BadVPN – Rev 1
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/**
* @file NCDObject.h
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef BADVPN_NCDOBJECT_H
#define BADVPN_NCDOBJECT_H
#include <stddef.h>
#include <misc/debug.h>
#include <structure/LinkedList0.h>
#include <ncd/NCDVal_types.h>
#include <ncd/NCDStringIndex.h>
#include <ncd/static_strings.h>
/**
* Represents an NCD object.
* Objects expose the following functionalities:
* - resolving variables by name,
* - resolving objects by name,
* - provide information for calling method-like statements.
*
* The NCDObject structure must not be stored persistently; it is only
* valid at the time it was obtained, and any change of state in the
* execution of the NCD program may render the object invalid.
* However, the structure does not contain any resources, and can freely
* be passed around by value.
*/
typedef struct NCDObject_s NCDObject;
/**
* Serves as an anchor point for NCDObjRef weak references.
* A callback produces the temporary NCDObject values on demand.
*/
typedef struct NCDPersistentObj_s NCDPersistentObj;
/**
* A weak reference to an NCDPersistentObj.
* This means that the existence of a reference does not prevent
* the NCDPersistentObj from going away, rather when it goes away
* the NCDObjRef becomes a broken reference - any further
* dereference operations will fail "gracefully".
*/
typedef struct NCDObjRef_s NCDObjRef;
/**
* Callback function for variable resolution requests.
*
* @param obj const pointer to the NCDObject this is being called for.
* {@link NCDObject_DataPtr} and {@link NCDObject_DataInt} can be
* used to retrieve state information which was passed to
* {@link NCDObject_Build} or {@link NCDObject_BuildFull}.
* @param name name of the variable being resolved, in form of an {@link NCDStringIndex}
* string identifier
* @param mem pointer to the memory object where the resulting value should be
* constructed
* @param out_value If the variable exists, *out_value should be set to the value
* reference to the result value. If the variable exists but there
* was an error constructing the value, should be set to an
* invalid value reference. Can be modified even if the variable
* does not exist.
* @return 1 if the variable exists, 0 if not
*/
typedef int (*NCDObject_func_getvar) (const NCDObject *obj, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out_value);
/**
* Callback function for object resolution requests.
*
* @param obj const pointer to the NCDObject this is being called for.
* {@link NCDObject_DataPtr} and {@link NCDObject_DataInt} can be
* used to retrieve state information which was passed to
* {@link NCDObject_Build} or {@link NCDObject_BuildFull}.
* @param name name of the object being resolved, in form of an {@link NCDStringIndex}
* string identifier
* @param out_object If the object exists, *out_object should be set to the result
* object. Can be modified even if the object does not exist.
* @return 1 if the object exists, 0 if not
*/
typedef int (*NCDObject_func_getobj) (const NCDObject *obj, NCD_string_id_t name, NCDObject *out_object);
/**
* A callback of NCDPersistentObj which produces the corresponding temporary
* NCDObject value.
*/
typedef NCDObject (*NCDPersistentObj_func_retobj) (NCDPersistentObj const *pobj);
struct NCDObject_s {
NCD_string_id_t type;
int data_int;
void *data_ptr;
void *method_user;
NCDObject_func_getvar func_getvar;
NCDObject_func_getobj func_getobj;
NCDPersistentObj *pobj;
};
struct NCDPersistentObj_s {
NCDPersistentObj_func_retobj func_retobj;
LinkedList0 refs_list;
};
struct NCDObjRef_s {
NCDPersistentObj *pobj;
LinkedList0Node refs_list_node;
};
/**
* Basic object construction function.
* This is equivalent to calling {@link NCDObject_BuildFull} with data_int=0,
* method_user=data_ptr and pobj=NULL. See that function for detailed documentation.
*/
NCDObject NCDObject_Build (NCD_string_id_t type, void *data_ptr, NCDObject_func_getvar func_getvar, NCDObject_func_getobj func_getobj);
/**
* Constructs an {@link NCDObject} structure.
* This is the full version where all supported parameters have to be provided.
* In most cases, {@link NCDObject_Build} will suffice.
*
* @param type type of the object for the purpose of calling method-like statements
* on the object, in form of an {@link NCDStringIndex} string identifier.
* May be set to -1 if the object has no methods.
* @param data_ptr state-keeping pointer which can be restored from callbacks using
* {@link NCDObject_DataPtr}
* @param data_int state-keeping integer which can be restored from callbacks using
* {@link NCDObject_DataInt}
* @param method_user state-keeping pointer to be passed to new method-like statements
* created using this object. The value of this argument will be
* available as params->method_user within the {@link NCDModule_func_new2}
* module backend callback.
* @param func_getvar callback for resolving variables within the object. This must not
* be NULL; if the object exposes no variables, pass {@link NCDObject_no_getvar}.
* @param func_getobj callback for resolving objects within the object. This must not
* be NULL; if the object exposes no objects, pass {@link NCDObject_no_getobj}.
* @param pobj pointer to an NCDPersistentObj, serving as a reference anchor for this
* object. NULL if references are not supported by the object.
* @return an NCDObject structure encapsulating the information given
*/
NCDObject NCDObject_BuildFull (NCD_string_id_t type, void *data_ptr, int data_int, void *method_user, NCDObject_func_getvar func_getvar, NCDObject_func_getobj func_getobj, NCDPersistentObj *pobj);
/**
* Returns the 'type' attribute; see {@link NCDObject_BuildFull}.
*/
NCD_string_id_t NCDObject_Type (const NCDObject *o);
/**
* Returns the 'data_ptr' attribute; see {@link NCDObject_BuildFull}.
*/
void * NCDObject_DataPtr (const NCDObject *o);
/**
* Returns the 'data_int' attribute; see {@link NCDObject_BuildFull}.
*/
int NCDObject_DataInt (const NCDObject *o);
/**
* Returns the 'method_user' attribute; see {@link NCDObject_BuildFull}.
*/
void * NCDObject_MethodUser (const NCDObject *o);
/**
* Attempts to resolve a variable within the object.
* This just calls {@link NCDObject_func_getvar}, but also has some assertions to detect
* incorrect behavior of the callback.
*/
int NCDObject_GetVar (const NCDObject *o, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out_value) WARN_UNUSED;
/**
* Attempts to resolve an object within the object.
* This just calls {@link NCDObject_func_getobj}, but also has some assertions to detect
* incorrect behavior of the callback.
*/
int NCDObject_GetObj (const NCDObject *o, NCD_string_id_t name, NCDObject *out_object) WARN_UNUSED;
/**
* Returns a pointer to the NCDPersistentObj pointer for this
* object (if any).
*/
NCDPersistentObj * NCDObject_Pobj (const NCDObject *o);
/**
* Resolves a variable expression starting with this object.
* A variable expression is usually represented in dotted form,
* e.g. object1.object2.variable (for a named variable) or object1.object2.object3
* (for an empty string variable). This function however receives the expression
* as an array of string identifiers.
*
* Consult the implementation for exact semantics of variable expression resolution.
*
* @param o object to start the resolution with
* @param names pointer to an array of names for the resolution. May be NULL if num_names is 0.
* @param num_names number in names in the array
* @param mem pointer to the memory object where the resulting value
* should be constructed
* @param out_value If the variable exists, *out_value will be set to the value
* reference to the result value. If the variable exists but there
* was an error constructing the value, will be set to an
* invalid value reference. May be modified even if the variable
* does not exist.
* @return 1 if the variable exists, 0 if not
*/
int NCDObject_ResolveVarExprCompact (const NCDObject *o, const NCD_string_id_t *names, size_t num_names, NCDValMem *mem, NCDValRef *out_value) WARN_UNUSED;
/**
* Resolves an object expression starting with this object.
* An object expression is usually represented in dotted form,
* e.g. object1.object2.object3. This function however receives the expression
* as an array of string identifiers.
*
* Consult the implementation for exact semantics of object expression resolution.
*
* @param o object to start the resolution with
* @param names pointer to an array of names for the resolution. May be NULL if num_names is 0.
* @param num_names number in names in the array
* @param out_object If the object exists, *out_object will be set to the result
* object. May be modified even if the object does not exist.
* @return 1 if the object exists, 0 if not
*/
int NCDObject_ResolveObjExprCompact (const NCDObject *o, const NCD_string_id_t *names, size_t num_names, NCDObject *out_object) WARN_UNUSED;
/**
* Returns 0. This can be used as a dummy variable resolution callback.
*/
int NCDObject_no_getvar (const NCDObject *obj, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out_value);
/**
* Returns 0. This can be used as a dummy object resolution callback.
*/
int NCDObject_no_getobj (const NCDObject *obj, NCD_string_id_t name, NCDObject *out_object);
/**
* Initializes an NCDPersistentObj, an anchor point for NCDObjRef
* refrences.
*
* @param func_retobj callback for producing NCDObject temporary objects
*/
void NCDPersistentObj_Init (NCDPersistentObj *o, NCDPersistentObj_func_retobj func_retobj);
/**
* Frees the NCDPersistentObj.
* This breaks any NCDObjRef references referencing this object.
* This means that any further NCDObjRef_Deref calls on those
* references will fail.
*/
void NCDPersistentObj_Free (NCDPersistentObj *o);
/**
* Initializes an object reference.
*
* @param pobj the NCDPersistentObj for the reference, or NULL to make
* a broken reference
*/
void NCDObjRef_Init (NCDObjRef *o, NCDPersistentObj *pobj);
/**
* Frees the object reference.
*/
void NCDObjRef_Free (NCDObjRef *o);
/**
* Dereferences the object reference.
* Note that the refernce will be broken if the originally
* reference NCDPersistentObj was freed.
*
* @param res on success, *res will be set to the resulting NCDObject
* @return 1 on success, 0 on failure (broken reference)
*/
int NCDObjRef_Deref (NCDObjRef *o, NCDObject *res) WARN_UNUSED;
#endif