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Turbo C v2.0
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SSIGNAL.C
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1988-08-29
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/*-----------------------------------------------------------------------*
* filename - ssignal.c
*
* function(s)
* ssignal - implements software signals
* gsignal - implements software signals
*-----------------------------------------------------------------------*/
/*[]---------------------------------------------------[]*/
/*| |*/
/*| Turbo C Run Time Library - Version 1.5 |*/
/*| |*/
/*| |*/
/*| Copyright (c) 1987,88 by Borland International |*/
/*| All Rights Reserved. |*/
/*| |*/
/*[]---------------------------------------------------[]*/
#include <signal.h>
#pragma warn -sus
static int (*Sigtbl[16])() =
{
0,
SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL,
SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL,
SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL, SIG_DFL,
};
#pragma warn .sus
/*---------------------------------------------------------------------*
Name ssignal - implements software signals
Usage int (*ssignal(int sig, int (*action)( ))( );
Related
functions usage int gsignal(int sig);
Prototype in signal.h
Description ssignal and gsignal implement a software-signalling
facility. Software signals are associated with integers in the
range from 1 to 15.
gsignal raises the signal given by sig and executes the action
routine.
ssignal is used to establish an action routine for servicing a
signal. The first argument to ssignal, sig, is a number
identifying the type of signal for which an action is
established.
The second argument, action, defines the action; it is either
the name of a user-defined action function or one of the
constants SIG_DFL (default) or SIG_IGN (ignore). These constants
are defined in signal.h.
If an action function has been established for sig, then that
action is reset to SIG_DFL, and the action function is entered
with argument sig.
Return value ssignal returns the action previously established
or, if the signal number is illegal, returns SIG_DFL.
gsignal returns the value returned to it by the action
function. gsignal's return values for actions assigned to sig
are listed in the following:
Action Return
SIG_IGN 1
SIG_DFL 0
Illegal value or 0
no action specified
In all cases, gsignal takes no action other than returning a
value.
*---------------------------------------------------------------------*/
int (*ssignal(register int sig, int (*action)()))()
{
int (*oldact)();
#pragma warn -sus
if (sig < 1 || sig > 15)
return (SIG_DFL);
#pragma warn .sus
oldact = Sigtbl[sig];
Sigtbl[sig] = action;
return (oldact);
}
/*---------------------------------------------------------------------*
Name gsignal - implements software signals
Usage int gsignal(int sig);
Prototype in signal.h
Description see ssignal above
*---------------------------------------------------------------------*/
int gsignal(register int sig)
{
int (*action)(int);
if (sig < 1 || sig > 15)
return (0);
#pragma warn -sus
action = Sigtbl[sig];
if (action == SIG_IGN)
return (1);
if (action == SIG_DFL)
return (0);
Sigtbl[sig] = SIG_DFL;
#pragma warn .sus
return ((*action)(sig));
}