413 lines
8.8 KiB
C
413 lines
8.8 KiB
C
/* sighandle.c -- Library routines for manipulating chains of signal handlers
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Copyright (C) 1992 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* Written by Paul Sander, HaL Computer Systems, Inc. <paul@hal.com>
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Brian Berliner <berliner@Sun.COM> added POSIX support */
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/*************************************************************************
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*
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* signal.c -- This file contains code that manipulates chains of signal
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* handlers.
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*
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* Facilities are provided to register a signal handler for
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* any specific signal. When a signal is received, all of the
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* registered signal handlers are invoked in the reverse order
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* in which they are registered. Note that the signal handlers
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* must not themselves make calls to the signal handling
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* facilities.
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*
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* @(#)sighandle.c 1.9 92/03/31
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*
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*************************************************************************/
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#include <sys/types.h>
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#include <stdio.h>
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#include <signal.h>
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#ifdef STDC_HEADERS
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#include <stdlib.h>
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#else
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#if __STDC__
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char *calloc(unsigned nelem, unsigned size);
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char *malloc(unsigned size);
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#else
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char *calloc();
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char *malloc();
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#endif /* __STDC__ */
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#endif /* STDC_HEADERS */
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#ifdef _MINIX
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#undef POSIX /* Minix 1.6 doesn't support POSIX.1 sigaction yet */
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#endif
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#ifndef SIGTYPE
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#define SIGTYPE void
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#endif
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/* Define the highest signal number (usually) */
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#ifndef SIGMAX
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#define SIGMAX 32
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#endif
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/* Define linked list of signal handlers structure */
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struct SIG_hlist {
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SIGTYPE (*handler)();
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struct SIG_hlist *next;
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};
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/*
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* Define array of lists of signal handlers. Note that this depends on
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* the implementation to initialize each element to a null pointer.
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*/
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static struct SIG_hlist **SIG_handlers;
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/* Define array of default signal vectors */
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#ifdef POSIX
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static struct sigaction *SIG_defaults;
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#else
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#ifdef BSD_SIGNALS
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static struct sigvec *SIG_defaults;
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#else
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static SIGTYPE (**SIG_defaults)();
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#endif
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#endif
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/* Critical section housekeeping */
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static int SIG_crSectNest = 0; /* Nesting level */
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#ifdef POSIX
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static sigset_t SIG_crSectMask; /* Signal mask */
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#else
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static int SIG_crSectMask; /* Signal mask */
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#endif
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/*
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* Initialize the signal handler arrays
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*/
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static int SIG_init()
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{
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int i;
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#ifdef POSIX
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sigset_t sigset_test;
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#endif
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if (SIG_defaults && SIG_handlers) /* already allocated */
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return (0);
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#ifdef POSIX
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(void) sigfillset(&sigset_test);
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for (i = 1; sigismember(&sigset_test, i) == 1; i++)
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#ifdef BROKEN_SIGISMEMBER
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if ( i >= NSIG )
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break
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#endif
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;
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if (i < SIGMAX)
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i = SIGMAX;
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i++;
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if (!SIG_defaults)
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SIG_defaults = (struct sigaction *)
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calloc(i, sizeof(struct sigaction));
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(void) sigemptyset(&SIG_crSectMask);
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#else
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i = SIGMAX+1;
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#ifdef BSD_SIGNALS
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if (!SIG_defaults)
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SIG_defaults = (struct sigvec *)
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calloc(i, sizeof(struct sigvec));
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#else
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if (!SIG_defaults)
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SIG_defaults = (SIGTYPE (**)())
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calloc(i, sizeof(SIGTYPE (**)()));
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#endif
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SIG_crSectMask = 0;
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#endif
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if (!SIG_handlers)
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SIG_handlers = (struct SIG_hlist **)
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calloc(i, sizeof(struct SIG_hlist *));
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return (!SIG_defaults || !SIG_handlers);
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}
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/*
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* The following invokes each signal handler in the reverse order in which
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* they were registered.
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*/
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static SIGTYPE SIG_handle(sig)
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int sig;
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{
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struct SIG_hlist *this;
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/* Dispatch signal handlers */
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this = SIG_handlers[sig];
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while (this != (struct SIG_hlist *) NULL)
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{
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(*this->handler)(sig);
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this = this->next;
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}
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return;
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}
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/*
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* The following registers a signal handler. If the handler is already
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* registered, it is not registered twice, nor is the order in which signal
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* handlers are invoked changed. If this is the first signal handler
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* registered for a given signal, the old sigvec structure is saved for
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* restoration later.
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*/
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int SIG_register(sig,fn)
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int sig;
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SIGTYPE (*fn)();
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{
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int val;
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struct SIG_hlist *this;
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#ifdef POSIX
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struct sigaction act;
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sigset_t sigset_mask, sigset_omask;
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#else
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#ifdef BSD_SIGNALS
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struct sigvec vec;
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int mask;
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#endif
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#endif
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/* Initialize */
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if (SIG_init() != 0)
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return (-1);
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val = 0;
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/* Block this signal while we look at handler chain */
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#ifdef POSIX
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(void) sigemptyset(&sigset_mask);
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(void) sigaddset(&sigset_mask, sig);
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(void) sigprocmask(SIG_BLOCK, &sigset_mask, &sigset_omask);
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#else
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#ifdef BSD_SIGNALS
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mask = sigblock(sigmask(sig));
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#endif
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#endif
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/* See if this handler was already registered */
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this = SIG_handlers[sig];
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while (this != (struct SIG_hlist *) NULL)
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{
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if (this->handler == fn) break;
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this = this->next;
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}
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/* Register the new handler only if it is not already registered. */
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if (this == (struct SIG_hlist *) NULL)
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{
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/*
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* If this is the first handler registered for this signal,
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* set up the signal handler dispatcher
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*/
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if (SIG_handlers[sig] == (struct SIG_hlist *) NULL)
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{
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#ifdef POSIX
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act.sa_handler = SIG_handle;
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(void) sigemptyset(&act.sa_mask);
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act.sa_flags = 0;
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val = sigaction(sig, &act, &SIG_defaults[sig]);
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#else
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#ifdef BSD_SIGNALS
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bzero((char *)&vec, sizeof(vec));
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vec.sv_handler = SIG_handle;
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val = sigvec(sig, &vec, &SIG_defaults[sig]);
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#else
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if ((SIG_defaults[sig] = signal(sig, SIG_handle)) ==
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(SIGTYPE (*)()) -1)
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val = -1;
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#endif
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#endif
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}
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/* If not, register it */
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if ((val == 0) && (this == (struct SIG_hlist *) NULL))
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{
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this = (struct SIG_hlist *)
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malloc(sizeof(struct SIG_hlist));
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if (this == NULL)
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{
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val = -1;
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}
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else
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{
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this->handler = fn;
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this->next = SIG_handlers[sig];
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SIG_handlers[sig] = this;
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}
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}
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}
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/* Unblock the signal */
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#ifdef POSIX
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(void) sigprocmask(SIG_SETMASK, &sigset_omask, NULL);
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#else
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#ifdef BSD_SIGNALS
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(void) sigsetmask(mask);
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#endif
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#endif
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return val;
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}
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/*
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* The following deregisters a signal handler. If the last signal handler for
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* a given signal is deregistered, the default sigvec information is restored.
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*/
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int SIG_deregister(sig,fn)
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int sig;
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SIGTYPE (*fn)();
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{
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int val;
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struct SIG_hlist *this;
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struct SIG_hlist *last;
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#ifdef POSIX
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sigset_t sigset_mask, sigset_omask;
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#else
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#ifdef BSD_SIGNALS
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int mask;
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#endif
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#endif
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/* Initialize */
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if (SIG_init() != 0)
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return (-1);
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val = 0;
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last = (struct SIG_hlist *) NULL;
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/* Block this signal while we look at handler chain */
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#ifdef POSIX
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(void) sigemptyset(&sigset_mask);
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(void) sigaddset(&sigset_mask, sig);
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(void) sigprocmask(SIG_BLOCK, &sigset_mask, &sigset_omask);
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#else
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#ifdef BSD_SIGNALS
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mask = sigblock(sigmask(sig));
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#endif
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#endif
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/* Search for the signal handler */
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this = SIG_handlers[sig];
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while ((this != (struct SIG_hlist *) NULL) && (this->handler != fn))
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{
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last = this;
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this = this->next;
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}
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/* If it was registered, remove it */
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if (this != (struct SIG_hlist *) NULL)
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{
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if (last == (struct SIG_hlist *) NULL)
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{
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SIG_handlers[sig] = this->next;
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}
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else
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{
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last->next = this->next;
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}
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free((char *) this);
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}
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/* Restore default behavior if there are no registered handlers */
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if (SIG_handlers[sig] == (struct SIG_hlist *) NULL)
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{
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#ifdef POSIX
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val = sigaction(sig, &SIG_defaults[sig],
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(struct sigaction *) NULL);
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#else
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#ifdef BSD_SIGNALS
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val = sigvec(sig, &SIG_defaults[sig], (struct sigvec *) NULL);
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#else
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if (signal(sig, SIG_defaults[sig]) == (SIGTYPE (*)()) -1)
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val = -1;
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#endif
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#endif
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}
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/* Unblock the signal */
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#ifdef POSIX
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(void) sigprocmask(SIG_SETMASK, &sigset_omask, NULL);
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#else
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#ifdef BSD_SIGNALS
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(void) sigsetmask(mask);
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#endif
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#endif
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return val;
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}
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/*
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* The following begins a critical section.
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*/
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void SIG_beginCrSect()
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{
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if (SIG_init() == 0)
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{
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if (SIG_crSectNest == 0)
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{
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#ifdef POSIX
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sigset_t sigset_mask;
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(void) sigfillset(&sigset_mask);
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(void) sigprocmask(SIG_SETMASK,
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&sigset_mask, &SIG_crSectMask);
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#else
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#ifdef BSD_SIGNALS
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SIG_crSectMask = sigblock(~0);
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#else
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/* TBD */
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#endif
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#endif
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}
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SIG_crSectNest++;
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}
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}
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/*
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* The following ends a critical section.
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*/
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void SIG_endCrSect()
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{
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if (SIG_init() == 0)
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{
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SIG_crSectNest--;
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if (SIG_crSectNest == 0)
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{
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#ifdef POSIX
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(void) sigprocmask(SIG_SETMASK, &SIG_crSectMask, NULL);
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#else
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#ifdef BSD_SIGNALS
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(void) sigsetmask(SIG_crSectMask);
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#else
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/* TBD */
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#endif
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#endif
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}
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}
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}
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