226 lines
8.4 KiB
Scheme
226 lines
8.4 KiB
Scheme
;;; Copyright (c) 1993 by Olin Shivers.
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;;; Signal handler system
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;;; The principal trickiness here is that we have to interface to Unix signals
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;;; *through* an intermediate interface, the S48 vm's idea of interrupts.
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;;; So there is a difference between delivering a signal to the underlying
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;;; Unix process and delivering it to the program that runs on the VM.
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;;;
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;;; One effect is that we have two separate codes for the same thing -- the
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;;; Unix signal code, and the S48 interrupt value. E.g., SIGNAL/TSTP and
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;;; INTERRUPT/TSTP.
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;;; These system calls can return EINTR or restart. In order for the S48 vm's
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;;; interrupt system to detect a signal and invoke the handler, they *must*
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;;; return EINTR, and this must cause a return from C to Scheme.
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;;;
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;;; open close dup2 accept connect
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;;; read recv recvfrom recvmsg
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;;; write send sendto sendmsg
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;;; select
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;;; wait
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;;; fcntl* ioctl
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;;; sigsuspend
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;;; HP-UX, but I don't use: poll lockf msem_lock msgsnd msgrcv semop
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;;;
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;;; * Only during a F_SETLKW
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;;;
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;;; From rts/interrupt.scm (package interrupts, interface interrupts-interface)
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;;; WITH-INTERRUPTS INTERRUPT-HANDLERS SET-ENABLED-INTERRUPTS !
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;;; ENABLED-INTERRUPTS
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;;; Must define WITH-INTERRUPTS* and WITH-INTERRUPTS.
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(foreign-source
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"extern int errno;"
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""
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"/* Make sure foreign-function stubs interface to the C funs correctly: */"
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"#include \"sighandlers1.h\""
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"" "")
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;;; Map a Unix async signal to its S48 interrupt value.
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;;; -1 => Not defined.
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(define-foreign %signal->interrupt (sig2interrupt (integer sig))
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integer)
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(define (signal->interrupt sig)
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(let ((int (%signal->interrupt sig)))
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(if (>= int 0) int
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(error "Unix signal has no Scheme 48 interrupt." sig))))
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(define (interrupt-set . interrupts)
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(let lp ((ints interrupts) (ans 0))
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(if (pair? ints)
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(lp (cdr ints) (bitwise-ior ans (arithmetic-shift 1 (- (car ints) 1))))
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ans)))
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;;; I'm trying to be consistent about the ! suffix -- I don't use it
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;;; when frobbing process state. This is not a great rule; perhaps I
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;;; should change it.
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(define set-enabled-interrupts set-enabled-interrupts!)
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(define-simple-syntax (with-enabled-interrupts mask body ...)
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(with-interrupts mask (lambda () body ...)))
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(define with-enabled-interrupts* with-interrupts)
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(define interrupt/alarm (enum interrupt alarm))
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(define interrupt/keyboard (enum interrupt keyboard))
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(define interrupt/memory-shortage (enum interrupt memory-shortage))
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(define interrupt/chld (enum interrupt chld))
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(define interrupt/cont (enum interrupt cont))
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(define interrupt/hup (enum interrupt hup))
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(define interrupt/quit (enum interrupt quit))
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(define interrupt/term (enum interrupt term))
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(define interrupt/tstp (enum interrupt tstp))
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(define interrupt/usr1 (enum interrupt usr1))
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(define interrupt/usr2 (enum interrupt usr2))
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(define interrupt/info (enum interrupt info))
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(define interrupt/io (enum interrupt io))
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(define interrupt/poll (enum interrupt poll))
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(define interrupt/prof (enum interrupt prof))
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(define interrupt/pwr (enum interrupt pwr))
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(define interrupt/urg (enum interrupt urg))
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(define interrupt/vtalrm (enum interrupt vtalrm))
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(define interrupt/winch (enum interrupt winch))
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(define interrupt/xcpu (enum interrupt xcpu))
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(define interrupt/xfsz (enum interrupt xfsz))
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(define interrupt/int interrupt/keyboard)
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(define interrupt/alrm interrupt/alarm)
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;;; Get/Set signal handlers
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; When you set a signal's handler to "default," if the default for that
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;;; signal is something other than "ignore," we actually install this guy.
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;;; When he is called by the S48 interrupt system, he'll magically make
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;;; the default action happen (by calling C code that *really* sets the
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;;; handler to SIGDFL, and then re-sending the signal). This basically
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;;; terminates the process, since if the default isn't "ignore," it's always
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;;; "terminate" of some kind. Doing it this way means the exit code given
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;;; to our waiting parent proc correctly reflects how we died, and also
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;;; makes the core dump happen if it should. Details, details.
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(define-foreign %do-default-sigaction (do_default_sigaction (fixnum signal))
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ignore)
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(define default-int-handler-vec
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;; Non-Unix-signal interrupts just get their default values from
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;; the current value of I-H.
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(let ((v (copy-vector interrupt-handlers)))
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(do ((sig 31 (- sig 1))) ; For each Unix signal
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((< sig 0)) ; make & install a default
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(let ((i (%signal->interrupt sig))) ; signal handler.
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(if (>= i 0) ; Don't mess with non-signal interrupts.
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(vector-set! v i (if (memv sig signals-ignored-by-default)
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(lambda (enabled-interrupts) #f)
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(lambda (enabled-interrupts)
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(%do-default-sigaction sig)))))))
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v))
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;;; HANDLER is #f (ignore), #t (default), or a procedure taking an integer
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;;; argument. The interrupt is delivered to a procedure by (1) setting the
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;;; ENABLED-INTERRUPTS register to 0 (i.e., blocking all interrupts), and (2)
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;;; applying the procedure to the previous value of the ENABLED-INTERRUPTS
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;;; register. If the procedure returns normally, the ENABLED-INTERRUPTS
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;;; register will be restored to its previous value.
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;;; This handler does nothing -- used when the handler is #f.
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(define (noop-sig-handler enabled-interrupts) #f)
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(define (set-interrupt-handler int handler)
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(let ((ohandler (interrupt-handler int)))
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(vector-set! interrupt-handlers int
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(case handler
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((#t) (vector-ref default-int-handler-vec int))
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((#f) noop-sig-handler)
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(else handler)))
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(cond ((and (not handler) ohandler ; Toggling from something
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(int->signal int)) => ; to ignored.
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(lambda (sig)
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(%set-unix-signal-handler sig 0)))
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((and handler (not ohandler) ; Toggling from ignored
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(int->signal int)) => ; to something.
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(lambda (sig)
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(%set-unix-signal-handler sig 2))))
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ohandler))
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(define (interrupt-handler int)
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(let ((handler (vector-ref interrupt-handlers int)))
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(cond ((eq? handler (vector-ref default-int-handler-vec int)) #t)
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((eq? handler noop-sig-handler) #f)
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(else handler))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; Set the Unix signal handler. One doesn't usually use this; one usually
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;;; uses the S48 VM's interrupt system.
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;;; HANDLER-CODE: 0 => ignore, 1 => default, 2 => S48 VM
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;;; Returns equivalent code, additionally 3 => other handler.
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;;; Raises an error exception if there's a problem.
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(define (%set-unix-signal-handler sig handler-code)
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(check-arg (lambda (x) (and (integer? sig) (< 0 sig 32)))
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sig
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%set-unix-signal-handler)
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(check-arg (lambda (x) (and (integer? handler-code) (<= 0 handler-code 2)))
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handler-code
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%set-unix-signal-handler)
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(let retry ()
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(receive (err old-hc old-flags)
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(%%set-unix-signal-handler sig handler-code 0)
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(cond ((not err) old-hc)
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((= err errno/intr) (retry))
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(else (errno-error err %set-unix-signal-handler sig handler-code))))))
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(define-foreign %%set-unix-signal-handler
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(scsh_set_sig (fixnum sig) (fixnum hc) (fixnum flags))
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desc ; #f or errno
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integer ; previous handler-code
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integer) ; previous handler flags
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(define (%unix-signal-handler sig)
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(check-arg (lambda (x) (and (integer? sig) (< 0 sig 32)))
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sig
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%unix-signal-handler)
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(let retry ()
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(receive (err hc flags) (%%unix-signal-handler sig)
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(cond ((not err) hc)
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((= err errno/intr) (retry))
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(else (errno-error err %unix-signal-handler sig))))))
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(define-foreign %%unix-signal-handler (scsh_get_sig (fixnum sig))
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desc ; #f or errno
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integer ; previous handler-code
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integer) ; previous handler flags
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(define-foreign %install-unix-scsh-handlers (install_scsh_handlers) ignore)
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(define-foreign %%get-int-handlers (get_int_handlers) desc)
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(define (%install-scsh-handlers)
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(do ((sig 32 (- sig 1)))
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((< sig 0))
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(let ((i (%signal->interrupt sig)))
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(if (not (or (= i -1)
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(= sig signal/int) ; Leave ^c and
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(= sig signal/alrm))) ; alarm handlers alone.
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(vector-set! interrupt-handlers i
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(vector-ref default-int-handler-vec i))))))
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;;; I am ashamed to say the 33 below is completely bogus.
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;;; What we want is a value that is 1 + max interrupt value.
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(define int->sig-vec
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(let ((v (make-vector 33 #f)))
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(do ((sig 32 (- sig 1)))
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((< sig 0))
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(let ((i (%signal->interrupt sig)))
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(if (not (= i -1)) (vector-set! v i sig))))
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v))
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(define (int->signal i) (and (<= 0 i 32) (vector-ref int->sig-vec i)))
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