1 ;;;; code for handling UNIX signals
3 ;;;; This software is part of the SBCL system. See the README file for
6 ;;;; This software is derived from the CMU CL system, which was
7 ;;;; written at Carnegie Mellon University and released into the
8 ;;;; public domain. The software is in the public domain and is
9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
10 ;;;; files for more information.
12 (in-package "SB!UNIX")
14 (defmacro with-interrupt-bindings
(&body body
)
16 ;; KLUDGE: Whatever is on the PCL stacks before the interrupt
17 ;; handler runs doesn't really matter, since we're not on the
18 ;; same call stack, really -- and if we don't bind these (esp.
19 ;; the cache one) we can get a bogus metacircle if an interrupt
20 ;; handler calls a GF that was being computed when the interrupt
22 ((sb!pcl
::*cache-miss-values-stack
* nil
)
23 (sb!pcl
::*dfun-miss-gfs-on-stack
* nil
))
26 ;;; Evaluate CLEANUP-FORMS iff PROTECTED-FORM does a non-local exit.
27 (defmacro nlx-protect
(protected-form &rest cleanup-froms
)
28 (with-unique-names (completep)
29 `(let ((,completep nil
))
33 (allow-with-interrupts
39 (defun invoke-interruption (function)
41 ;; Reset signal mask: the C-side handler has blocked all
42 ;; deferrable signals before funcalling into lisp. They are to be
43 ;; unblocked the first time interrupts are enabled. With this
44 ;; mechanism there are no extra frames on the stack from a
45 ;; previous signal handler when the next signal is delivered
46 ;; provided there is no WITH-INTERRUPTS.
47 (let ((*unblock-deferrables-on-enabling-interrupts-p
* t
)
48 (sb!debug
:*stack-top-hint
* (or sb
!debug
:*stack-top-hint
* 'invoke-interruption
)))
49 (with-interrupt-bindings
50 (sb!thread
::without-thread-waiting-for
(:already-without-interrupts t
)
51 (allow-with-interrupts
52 (nlx-protect (funcall function
)
53 ;; We've been running with deferrables
54 ;; blocked in Lisp called by a C signal
55 ;; handler. If we return normally the sigmask
56 ;; in the interrupted context is restored.
57 ;; However, if we do an nlx the operating
58 ;; system will not restore it for us.
59 (when *unblock-deferrables-on-enabling-interrupts-p
*
60 ;; This means that storms of interrupts
61 ;; doing an nlx can still run out of stack.
62 (unblock-deferrable-signals)))))))))
64 (defmacro in-interruption
((&key
) &body body
)
66 "Convenience macro on top of INVOKE-INTERRUPTION."
67 `(dx-flet ((interruption () ,@body
))
68 (invoke-interruption #'interruption
)))
70 ;;;; system calls that deal with signals
72 ;;; Send the signal SIGNAL to the process with process id PID. SIGNAL
73 ;;; should be a valid signal number
74 #!-sb-fluid
(declaim (inline unix-kill
))
75 (define-alien-routine ("kill" unix-kill
) int
79 ;;; Send the signal SIGNAL to the all the process in process group
80 ;;; PGRP. SIGNAL should be a valid signal number
81 #!-sb-fluid
(declaim (inline unix-killpg
))
82 (define-alien-routine ("killpg" unix-killpg
) int
86 ;;; Reset the current set of masked signals (those being blocked from
89 ;;; (Note: CMU CL had a more general SIGSETMASK call and a SIGMASK
90 ;;; operator to create masks, but since we only ever reset to 0, we no
91 ;;; longer support it. If you need it, you can pull it out of the CMU
92 ;;; CL sources, or the old SBCL sources; but you might also consider
93 ;;; doing things the SBCL way and moving this kind of C-level work
94 ;;; down to C wrapper functions.)
96 (declaim (inline %unblock-deferrable-signals %unblock-gc-signals
))
97 (define-alien-routine ("unblock_deferrable_signals"
98 %unblock-deferrable-signals
)
100 (where unsigned-long
)
103 (define-alien-routine ("unblock_gc_signals" %unblock-gc-signals
)
105 (where unsigned-long
)
108 (defun unblock-deferrable-signals ()
109 (%unblock-deferrable-signals
0 0))
112 (defun unblock-gc-signals ()
113 (%unblock-gc-signals
0 0))
116 ;;;; C routines that actually do all the work of establishing signal handlers
117 (define-alien-routine ("install_handler" install-handler
)
120 (handler unsigned-long
)
121 (synchronous boolean
))
123 ;;;; interface to enabling and disabling signal handlers
125 ;;; Note on the SYNCHRONOUS argument: On builds without pseudo-atomic,
126 ;;; we have no way of knowing whether interrupted code was in an
127 ;;; allocation sequence, and cannot delay signals until after
128 ;;; allocation. Any signal that can occur asynchronously must be
129 ;;; considered unsafe for immediate execution, and the invocation of its
130 ;;; lisp handler will get delayed into a newly spawned signal handler
131 ;;; thread. However, there are signals which we must handle
132 ;;; immediately, because they occur synchonously (hence the boolean flag
133 ;;; SYNCHRONOUS to this function), luckily implying that the signal
134 ;;; happens only in specific places (illegal instructions, floating
135 ;;; point instructions, certain system calls), hopefully ruling out the
136 ;;; possibility that we would trigger it during allocation.
138 (defun enable-interrupt (signal handler
&key synchronous
)
139 (declare (type (or function fixnum
(member :default
:ignore
)) handler
))
140 (/show0
"enable-interrupt")
141 (flet ((run-handler (&rest args
)
142 (declare (truly-dynamic-extent args
))
144 (apply handler args
))))
146 (let ((result (install-handler signal
151 (sb!kernel
:get-lisp-obj-address
154 (cond ((= result sig-dfl
) :default
)
155 ((= result sig-ign
) :ignore
)
156 (t (the (or function fixnum
)
157 (sb!kernel
:make-lisp-obj result
))))))))
159 (defun default-interrupt (signal)
160 (enable-interrupt signal
:default
))
162 (defun ignore-interrupt (signal)
163 (enable-interrupt signal
:ignore
))
165 ;;;; Support for signal handlers which aren't.
167 ;;;; On safepoint builds, user-defined Lisp signal handlers do not run
168 ;;;; in the handler for their signal, because we have no pseudo atomic
169 ;;;; mechanism to prevent handlers from hitting during allocation.
170 ;;;; Rather, the signal spawns off a fresh native thread, which calls
171 ;;;; into lisp with a fake context through this callback:
173 #!+(and sb-safepoint-strictly
(not win32
))
174 (defun signal-handler-callback (run-handler signal args
)
175 (sb!thread
::initial-thread-function-trampoline
176 (sb!thread
::make-signal-handling-thread
:name
"signal handler"
177 :signal-number signal
)
179 (let* ((info (sap-ref-sap args
0))
180 (context (sap-ref-sap args sb
!vm
:n-word-bytes
)))
181 (funcall run-handler signal info context
)))
185 ;;;; default LISP signal handlers
187 ;;;; Most of these just call ERROR to report the presence of the signal.
189 ;;; SIGINT is handled like BREAK, except that ANSI BREAK ignores
190 ;;; *DEBUGGER-HOOK*, but we want SIGINT's BREAK to respect it, so that
191 ;;; SIGINT in --disable-debugger mode will cleanly terminate the system
192 ;;; (by respecting the *DEBUGGER-HOOK* established in that mode).
193 (eval-when (:compile-toplevel
:execute
)
194 (sb!xc
:defmacro define-signal-handler
(name what
&optional
(function 'error
))
195 `(defun ,name
(signal info context
)
196 (declare (ignore signal info
))
197 (declare (type system-area-pointer context
))
198 (/show
"in Lisp-level signal handler" ,(symbol-name name
)
201 (,function
,(concatenate 'simple-string what
" at #X~X")
202 (with-alien ((context (* os-context-t
) context
))
203 (sap-int (sb!vm
:context-pc context
))))))))
205 (define-signal-handler sigill-handler
"illegal instruction")
206 #!-
(or linux android
)
207 (define-signal-handler sigemt-handler
"SIGEMT")
208 (define-signal-handler sigbus-handler
"bus error")
209 #!-
(or linux android
)
210 (define-signal-handler sigsys-handler
"bad argument to a system call")
212 (defun sigint-handler (signal info context
)
213 (declare (ignore signal info
))
214 (declare (type system-area-pointer context
))
215 (/show
"in Lisp-level SIGINT handler" (sap-int context
))
216 (flet ((interrupt-it ()
217 ;; This seems wrong to me on multi-threaded builds. The
218 ;; closed-over signal context belongs to a SIGINT handler.
219 ;; But this function gets run through INTERRUPT-THREAD,
220 ;; i.e. in in a SIGPIPE handler, at a different point in time
221 ;; or even a different thread. How do we know that the
222 ;; SIGINT's context structure from the other thread is still
223 ;; alive and meaningful? Why do we care? If we even need
224 ;; the context and PC, shouldn't they come from the SIGPIPE's
226 (with-alien ((context (* os-context-t
) context
))
228 (let ((int (make-condition 'interactive-interrupt
230 :address
(sap-int (sb!vm
:context-pc context
)))))
231 ;; First SIGNAL, so that handlers can run.
233 ;; Then enter the debugger like BREAK.
234 (%break
'sigint int
))))))
236 (let ((target (sb!thread
::foreground-thread
)))
237 ;; Note that INTERRUPT-THREAD on *CURRENT-THREAD* doesn't actually
238 ;; interrupt right away, because deferrables are blocked. Rather,
239 ;; the kernel would arrange for the SIGPIPE to hit when the SIGINT
240 ;; handler is done. However, on safepoint builds, we don't use
241 ;; SIGPIPE and lack an appropriate mechanism to handle pending
242 ;; thruptions upon exit from signal handlers (and this situation is
243 ;; unlike WITHOUT-INTERRUPTS, which handles pending interrupts
244 ;; explicitly at the end). Only as long as safepoint builds pretend
245 ;; to cooperate with signals -- that is, as long as SIGINT-HANDLER
246 ;; is used at all -- detect this situation and work around it.
247 (if (eq target sb
!thread
:*current-thread
*)
249 (sb!thread
:interrupt-thread target
#'interrupt-it
)))
251 (sb!thread
:interrupt-thread
(sb!thread
::foreground-thread
)
255 (defun sigalrm-handler (signal info context
)
256 (declare (ignore signal info context
))
257 (declare (type system-area-pointer context
))
258 (sb!impl
::run-expired-timers
))
260 (defun sigterm-handler (signal code context
)
261 (declare (ignore signal code context
))
265 ;;; SIGPIPE is not used in SBCL for its original purpose, instead it's
266 ;;; for signalling a thread that it should look at its interruption
267 ;;; queue. The handler (RUN_INTERRUPTION) just returns if there is
268 ;;; nothing to do so it's safe to receive spurious SIGPIPEs coming
270 (defun sigpipe-handler (signal code context
)
271 (declare (ignore signal code context
))
272 (sb!thread
::run-interruption
))
274 ;;; the handler for SIGCHLD signals for RUN-PROGRAM
275 (defun sigchld-handler (signal code context
)
276 (declare (ignore signal code context
))
277 (sb!impl
::get-processes-status-changes
))
279 (defun sb!kernel
:signal-cold-init-or-reinit
()
281 "Enable all the default signals that Lisp knows how to deal with."
282 (enable-interrupt sigint
#'sigint-handler
)
283 (enable-interrupt sigterm
#'sigterm-handler
)
284 (enable-interrupt sigill
#'sigill-handler
:synchronous t
)
285 #!-
(or linux android
)
286 (enable-interrupt sigemt
#'sigemt-handler
)
287 (enable-interrupt sigfpe
#'sb
!vm
:sigfpe-handler
:synchronous t
)
288 (enable-interrupt sigbus
#'sigbus-handler
:synchronous t
)
289 #!-
(or linux android
)
290 (enable-interrupt sigsys
#'sigsys-handler
:synchronous t
)
292 (enable-interrupt sigalrm
#'sigalrm-handler
)
294 (enable-interrupt sigpipe
#'sigpipe-handler
)
295 (enable-interrupt sigchld
#'sigchld-handler
)
296 #!+hpux
(ignore-interrupt sigxcpu
)
297 #!-sb-safepoint
(unblock-gc-signals)
298 (unblock-deferrable-signals)
303 ;;; extract si_code from siginfo_t
304 (define-alien-routine ("siginfo_code" siginfo-code
) int
305 (info system-area-pointer
))
308 ;;; Magically converted by the compiler into a break instruction.
309 (defun receive-pending-interrupt ()
310 (receive-pending-interrupt))