lib/ublksrv_json.cpp

// SPDX-License-Identifier: MIT or LGPL-2.1-only

#include <config.h>

#include <iostream>
#include "nlohmann/json.hpp"
#include "ublksrv_priv.h"

#define  parse_json(j, jbuf)	\
	try {						\
		j = json::parse(std::string(jbuf));	\
	} catch (json::parse_error& ex) {		\
		std::cerr << "parse error at byte " << ex.byte << std::endl; \
		return -EINVAL;				\
	}						\

using json = nlohmann::json;

static inline int dump_json_to_buf(json &j, char *jbuf, int len)
{
	std::string s;
	int j_len;

	s = j.dump();
	j_len = s.length();
	if (j_len < len) {
		strcpy(jbuf, s.c_str());
		return j_len;
	}
	return -EINVAL;
}

NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(ublksrv_ctrl_dev_info,
	nr_hw_queues,
	queue_depth,
	state,
	pad0,
	max_io_buf_bytes,
	dev_id,
	ublksrv_pid,
	pad1,
	flags,
	ublksrv_flags,
	owner_uid,
	owner_gid,
	reserved1,
	reserved2)

/*
 * build one json string with dev_info head, and result is stored
 * in 'buf'.
 */
int ublksrv_json_write_dev_info(const struct ublksrv_ctrl_dev *cdev,
		char *jbuf, int len)
{
	const struct ublksrv_ctrl_dev_info *info = &cdev->dev_info;
	json j_info = *info;
	json j;

	j["dev_info"] = j_info;

	return dump_json_to_buf(j, jbuf, len);
}

/* Fill 'info' from the json string pointed by 'json_buf' */
int ublksrv_json_read_dev_info(const char *jbuf,
		struct ublksrv_ctrl_dev_info *info)
{
	json j;

	parse_json(j, jbuf);

	if (!j.contains("dev_info"))
		return -EINVAL;

	auto sj = j["dev_info"];

	*info = sj.get<struct ublksrv_ctrl_dev_info>();

	return 0;
}

NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(struct ublk_param_basic,
	attrs,
	logical_bs_shift,
	physical_bs_shift,
	io_opt_shift,
	io_min_shift,
	max_sectors,
	chunk_sectors,
	dev_sectors,
	virt_boundary_mask)

NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(struct ublk_param_discard,
	discard_alignment,
	discard_granularity,
	max_discard_sectors,
	max_write_zeroes_sectors,
	max_discard_segments,
	reserved0)
NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(struct ublk_params,
	len, types, basic, discard)

int ublksrv_json_write_params(const struct ublk_params *p,
		char *jbuf, int len)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	j["params"] = *p;

	return dump_json_to_buf(j, jbuf, len);
}

int ublksrv_json_read_params(struct ublk_params *p,
		const char *jbuf)
{
	json j, sj;
	std::string s;

	parse_json(j, jbuf);

	if (!j.contains("params"))
		return -EINVAL;

	*p = j["params"];

	return 0;
}

int ublksrv_json_dump_params(const char *jbuf)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	if (!j.contains("params"))
		return -EINVAL;

	std::cout << std::setw(4) << j["params"] << '\n';

	return 0;
}

int ublksrv_json_read_target_str_info(const char *jbuf, int len,
		const char *name, char *val)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	if (!j.contains("target"))
		return -EINVAL;

	auto tj = j["target"];

	if (!tj.contains(name))
		return -EINVAL;

	std::string str = tj[std::string(name)];
	if (str.length() < (unsigned)len) {
		strcpy(val, str.c_str());
		return 0;
	}

	return -EINVAL;
}

int ublksrv_json_read_target_ulong_info(const char *jbuf,
		const char *name, long *val)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	if (!j.contains("target"))
		return -EINVAL;

	auto tj = j["target"];

	if (!tj.contains(name))
		return -EINVAL;

	*val = tj[std::string(name)];

	return 0;
}

int ublksrv_json_write_target_str_info(char *jbuf, int len,
		const char *name, const char *val)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	j["target"][std::string(name)] = val;;

	return dump_json_to_buf(j, jbuf, len);
}

int ublksrv_json_write_target_long_info(char *jbuf, int len,
		const char *name, long val)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	j["target"][std::string(name)] = val;;

	return dump_json_to_buf(j, jbuf, len);
}

int ublksrv_json_write_target_ulong_info(char *jbuf, int len, const char *name,
		unsigned long val)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	j["target"][std::string(name)] = val;;

	return dump_json_to_buf(j, jbuf, len);
}

int ublksrv_json_write_target_base_info(char *jbuf, int len,
		const struct ublksrv_tgt_base_json *tgt)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	j["target"]["name"] = tgt->name;
	j["target"]["type"] = tgt->type;
	j["target"]["dev_size"] = tgt->dev_size;

	return dump_json_to_buf(j, jbuf, len);
}

int ublksrv_json_read_target_base_info(const char *jbuf,
		struct ublksrv_tgt_base_json *tgt)
{
	json j;
	std::string s;

	parse_json(j, jbuf);

	if (!j.contains("target"))
		return -EINVAL;

	auto tj = j["target"];

	if (!tj.contains("name") || !tj.contains("type") ||
			!tj.contains("dev_size"))
		return -EINVAL;

	std::string str = tj["name"];
	if (str.length() >= UBLKSRV_TGT_NAME_MAX_LEN)
		return -EINVAL;
	strcpy(tgt->name, str.c_str());
	tgt->type = tj["type"];
	tgt->dev_size = tj["dev_size"];

	return 0;
}

int ublksrv_json_read_target_info(const char *jbuf, char *tgt_buf, int len)
{
	json j;

	parse_json(j, jbuf);

	if (j.contains("target")) {
		auto tj = j["target"];

		return dump_json_to_buf(tj, tgt_buf, len);
	}
	return 0;
}

int ublksrv_json_write_queue_info(const struct ublksrv_ctrl_dev *cdev,
		char *jbuf, int len, int qid, int ubq_daemon_tid)
{
	json j;
	std::string s;
	char name[16];
	char cpus[4096];
	cpu_set_t *cpuset = ublksrv_get_queue_affinity(cdev, qid);

	parse_json(j, jbuf);

	snprintf(name, 16, "%d", qid);

	ublksrv_build_cpu_str(cpus, 512, cpuset);

	j["queues"][std::string(name)]["qid"] = qid;
	j["queues"][std::string(name)]["tid"] = ubq_daemon_tid;
	j["queues"][std::string(name)]["affinity"] = cpus;

	return dump_json_to_buf(j, jbuf, len);
}

int ublksrv_json_read_queue_info(const char *jbuf, int qid, unsigned *tid,
		char *affinity_buf, int len)
{
	json j;
	char name[16];
	std::string str;

	parse_json(j, jbuf);

	snprintf(name, 16, "%d", qid);

	auto qj = j["queues"][name];

	*tid = qj["tid"];
	str = qj["affinity"];

	if (str.length() < (unsigned)len) {
		strcpy(affinity_buf, str.c_str());
		return 0;
	}
	return -EINVAL;
}

void ublksrv_json_dump(const char *jbuf)
{
	auto j = json::parse(jbuf);

	std::cout << std::setw(4) << j << '\n';
}

/* the end null character is always counted */
int ublksrv_json_get_length(const char *jbuf)
{
	auto j = json::parse(jbuf);

	return j.dump().length() + 1;
}