127 lines
3.7 KiB
C++
127 lines
3.7 KiB
C++
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/*-----------------------------------------------------------------------*
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* filename - ssignal.c
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*
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* function(s)
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* ssignal - implements software signals
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* gsignal - implements software signals
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*-----------------------------------------------------------------------*/
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/*[]---------------------------------------------------[]*/
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/*| |*/
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/*| Turbo C Run Time Library - Version 1.5 |*/
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/*| |*/
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/*| |*/
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/*| Copyright (c) 1987,88 by Borland International |*/
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/*| All Rights Reserved. |*/
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/*| |*/
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/*[]---------------------------------------------------[]*/
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#include <signal.h>
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#pragma warn -sus
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static int (*Sigtbl[16])() =
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{
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0,
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SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL,
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SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL,
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SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL,
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};
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#pragma warn .sus
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/*---------------------------------------------------------------------*
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Name ssignal - implements software signals
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Usage int (*ssignal(int sig, int (*action)( ))( );
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Related
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functions usage int gsignal(int sig);
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Prototype in signal.h
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Description ssignal and gsignal implement a software-signalling
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facility. Software signals are associated with integers in the
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range from 1 to 15.
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gsignal raises the signal given by sig and executes the action
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routine.
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ssignal is used to establish an action routine for servicing a
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signal. The first argument to ssignal, sig, is a number
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identifying the type of signal for which an action is
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established.
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The second argument, action, defines the action; it is either
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the name of a user-defined action function or one of the
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constants SIG_DFL (default) or SIG_IGN (ignore). These constants
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are defined in signal.h.
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If an action function has been established for sig, then that
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action is reset to SIG_DFL, and the action function is entered
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with argument sig.
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Return value ssignal returns the action previously established
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or, if the signal number is illegal, returns SIG_DFL.
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gsignal returns the value returned to it by the action
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function. gsignal's return values for actions assigned to sig
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are listed in the following:
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Action Return
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SIG_IGN 1
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SIG_DFL 0
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Illegal value or 0
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no action specified
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In all cases, gsignal takes no action other than returning a
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value.
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*---------------------------------------------------------------------*/
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int (*ssignal(register int sig, int (*action)()))()
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{
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int (*oldact)();
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#pragma warn -sus
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if (sig < 1 || sig > 15)
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return (SIG_DFL);
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#pragma warn .sus
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oldact = Sigtbl[sig];
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Sigtbl[sig] = action;
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return (oldact);
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}
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/*---------------------------------------------------------------------*
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Name gsignal - implements software signals
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Usage int gsignal(int sig);
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Prototype in signal.h
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Description see ssignal above
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*---------------------------------------------------------------------*/
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int gsignal(register int sig)
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{
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int (*action)(int);
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if (sig < 1 || sig > 15)
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return (0);
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#pragma warn -sus
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action = Sigtbl[sig];
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if (action == SIG_IGN)
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return (1);
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if (action == SIG_DFL)
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return (0);
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Sigtbl[sig] = SIG_DFL;
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#pragma warn .sus
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return ((*action)(sig));
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}
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