src/code/signal.lisp

   1 ;;;; handling UNIX signals
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   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.
  11
  12 (in-package "SB!UNIX")
  13 \f
  14 ;;;; macros for dynamically enabling and disabling signal handling
  15
  16 ;;; Notes on how the without-interrupts/with-interrupts stuff works:
  17 ;;;
  18 ;;; Before invoking the supplied handler for any of the signals that
  19 ;;; can be blocked, the C interrupt support code checks to see whether
  20 ;;; *interrupts-enabled* has been bound to NIL. If so, it saves the
  21 ;;; signal number and the value of the signal mask (from the signal
  22 ;;; context), sets the signal mask to block all blockable signals,
  23 ;;; sets *interrupt-pending* and returns without handling the signal.
  24 ;;;
  25 ;;; When we drop out the without interrupts, we check to see whether
  26 ;;; *INTERRUPT-PENDING* has been set. If so, we call
  27 ;;; RECEIVE-PENDING-INTERRUPT, which generates a SIGTRAP. The C code
  28 ;;; invokes the handler for the saved signal instead of the SIGTRAP
  29 ;;; after replacing the signal mask in the signal context with the
  30 ;;; saved value. When that hander returns, the original signal mask is
  31 ;;; installed, allowing any other pending signals to be handled.
  32 ;;;
  33 ;;; This means that the cost of WITHOUT-INTERRUPTS is just a special
  34 ;;; binding in the case when no signals are delivered (the normal
  35 ;;; case). It's only when a signal is actually delivered that we use
  36 ;;; any system calls, and by then the cost of the extra system calls
  37 ;;; are lost in the noise when compared with the cost of delivering
  38 ;;; the signal in the first place.
  39
  40 (defvar *interrupts-enabled* t)
  41 (defvar *interrupt-pending* nil)
  42
  43 (sb!xc:defmacro without-interrupts (&body body)
  44   #!+sb-doc
  45   "Execute BODY in a context impervious to interrupts."
  46   (let ((name (gensym "WITHOUT-INTERRUPTS-BODY-")))
  47     `(flet ((,name () ,@body))
  48        (if *interrupts-enabled*
  49            (unwind-protect
  50                (let ((*interrupts-enabled* nil))
  51                  (,name))
  52              ;; FIXME: Does it matter that an interrupt coming in here
  53              ;; could be executed before any of the pending interrupts?
  54              ;; Or do incoming interrupts have the good grace to check
  55              ;; whether interrupts are pending before executing themselves
  56              ;; immediately?
  57              (when *interrupt-pending*
  58                (receive-pending-interrupt)))
  59            (,name)))))
  60
  61 (sb!xc:defmacro with-interrupts (&body body)
  62   #!+sb-doc
  63   "Allow interrupts while executing BODY. As interrupts are normally allowed,
  64   this is only useful inside a WITHOUT-INTERRUPTS."
  65   (let ((name (gensym)))
  66     `(flet ((,name () ,@body))
  67        (if *interrupts-enabled*
  68            (,name)
  69            (let ((*interrupts-enabled* t))
  70              (when *interrupt-pending*
  71                (receive-pending-interrupt))
  72              (,name))))))
  73 \f
  74 ;;;; utilities for dealing with signal names and numbers
  75
  76 (defstruct (unix-signal
  77             (:constructor make-unix-signal (%name %number))
  78             (:copier nil))
  79   ;; signal keyword (e.g. :SIGINT for the Unix SIGINT signal)
  80   (%name   (missing-arg) :type keyword :read-only t)
  81   ;; signal number
  82   (%number (missing-arg) :type integer :read-only t))
  83
  84 ;;; list of all defined UNIX-SIGNALs
  85 (defvar *unix-signals* nil)
  86
  87 (defmacro !def-unix-signal (name number)
  88   (declare (type keyword name))
  89   (declare (type (and fixnum unsigned-byte) number))
  90   `(push (make-unix-signal ,name ,number) *unix-signals*))
  91
  92 (/show0 "signal.lisp 131")
  93
  94 (defun unix-signal-or-lose (designator)
  95   (or (find designator (the list *unix-signals*)
  96             :key (etypecase designator
  97                    (symbol #'unix-signal-%name)
  98                    (number #'unix-signal-%number)))
  99       (error "not a valid signal name or number: ~S" designator)))
 100
 101 (/show0 "signal.lisp 142")
 102
 103 ;;; Return the name of the designated signal.
 104 (defun unix-signal-name (designator)
 105   (symbol-name (unix-signal-%name (unix-signal-or-lose designator))))
 106
 107 (/show0 "signal.lisp 150")
 108
 109 ;;; Return the number of the designated signal.
 110 (defun unix-signal-number (designator)
 111   (unix-signal-%number (unix-signal-or-lose designator)))
 112
 113 (/show0 "signal.lisp 168")
 114
 115 ;;; known signals
 116 (/show0 "defining Unix signals")
 117 (!def-unix-signal :CHECK 0) ; check
 118 (/show0 "done defining CHECK")
 119 (!def-unix-signal :SIGHUP 1) ; hangup
 120 (/show0 "done defining SIGHUP")
 121 (!def-unix-signal :SIGINT 2) ; interrupt
 122 (/show0 "done defining SIGINT")
 123 (!def-unix-signal :SIGQUIT 3) ; quit
 124 (!def-unix-signal :SIGILL 4) ; illegal instruction
 125 (!def-unix-signal :SIGTRAP 5) ; trace trap
 126 (!def-unix-signal :SIGIOT 6) ; IOT instruction
 127 #!-linux
 128 (!def-unix-signal :SIGEMT 7) ; EMT instruction
 129 (!def-unix-signal :SIGFPE 8) ; floating point exception
 130 (!def-unix-signal :SIGKILL 9) ; kill
 131 (!def-unix-signal :SIGBUS #!-linux 10 #!+linux 7) ; bus error
 132 (!def-unix-signal :SIGSEGV 11) ; segmentation violation
 133 #!-linux
 134 (!def-unix-signal :SIGSYS 12) ; bad argument to system call
 135 (!def-unix-signal :SIGPIPE 13) ; write on a pipe with no one to read it
 136 (!def-unix-signal :SIGALRM 14) ; alarm clock
 137 (!def-unix-signal :SIGTERM 15) ; software termination signal
 138 #!+linux
 139 (!def-unix-signal :SIGSTKFLT 16) ; stack fault on coprocessor
 140 (!def-unix-signal :SIGURG ; urgent condition present on socket
 141   #!+svr4 21
 142   #!-(or hpux svr4 linux) 16
 143   #!+hpux 29
 144   #!+linux 23)
 145 (!def-unix-signal :SIGSTOP ; stop
 146   #!-(or hpux svr4 linux) 17
 147   #!+hpux 24
 148   #!+svr4 23
 149   #!+linux 19)
 150 (!def-unix-signal :SIGTSTP ;  stop signal generated from keyboard
 151   #!-(or hpux svr4 linux) 18
 152   #!+hpux 25
 153   #!+svr4 24
 154   #!+linux 20)
 155 (!def-unix-signal :SIGCONT ; continue after stop
 156   #!-(or hpux svr4 linux) 19
 157   #!+hpux 26
 158   #!+svr4 25
 159   #!+linux 18)
 160 (!def-unix-signal :SIGCHLD ; Child status has changed.
 161   #!-(or linux hpux) 20
 162   #!+hpux 18
 163   #!+linux 17)
 164 (!def-unix-signal :SIGTTIN ; background read attempted from control terminal
 165   #!-(or hpux svr4) 21
 166   #!+hpux 27
 167   #!+svr4 26)
 168 (!def-unix-signal :SIGTTOU ; background write attempted to control terminal
 169   #!-(or hpux svr4) 22
 170   #!+hpux 28
 171   #!+svr4 27)
 172 (!def-unix-signal :SIGIO ; I/O is possible on a descriptor.
 173   #!-(or hpux irix linux) 23
 174   #!+(or hpux irix) 22
 175   #!+linux 29)
 176 #!-hpux
 177 (!def-unix-signal :SIGXCPU ; CPU time limit exceeded
 178   #!-svr4 24
 179   #!+svr4 30)
 180 #!-hpux
 181 (!def-unix-signal :SIGXFSZ ;  file size limit exceeded
 182   #!-svr4 25
 183   #!+svr4 31)
 184 (!def-unix-signal :SIGVTALRM ; virtual time alarm
 185   #!-(or hpux svr4) 26
 186   #!+hpux 20
 187   #!+svr4 28)
 188 (!def-unix-signal :SIGPROF ;  profiling timer alarm
 189   #!-(or hpux svr4 linux) 27
 190   #!+hpux 21
 191   #!+svr4 29
 192   #!+linux 30)
 193 (!def-unix-signal :SIGWINCH ; window size change
 194   #!-(or hpux svr4) 28
 195   #!+hpux 23
 196   #!+svr4 20)
 197 (!def-unix-signal :SIGUSR1 ;  user-defined signal 1
 198   #!-(or hpux svr4 linux) 30
 199   #!+(or hpux svr4) 16
 200   #!+linux 10)
 201 (!def-unix-signal :SIGUSR2 ; user-defined signal 2
 202   #!-(or hpux svr4 linux) 31
 203   #!+(or hpux svr4) 17
 204   #!+linux 12)
 205
 206 ;;; SVR4 (or Solaris?) specific signals
 207 #!+svr4
 208 (!def-unix-signal :SIGWAITING 32) ; Process's LWPs are blocked.
 209
 210 (/show0 "done with signal.lisp")