1 /* 2 * Copyright (c) 2016 Alexadru Ardelean. 3 * 4 * This is free software; you can redistribute it and/or modify 5 * it under the terms of the MIT license. See COPYING for details. 6 * 7 */ 8 9 /** 10 * @file 11 * @brief JSON Pointer (RFC 6901) implementation for retrieving 12 * objects from a json-c object tree. 13 */ 14 #ifndef _json_pointer_h_ 15 #define _json_pointer_h_ 16 17 #include "json_object.h" 18 19 #ifdef __cplusplus 20 extern "C" { 21 #endif 22 23 /** 24 * Retrieves a JSON sub-object from inside another JSON object 25 * using the JSON pointer notation as defined in RFC 6901 26 * https://tools.ietf.org/html/rfc6901 27 * 28 * The returned JSON sub-object is equivalent to parsing manually the 29 * 'obj' JSON tree ; i.e. it's not a new object that is created, but rather 30 * a pointer inside the JSON tree. 31 * 32 * Internally, this is equivalent to doing a series of 'json_object_object_get()' 33 * and 'json_object_array_get_idx()' along the given 'path'. 34 * 35 * Note that the 'path' string supports 'printf()' type arguments, so, whatever 36 * is added after the 'res' param will be treated as an argument for 'path' 37 * Example: json_pointer_get(obj, "/foo/%d/%s", &res, 0, bar) 38 * This means, that you need to escape '%' with '%%' (just like in printf()) 39 * 40 * @param obj the json_object instance/tree from where to retrieve sub-objects 41 * @param path a (RFC6901) string notation for the sub-object to retrieve 42 * @param res a pointer that stores a reference to the json_object 43 * associated with the given path 44 * 45 * @return negative if an error (or not found), or 0 if succeeded 46 */ 47 JSON_EXPORT int json_pointer_get(struct json_object *obj, const char *path, struct json_object **res); 48 49 /** 50 * This is a variant of 'json_pointer_get()' that supports printf() style arguments. 51 * 52 * Example: json_pointer_getf(obj, res, "/foo/%d/%s", 0, bak) 53 * This also means that you need to escape '%' with '%%' (just like in printf()) 54 * 55 * Please take into consideration all recommended 'printf()' format security 56 * aspects when using this function. 57 * 58 * @param obj the json_object instance/tree to which to add a sub-object 59 * @param res a pointer that stores a reference to the json_object 60 * associated with the given path 61 * @param path_fmt a printf() style format for the path 62 * 63 * @return negative if an error (or not found), or 0 if succeeded 64 */ 65 JSON_EXPORT int json_pointer_getf(struct json_object *obj, struct json_object **res, const char *path_fmt, ...); 66 67 /** 68 * Sets JSON object 'value' in the 'obj' tree at the location specified 69 * by the 'path'. 'path' is JSON pointer notation as defined in RFC 6901 70 * https://tools.ietf.org/html/rfc6901 71 * 72 * Note that 'obj' is a double pointer, mostly for the "" (empty string) 73 * case, where the entire JSON object would be replaced by 'value'. 74 * In the case of the "" path, the object at '*obj' will have it's refcount 75 * decremented with 'json_object_put()' and the 'value' object will be assigned to it. 76 * 77 * For other cases (JSON sub-objects) ownership of 'value' will be transferred into 78 * '*obj' via 'json_object_object_add()' & 'json_object_array_put_idx()', so the 79 * only time the refcount should be decremented for 'value' is when the return value of 80 * 'json_pointer_set()' is negative (meaning the 'value' object did not get set into '*obj'). 81 * 82 * That also implies that 'json_pointer_set()' does not do any refcount incrementing. 83 * (Just that single decrement that was mentioned above). 84 * 85 * Note that the 'path' string supports 'printf()' type arguments, so, whatever 86 * is added after the 'value' param will be treated as an argument for 'path' 87 * Example: json_pointer_set(obj, "/foo/%d/%s", value, 0, bak) 88 * This means, that you need to escape '%' with '%%' (just like in printf()) 89 * 90 * @param obj the json_object instance/tree to which to add a sub-object 91 * @param path a (RFC6901) string notation for the sub-object to set in the tree 92 * @param value object to set at path 93 * 94 * @return negative if an error (or not found), or 0 if succeeded 95 */ 96 JSON_EXPORT int json_pointer_set(struct json_object **obj, const char *path, struct json_object *value); 97 98 /** 99 * This is a variant of 'json_pointer_set()' that supports printf() style arguments. 100 * 101 * Example: json_pointer_setf(obj, value, "/foo/%d/%s", 0, bak) 102 * This also means that you need to escape '%' with '%%' (just like in printf()) 103 * 104 * Please take into consideration all recommended 'printf()' format security 105 * aspects when using this function. 106 * 107 * @param obj the json_object instance/tree to which to add a sub-object 108 * @param value object to set at path 109 * @param path_fmt a printf() style format for the path 110 * 111 * @return negative if an error (or not found), or 0 if succeeded 112 */ 113 JSON_EXPORT int json_pointer_setf(struct json_object **obj, struct json_object *value, const char *path_fmt, ...); 114 115 116 #ifdef __cplusplus 117 } 118 #endif 119 120 #endif 121