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/* Copyright (C) 1989, 2000 Aladdin Enterprises.  All rights reserved.

  This software is provided AS-IS with no warranty, either express or

  implied.

  This software is distributed under license and may not be copied,

  modified or distributed except as expressly authorized under the terms

  of the license contained in the file LICENSE in this distribution.

  For more information about licensing, please refer to

  http://www.ghostscript.com/licensing/. For information on

  commercial licensing, go to http://www.artifex.com/licensing/ or

  contact Artifex Software, Inc., 101 Lucas Valley Road #110,

  San Rafael, CA  94903, U.S.A., +1(415)492-9861.

*/

/* $Id: zcontrol.c,v 1.11 2004/08/04 19:36:13 stefan Exp $ */

/* Control operators */

#include "string_.h"

#include "ghost.h"

#include "stream.h"

#include "oper.h"

#include "estack.h"

#include "files.h"

#include "ipacked.h"

#include "iutil.h"

#include "store.h"

/* Forward references */

private int no_cleanup(i_ctx_t *);

private uint count_exec_stack(i_ctx_t *, bool);

private uint count_to_stopped(i_ctx_t *, long);

private int unmatched_exit(os_ptr, op_proc_t);

/* See the comment in opdef.h for an invariant which allows */

/* more efficient implementation of for, loop, and repeat. */

/* <[test0 body0 ...]> .cond - */

private int cond_continue(i_ctx_t *);

private int

zcond(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    es_ptr ep = esp;

    /* Push the array on the e-stack and call the continuation. */

    if (!r_is_array(op))

	return_op_typecheck(op);

    check_execute(*op);

    if ((r_size(op) & 1) != 0)

	return_error(e_rangecheck);

    if (r_size(op) == 0)

	return zpop(i_ctx_p);

    check_estack(3);

    esp = ep += 3;

    ref_assign(ep - 2, op);	/* the cond body */

    make_op_estack(ep - 1, cond_continue);

    array_get(imemory, op, 0L, ep);

    esfile_check_cache();

    pop(1);

    return o_push_estack;

}

private int

cond_continue(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    es_ptr ep = esp;

    int code;

    /* The top element of the e-stack is the remaining tail of */

    /* the cond body.  The top element of the o-stack should be */

    /* the (boolean) result of the test that is the first element */

    /* of the tail. */

    check_type(*op, t_boolean);

    if (op->value.boolval) {	/* true */

        array_get(imemory, ep, 1L, ep);

	esfile_check_cache();

	code = o_pop_estack;

    } else if (r_size(ep) > 2) {	/* false */

	const ref_packed *elts = ep->value.packed;

	check_estack(2);

	r_dec_size(ep, 2);

	elts = packed_next(elts);

	elts = packed_next(elts);

	ep->value.packed = elts;

	array_get(imemory, ep, 0L, ep + 2);

	make_op_estack(ep + 1, cond_continue);

	esp = ep + 2;

	esfile_check_cache();

	code = o_push_estack;

    } else {			/* fall off end of cond */

	esp = ep - 1;

	code = o_pop_estack;

    }

    pop(1);			/* get rid of the boolean */

    return code;

}

/* <obj> exec - */

int

zexec(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_op(1);

    if (!r_has_attr(op, a_executable))

	return 0;		/* literal object just gets pushed back */

    check_estack(1);

    ++esp;

    ref_assign(esp, op);

    esfile_check_cache();

    pop(1);

    return o_push_estack;

}

/* <obj1> ... <objn> <n> .execn - */

private int

zexecn(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    uint n, i;

    es_ptr esp_orig;

    check_int_leu(*op, max_uint - 1);

    n = (uint) op->value.intval;

    check_op(n + 1);

    check_estack(n);

    esp_orig = esp;

    for (i = 0; i < n; ++i) {

	const ref *rp = ref_stack_index(&o_stack, (long)(i + 1));

	/* Make sure this object is legal to execute. */

	if (ref_type_uses_access(r_type(rp))) {

	    if (!r_has_attr(rp, a_execute) &&

		r_has_attr(rp, a_executable)

		) {

		esp = esp_orig;

		return_error(e_invalidaccess);

	    }

	}

	/* Executable nulls have a special meaning on the e-stack, */

	/* so since they are no-ops, don't push them. */

	if (!r_has_type_attrs(rp, t_null, a_executable)) {

	    ++esp;

	    ref_assign(esp, rp);

	}

    }

    esfile_check_cache();

    pop(n + 1);

    return o_push_estack;

}

/* <obj> superexec - */

private int end_superexec(i_ctx_t *);

private int

zsuperexec(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    es_ptr ep;

    check_op(1);

    if (!r_has_attr(op, a_executable))

	return 0;		/* literal object just gets pushed back */

    check_estack(2);

    ep = esp += 3;

    make_mark_estack(ep - 2, es_other, end_superexec); /* error case */

    make_op_estack(ep - 1,  end_superexec); /* normal case */

    ref_assign(ep, op);

    esfile_check_cache();

    pop(1);

    i_ctx_p->in_superexec++;

    return o_push_estack;

}

private int

end_superexec(i_ctx_t *i_ctx_p)

{

    i_ctx_p->in_superexec--;

    return 0;

}

/* <array> <executable> .runandhide <obj>				*/

/* 	before executing  <executable>, <array> is been removed from	*/

/*	the operand stack and placed on the execstack with attributes	*/

/* 	changed to 'noaccess'.						*/

/* 	After execution, the array will be placed on  the top of the	*/

/*	operand stack (on top of any elemetns pushed by <executable>	*/

/*	for both the normal case and for the error case.		*/

private int end_runandhide(i_ctx_t *);

private int err_end_runandhide(i_ctx_t *);

private int

zrunandhide(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    es_ptr ep;

    check_op(2);

    if (!r_is_array(op - 1))

	return_op_typecheck(op);

    if (!r_has_attr(op, a_executable))

	return 0;		/* literal object just gets pushed back */

    check_estack(5);

    ep = esp += 5;

    make_mark_estack(ep - 4, es_other, err_end_runandhide); /* error case */

    make_op_estack(ep - 1,  end_runandhide); /* normal case */

    ref_assign(ep, op);

    /* Store the object we are hiding  and it's current tas.type_attrs */

    /* on the exec stack then change to 'noaccess' */

    make_int(ep - 3, (int)op[-1].tas.type_attrs);

    ref_assign(ep - 2, op - 1);

    r_clear_attrs(ep - 2, a_all);

    /* replace the array with a special kind of mark that has a_read access */

    esfile_check_cache();

    pop(2);

    return o_push_estack;

}

private int

runandhide_restore_hidden(i_ctx_t *i_ctx_p, ref *obj, ref *attrs)

{

    os_ptr op = osp;

    push(1);

    /* restore the hidden_object and its type_attrs */

    ref_assign(op, obj);

    r_clear_attrs(op, a_all);

    r_set_attrs(op, attrs->value.intval);

    return 0;

}

/* - %end_runandhide hiddenobject */

private int

end_runandhide(i_ctx_t *i_ctx_p)

{

    int code;

    if ((code = runandhide_restore_hidden(i_ctx_p, esp, esp - 1)) < 0)

        return code;

    esp -= 2;		/* pop the hidden value and its atributes */

    return o_pop_estack;

}

/* restore hidden object for error returns */

private int

err_end_runandhide(i_ctx_t *i_ctx_p)

{

    int code;

    if ((code = runandhide_restore_hidden(i_ctx_p, esp + 3, esp + 2)) < 0)

        return code;

    return 0;

}

/* <bool> <proc> if - */

int

zif(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_type(op[-1], t_boolean);

    check_proc(*op);

    if (op[-1].value.boolval) {

	check_estack(1);

	++esp;

	ref_assign(esp, op);

	esfile_check_cache();

    }

    pop(2);

    return o_push_estack;

}

/* <bool> <proc_true> <proc_false> ifelse - */

int

zifelse(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_type(op[-2], t_boolean);

    check_proc(op[-1]);

    check_proc(*op);

    check_estack(1);

    ++esp;

    if (op[-2].value.boolval) {

	ref_assign(esp, op - 1);

    } else {

	ref_assign(esp, op);

    }

    esfile_check_cache();

    pop(3);

    return o_push_estack;

}

/* <init> <step> <limit> <proc> for - */

private int

    for_pos_int_continue(i_ctx_t *),

    for_neg_int_continue(i_ctx_t *),

    for_real_continue(i_ctx_t *);

int

zfor(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    register es_ptr ep;

    check_estack(7);

    ep = esp + 6;

    check_proc(*op);

    /* Push a mark, the control variable set to the initial value, */

    /* the increment, the limit, and the procedure, */

    /* and invoke the continuation operator. */

    if (r_has_type(op - 3, t_integer) &&

	r_has_type(op - 2, t_integer)

	) {

	make_int(ep - 4, op[-3].value.intval);

	make_int(ep - 3, op[-2].value.intval);

	switch (r_type(op - 1)) {

	    case t_integer:

		make_int(ep - 2, op[-1].value.intval);

		break;

	    case t_real:

		make_int(ep - 2, (long)op[-1].value.realval);

		break;

	    default:

		return_op_typecheck(op - 1);

	}

	if (ep[-3].value.intval >= 0)

	    make_op_estack(ep, for_pos_int_continue);

	else

	    make_op_estack(ep, for_neg_int_continue);

    } else {

	float params[3];

	int code;

	if ((code = float_params(op - 1, 3, params)) < 0)

	    return code;

	make_real(ep - 4, params[0]);

	make_real(ep - 3, params[1]);

	make_real(ep - 2, params[2]);

	make_op_estack(ep, for_real_continue);

    }

    make_mark_estack(ep - 5, es_for, no_cleanup);

    ref_assign(ep - 1, op);

    esp = ep;

    pop(4);

    return o_push_estack;

}

/* Continuation operators for for, separate for positive integer, */

/* negative integer, and real. */

/* Execution stack contains mark, control variable, increment, */

/* limit, and procedure (procedure is topmost.) */

/* Continuation operator for positive integers. */

private int

for_pos_int_continue(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    register es_ptr ep = esp;

    long var = ep[-3].value.intval;

    if (var > ep[-1].value.intval) {

	esp -= 5;		/* pop everything */

	return o_pop_estack;

    }

    push(1);

    make_int(op, var);

    ep[-3].value.intval = var + ep[-2].value.intval;

    ref_assign_inline(ep + 2, ep);	/* saved proc */

    esp = ep + 2;

    return o_push_estack;

}

/* Continuation operator for negative integers. */

private int

for_neg_int_continue(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    register es_ptr ep = esp;

    long var = ep[-3].value.intval;

    if (var < ep[-1].value.intval) {

	esp -= 5;		/* pop everything */

	return o_pop_estack;

    }

    push(1);

    make_int(op, var);

    ep[-3].value.intval = var + ep[-2].value.intval;

    ref_assign(ep + 2, ep);	/* saved proc */

    esp = ep + 2;

    return o_push_estack;

}

/* Continuation operator for reals. */

private int

for_real_continue(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    es_ptr ep = esp;

    float var = ep[-3].value.realval;

    float incr = ep[-2].value.realval;

    if (incr >= 0 ? (var > ep[-1].value.realval) :

	(var < ep[-1].value.realval)

	) {

	esp -= 5;		/* pop everything */

	return o_pop_estack;

    }

    push(1);

    ref_assign(op, ep - 3);

    ep[-3].value.realval = var + incr;

    esp = ep + 2;

    ref_assign(ep + 2, ep);	/* saved proc */

    return o_push_estack;

}

/*

 * Here we provide an internal variant of 'for' that enumerates the values

 * A, ((N-1)*A+1*B)/N, ((N-2)*A+2*B)/N, ..., B precisely.  The arguments are

 * A (real), N (integer), and B (real).  We need this for loading caches such

 * as the transfer function cache.

 *

 * NOTE: This computation must match the SAMPLE_LOOP_VALUE macro in gscie.h.

 */

private int for_samples_continue(i_ctx_t *);

/* <first> <count> <last> <proc> %for_samples - */

int

zfor_samples(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    es_ptr ep;

    check_type(op[-3], t_real);

    check_type(op[-2], t_integer);

    check_type(op[-1], t_real);

    check_proc(*op);

    check_estack(8);

    ep = esp + 7;

    make_mark_estack(ep - 6, es_for, no_cleanup);

    make_int(ep - 5, 0);

    memcpy(ep - 4, op - 3, 3 * sizeof(ref));

    ref_assign(ep - 1, op);

    make_op_estack(ep, for_samples_continue);

    esp = ep;

    pop(4);

    return o_push_estack;

}

/* Continuation procedure */

private int

for_samples_continue(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    es_ptr ep = esp;

    long var = ep[-4].value.intval;

    float a = ep[-3].value.realval;

    long n = ep[-2].value.intval;

    float b = ep[-1].value.realval;

    if (var > n) {

	esp -= 6;		/* pop everything */

	return o_pop_estack;

    }

    push(1);

    make_real(op, ((n - var) * a + var * b) / n);

    ep[-4].value.intval = var + 1;

    ref_assign_inline(ep + 2, ep);	/* saved proc */

    esp = ep + 2;

    return o_push_estack;

}

/* <int> <proc> repeat - */

private int repeat_continue(i_ctx_t *);

private int

zrepeat(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_type(op[-1], t_integer);

    check_proc(*op);

    if (op[-1].value.intval < 0)

	return_error(e_rangecheck);

    check_estack(5);

    /* Push a mark, the count, and the procedure, and invoke */

    /* the continuation operator. */

    push_mark_estack(es_for, no_cleanup);

    *++esp = op[-1];

    *++esp = *op;

    make_op_estack(esp + 1, repeat_continue);

    pop(2);

    return repeat_continue(i_ctx_p);

}

/* Continuation operator for repeat */

private int

repeat_continue(i_ctx_t *i_ctx_p)

{

    es_ptr ep = esp;		/* saved proc */

    if (--(ep[-1].value.intval) >= 0) {		/* continue */

	esp += 2;

	ref_assign(esp, ep);

	return o_push_estack;

    } else {			/* done */

	esp -= 3;		/* pop mark, count, proc */

	return o_pop_estack;

    }

}

/* <proc> loop */

private int loop_continue(i_ctx_t *);

private int

zloop(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_proc(*op);

    check_estack(4);

    /* Push a mark and the procedure, and invoke */

    /* the continuation operator. */

    push_mark_estack(es_for, no_cleanup);

    *++esp = *op;

    make_op_estack(esp + 1, loop_continue);

    pop(1);

    return loop_continue(i_ctx_p);

}

/* Continuation operator for loop */

private int

loop_continue(i_ctx_t *i_ctx_p)

{

    register es_ptr ep = esp;	/* saved proc */

    ref_assign(ep + 2, ep);

    esp = ep + 2;

    return o_push_estack;

}

/* - exit - */

private int

zexit(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    ref_stack_enum_t rsenum;

    uint scanned = 0;

    ref_stack_enum_begin(&rsenum, &e_stack);

    do {

	uint used = rsenum.size;

	es_ptr ep = rsenum.ptr + used - 1;

	uint count = used;

	for (; count; count--, ep--)

	    if (r_is_estack_mark(ep))

		switch (estack_mark_index(ep)) {

		    case es_for:

			pop_estack(i_ctx_p, scanned + (used - count + 1));

			return o_pop_estack;

		    case es_stopped:

			return_error(e_invalidexit);	/* not a loop */

		}

	scanned += used;

    } while (ref_stack_enum_next(&rsenum));

    /* No mark, quit.  (per Adobe documentation) */

    push(2);

    return unmatched_exit(op, zexit);

}

/*

 * .stopped pushes the following on the e-stack:

 *      - A mark with type = es_stopped and procedure = no_cleanup.

 *      - The result to be pushed on a normal return.

 *      - The signal mask for .stop.

 *      - The procedure %stopped_push, to handle the normal return case.

 */

/* In the normal (no-error) case, pop the mask from the e-stack, */

/* and move the result to the o-stack. */

private int

stopped_push(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    push(1);

    *op = esp[-1];

    esp -= 3;

    return o_pop_estack;

}

/* - stop - */

/* Equivalent to true 1 .stop. */

/* This is implemented in C because if were a pseudo-operator, */

/* the stacks would get restored in case of an error. */

private int

zstop(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    uint count = count_to_stopped(i_ctx_p, 1L);

    if (count) {

	/*

	 * If there are any t_oparrays on the e-stack, they will pop

	 * any new items from the o-stack.  Wait to push the 'true'

	 * until we have run all the unwind procedures.

	 */

	check_ostack(2);

	pop_estack(i_ctx_p, count);

	op = osp;

	push(1);

	make_true(op);

	return o_pop_estack;

    }

    /* No mark, quit.  (per Adobe documentation) */

    push(2);

    return unmatched_exit(op, zstop);

}

/* <result> <mask> .stop - */

private int

zzstop(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    uint count;

    check_type(*op, t_integer);

    count = count_to_stopped(i_ctx_p, op->value.intval);

    if (count) {

	/*

	 * If there are any t_oparrays on the e-stack, they will pop

	 * any new items from the o-stack.  Wait to push the result

	 * until we have run all the unwind procedures.

	 */

	ref save_result;

	check_op(2);

	save_result = op[-1];

	pop(2);

	pop_estack(i_ctx_p, count);

	op = osp;

	push(1);

	*op = save_result;

	return o_pop_estack;

    }

    /* No mark, quit.  (per Adobe documentation) */

    return unmatched_exit(op, zzstop);

}

/* <obj> stopped <stopped> */

/* Equivalent to false 1 .stopped. */

/* This is implemented in C because if were a pseudo-operator, */

/* the stacks would get restored in case of an error. */

private int

zstopped(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_op(1);

    /* Mark the execution stack, and push the default result */

    /* in case control returns normally. */

    check_estack(5);

    push_mark_estack(es_stopped, no_cleanup);

    ++esp;

    make_false(esp);		/* save the result */

    ++esp;

    make_int(esp, 1);		/* save the signal mask */

    push_op_estack(stopped_push);

    *++esp = *op;		/* execute the operand */

    esfile_check_cache();

    pop(1);

    return o_push_estack;

}

/* <obj> <result> <mask> .stopped <result> */

private int

zzstopped(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_type(*op, t_integer);

    check_op(3);

    /* Mark the execution stack, and push the default result */

    /* in case control returns normally. */

    check_estack(5);

    push_mark_estack(es_stopped, no_cleanup);

    *++esp = op[-1];		/* save the result */

    *++esp = *op;		/* save the signal mask */

    push_op_estack(stopped_push);

    *++esp = op[-2];		/* execute the operand */

    esfile_check_cache();

    pop(3);

    return o_push_estack;

}

/* <mask> .instopped false */

/* <mask> .instopped <result> true */

private int

zinstopped(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    uint count;

    check_type(*op, t_integer);

    count = count_to_stopped(i_ctx_p, op->value.intval);

    if (count) {

	push(1);

	op[-1] = *ref_stack_index(&e_stack, count - 2);		/* default result */

	make_true(op);

    } else

	make_false(op);

    return 0;

}

/* <include_marks> .countexecstack <int> */

/* - countexecstack <int> */

/* countexecstack is an operator solely for the sake of the Genoa tests. */

private int

zcountexecstack(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    push(1);

    make_int(op, count_exec_stack(i_ctx_p, false));

    return 0;

}

private int

zcountexecstack1(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_type(*op, t_boolean);

    make_int(op, count_exec_stack(i_ctx_p, op->value.boolval));

    return 0;

}

/* <array> <include_marks> .execstack <subarray> */

/* <array> execstack <subarray> */

/* execstack is an operator solely for the sake of the Genoa tests. */

private int execstack_continue(i_ctx_t *);

private int execstack2_continue(i_ctx_t *);

private int

push_execstack(i_ctx_t *i_ctx_p, os_ptr op1, bool include_marks,

	       op_proc_t cont)

{

    uint size;

    /*

     * We can't do this directly, because the interpreter

     * might have cached some state.  To force the interpreter

     * to update the stored state, we push a continuation on

     * the exec stack; the continuation is executed immediately,

     * and does the actual transfer.

     */

    uint depth;

    check_write_type(*op1, t_array);

    size = r_size(op1);

    depth = count_exec_stack(i_ctx_p, include_marks);

    if (depth > size)

	return_error(e_rangecheck);

    {

	int code = ref_stack_store_check(&e_stack, op1, size, 0);

	if (code < 0)

	    return code;

    }

    check_estack(1);

    r_set_size(op1, depth);

    push_op_estack(cont);

    return o_push_estack;

}

private int

zexecstack(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    return push_execstack(i_ctx_p, op, false, execstack_continue);

}

private int

zexecstack2(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_type(*op, t_boolean);

    return push_execstack(i_ctx_p, op - 1, op->value.boolval, execstack2_continue);

}

/* Continuation operator to do the actual transfer. */

/* r_size(op1) was set just above. */

private int

do_execstack(i_ctx_t *i_ctx_p, bool include_marks, os_ptr op1)

{

    os_ptr op = osp;

    ref *arefs = op1->value.refs;

    uint asize = r_size(op1);

    uint i;

    ref *rq;

    /*

     * Copy elements from the stack to the array,

     * optionally skipping executable nulls.

     * Clear the executable bit in any internal operators, and

     * convert t_structs and t_astructs (which can only appear

     * in connection with stack marks, which means that they will

     * probably be freed when unwinding) to something harmless.

     */

    for (i = 0, rq = arefs + asize; rq != arefs; ++i) {

	const ref *rp = ref_stack_index(&e_stack, (long)i);

	if (r_has_type_attrs(rp, t_null, a_executable) && !include_marks)

	    continue;

	--rq;

	ref_assign_old(op1, rq, rp, "execstack");

	switch (r_type(rq)) {

	    case t_operator: {

		uint opidx = op_index(rq);

		if (opidx == 0 || op_def_is_internal(op_index_def(opidx)))

		    r_clear_attrs(rq, a_executable);

		break;

	    }

	    case t_struct:

	    case t_astruct: {

		const char *tname =

		    gs_struct_type_name_string(

				gs_object_type(imemory, rq->value.pstruct));

		make_const_string(rq, a_readonly | avm_foreign,

				  strlen(tname), (const byte *)tname);

		break;

	    }

	    default:

		;

	}

    }

    pop(op - op1);

    return 0;

}

private int

execstack_continue(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    return do_execstack(i_ctx_p, false, op);

}

private int

execstack2_continue(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    return do_execstack(i_ctx_p, op->value.boolval, op - 1);

}

/* - .needinput - */

private int

zneedinput(i_ctx_t *i_ctx_p)

{

    return e_NeedInput;		/* interpreter will exit to caller */

}

/* <obj> <int> .quit - */

private int

zquit(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    check_op(2);

    check_type(*op, t_integer);

    return_error(e_Quit);	/* Interpreter will do the exit */

}

/* - currentfile <file> */

private ref *zget_current_file(i_ctx_t *);

private int

zcurrentfile(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    ref *fp;

    push(1);

    /* Check the cache first */

    if (esfile != 0) {

#ifdef DEBUG

	/* Check that esfile is valid. */

	ref *efp = zget_current_file(i_ctx_p);

	if (esfile != efp) {

	    lprintf2("currentfile: esfile=0x%lx, efp=0x%lx\n",

		     (ulong) esfile, (ulong) efp);

	    ref_assign(op, efp);

	} else

#endif

	    ref_assign(op, esfile);

    } else if ((fp = zget_current_file(i_ctx_p)) == 0) {	/* Return an invalid file object. */

	/* This doesn't make a lot of sense to me, */