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// SPDX-License-Identifier: ISC
/*
* Copyright (c) 2015-16 David Lamparter, for NetDEF, Inc.
*/
#ifndef _QOBJ_H
#define _QOBJ_H
#include <stdint.h>
#include <stdlib.h>
#include <stddef.h>
#include "typesafe.h"
#ifdef __cplusplus
extern "C" {
#endif
/* reserve a specific amount of bytes for a struct, which can grow up to
* that size (or be dummy'd out if not needed)
*
* note the padding's array size will be an error if it gets negative or zero;
* this is intentional to prevent the struct from growing beyond the allocated
* space.
*/
#ifndef __cplusplus
#define RESERVED_SPACE_STRUCT(name, fieldname, size) \
struct { \
struct name fieldname; \
char padding##fieldname[size - sizeof(struct name)]; \
};
#else
#define RESERVED_SPACE_STRUCT(name, fieldname, size) \
struct name fieldname; \
char padding##fieldname[size - sizeof(struct name)];
#endif
/* don't need struct definitions for these here. code actually using
* these needs to define the struct *before* including this header.
* HAVE_QOBJ_xxx should be defined to +1 in that case, like this:
*
* #if defined(HAVE_QOBJ_NODETYPE_CLI) && HAVE_QOBJ_NODETYPE_CLI < 0
* #error include files are in wrong order
* #else
* #define HAVE_QOBJ_NODETYPE_CLI 1
* struct qobj_nodetype_cli { ... }
* #endif
*/
#ifndef HAVE_QOBJ_NODETYPE_CLI
#define HAVE_QOBJ_NODETYPE_CLI -1
struct qobj_nodetype_cli {
int dummy;
};
#endif
#ifndef HAVE_QOBJ_NODETYPE_CAPNP
#define HAVE_QOBJ_NODETYPE_CAPNP -1
struct qobj_nodetype_capnp {
int dummy;
};
#endif
#include "typesafe.h"
/* each different kind of object will have a global variable of this type,
* which can be used by various other pieces to store type-related bits.
* type equality can be tested as pointer equality. (cf. QOBJ_GET_TYPESAFE)
*/
struct qobj_nodetype {
ptrdiff_t node_member_offset;
RESERVED_SPACE_STRUCT(qobj_nodetype_cli, cli, 256)
RESERVED_SPACE_STRUCT(qobj_nodetype_capnp, capnp, 256)
};
PREDECL_HASH(qobj_nodes);
/* anchor to be embedded somewhere in the object's struct */
struct qobj_node {
uint64_t nid;
struct qobj_nodes_item nodehash;
const struct qobj_nodetype *type;
};
#define QOBJ_FIELDS struct qobj_node qobj_node
/* call these at the end of any _create function (QOBJ_REG)
* and beginning of any _destroy function (QOBJ_UNREG) */
#define QOBJ_REG(n, structname) qobj_reg(&n->qobj_node, &qobj_t_##structname)
#define QOBJ_UNREG(n) qobj_unreg(&n->qobj_node)
/* internals - should not be directly used without a good reason
*
* note: qobj_get is essentially never safe to use in MT context because
* the object could be deleted by another thread -- and worse, it could be
* of the "wrong" type and deleted.
*
* with qobj_get_typed, the type check is done under lock, which means that
* it can be used as long as another lock prevents the deletion of objects
* of the expected type.
*
* in the long this may need another touch, e.g. built-in per-object locking.
*/
void qobj_reg(struct qobj_node *node, const struct qobj_nodetype *type);
void qobj_unreg(struct qobj_node *node);
struct qobj_node *qobj_get(uint64_t id);
void *qobj_get_typed(uint64_t id, const struct qobj_nodetype *type);
/* type declarations */
#define DECLARE_QOBJ_TYPE(structname) \
extern const struct qobj_nodetype qobj_t_##structname \
/* end */
#define DEFINE_QOBJ_TYPE(structname) \
const struct qobj_nodetype qobj_t_##structname = { \
.node_member_offset = \
(ptrdiff_t)offsetof(struct structname, qobj_node)} \
/* end */
#define DEFINE_QOBJ_TYPE_INIT(structname, ...) \
const struct qobj_nodetype qobj_t_##structname = { \
.node_member_offset = \
(ptrdiff_t)offsetof(struct structname, qobj_node), \
__VA_ARGS__} \
/* end */
/* ID dereference with typecheck.
* will return NULL if id not found or wrong type. */
#define QOBJ_GET_TYPESAFE(id, structname) \
((struct structname *)qobj_get_typed((id), &qobj_t_##structname))
#define QOBJ_ID(ptr) ((ptr)->qobj_node.nid)
#define QOBJ_ID_0SAFE(ptr) \
({ \
typeof(ptr) _ptr = (ptr); \
_ptr ? _ptr->qobj_node.nid : 0ULL; \
})
void qobj_init(void);
void qobj_finish(void);
#ifdef __cplusplus
}
#endif
#endif /* _QOBJ_H */
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