Bug#4232: bison dumps core

[Thomas Koenig <ig25@mvmampc66.ciw.uni-karlsruhe.de>]

Package: bison
Version: A2.6-12

The following input file (which contains errors, I know :-) causes
bison to dump core.

I have no idea wether this is a libc or a bison error.  Gdb tells me
the following:

$ gdb /usr/bin/bison core
GDB is free software and you are welcome to distribute copies of it
 under certain conditions; type "show copying" to see the conditions.
There is absolutely no warranty for GDB; type "show warranty" for details.
GDB 4.15.1 (i486-linux), Copyright 1995 Free Software Foundation, Inc...
(no debugging symbols found)...
Core was generated by `bison crash.y'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /lib/libc.so.5.2.18...(no debugging symbols found)...done.
Reading symbols from /lib/ld-linux.so.1...(no debugging symbols found)...done.
#0  0x4003c567 in malloc ()

Here's the input file (called crash.y):

%{
#include <time.h>


#define YYDEBUG 1

time_t currtime;
struct tm currtm;
struct tm exectm;

%}

%union {
	struct tm	tmstruct;
	time_t		timet;
	int	  	intval;
}

%token INT
%token NOW
%token TIMEZONE_NAME
%token AM PM
%token NOON MIDNIGHT TEATIME
%token SUN MON TUE WED THU FRI SAT
%token TODAY TOMORROW
%token NEXT
%token MINUTE HOUR DAY WEEK MONTH YEAR
%token JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
%token WORD

%type <intval> inc_period

%start timespec
%%
timespec        : time
                | time date
                | time increment
                | time date increment
		| time decrement
		| time date decrement
                | nowspec
                ;

nowspec         : now
                | now increment
		| now decrement
                ;

now:		: NOW
		;

time            : hr24clock_hr_min
                | hr24clock_hr_min timezone_name
                | hr24clock_hour time_sep minute
                | hr24clock_hour time_sep minute timezone_name
                | hr24clock_hour am_pm
                | hr24clock_hour am_pm timezone_name
                | hr24clock_hour time_sep minute am_pm
                | hr24clock_hour time_sep minute am_pm timezone_name
                | NOON
                | MIDNIGHT
		| TEATIME

                ;

date            : month_name day_number
                | month_name day_number ',' year_number
                | day_of_week
                | TODAY
                | TOMORROW
                ;

increment       : '+' inc_number inc_period
		    {
			switch($3) {
			case MINUTE:
			    exectm.tm_min
			    break;
			default:
			    yyerror("Internal parser error");
			    YYERROR;
			}
		    }
                | NEXT inc_period
                ;

decrement	: '-' inc_number inc_period
		;

inc_period      : MINUTE { $$ = MINUTE ; }
                | HOUR	 { $$ = HOUR ; }
                | DAY	 { $$ = DAY ; }
                | WEEK   { $$ = WEEK ; }
                | MONTH  { $$ = MONTH ; }
                | YEAR   { $$ = YEAR ; }
                ;

hr24clock_hr_min: INT
		;

timezone_name	: TIMEZONE_NAME
		;

hr24clock_hour	: INT
		;

minute		: INT
		;

am_pm		: AM
		| PM
		;


month_name	: JAN
		| FEB
		| MAR
		| APR
		| MAY
		| JUN
		| JUL
		| AUG
		| SEP
		| OCT
		| NOV
		| DEC
		;

day_number	: INT
		;

year_number	: INT
		;


day_of_week	: SUN
		| MON
		| TUE
		| WED
		| THU
		| FRI
		| SAT
		;

inc_number	: INT
		;

time_sep	: ':'
		| '\''
		| '.'
		| 'h'
		| ','
		;

%%

#include "mydate.h"

time_t parsetime(int, char **);

int
main(int argc, char **argv)
{
#ifdef YYDEBUG
	yydebug = 1;
#endif
	currtime = time(NULL);
	currtm = *localtime(&currtime);
	yyparse();
}

int yyerror(char *s)
{
    fprintf(stderr,"%s. Last token seen: %s\n",s, last_token);
    return 0;
}