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Annotation of 42BSD/usr.lib/libF77/signal_.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  *     "@(#)signal_.c  1.1"
                      3:  *
                      4:  * change the action for a specified signal
                      5:  *
                      6:  * calling sequence:
                      7:  *     integer cursig, signal, savsig
                      8:  *     external proc
                      9:  *     cursig = signal(signum, proc, flag)
                     10:  * where:
                     11:  *     'cursig' will receive the current value of signal(2)
                     12:  *     'signum' must be in the range 0 <= signum <= 16
                     13:  *
                     14:  *     If 'flag' is negative, 'proc' must be an external proceedure name.
                     15:  *     
                     16:  *     If 'flag' is 0 or positive, it will be passed to signal(2) as the
                     17:  *     signal action flag. 0 resets the default action; 1 sets 'ignore'.
                     18:  *     'flag' may be the value returned from a previous call to signal.
                     19:  *
                     20:  * This routine arranges to trap user specified signals so that it can
                     21:  * pass the signum fortran style - by address. (boo)
                     22:  */
                     23: 
                     24: #include       "../libI77/f_errno.h"
                     25: 
                     26: static int (*dispatch[17])();
                     27: int (*signal())();
                     28: int sig_trap();
                     29: 
                     30: long signal_(sigp, procp, flag)
                     31: long *sigp, *flag;
                     32: int (*procp)();
                     33: {
                     34:        int (*oldsig)();
                     35:        int (*oldispatch)();
                     36: 
                     37:        oldispatch = dispatch[*sigp];
                     38: 
                     39:        if (*sigp < 0 || *sigp > 16)
                     40:                return(-((long)(errno=F_ERARG)));
                     41: 
                     42:        if (*flag < 0)  /* function address passed */
                     43:        {
                     44:                dispatch[*sigp] = procp;
                     45:                oldsig = signal((int)*sigp, sig_trap);
                     46:        }
                     47: 
                     48:        else            /* integer value passed */
                     49:                oldsig = signal((int)*sigp, (int)*flag);
                     50: 
                     51:        if (oldsig == sig_trap)
                     52:                return((long)oldispatch);
                     53:        return((long)oldsig);
                     54: }
                     55: 
                     56: sig_trap(sn)
                     57: int sn;
                     58: {
                     59:        long lsn = (long)sn;
                     60:        return((*dispatch[sn])(&lsn));
                     61: }

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