| /* |
| * Copyright (c) 2017 Intel Corporation |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #ifndef ZEPHYR_INCLUDE_DATA_JSON_H_ |
| #define ZEPHYR_INCLUDE_DATA_JSON_H_ |
| |
| #include <sys/util.h> |
| #include <stddef.h> |
| #include <zephyr/types.h> |
| #include <sys/types.h> |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| /** |
| * @brief Structured Data |
| * @defgroup structured_data Structured Data |
| */ |
| |
| |
| /** |
| * @defgroup json JSON |
| * @ingroup structured_data |
| * @{ |
| */ |
| |
| enum json_tokens { |
| /* Before changing this enum, ensure that its maximum |
| * value is still within 7 bits. See comment next to the |
| * declaration of `type` in struct json_obj_descr. |
| */ |
| |
| JSON_TOK_NONE = '_', |
| JSON_TOK_OBJECT_START = '{', |
| JSON_TOK_OBJECT_END = '}', |
| JSON_TOK_LIST_START = '[', |
| JSON_TOK_LIST_END = ']', |
| JSON_TOK_STRING = '"', |
| JSON_TOK_COLON = ':', |
| JSON_TOK_COMMA = ',', |
| JSON_TOK_NUMBER = '0', |
| JSON_TOK_TRUE = 't', |
| JSON_TOK_FALSE = 'f', |
| JSON_TOK_NULL = 'n', |
| JSON_TOK_ERROR = '!', |
| JSON_TOK_EOF = '\0', |
| }; |
| |
| struct json_obj_descr { |
| const char *field_name; |
| |
| /* Alignment can be 1, 2, 4, or 8. The macros to create |
| * a struct json_obj_descr will store the alignment's |
| * power of 2 in order to keep this value in the 0-3 range |
| * and thus use only 2 bits. |
| */ |
| uint32_t align_shift : 2; |
| |
| /* 127 characters is more than enough for a field name. */ |
| uint32_t field_name_len : 7; |
| |
| /* Valid values here (enum json_tokens): JSON_TOK_STRING, |
| * JSON_TOK_NUMBER, JSON_TOK_TRUE, JSON_TOK_FALSE, |
| * JSON_TOK_OBJECT_START, JSON_TOK_LIST_START. (All others |
| * ignored.) Maximum value is '}' (125), so this has to be 7 bits |
| * long. |
| */ |
| uint32_t type : 7; |
| |
| /* 65535 bytes is more than enough for many JSON payloads. */ |
| uint32_t offset : 16; |
| |
| union { |
| struct { |
| const struct json_obj_descr *sub_descr; |
| size_t sub_descr_len; |
| } object; |
| struct { |
| const struct json_obj_descr *element_descr; |
| size_t n_elements; |
| } array; |
| }; |
| }; |
| |
| /** |
| * @brief Function pointer type to append bytes to a buffer while |
| * encoding JSON data. |
| * |
| * @param bytes Contents to write to the output |
| * @param len Number of bytes to append to output |
| * @param data User-provided pointer |
| * |
| * @return This callback function should return a negative number on |
| * error (which will be propagated to the return value of |
| * json_obj_encode()), or 0 on success. |
| */ |
| typedef int (*json_append_bytes_t)(const char *bytes, size_t len, |
| void *data); |
| |
| #define Z_ALIGN_SHIFT(type) (__alignof__(type) == 1 ? 0 : \ |
| __alignof__(type) == 2 ? 1 : \ |
| __alignof__(type) == 4 ? 2 : 3) |
| |
| /** |
| * @brief Helper macro to declare a descriptor for supported primitive |
| * values. |
| * |
| * @param struct_ Struct packing the values |
| * @param field_name_ Field name in the struct |
| * @param type_ Token type for JSON value corresponding to a primitive |
| * type. Must be one of: JSON_TOK_STRING for strings, JSON_TOK_NUMBER |
| * for numbers, JSON_TOK_TRUE (or JSON_TOK_FALSE) for booleans. |
| * |
| * Here's an example of use: |
| * |
| * struct foo { |
| * int some_int; |
| * }; |
| * |
| * struct json_obj_descr foo[] = { |
| * JSON_OBJ_DESCR_PRIM(struct foo, some_int, JSON_TOK_NUMBER), |
| * }; |
| */ |
| #define JSON_OBJ_DESCR_PRIM(struct_, field_name_, type_) \ |
| { \ |
| .field_name = (#field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = sizeof(#field_name_) - 1, \ |
| .type = type_, \ |
| .offset = offsetof(struct_, field_name_), \ |
| } |
| |
| /** |
| * @brief Helper macro to declare a descriptor for an object value |
| * |
| * @param struct_ Struct packing the values |
| * @param field_name_ Field name in the struct |
| * @param sub_descr_ Array of json_obj_descr describing the subobject |
| * |
| * Here's an example of use: |
| * |
| * struct nested { |
| * int foo; |
| * struct { |
| * int baz; |
| * } bar; |
| * }; |
| * |
| * struct json_obj_descr nested_bar[] = { |
| * { ... declare bar.baz descriptor ... }, |
| * }; |
| * struct json_obj_descr nested[] = { |
| * { ... declare foo descriptor ... }, |
| * JSON_OBJ_DESCR_OBJECT(struct nested, bar, nested_bar), |
| * }; |
| */ |
| #define JSON_OBJ_DESCR_OBJECT(struct_, field_name_, sub_descr_) \ |
| { \ |
| .field_name = (#field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = (sizeof(#field_name_) - 1), \ |
| .type = JSON_TOK_OBJECT_START, \ |
| .offset = offsetof(struct_, field_name_), \ |
| { \ |
| .object = { \ |
| .sub_descr = sub_descr_, \ |
| .sub_descr_len = ARRAY_SIZE(sub_descr_), \ |
| }, \ |
| }, \ |
| } |
| |
| /** |
| * @brief Helper macro to declare a descriptor for an array of primitives |
| * |
| * @param struct_ Struct packing the values |
| * @param field_name_ Field name in the struct |
| * @param max_len_ Maximum number of elements in array |
| * @param len_field_ Field name in the struct for the number of elements |
| * in the array |
| * @param elem_type_ Element type, must be a primitive type |
| * |
| * Here's an example of use: |
| * |
| * struct example { |
| * int foo[10]; |
| * size_t foo_len; |
| * }; |
| * |
| * struct json_obj_descr array[] = { |
| * JSON_OBJ_DESCR_ARRAY(struct example, foo, 10, foo_len, |
| * JSON_TOK_NUMBER) |
| * }; |
| */ |
| #define JSON_OBJ_DESCR_ARRAY(struct_, field_name_, max_len_, \ |
| len_field_, elem_type_) \ |
| { \ |
| .field_name = (#field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = sizeof(#field_name_) - 1, \ |
| .type = JSON_TOK_LIST_START, \ |
| .offset = offsetof(struct_, field_name_), \ |
| { \ |
| .array = { \ |
| .element_descr = (struct json_obj_descr[]) { { \ |
| .align_shift = \ |
| Z_ALIGN_SHIFT(struct_), \ |
| .type = elem_type_, \ |
| .offset = \ |
| offsetof(struct_, \ |
| len_field_), \ |
| } }, \ |
| .n_elements = (max_len_), \ |
| }, \ |
| }, \ |
| } |
| |
| /** |
| * @brief Helper macro to declare a descriptor for an array of objects |
| * |
| * @param struct_ Struct packing the values |
| * @param field_name_ Field name in the struct containing the array |
| * @param max_len_ Maximum number of elements in the array |
| * @param len_field_ Field name in the struct for the number of elements |
| * in the array |
| * @param elem_descr_ Element descriptor, pointer to a descriptor array |
| * @param elem_descr_len_ Number of elements in elem_descr_ |
| * |
| * Here's an example of use: |
| * |
| * struct person_height { |
| * const char *name; |
| * int height; |
| * }; |
| * |
| * struct people_heights { |
| * struct person_height heights[10]; |
| * size_t heights_len; |
| * }; |
| * |
| * struct json_obj_descr person_height_descr[] = { |
| * JSON_OBJ_DESCR_PRIM(struct person_height, name, JSON_TOK_STRING), |
| * JSON_OBJ_DESCR_PRIM(struct person_height, height, JSON_TOK_NUMBER), |
| * }; |
| * |
| * struct json_obj_descr array[] = { |
| * JSON_OBJ_DESCR_OBJ_ARRAY(struct people_heights, heights, 10, |
| * heights_len, person_height_descr, |
| * ARRAY_SIZE(person_height_descr)), |
| * }; |
| */ |
| #define JSON_OBJ_DESCR_OBJ_ARRAY(struct_, field_name_, max_len_, \ |
| len_field_, elem_descr_, elem_descr_len_) \ |
| { \ |
| .field_name = (#field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = sizeof(#field_name_) - 1, \ |
| .type = JSON_TOK_LIST_START, \ |
| .offset = offsetof(struct_, field_name_), \ |
| { \ |
| .array = { \ |
| .element_descr = (struct json_obj_descr[]) { { \ |
| .align_shift = \ |
| Z_ALIGN_SHIFT(struct_), \ |
| .type = JSON_TOK_OBJECT_START, \ |
| .offset = offsetof(struct_, \ |
| len_field_), \ |
| { \ |
| .object = { \ |
| .sub_descr = \ |
| elem_descr_, \ |
| .sub_descr_len = \ |
| elem_descr_len_, \ |
| }, \ |
| }, \ |
| } }, \ |
| .n_elements = (max_len_), \ |
| }, \ |
| }, \ |
| } |
| |
| /** |
| * @brief Helper macro to declare a descriptor for an array of array |
| * |
| * @param struct_ Struct packing the values |
| * @param field_name_ Field name in the struct containing the array |
| * @param max_len_ Maximum number of elements in the array |
| * @param len_field_ Field name in the struct for the number of elements |
| * in the array |
| * @param elem_descr_ Element descriptor, pointer to a descriptor array |
| * @param elem_descr_len_ Number of elements in elem_descr_ |
| * |
| * Here's an example of use: |
| * |
| * struct person_height { |
| * const char *name; |
| * int height; |
| * }; |
| * |
| * struct person_heights_array { |
| * struct person_height heights; |
| * } |
| * |
| * struct people_heights { |
| * struct person_height_array heights[10]; |
| * size_t heights_len; |
| * }; |
| * |
| * struct json_obj_descr person_height_descr[] = { |
| * JSON_OBJ_DESCR_PRIM(struct person_height, name, JSON_TOK_STRING), |
| * JSON_OBJ_DESCR_PRIM(struct person_height, height, JSON_TOK_NUMBER), |
| * }; |
| * |
| * struct json_obj_descr person_height_array_descr[] = { |
| * JSON_OBJ_DESCR_OBJECT(struct person_heights_array, |
| * heights, person_heigth_descr), |
| * }; |
| * |
| * struct json_obj_descr array_array[] = { |
| * JSON_OBJ_DESCR_ARRAY_ARRAY(struct people_heights, heights, 10, |
| * heights_len, person_height_array_descr, |
| * ARRAY_SIZE(person_height_array_descr)), |
| * }; |
| */ |
| #define JSON_OBJ_DESCR_ARRAY_ARRAY(struct_, field_name_, max_len_, len_field_, \ |
| elem_descr_, elem_descr_len_) \ |
| { \ |
| .field_name = (#field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = sizeof(#field_name_) - 1, \ |
| .type = JSON_TOK_LIST_START, \ |
| .offset = offsetof(struct_, field_name_), \ |
| { \ |
| .array = { \ |
| .element_descr = (struct json_obj_descr[]) { { \ |
| .align_shift = \ |
| Z_ALIGN_SHIFT(struct_), \ |
| .type = JSON_TOK_LIST_START, \ |
| .offset = offsetof(struct_, \ |
| len_field_), \ |
| { \ |
| .array = { \ |
| .element_descr = \ |
| elem_descr_, \ |
| .n_elements = \ |
| 1 + \ |
| ZERO_OR_COMPILE_ERROR( \ |
| elem_descr_len_ == 1 \ |
| ), \ |
| }, \ |
| }, \ |
| } }, \ |
| .n_elements = (max_len_), \ |
| }, \ |
| }, \ |
| } |
| |
| /** |
| * @brief Variant of JSON_OBJ_DESCR_PRIM that can be used when the |
| * structure and JSON field names differ. |
| * |
| * This is useful when the JSON field is not a valid C identifier. |
| * |
| * @param struct_ Struct packing the values. |
| * @param json_field_name_ String, field name in JSON strings |
| * @param struct_field_name_ Field name in the struct |
| * @param type_ Token type for JSON value corresponding to a primitive |
| * type. |
| * |
| * @see JSON_OBJ_DESCR_PRIM |
| */ |
| #define JSON_OBJ_DESCR_PRIM_NAMED(struct_, json_field_name_, \ |
| struct_field_name_, type_) \ |
| { \ |
| .field_name = (json_field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = sizeof(json_field_name_) - 1, \ |
| .type = type_, \ |
| .offset = offsetof(struct_, struct_field_name_), \ |
| } |
| |
| /** |
| * @brief Variant of JSON_OBJ_DESCR_OBJECT that can be used when the |
| * structure and JSON field names differ. |
| * |
| * This is useful when the JSON field is not a valid C identifier. |
| * |
| * @param struct_ Struct packing the values |
| * @param json_field_name_ String, field name in JSON strings |
| * @param struct_field_name_ Field name in the struct |
| * @param sub_descr_ Array of json_obj_descr describing the subobject |
| * |
| * @see JSON_OBJ_DESCR_OBJECT |
| */ |
| #define JSON_OBJ_DESCR_OBJECT_NAMED(struct_, json_field_name_, \ |
| struct_field_name_, sub_descr_) \ |
| { \ |
| .field_name = (json_field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = (sizeof(json_field_name_) - 1), \ |
| .type = JSON_TOK_OBJECT_START, \ |
| .offset = offsetof(struct_, struct_field_name_), \ |
| { \ |
| .object = { \ |
| .sub_descr = sub_descr_, \ |
| .sub_descr_len = ARRAY_SIZE(sub_descr_), \ |
| }, \ |
| }, \ |
| } |
| |
| /** |
| * @brief Variant of JSON_OBJ_DESCR_ARRAY that can be used when the |
| * structure and JSON field names differ. |
| * |
| * This is useful when the JSON field is not a valid C identifier. |
| * |
| * @param struct_ Struct packing the values |
| * @param json_field_name_ String, field name in JSON strings |
| * @param struct_field_name_ Field name in the struct |
| * @param max_len_ Maximum number of elements in array |
| * @param len_field_ Field name in the struct for the number of elements |
| * in the array |
| * @param elem_type_ Element type, must be a primitive type |
| * |
| * @see JSON_OBJ_DESCR_ARRAY |
| */ |
| #define JSON_OBJ_DESCR_ARRAY_NAMED(struct_, json_field_name_,\ |
| struct_field_name_, max_len_, len_field_, \ |
| elem_type_) \ |
| { \ |
| .field_name = (json_field_name_), \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = sizeof(json_field_name_) - 1, \ |
| .type = JSON_TOK_LIST_START, \ |
| .offset = offsetof(struct_, struct_field_name_), \ |
| { \ |
| .array = { \ |
| .element_descr = (struct json_obj_descr[]) { { \ |
| .align_shift = \ |
| Z_ALIGN_SHIFT(struct_), \ |
| .type = elem_type_, \ |
| .offset = offsetof(struct_, \ |
| len_field_), \ |
| } }, \ |
| .n_elements = (max_len_), \ |
| }, \ |
| }, \ |
| } |
| |
| /** |
| * @brief Variant of JSON_OBJ_DESCR_OBJ_ARRAY that can be used when |
| * the structure and JSON field names differ. |
| * |
| * This is useful when the JSON field is not a valid C identifier. |
| * |
| * @param struct_ Struct packing the values |
| * @param json_field_name_ String, field name of the array in JSON strings |
| * @param struct_field_name_ Field name in the struct containing the array |
| * @param max_len_ Maximum number of elements in the array |
| * @param len_field_ Field name in the struct for the number of elements |
| * in the array |
| * @param elem_descr_ Element descriptor, pointer to a descriptor array |
| * @param elem_descr_len_ Number of elements in elem_descr_ |
| * |
| * Here's an example of use: |
| * |
| * struct person_height { |
| * const char *name; |
| * int height; |
| * }; |
| * |
| * struct people_heights { |
| * struct person_height heights[10]; |
| * size_t heights_len; |
| * }; |
| * |
| * struct json_obj_descr person_height_descr[] = { |
| * JSON_OBJ_DESCR_PRIM(struct person_height, name, JSON_TOK_STRING), |
| * JSON_OBJ_DESCR_PRIM(struct person_height, height, JSON_TOK_NUMBER), |
| * }; |
| * |
| * struct json_obj_descr array[] = { |
| * JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct people_heights, |
| * "people-heights", heights, |
| * 10, heights_len, |
| * person_height_descr, |
| * ARRAY_SIZE(person_height_descr)), |
| * }; |
| */ |
| #define JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct_, json_field_name_, \ |
| struct_field_name_, max_len_, \ |
| len_field_, elem_descr_, \ |
| elem_descr_len_) \ |
| { \ |
| .field_name = json_field_name_, \ |
| .align_shift = Z_ALIGN_SHIFT(struct_), \ |
| .field_name_len = sizeof(json_field_name_) - 1, \ |
| .type = JSON_TOK_LIST_START, \ |
| .offset = offsetof(struct_, struct_field_name_), \ |
| { \ |
| .array = { \ |
| .element_descr = (struct json_obj_descr[]) { { \ |
| .align_shift = \ |
| Z_ALIGN_SHIFT(struct_), \ |
| .type = JSON_TOK_OBJECT_START, \ |
| .offset = offsetof(struct_, \ |
| len_field_), \ |
| { \ |
| .object = { \ |
| .sub_descr = \ |
| elem_descr_, \ |
| .sub_descr_len = \ |
| elem_descr_len_, \ |
| }, \ |
| }, \ |
| } }, \ |
| .n_elements = (max_len_), \ |
| }, \ |
| }, \ |
| } |
| |
| /** |
| * @brief Parses the JSON-encoded object pointer to by @a json, with |
| * size @a len, according to the descriptor pointed to by @a descr. |
| * Values are stored in a struct pointed to by @a val. Set up the |
| * descriptor like this: |
| * |
| * struct s { int foo; char *bar; } |
| * struct json_obj_descr descr[] = { |
| * JSON_OBJ_DESCR_PRIM(struct s, foo, JSON_TOK_NUMBER), |
| * JSON_OBJ_DESCR_PRIM(struct s, bar, JSON_TOK_STRING), |
| * }; |
| * |
| * Since this parser is designed for machine-to-machine communications, some |
| * liberties were taken to simplify the design: |
| * (1) strings are not unescaped (but only valid escape sequences are |
| * accepted); |
| * (2) no UTF-8 validation is performed; and |
| * (3) only integer numbers are supported (no strtod() in the minimal libc). |
| * |
| * @param json Pointer to JSON-encoded value to be parsed |
| * @param len Length of JSON-encoded value |
| * @param descr Pointer to the descriptor array |
| * @param descr_len Number of elements in the descriptor array. Must be less |
| * than 31 due to implementation detail reasons (if more fields are |
| * necessary, use two descriptors) |
| * @param val Pointer to the struct to hold the decoded values |
| * |
| * @return < 0 if error, bitmap of decoded fields on success (bit 0 |
| * is set if first field in the descriptor has been properly decoded, etc). |
| */ |
| int json_obj_parse(char *json, size_t len, |
| const struct json_obj_descr *descr, size_t descr_len, |
| void *val); |
| |
| /** |
| * @brief Escapes the string so it can be used to encode JSON objects |
| * |
| * @param str The string to escape; the escape string is stored the |
| * buffer pointed to by this parameter |
| * @param len Points to a size_t containing the size before and after |
| * the escaping process |
| * @param buf_size The size of buffer str points to |
| * |
| * @return 0 if string has been escaped properly, or -ENOMEM if there |
| * was not enough space to escape the buffer |
| */ |
| ssize_t json_escape(char *str, size_t *len, size_t buf_size); |
| |
| /** |
| * @brief Calculates the JSON-escaped string length |
| * |
| * @param str The string to analyze |
| * @param len String size |
| * |
| * @return The length str would have if it were escaped |
| */ |
| size_t json_calc_escaped_len(const char *str, size_t len); |
| |
| /** |
| * @brief Calculates the string length to fully encode an object |
| * |
| * @param descr Pointer to the descriptor array |
| * @param descr_len Number of elements in the descriptor array |
| * @param val Struct holding the values |
| * |
| * @return Number of bytes necessary to encode the values if >0, |
| * an error code is returned. |
| */ |
| ssize_t json_calc_encoded_len(const struct json_obj_descr *descr, |
| size_t descr_len, const void *val); |
| |
| /** |
| * @brief Encodes an object in a contiguous memory location |
| * |
| * @param descr Pointer to the descriptor array |
| * @param descr_len Number of elements in the descriptor array |
| * @param val Struct holding the values |
| * @param buffer Buffer to store the JSON data |
| * @param buf_size Size of buffer, in bytes, with space for the terminating |
| * NUL character |
| * |
| * @return 0 if object has been successfully encoded. A negative value |
| * indicates an error (as defined on errno.h). |
| */ |
| int json_obj_encode_buf(const struct json_obj_descr *descr, size_t descr_len, |
| const void *val, char *buffer, size_t buf_size); |
| |
| /** |
| * @brief Encodes an array in a contiguous memory location |
| * |
| * @param descr Pointer to the descriptor array |
| * @param val Struct holding the values |
| * @param buffer Buffer to store the JSON data |
| * @param buf_size Size of buffer, in bytes, with space for the terminating |
| * NUL character |
| * |
| * @return 0 if object has been successfully encoded. A negative value |
| * indicates an error (as defined on errno.h). |
| */ |
| int json_arr_encode_buf(const struct json_obj_descr *descr, const void *val, |
| char *buffer, size_t buf_size); |
| |
| /** |
| * @brief Encodes an object using an arbitrary writer function |
| * |
| * @param descr Pointer to the descriptor array |
| * @param descr_len Number of elements in the descriptor array |
| * @param val Struct holding the values |
| * @param append_bytes Function to append bytes to the output |
| * @param data Data pointer to be passed to the append_bytes callback |
| * function. |
| * |
| * @return 0 if object has been successfully encoded. A negative value |
| * indicates an error. |
| */ |
| int json_obj_encode(const struct json_obj_descr *descr, size_t descr_len, |
| const void *val, json_append_bytes_t append_bytes, |
| void *data); |
| |
| /** |
| * @brief Encodes an array using an arbitrary writer function |
| * |
| * @param descr Pointer to the descriptor array |
| * @param val Struct holding the values |
| * @param append_bytes Function to append bytes to the output |
| * @param data Data pointer to be passed to the append_bytes callback |
| * function. |
| * |
| * @return 0 if object has been successfully encoded. A negative value |
| * indicates an error. |
| */ |
| int json_arr_encode(const struct json_obj_descr *descr, const void *val, |
| json_append_bytes_t append_bytes, void *data); |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| /** |
| * @} |
| */ |
| #endif /* ZEPHYR_INCLUDE_DATA_JSON_H_ */ |
