c:*backend-page-bytes*)) (initial-offset (logand csp (1- bytes-per-scrub-unit)))) (labels ((scrub (ptr offset count) (declare (type system-area-pointer ptr) (type (unsigned-byte 16) offset) (type (unsigned-byte 20) count) (values (unsigned-byte 20))) (let ((loc (int-sap (- (sap-int ptr) (+ offset sb!vm:n-word-bytes))))) (cond ((< (sap-int loc) end-of-stack) 0) ((= offset bytes-per-scrub-unit) (look (int-sap (- (sap-int ptr) bytes-per-scrub-unit)) 0 count)) (t ;; need to fix bug in %SET-STACK-REF (setf (sap-ref-word loc 0) 0) (scrub ptr (+ offset sb!vm:n-word-bytes) count))))) (look (ptr offset count) (declare (type system-area-pointer ptr) (type (unsigned-byte 16) offset) (type (unsigned-byte 20) count) (values (unsigned-byte 20))) (let ((loc (int-sap (- (sap-int ptr) offset)))) (cond ((< (sap-int loc) end-of-stack) 0) ((= offset bytes-per-scrub-unit) count) ((zerop (sb!kernel::get-lisp-obj-address (stack-ref loc 0))) (look ptr (+ offset sb!vm:n-word-bytes) count)) (t (scrub ptr offset (+ count sb!vm:n-word-bytes))))))) (declare (type sb!vm::word csp)) (scrub (int-sap (+ csp initial-offset)) (* (floor initial-offset sb!vm:n-word-bytes) sb!vm:n-word-bytes) 0)))) ;;;; the default toplevel function (defvar / nil #!+sb-doc "a list of all the values returned by the most recent top level EVAL") (defvar // nil #!+sb-doc "the previous value of /") (defvar /// nil #!+sb-doc "the previous value of //") (defvar * nil #!+sb-doc "the value of the most recent top level EVAL") (defvar ** nil #!+sb-doc "the previous value of *") (defvar *** nil #!+sb-doc "the previous value of **") (defvar + nil #!+sb-doc "the value of the most recent top level READ") (defvar ++ nil #!+sb-doc "the previous value of +") (defvar +++ nil #!+sb-doc "the previous value of ++") (defvar - nil #!+sb-doc "the form currently being evaluated") (defun interactive-eval (form) #!+sb-doc "Evaluate FORM, returning whatever it returns and adjusting ***, **, *, +++, ++, +, ///, //, /, and -." (setf - form) (unwind-protect (let ((results (multiple-value-list (eval form)))) (setf /// // // / / results *** ** ** * * (car results))) (setf +++ ++ ++ + + -)) (unless (boundp '*) ;; The bogon returned an unbound marker. ;; FIXME: It would be safer to check every one of the values in RESULTS, ;; instead of just the first one. (setf * nil) (cerror "Go on with * set to NIL." "EVAL returned an unbound marker.")) (values-list /)) ;;; Flush anything waiting on one of the ANSI Common Lisp standard ;;; output streams before proceeding. (defun flush-standard-output-streams () (dolist (name '(*debug-io* *error-output* *query-io* *standard-output* *trace-output* *terminal-io*)) ;; FINISH-OUTPUT may block more easily than FORCE-OUTPUT (force-output (symbol-value name))) (values)) (defun process-init-file (specified-pathname kind) (multiple-value-bind (context default-function) (ecase kind (:system (values "sysinit" *sysinit-pathname-function*)) (:user (values "userinit" *userinit-pathname-function*))) (flet ((process-stream (stream pathname) (with-simple-restart (abort "Skip rest of ~A file ~S." context (native-namestring pathname)) (loop (with-simple-restart (continue "Ignore error and continue processing ~A file ~S." context (native-namestring pathname)) (let ((form (read stream nil stream))) (if (eq stream form) (return-from process-init-file nil) (eval form)))))))) (if specified-pathname (with-open-file (stream (parse-native-namestring specified-pathname) :if-does-not-exist nil) (if stream (process-stream stream (pathname stream)) (cerror "Ignore missing init file" "The specified ~A file ~A was not found." context specified-pathname))) (let ((default (funcall default-function))) (when default (with-open-file (stream (pathname default) :if-does-not-exist nil) (when stream (process-stream stream (pathname stream)))))))))) (defun process-eval/load-options (options) (/show0 "handling --eval and --load options") (flet ((process-1 (cons) (destructuring-bind (opt . value) cons (ecase opt (:eval (with-simple-restart (continue "Ignore runtime option --eval ~S." value) (multiple-value-bind (expr pos) (read-from-string value) (if (eq value (read-from-string value nil value :start pos)) (eval expr) (error "Multiple expressions in --eval option: ~S" value))))) (:load (with-simple-restart (continue "Ignore runtime option --load ~S." value) (load (native-pathname value)))))) (flush-standard-output-streams))) (with-simple-restart (abort "Skip rest of --eval and --load options.") (dolist (option options) (process-1 option))))) ;;; Skips past the shebang line on stream, if any. (defun maybe-skip-shebang-line (stream) (let ((p (file-position stream))) (flet ((next () (read-byte stream nil))) (unwind-protect (when (and (eq (next) (char-code #\#)) (eq (next) (char-code #\!))) (setf p nil) (loop for x = (next) until (or (not x) (eq x (char-code #\newline))))) (when p (file-position stream p)))) t)) (defun process-script (script) (let ((pathname (native-pathname script)) (ok nil)) (unwind-protect (with-open-file (f pathname :element-type :default) (maybe-skip-shebang-line f) (load f :verbose nil :print nil) (setf ok t)) (quit :unix-status (if ok 0 1))))) ;; Errors while processing the command line cause the system to QUIT, ;; instead of trying to go into the Lisp debugger, because trying to ;; go into the Lisp debugger would get into various annoying issues of ;; where we should go after the user tries to return from the ;; debugger. (defun startup-error (control-string &rest args) (format *error-output* "fatal error before reaching READ-EVAL-PRINT loop: ~% ~?~%" control-string args) (quit :unix-status 1)) ;;; the default system top level function (defun toplevel-init () (/show0 "entering TOPLEVEL-INIT") (let ( ;; value of --sysinit option (sysinit nil) ;; t if --no-sysinit option given (no-sysinit nil) ;; value of --userinit option (userinit nil) ;; t if --no-userinit option given (no-userinit nil) ;; t if --disable-debugger option given (disable-debugger nil) ;; list of ( . ) conses representing --eval and --load ;; options. options. --eval options are stored as strings, so that ;; they can be passed to READ only after their predecessors have been ;; EVALed, so that things work when e.g. REQUIRE in one EVAL form ;; creates a package referred to in the next EVAL form. Storing the ;; original string also makes for easier debugging. (reversed-options nil) ;; Has a --noprint option been seen? (noprint nil) ;; Has a --script option been seen? (script nil) ;; everything in *POSIX-ARGV* except for argv[0]=programname (options (rest *posix-argv*))) (declare (type list options)) (/show0 "done with outer LET in TOPLEVEL-INIT") ;; FIXME: There are lots of ways for errors to happen around here ;; (e.g. bad command line syntax, or READ-ERROR while trying to ;; READ an --eval string). Make sure that they're handled ;; reasonably. ;; Process command line options. (loop while options do (/show0 "at head of LOOP WHILE OPTIONS DO in TOPLEVEL-INIT") (let ((option (first options))) (flet ((pop-option () (if options (pop options) (startup-error "unexpected end of command line options")))) (cond ((string= option "--script") (pop-option) (setf disable-debugger t no-userinit t no-sysinit t script (pop-option)) (return)) ((string= option "--sysinit") (pop-option) (if sysinit (startup-error "multiple --sysinit options") (setf sysinit (pop-option)))) ((string= option "--no-sysinit") (pop-option) (setf no-sysinit t)) ((string= option "--userinit") (pop-option) (if userinit (startup-error "multiple --userinit options") (setf userinit (pop-option)))) ((string= option "--no-userinit") (pop-option) (setf no-userinit t)) ((string= option "--eval") (pop-option) (push (cons :eval (pop-option)) reversed-options)) ((string= option "--load") (pop-option) (push (cons :load (pop-option)) reversed-options)) ((string= option "--noprint") (pop-option) (setf noprint t)) ((string= option "--disable-debugger") (pop-option) (setf disable-debugger t)) ((string= option "--end-toplevel-options") (pop-option) (return)) (t ;; Anything we don't recognize as a toplevel ;; option must be the start of user-level ;; options.. except that if we encounter ;; "--end-toplevel-options" after we gave up ;; because we didn't recognize an option as a ;; toplevel option, then the option we gave up on ;; must have been an error. (E.g. in ;; "sbcl --eval '(a)' --eval'(b)' --end-toplevel-options" ;; this test will let us detect that the string ;; "--eval(b)" is an error.) (if (find "--end-toplevel-options" options :test #'string=) (startup-error "bad toplevel option: ~S" (first options)) (return))))))) (/show0 "done with LOOP WHILE OPTIONS DO in TOPLEVEL-INIT") ;; Delete all the options that we processed, so that only ;; user-level options are left visible to user code. (setf (rest *posix-argv*) options) ;; Disable debugger before processing initialization files & co. (when disable-debugger (sb!ext:disable-debugger)) ;; Handle initialization files. (/show0 "handling initialization files in TOPLEVEL-INIT") ;; This CATCH is needed for the debugger command TOPLEVEL to ;; work. (catch 'toplevel-catcher ;; We wrap all the pre-REPL user/system customized startup ;; code in a restart. ;; ;; (Why not wrap everything, even the stuff above, in this ;; restart? Errors above here are basically command line ;; or Unix environment errors, e.g. a missing file or a ;; typo on the Unix command line, and you don't need to ;; get into Lisp to debug them, you should just start over ;; and do it right at the Unix level. Errors below here ;; are generally errors in user Lisp code, and it might be ;; helpful to let the user reach the REPL in order to help ;; figure out what's going on.) (restart-case (progn (unless no-sysinit (process-init-file sysinit :system)) (unless no-userinit (process-init-file userinit :user)) (process-eval/load-options (nreverse reversed-options)) (when script (process-script script) (bug "PROCESS-SCRIPT returned"))) (abort () :report (lambda (s) (write-string (if script ;; In case script calls (enable-debugger)! "Abort script, exiting lisp." "Skip to toplevel READ/EVAL/PRINT loop.") s)) (/show0 "CONTINUEing from pre-REPL RESTART-CASE") (values)) ; (no-op, just fall through) (quit () :report "Quit SBCL (calling #'QUIT, killing the process)." :test (lambda (c) (declare (ignore c)) (not script)) (/show0 "falling through to QUIT from pre-REPL RESTART-CASE") (quit :unix-status 1)))) ;; one more time for good measure, in case we fell out of the ;; RESTART-CASE above before one of the flushes in the ordinary ;; flow of control had a chance to operate (flush-standard-output-streams) (/show0 "falling into TOPLEVEL-REPL from TOPLEVEL-INIT") (toplevel-repl noprint) ;; (classic CMU CL error message: "You're certainly a clever child.":-) (critically-unreachable "after TOPLEVEL-REPL"))) ;;; hooks to support customized toplevels like ACL-style toplevel from ;;; KMR on sbcl-devel 2002-12-21. Altered by CSR 2003-11-16 for ;;; threaded operation: altered *REPL-FUN* to *REPL-FUN-GENERATOR*. (defvar *repl-read-form-fun* #'repl-read-form-fun #!+sb-doc "A function of two stream arguments IN and OUT for the toplevel REPL to call: Return the next Lisp form to evaluate (possibly handling other magic -- like ACL-style keyword commands -- which precede the next Lisp form). The OUT stream is there to support magic which requires issuing new prompts.") (defvar *repl-prompt-fun* #'repl-prompt-fun #!+sb-doc "A function of one argument STREAM for the toplevel REPL to call: Prompt the user for input.") (defvar *repl-fun-generator* (constantly #'repl-fun) #!+sb-doc "A function of no arguments returning a function of one argument NOPRINT that provides the REPL for the system. Assumes that *STANDARD-INPUT* and *STANDARD-OUTPUT* are set up.") ;;; read-eval-print loop for the default system toplevel (defun toplevel-repl (noprint) (/show0 "entering TOPLEVEL-REPL") (let ((* nil) (** nil) (*** nil) (- nil) (+ nil) (++ nil) (+++ nil) (/// nil) (// nil) (/ nil)) (/show0 "about to funcall *REPL-FUN-GENERATOR*") (let ((repl-fun (funcall *repl-fun-generator*))) ;; Each REPL in a multithreaded world should have bindings of ;; most CL specials (most critically *PACKAGE*). (with-rebound-io-syntax (handler-bind ((step-condition 'invoke-stepper)) (loop (/show0 "about to set up restarts in TOPLEVEL-REPL") ;; CLHS recommends that there should always be an ;; ABORT restart; we have this one here, and one per ;; debugger level. (with-simple-restart (abort "~@") (catch 'toplevel-catcher #!-win32 (sb!unix::reset-signal-mask) ;; In the event of a control-stack-exhausted-error, we ;; should have unwound enough stack by the time we get ;; here that this is now possible. #!-win32 (sb!kernel::protect-control-stack-guard-page 1) (funcall repl-fun noprint) (critically-unreachable "after REPL"))))))))) ;;; Our default REPL prompt is the minimal traditional one. (defun repl-prompt-fun (stream) (fresh-line stream) (write-string "* " stream)) ; arbitrary but customary REPL prompt ;;; Our default form reader does relatively little magic, but does ;;; handle the Unix-style EOF-is-end-of-process convention. (defun repl-read-form-fun (in out) (declare (type stream in out) (ignore out)) (let* ((eof-marker (cons nil nil)) (form (read in nil eof-marker))) (if (eq form eof-marker) (quit) form))) (defun repl-fun (noprint) (/show0 "entering REPL") (loop (unwind-protect (progn ;; (See comment preceding the definition of SCRUB-CONTROL-STACK.) (scrub-control-stack) (sb!thread::get-foreground) (unless noprint (flush-standard-output-streams) (funcall *repl-prompt-fun* *standard-output*) ;; (Should *REPL-PROMPT-FUN* be responsible for doing its own ;; FORCE-OUTPUT? I can't imagine a valid reason for it not to ;; be done here, so leaving it up to *REPL-PROMPT-FUN* seems ;; odd. But maybe there *is* a valid reason in some ;; circumstances? perhaps some deadlock issue when being driven ;; by another process or something...) (force-output *standard-output*)) (let* ((form (funcall *repl-read-form-fun* *standard-input* *standard-output*)) (results (multiple-value-list (interactive-eval form)))) (unless noprint (dolist (result results) (fresh-line) (prin1 result))))) ;; If we started stepping in the debugger we want to stop now. (disable-stepping)))) ;;; a convenient way to get into the assembly-level debugger (defun %halt () (%primitive sb!c:halt))