usr/src/usr.lib/libF77/signal_.c

/*
 *      "@(#)signal_.c  1.1"
 *
 * change the action for a specified signal
 *
 * calling sequence:
 *      integer cursig, signal, savsig
 *      external proc
 *      cursig = signal(signum, proc, flag)
 * where:
 *      'cursig' will receive the current value of signal(2)
 *      'signum' must be in the range 0 <= signum <= 16
 *
 *      If 'flag' is negative, 'proc' must be an external proceedure name.
 *
 *      If 'flag' is 0 or positive, it will be passed to signal(2) as the
 *      signal action flag. 0 resets the default action; 1 sets 'ignore'.
 *      'flag' may be the value returned from a previous call to signal.
 *
 * This routine arranges to trap user specified signals so that it can
 * pass the signum fortran style - by address. (boo)
 */

#include        "../libI77/f_errno.h"

static int (*dispatch[17])();
int (*signal())();
int sig_trap();

long signal_(sigp, procp, flag)
long *sigp, *flag;
int (*procp)();
{
        int (*oldsig)();
        int (*oldispatch)();

        oldispatch = dispatch[*sigp];

        if (*sigp < 0 || *sigp > 16)
                return(-((long)(errno=F_ERARG)));

        if (*flag < 0)  /* function address passed */
        {
                dispatch[*sigp] = procp;
                oldsig = signal((int)*sigp, sig_trap);
        }

        else            /* integer value passed */
                oldsig = signal((int)*sigp, (int)*flag);

        if (oldsig == sig_trap)
                return((long)oldispatch);
        return((long)oldsig);
}

sig_trap(sn)
int sn;
{
        long lsn = (long)sn;
        return((*dispatch[sn])(&lsn));
}