Objects/accessobject.c

/***********************************************************
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

                        All Rights Reserved

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******************************************************************/

#ifdef SUPPORT_OBSOLETE_ACCESS /* This object type is no longer supported */

/* Access object implementation */

/* XXX TO DO LIST
   - __init__ and __del__ (and all other similar methods)
     should be usable even when private, not ignored
*/

#include "allobjects.h"
#include "ceval.h"
#include "structmember.h"
#include "modsupport.h"		/* For getargs() etc. */

typedef struct {
	OB_HEAD
	object		*ac_value;
	object		*ac_owner;
	typeobject	*ac_type;
	int		ac_mode;
} accessobject;

/* Forward */
static int typecheck PROTO((object *, typeobject *));
static int ownercheck PROTO((object *, object *, int, int));

object *
newaccessobject(value, owner, type, mode)
	object *value;
	object *owner;
	typeobject *type;
	int mode;
{
	accessobject *ap;
	if (!typecheck(value, type)) {
		err_setstr(AccessError,
		"access: initial value has inappropriate type");
		return NULL;
	}
	ap = NEWOBJ(accessobject, &Accesstype);
	if (ap == NULL)
		return NULL;
	XINCREF(value);
	ap->ac_value = value;
	XINCREF(owner);
	ap->ac_owner = owner;
	XINCREF(type);
	ap->ac_type = (typeobject *)type;
	ap->ac_mode = mode;
	return (object *)ap;
}

object *
cloneaccessobject(op)
	object *op;
{
	register accessobject *ap;
	if (!is_accessobject(op)) {
		err_badcall();
		return NULL;
	}
	ap = (accessobject *)op;
	return newaccessobject(ap->ac_value, ap->ac_owner,
			       ap->ac_type, ap->ac_mode);
}

void
setaccessowner(op, owner)
	object *op;
	object *owner;
{
	register accessobject *ap;
	if (!is_accessobject(op))
		return; /* XXX no error */
	ap = (accessobject *)op;
	XDECREF(ap->ac_owner);
	XINCREF(owner);
	ap->ac_owner = owner;
}

int
hasaccessvalue(op)
	object *op;
{	
	if (!is_accessobject(op))
		return 0;
	return ((accessobject *)op)->ac_value != NULL;
}

object *
getaccessvalue(op, caller)
	object *op;
	object *caller;
{
	register accessobject *ap;
	if (!is_accessobject(op)) {
		err_badcall();
		return NULL;
	}
	ap = (accessobject *)op;
	
	if (!ownercheck(caller, ap->ac_owner, AC_R, ap->ac_mode)) {
		err_setstr(AccessError, "read access denied");
		return NULL;
	}
	
	if (ap->ac_value == NULL) {
		err_setstr(AccessError, "no current value");
		return NULL;
	}
	INCREF(ap->ac_value);
	return ap->ac_value;
}

int
setaccessvalue(op, caller, value)
	object *op;
	object *caller;
	object *value;
{
	register accessobject *ap;
	if (!is_accessobject(op)) {
		err_badcall();
		return -1;
	}
	ap = (accessobject *)op;
	
	if (!ownercheck(caller, ap->ac_owner, AC_W, ap->ac_mode)) {
		err_setstr(AccessError, "write access denied");
		return -1;
	}
	
	if (!typecheck(value, ap->ac_type)) {
		err_setstr(AccessError, "assign value of inappropriate type");
		return -1;
	}
	
	if (value == NULL) { /* Delete it */
		if (ap->ac_value == NULL) {
			err_setstr(AccessError, "no current value");
			return -1;
		}
		DECREF(ap->ac_value);
		ap->ac_value = NULL;
		return 0;
	}
	XDECREF(ap->ac_value);
	INCREF(value);
	ap->ac_value = value;
	return 0;
}

static int
typecheck(value, type)
	object *value;
	typeobject *type;
{
	object *x;
	if (value == NULL || type == NULL)
		return 1; /* No check */
	if (value->ob_type == type)
		return 1; /* Exact match */
	if (type == &Anynumbertype) {
		if (value->ob_type->tp_as_number == NULL)
			return 0;
		if (!is_instanceobject(value))
			return 1;
		/* For instances, make sure it really looks like a number */
		x = getattr(value, "__sub__");
		if (x == NULL) {
			err_clear();
			return 0;
		}
		DECREF(x);
		return 1;
	}
	if (type == &Anysequencetype) {
		if (value->ob_type->tp_as_sequence == NULL)
			return 0;
		if (!is_instanceobject(value))
			return 1;
		/* For instances, make sure it really looks like a sequence */
		x = getattr(value, "__getslice__");
		if (x == NULL) {
			err_clear();
			return 0;
		}
		DECREF(x);
		return 1;
	}
	if (type == &Anymappingtype) {
		if (value->ob_type->tp_as_mapping == NULL)
			return 0;
		if (!is_instanceobject(value))
			return 1;
		/* For instances, make sure it really looks like a mapping */
		x = getattr(value, "__getitem__");
		if (x == NULL) {
			err_clear();
			return 0;
		}
		DECREF(x);
		return 1;
	}
	return 0;
}

static int
isprivileged(caller)
	object *caller;
{
	object *g;
	static char privileged[] = "__privileged__";
	if (caller != NULL && hasattr(caller, privileged))
		return 1;
	g = getglobals();
	if (g != NULL && dictlookup(g, privileged))
		return 1;
	return 0;
}

static int
ownercheck(caller, owner, access, mode)
	object *caller;
	object *owner;
	int access;
	int mode;
{
	int mask = AC_PUBLIC;
	if (caller == owner || isprivileged(caller))
		mask |= AC_PRIVATE | AC_PROTECTED;
	else if (caller != NULL && owner != NULL &&
		 is_classobject(owner) && is_classobject(caller) &&
		 (issubclass(caller, owner) ||
		  issubclass(owner, caller)))
			mask |= AC_PROTECTED;
	return access & mode & mask;
}

/* Access methods */

static void
access_dealloc(ap)
	accessobject *ap;
{
	XDECREF(ap->ac_value);
	XDECREF(ap->ac_owner);
	XDECREF(ap->ac_type);
	DEL(ap);
}

#define OFF(x) offsetof(accessobject, x)

static struct memberlist access_memberlist[] = {
	{"ac_value",	T_OBJECT,	OFF(ac_value)},
	{"ac_owner",	T_OBJECT,	OFF(ac_owner)},
	{"ac_type",	T_OBJECT,	OFF(ac_type)},
	{"ac_mode",	T_INT,		OFF(ac_mode)},
	{NULL}	/* Sentinel */
};

static object *
access_getattr(ap, name)
	accessobject *ap;
	char *name;
{
	return getmember((char *)ap, access_memberlist, name);
}

static object *
access_repr(ap)
	accessobject *ap;
{
	char buf[300];
	char buf2[20];
	char *ownername;
	typeobject *type = ap->ac_type;
	if (is_classobject(ap->ac_owner)) {
		ownername =
			getstringvalue(((classobject *)ap->ac_owner)->cl_name);
	}
	else {
		sprintf(buf2, "0x%lx", (long)ap->ac_owner);
		ownername = buf2;
	}
	sprintf(buf,
	"<access object, value 0x%lx, owner %.100s, type %.100s, mode %04o>",
		(long)(ap->ac_value),
		ownername,
		type ? type->tp_name : "-",
		ap->ac_mode);
	return newstringobject(buf);
}

typeobject Accesstype = {
	OB_HEAD_INIT(&Typetype)
	0,			/*ob_size*/
	"access",		/*tp_name*/
	sizeof(accessobject),	/*tp_size*/
	0,			/*tp_itemsize*/
	/* methods */
	(destructor)access_dealloc, /*tp_dealloc*/
	0,			/*tp_print*/
	(getattrfunc)access_getattr, /*tp_getattr*/
	0,			/*tp_setattr*/
	0,			/*tp_compare*/
	(reprfunc)access_repr, /*tp_repr*/
	0,			/*tp_as_number*/
	0,			/*tp_as_sequence*/
	0,			/*tp_as_mapping*/
	0,			/*tp_hash*/
};


/* Pseudo type objects to indicate collections of types */

/* XXX This should be replaced by a more general "subclassing"
   XXX mechanism for type objects... */

typeobject Anynumbertype = {
	OB_HEAD_INIT(&Typetype)
	0,			/*ob_size*/
	"*number*",		/*tp_name*/
};

/* XXX Should really distinguish mutable and immutable sequences as well */

typeobject Anysequencetype = {
	OB_HEAD_INIT(&Typetype)
	0,			/*ob_size*/
	"*sequence*",		/*tp_name*/
};

typeobject Anymappingtype = {
	OB_HEAD_INIT(&Typetype)
	0,			/*ob_size*/
	"*mapping*",		/*tp_name*/
};

#endif /* SUPPORT_OBSOLETE_ACCESS */