source: trunk/minix/lib/ack/libm2/Traps.mod@ 20

(*
  (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
  See the copyright notice in the ACK home directory, in the file "Copyright".
*)

(*$R-*)
IMPLEMENTATION MODULE Traps;
(*
  Module:       Facility for handling traps
  Author:       Ceriel J.H. Jacobs
  Version:      $Header: /cvsup/minix/src/lib/ack/libm2/Traps.mod,v 1.1 2005/10/10 15:27:46 beng Exp $
*)

  FROM  EM IMPORT       SIG, LINO, FILN, TRP;
  FROM  Unix IMPORT     write;
  FROM  SYSTEM IMPORT   ADDRESS, ADR;
  FROM  Arguments IMPORT
                        Argv;

  PROCEDURE InstallTrapHandler(t: TrapHandler): TrapHandler;
  (* Install a new trap handler, and return the previous one.
     Parameter of trap handler is the trap number.
  *)
  BEGIN
        RETURN SIG(t);
  END InstallTrapHandler;

  PROCEDURE Message(str: ARRAY OF CHAR);
  (* Write message "str" on standard error, preceeded by filename and
     linenumber if possible
  *)
  VAR   p: POINTER TO CHAR;
        l: CARDINAL;
        lino: INTEGER;
        buf, buf2: ARRAY [0..255] OF CHAR;
        i, j: CARDINAL;
  BEGIN
        p := FILN();
        IF p # NIL THEN
                i := 1;
                buf[0] := '"';
                WHILE p^ # 0C DO
                        buf[i] := p^;
                        INC(i);
                        p := ADDRESS(p) + 1;
                END;
                buf[i] := '"';
                INC(i);
                IF write(2, ADR(buf), i) < 0 THEN END;
        ELSE
                l := Argv(0, buf);
                IF write(2, ADR(buf), l-1) < 0 THEN END;
        END;
        lino := LINO();
        i := 0;
        IF lino # 0 THEN
                i := 7;
                buf[0] := ','; buf[1] := ' ';
                buf[2] := 'l'; buf[3] := 'i'; buf[4] := 'n'; buf[5] := 'e';
                buf[6] := ' ';
                IF lino < 0 THEN
                        buf[7] := '-';
                        i := 8;
                        lino := - lino;
                END;
                j := 0;
                REPEAT
                        buf2[j] := CHR(CARDINAL(lino) MOD 10 + ORD('0'));
                        lino := lino DIV 10;
                        INC(j);
                UNTIL lino = 0;
                WHILE j > 0 DO
                        DEC(j);
                        buf[i] := buf2[j];
                        INC(i);
                END;
        END;
        buf[i] := ':';
        buf[i+1] := ' ';
        IF write(2, ADR(buf), i+2) < 0 THEN END;
        i := 0;
        WHILE (i <= HIGH(str)) AND (str[i] # 0C) DO
                INC(i);
        END;
        IF write(2, ADR(str), i) < 0 THEN END;
        buf[0] := 12C;
        IF write(2, ADR(buf), 1) < 0 THEN END;
  END Message;

  PROCEDURE Trap(n: INTEGER);
  (* cause trap number "n" to occur *)
  BEGIN
        TRP(n);
  END Trap;

END Traps.