--- /dev/null
+/*
+ * netlink/object-api.c Object API
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * Copyright (c) 2003-2007 Thomas Graf <tgraf@suug.ch>
+ */
+
+#ifndef NETLINK_OBJECT_API_H_
+#define NETLINK_OBJECT_API_H_
+
+#include <netlink/netlink.h>
+#include <netlink/utils.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @ingroup object
+ * @defgroup object_api Object API
+ * @brief
+ *
+ * @par 1) Object Definition
+ * @code
+ * // Define your object starting with the common object header
+ * struct my_obj {
+ * NLHDR_COMMON
+ * int my_data;
+ * };
+ *
+ * // Fill out the object operations structure
+ * struct nl_object_ops my_ops = {
+ * .oo_name = "my_obj",
+ * .oo_size = sizeof(struct my_obj),
+ * };
+ *
+ * // At this point the object can be allocated, you may want to provide a
+ * // separate _alloc() function to ease allocting objects of this kind.
+ * struct nl_object *obj = nl_object_alloc(&my_ops);
+ *
+ * // And release it again...
+ * nl_object_put(obj);
+ * @endcode
+ *
+ * @par 2) Allocating additional data
+ * @code
+ * // You may require to allocate additional data and store it inside
+ * // object, f.e. assuming there is a field `ptr'.
+ * struct my_obj {
+ * NLHDR_COMMON
+ * void * ptr;
+ * };
+ *
+ * // And at some point you may assign allocated data to this field:
+ * my_obj->ptr = calloc(1, ...);
+ *
+ * // In order to not introduce any memory leaks you have to release
+ * // this data again when the last reference is given back.
+ * static void my_obj_free_data(struct nl_object *obj)
+ * {
+ * struct my_obj *my_obj = nl_object_priv(obj);
+ *
+ * free(my_obj->ptr);
+ * }
+ *
+ * // Also when the object is cloned, you must ensure for your pointer
+ * // stay valid even if one of the clones is freed by either making
+ * // a clone as well or increase the reference count.
+ * static int my_obj_clone(struct nl_object *src, struct nl_object *dst)
+ * {
+ * struct my_obj *my_src = nl_object_priv(src);
+ * struct my_obj *my_dst = nl_object_priv(dst);
+ *
+ * if (src->ptr) {
+ * dst->ptr = calloc(1, ...);
+ * memcpy(dst->ptr, src->ptr, ...);
+ * }
+ * }
+ *
+ * struct nl_object_ops my_ops = {
+ * ...
+ * .oo_free_data = my_obj_free_data,
+ * .oo_clone = my_obj_clone,
+ * };
+ * @endcode
+ *
+ * @par 3) Object Dumping
+ * @code
+ * static int my_obj_dump_detailed(struct nl_object *obj,
+ * struct nl_dump_params *params)
+ * {
+ * struct my_obj *my_obj = nl_object_priv(obj);
+ *
+ * // It is absolutely essential to use nl_dump() when printing
+ * // any text to make sure the dumping parameters are respected.
+ * nl_dump(params, "Obj Integer: %d\n", my_obj->my_int);
+ *
+ * // Before we can dump the next line, make sure to prefix
+ * // this line correctly.
+ * nl_new_line(params);
+ *
+ * // You may also split a line into multiple nl_dump() calls.
+ * nl_dump(params, "String: %s ", my_obj->my_string);
+ * nl_dump(params, "String-2: %s\n", my_obj->another_string);
+ * }
+ *
+ * struct nl_object_ops my_ops = {
+ * ...
+ * .oo_dump[NL_DUMP_FULL] = my_obj_dump_detailed,
+ * };
+ * @endcode
+ *
+ * @par 4) Object Attributes
+ * @code
+ * // The concept of object attributes is optional but can ease the typical
+ * // case of objects that have optional attributes, e.g. a route may have a
+ * // nexthop assigned but it is not required to.
+ *
+ * // The first step to define your object specific bitmask listing all
+ * // attributes
+ * #define MY_ATTR_FOO (1<<0)
+ * #define MY_ATTR_BAR (1<<1)
+ *
+ * // When assigning an optional attribute to the object, make sure
+ * // to mark its availability.
+ * my_obj->foo = 123123;
+ * my_obj->ce_mask |= MY_ATTR_FOO;
+ *
+ * // At any time you may use this mask to check for the availability
+ * // of the attribute, e.g. while dumping
+ * if (my_obj->ce_mask & MY_ATTR_FOO)
+ * nl_dump(params, "foo %d ", my_obj->foo);
+ *
+ * // One of the big advantages of this concept is that it allows for
+ * // standardized comparisons which make it trivial for caches to
+ * // identify unique objects by use of unified comparison functions.
+ * // In order for it to work, your object implementation must provide
+ * // a comparison function and define a list of attributes which
+ * // combined together make an object unique.
+ *
+ * static int my_obj_compare(struct nl_object *_a, struct nl_object *_b,
+ * uint32_t attrs, int flags)
+ * {
+ * struct my_obj *a = nl_object_priv(_a):
+ * struct my_obj *b = nl_object_priv(_b):
+ * int diff = 0;
+ *
+ * // We help ourselves in defining our own DIFF macro which will
+ * // call ATTR_DIFF() on both objects which will make sure to only
+ * // compare the attributes if required.
+ * #define MY_DIFF(ATTR, EXPR) ATTR_DIFF(attrs, MY_ATTR_##ATTR, a, b, EXPR)
+ *
+ * // Call our own diff macro for each attribute to build a bitmask
+ * // representing the attributes which mismatch.
+ * diff |= MY_DIFF(FOO, a->foo != b->foo)
+ * diff |= MY_DIFF(BAR, strcmp(a->bar, b->bar))
+ *
+ * return diff;
+ * }
+ *
+ * // In order to identify identical objects with differing attributes
+ * // you must specify the attributes required to uniquely identify
+ * // your object. Make sure to not include too many attributes, this
+ * // list is used when caches look for an old version of an object.
+ * struct nl_object_ops my_ops = {
+ * ...
+ * .oo_id_attrs = MY_ATTR_FOO,
+ * .oo_compare = my_obj_compare,
+ * };
+ * @endcode
+ * @{
+ */
+
+/**
+ * Common Object Header
+ *
+ * This macro must be included as first member in every object
+ * definition to allow objects to be cached.
+ */
+#define NLHDR_COMMON \
+ int ce_refcnt; \
+ struct nl_object_ops * ce_ops; \
+ struct nl_cache * ce_cache; \
+ struct nl_list_head ce_list; \
+ int ce_msgtype; \
+ int ce_flags; \
+ uint32_t ce_mask;
+
+/**
+ * Return true if attribute is available in both objects
+ * @arg A an object
+ * @arg B another object
+ * @arg ATTR attribute bit
+ *
+ * @return True if the attribute is available, otherwise false is returned.
+ */
+#define AVAILABLE(A, B, ATTR) (((A)->ce_mask & (B)->ce_mask) & (ATTR))
+
+/**
+ * Return true if attributes mismatch
+ * @arg A an object
+ * @arg B another object
+ * @arg ATTR attribute bit
+ * @arg EXPR Comparison expression
+ *
+ * This function will check if the attribute in question is available
+ * in both objects, if not this will count as a mismatch.
+ *
+ * If available the function will execute the expression which must
+ * return true if the attributes mismatch.
+ *
+ * @return True if the attribute mismatch, or false if they match.
+ */
+#define ATTR_MISMATCH(A, B, ATTR, EXPR) (!AVAILABLE(A, B, ATTR) || (EXPR))
+
+/**
+ * Return attribute bit if attribute does not match
+ * @arg LIST list of attributes to be compared
+ * @arg ATTR attribute bit
+ * @arg A an object
+ * @arg B another object
+ * @arg EXPR Comparison expression
+ *
+ * This function will check if the attribute in question is available
+ * in both objects, if not this will count as a mismatch.
+ *
+ * If available the function will execute the expression which must
+ * return true if the attributes mismatch.
+ *
+ * In case the attributes mismatch, the attribute is returned, otherwise
+ * 0 is returned.
+ *
+ * @code
+ * diff |= ATTR_DIFF(attrs, MY_ATTR_FOO, a, b, a->foo != b->foo);
+ * @endcode
+ */
+#define ATTR_DIFF(LIST, ATTR, A, B, EXPR) \
+({ int diff = 0; \
+ if (((LIST) & (ATTR)) && ATTR_MISMATCH(A, B, ATTR, EXPR)) \
+ diff = ATTR; \
+ diff; })
+
+/**
+ * Object Operations
+ */
+struct nl_object;
+struct nl_object_ops
+{
+ /**
+ * Unique name of object type
+ *
+ * Must be in the form family/name, e.g. "route/addr"
+ */
+ char * oo_name;
+
+ /** Size of object including its header */
+ size_t oo_size;
+
+ /* List of attributes needed to uniquely identify the object */
+ uint32_t oo_id_attrs;
+
+ /**
+ * Constructor function
+ *
+ * Will be called when a new object of this type is allocated.
+ * Can be used to initialize members such as lists etc.
+ */
+ void (*oo_constructor)(struct nl_object *);
+
+ /**
+ * Destructor function
+ *
+ * Will be called when an object is freed. Must free all
+ * resources which may have been allocated as part of this
+ * object.
+ */
+ void (*oo_free_data)(struct nl_object *);
+
+ /**
+ * Cloning function
+ *
+ * Will be called when an object needs to be cloned. Please
+ * note that the generic object code will make an exact
+ * copy of the object first, therefore you only need to take
+ * care of members which require reference counting etc.
+ *
+ * May return a negative error code to abort cloning.
+ */
+ int (*oo_clone)(struct nl_object *, struct nl_object *);
+
+ /**
+ * Dumping functions
+ *
+ * Will be called when an object is dumped. The implementations
+ * have to use nl_dump(), nl_dump_line(), and nl_new_line() to
+ * dump objects.
+ *
+ * The functions must return the number of lines printed.
+ */
+ void (*oo_dump[NL_DUMP_MAX+1])(struct nl_object *,
+ struct nl_dump_params *);
+
+ /**
+ * Comparison function
+ *
+ * Will be called when two objects of the same type are
+ * compared. It takes the two objects in question, an object
+ * specific bitmask defining which attributes should be
+ * compared and flags to control the behaviour.
+ *
+ * The function must return a bitmask with the relevant bit
+ * set for each attribute that mismatches.
+ */
+ int (*oo_compare)(struct nl_object *, struct nl_object *,
+ uint32_t, int);
+
+
+ char *(*oo_attrs2str)(int, char *, size_t);
+};
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
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