blob: 4fd75d5911c7c3b6dd8d8a8bc3e4aa43e0735fbf [file] [log] [blame]
/**
* @file lyb.h
* @author Michal Vasko <mvasko@cesnet.cz>
* @brief Header for LYB format printer & parser
*
* Copyright (c) 2020 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 "set.h"
#include "tree.h"
struct hash_table;
struct ly_ctx;
struct lyd_node;
struct lysc_node;
/**
* @brief Internal structure for LYB parser/printer.
*/
struct lyd_lyb_ctx {
struct lyd_lyb_subtree {
size_t written;
size_t position;
uint8_t inner_chunks;
} *subtrees;
LY_ARRAY_COUNT_TYPE subtree_size;
size_t byte_count; /**< printed/parsed bytes */
const struct ly_ctx *ctx;
union {
struct {
int parse_options;
int validate_options;
};
int print_options;
};
/* LYB parser only */
const char *data;
int int_opts;
const struct lys_module **models;
struct ly_set unres_node_type;
struct ly_set unres_meta_type;
struct ly_set when_check;
struct lyd_node *op_ntf;
/* LYB printer only */
struct lyd_lyb_sib_ht {
struct lysc_node *first_sibling;
struct hash_table *ht;
} *sib_hts;
};
/**
* 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 subtrees. Each subtree begins
* with its metadata, which consist of 1) the whole subtree length in bytes and 2) number
* of included metadata chunks of nested subtrees.
*
* - since length of a subtree is not known before it is printed, holes are first written and
* after the subtree 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.
*/
/* just a shortcut */
#define LYB_LAST_SUBTREE(lybctx) lybctx->subtrees[LY_ARRAY_COUNT(lybctx->subtrees) - 1]
/* struct lyd_lyb_subtree allocation step */
#define LYB_SUBTREE_STEP 4
/* current LYB format version */
#define LYB_VERSION_NUM 0x10
/* LYB format version mask of the header byte */
#define LYB_VERSION_MASK 0x10
/**
* LYB schema hash constants
*
* Hash is divided to collision ID and hash itself.
*
* 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 ...
*/
/* 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 1
/* Maximum size that will be written into LYB_SIZE_BYTES (must be large enough) */
#define LYB_SIZE_MAX UINT8_MAX
/* How many bytes are reserved for one data chunk inner chunk count */
#define LYB_INCHUNK_BYTES 1
/* Maximum size that will be written into LYB_INCHUNK_BYTES (must be large enough) */
#define LYB_INCHUNK_MAX UINT8_MAX
/* Just a helper macro */
#define LYB_META_BYTES (LYB_INCHUNK_BYTES + LYB_SIZE_BYTES)
/* Type large enough for all meta data */
#define LYB_META uint16_t
#endif /* LY_LYB_H_ */