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/**
* @file lyb.h
* @author Michal Vasko <mvasko@cesnet.cz>
* @brief Header for LYB format printer & parser
*
* Copyright (c) 2020 - 2022 CESNET, z.s.p.o.
*
* This source code is licensed under BSD 3-Clause License (the "License").
* You may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://opensource.org/licenses/BSD-3-Clause
*/
#ifndef LY_LYB_H_
#define LY_LYB_H_
#include <stddef.h>
#include <stdint.h>
#include "parser_internal.h"
struct ly_ctx;
struct lysc_node;
/*
* LYB format
*
* Unlike XML or JSON, it is binary format so most data are represented in similar way but in binary.
* Some notable differences:
*
* - schema nodes are identified based on their hash instead of their string name. In case of collisions
* an array of hashes is created with each next hash one bit shorter until a unique sequence of all these
* hashes is found and then all of them are stored.
*
* - tree structure is represented as individual strictly bounded "siblings". Each "siblings" begins
* with its metadata, which consist of 1) the whole "sibling" length in bytes and 2) number
* of included metadata chunks of nested "siblings".
*
* - since length of a "sibling" is not known before it is printed, holes are first written and
* after the "sibling" is printed, they are filled with actual valid metadata. As a consequence,
* LYB data cannot be directly printed into streams!
*
* - data are preceded with information about all the used modules. It is needed because of
* possible augments and deviations which must be known beforehand, otherwise schema hashes
* could be matched to the wrong nodes.
*
* This is a short summary of the format:
* @verbatim
sb = siblings_start
se = siblings_end
siblings = zero-LYB_SIZE_BYTES | (sb instance+ se)
instance = node_type model hash node
model = 16bit_zero | (model_name_length model_name revision)
node = opaq | leaflist | list | any | inner | leaf
opaq = opaq_data siblings
leaflist = sb leaf+ se
list = sb (node_header siblings)+ se
any = node_header anydata_data
inner = node_header siblings
leaf = node_header term_value
node_header = metadata node_flags
@endverbatim
*/
/**
* @brief LYB data node type
*/
enum lylyb_node_type {
LYB_NODE_TOP, /**< top-level node */
LYB_NODE_CHILD, /**< child node with a parent */
LYB_NODE_OPAQ, /**< opaque node */
LYB_NODE_EXT /**< nested extension data node */
};
/**
* @brief LYB format parser context
*/
struct lylyb_ctx {
const struct ly_ctx *ctx;
uint64_t line; /* current line */
struct ly_in *in; /* input structure */
const struct lys_module **models;
struct lyd_lyb_sibling {
size_t written;
size_t position;
uint16_t inner_chunks;
} *siblings;
LY_ARRAY_COUNT_TYPE sibling_size;
/* LYB printer only */
struct lyd_lyb_sib_ht {
struct lysc_node *first_sibling;
struct ly_ht *ht;
} *sib_hts;
};
/**
* @brief Destructor for the lylyb_ctx structure
*/
void lyd_lyb_ctx_free(struct lyd_ctx *lydctx);
/* just a shortcut */
#define LYB_LAST_SIBLING(lybctx) lybctx->siblings[LY_ARRAY_COUNT(lybctx->siblings) - 1]
/* struct lyd_lyb_sibling allocation step */
#define LYB_SIBLING_STEP 4
/* current LYB format version */
#define LYB_VERSION_NUM 0x05
/* LYB format version mask of the header byte */
#define LYB_VERSION_MASK 0x0F
/**
* LYB schema hash constants
*
* Hash is divided to collision ID and hash itself.
*
* @anchor collisionid
*
* First bits are collision ID until 1 is found. The rest is truncated 32b hash.
* 1xxx xxxx - collision ID 0 (no collisions)
* 01xx xxxx - collision ID 1 (collision ID 0 hash collided)
* 001x xxxx - collision ID 2 ...
*
* When finding a match for a unique schema (siblings) hash (sequence of hashes with increasing collision ID), the highest
* collision ID can be read from the last hash (LYB parser).
*
* To learn what is the highest collision ID of a hash that must be included in a unique schema (siblings) hash,
* collisions with all the preceding sibling schema hashes must be checked (LYB printer).
*/
/* Number of bits the whole hash will take (including hash collision ID) */
#define LYB_HASH_BITS 8
/* Masking 32b hash (collision ID 0) */
#define LYB_HASH_MASK 0x7f
/* Type for storing the whole hash (used only internally, publicly defined directly) */
#define LYB_HASH uint8_t
/* Need to move this first >> collision number (from 0) to get collision ID hash part */
#define LYB_HASH_COLLISION_ID 0x80
/* How many bytes are reserved for one data chunk SIZE (8B is maximum) */
#define LYB_SIZE_BYTES 2
/* Maximum size that will be written into LYB_SIZE_BYTES (must be large enough) */
#define LYB_SIZE_MAX UINT16_MAX
/* How many bytes are reserved for one data chunk inner chunk count */
#define LYB_INCHUNK_BYTES 2
/* Maximum size that will be written into LYB_INCHUNK_BYTES (must be large enough) */
#define LYB_INCHUNK_MAX UINT16_MAX
/* Just a helper macro */
#define LYB_META_BYTES (LYB_INCHUNK_BYTES + LYB_SIZE_BYTES)
/* model revision as XXXX XXXX XXXX XXXX (2B) (year is offset from 2000)
* YYYY YYYM MMMD DDDD */
#define LYB_REV_YEAR_OFFSET 2000
#define LYB_REV_YEAR_MASK 0xfe00U
#define LYB_REV_YEAR_SHIFT 9
#define LYB_REV_MONTH_MASK 0x01E0U
#define LYB_REV_MONTH_SHIFT 5
#define LYB_REV_DAY_MASK 0x001fU
/**
* @brief Get single hash for a schema node to be used for LYB data. Read from cache, if possible.
*
* @param[in] node Node to hash.
* @param[in] collision_id Collision ID of the hash to generate, see @ref collisionid.
* @return Generated hash.
*/
LYB_HASH lyb_get_hash(const struct lysc_node *node, uint8_t collision_id);
/**
* @brief Fill the hash cache of all the schema nodes of a module.
*
* @param[in] mod Module to process.
*/
void lyb_cache_module_hash(const struct lys_module *mod);
/**
* @brief Check whether a node's module is in a module array.
*
* @param[in] node Node to check.
* @param[in] models Modules in a sized array.
* @return Boolean value whether @p node's module was found in the given @p models array.
*/
ly_bool lyb_has_schema_model(const struct lysc_node *node, const struct lys_module **models);
#endif /* LY_LYB_H_ */
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