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Sources/json-c/json_object.h

  1 /*
  2  * $Id: json_object.h,v 1.12 2006/01/30 23:07:57 mclark Exp $
  3  *
  4  * Copyright (c) 2004, 2005 Metaparadigm Pte. Ltd.
  5  * Michael Clark <michael@metaparadigm.com>
  6  * Copyright (c) 2009 Hewlett-Packard Development Company, L.P.
  7  *
  8  * This library is free software; you can redistribute it and/or modify
  9  * it under the terms of the MIT license. See COPYING for details.
 10  *
 11  */
 12 
 13 /**
 14  * @file
 15  * @brief Core json-c API.  Start here, or with json_tokener.h
 16  */
 17 #ifndef _json_object_h_
 18 #define _json_object_h_
 19 
 20 #ifdef __GNUC__
 21 #define JSON_C_CONST_FUNCTION(func) func __attribute__((const))
 22 #else
 23 #define JSON_C_CONST_FUNCTION(func) func
 24 #endif
 25 
 26 #include "json_inttypes.h"
 27 #include "json_types.h"
 28 #include "printbuf.h"
 29 
 30 #include <stddef.h>
 31 
 32 #ifdef __cplusplus
 33 extern "C" {
 34 #endif
 35 
 36 #define JSON_OBJECT_DEF_HASH_ENTRIES 16
 37 
 38 /**
 39  * A flag for the json_object_to_json_string_ext() and
 40  * json_object_to_file_ext() functions which causes the output
 41  * to have no extra whitespace or formatting applied.
 42  */
 43 #define JSON_C_TO_STRING_PLAIN 0
 44 /**
 45  * A flag for the json_object_to_json_string_ext() and
 46  * json_object_to_file_ext() functions which causes the output to have
 47  * minimal whitespace inserted to make things slightly more readable.
 48  */
 49 #define JSON_C_TO_STRING_SPACED (1 << 0)
 50 /**
 51  * A flag for the json_object_to_json_string_ext() and
 52  * json_object_to_file_ext() functions which causes
 53  * the output to be formatted.
 54  *
 55  * See the "Two Space Tab" option at http://jsonformatter.curiousconcept.com/
 56  * for an example of the format.
 57  */
 58 #define JSON_C_TO_STRING_PRETTY (1 << 1)
 59 /**
 60  * A flag for the json_object_to_json_string_ext() and
 61  * json_object_to_file_ext() functions which causes
 62  * the output to be formatted.
 63  *
 64  * Instead of a "Two Space Tab" this gives a single tab character.
 65  */
 66 #define JSON_C_TO_STRING_PRETTY_TAB (1 << 3)
 67 /**
 68  * A flag to drop trailing zero for float values
 69  */
 70 #define JSON_C_TO_STRING_NOZERO (1 << 2)
 71 
 72 /**
 73  * Don't escape forward slashes.
 74  */
 75 #define JSON_C_TO_STRING_NOSLASHESCAPE (1 << 4)
 76 
 77 /**
 78  * A flag for the json_object_object_add_ex function which
 79  * causes the value to be added without a check if it already exists.
 80  * Note: it is the responsibility of the caller to ensure that no
 81  * key is added multiple times. If this is done, results are
 82  * unpredictable. While this option is somewhat dangerous, it
 83  * permits potentially large performance savings in code that
 84  * knows for sure the key values are unique (e.g. because the
 85  * code adds a well-known set of constant key values).
 86  */
 87 #define JSON_C_OBJECT_ADD_KEY_IS_NEW (1 << 1)
 88 /**
 89  * A flag for the json_object_object_add_ex function which
 90  * flags the key as being constant memory. This means that
 91  * the key will NOT be copied via strdup(), resulting in a
 92  * potentially huge performance win (malloc, strdup and
 93  * free are usually performance hogs). It is acceptable to
 94  * use this flag for keys in non-constant memory blocks if
 95  * the caller ensure that the memory holding the key lives
 96  * longer than the corresponding json object. However, this
 97  * is somewhat dangerous and should only be done if really
 98  * justified.
 99  * The general use-case for this flag is cases where the
100  * key is given as a real constant value in the function
101  * call, e.g. as in
102  *   json_object_object_add_ex(obj, "ip", json,
103  *       JSON_C_OBJECT_KEY_IS_CONSTANT);
104  */
105 #define JSON_C_OBJECT_KEY_IS_CONSTANT (1 << 2)
106 
107 /**
108  * Set the global value of an option, which will apply to all
109  * current and future threads that have not set a thread-local value.
110  *
111  * @see json_c_set_serialization_double_format
112  */
113 #define JSON_C_OPTION_GLOBAL (0)
114 /**
115  * Set a thread-local value of an option, overriding the global value.
116  * This will fail if json-c is not compiled with threading enabled, and
117  * with the __thread specifier (or equivalent) available.
118  *
119  * @see json_c_set_serialization_double_format
120  */
121 #define JSON_C_OPTION_THREAD (1)
122 
123 /* reference counting functions */
124 
125 /**
126  * Increment the reference count of json_object, thereby taking ownership of it.
127  *
128  * Cases where you might need to increase the refcount include:
129  * - Using an object field or array index (retrieved through
130  *    `json_object_object_get()` or `json_object_array_get_idx()`)
131  *    beyond the lifetime of the parent object.
132  * - Detaching an object field or array index from its parent object
133  *    (using `json_object_object_del()` or `json_object_array_del_idx()`)
134  * - Sharing a json_object with multiple (not necesarily parallel) threads
135  *    of execution that all expect to free it (with `json_object_put()`) when
136  *    they're done.
137  *
138  * @param obj the json_object instance
139  * @see json_object_put()
140  * @see json_object_object_get()
141  * @see json_object_array_get_idx()
142  */
143 JSON_EXPORT struct json_object *json_object_get(struct json_object *obj);
144 
145 /**
146  * Decrement the reference count of json_object and free if it reaches zero.
147  *
148  * You must have ownership of obj prior to doing this or you will cause an
149  * imbalance in the reference count, leading to a classic use-after-free bug.
150  * In particular, you normally do not need to call `json_object_put()` on the
151  * json_object returned by `json_object_object_get()` or `json_object_array_get_idx()`.
152  *
153  * Just like after calling `free()` on a block of memory, you must not use
154  * `obj` after calling `json_object_put()` on it or any object that it
155  * is a member of (unless you know you've called `json_object_get(obj)` to
156  * explicitly increment the refcount).
157  *
158  * NULL may be passed, which which case this is a no-op.
159  *
160  * @param obj the json_object instance
161  * @returns 1 if the object was freed.
162  * @see json_object_get()
163  */
164 JSON_EXPORT int json_object_put(struct json_object *obj);
165 
166 /**
167  * Check if the json_object is of a given type
168  * @param obj the json_object instance
169  * @param type one of:
170      json_type_null (i.e. obj == NULL),
171      json_type_boolean,
172      json_type_double,
173      json_type_int,
174      json_type_object,
175      json_type_array,
176      json_type_string
177  */
178 JSON_EXPORT int json_object_is_type(const struct json_object *obj, enum json_type type);
179 
180 /**
181  * Get the type of the json_object.  See also json_type_to_name() to turn this
182  * into a string suitable, for instance, for logging.
183  *
184  * @param obj the json_object instance
185  * @returns type being one of:
186      json_type_null (i.e. obj == NULL),
187      json_type_boolean,
188      json_type_double,
189      json_type_int,
190      json_type_object,
191      json_type_array,
192      json_type_string
193  */
194 JSON_EXPORT enum json_type json_object_get_type(const struct json_object *obj);
195 
196 /** Stringify object to json format.
197  * Equivalent to json_object_to_json_string_ext(obj, JSON_C_TO_STRING_SPACED)
198  * The pointer you get is an internal of your json object. You don't
199  * have to free it, later use of json_object_put() should be sufficient.
200  * If you can not ensure there's no concurrent access to *obj use
201  * strdup().
202  * @param obj the json_object instance
203  * @returns a string in JSON format
204  */
205 JSON_EXPORT const char *json_object_to_json_string(struct json_object *obj);
206 
207 /** Stringify object to json format
208  * @see json_object_to_json_string() for details on how to free string.
209  * @param obj the json_object instance
210  * @param flags formatting options, see JSON_C_TO_STRING_PRETTY and other constants
211  * @returns a string in JSON format
212  */
213 JSON_EXPORT const char *json_object_to_json_string_ext(struct json_object *obj, int flags);
214 
215 /** Stringify object to json format
216  * @see json_object_to_json_string() for details on how to free string.
217  * @param obj the json_object instance
218  * @param flags formatting options, see JSON_C_TO_STRING_PRETTY and other constants
219  * @param length a pointer where, if not NULL, the length (without null) is stored
220  * @returns a string in JSON format and the length if not NULL
221  */
222 JSON_EXPORT const char *json_object_to_json_string_length(struct json_object *obj, int flags,
223                                                           size_t *length);
224 
225 /**
226  * Returns the userdata set by json_object_set_userdata() or
227  * json_object_set_serializer()
228  *
229  * @param jso the object to return the userdata for
230  */
231 JSON_EXPORT void *json_object_get_userdata(json_object *jso);
232 
233 /**
234  * Set an opaque userdata value for an object
235  *
236  * The userdata can be retrieved using json_object_get_userdata().
237  *
238  * If custom userdata is already set on this object, any existing user_delete
239  * function is called before the new one is set.
240  *
241  * The user_delete parameter is optional and may be passed as NULL, even if
242  * the userdata parameter is non-NULL.  It will be called just before the
243  * json_object is deleted, after it's reference count goes to zero
244  * (see json_object_put()).
245  * If this is not provided, it is up to the caller to free the userdata at
246  * an appropriate time. (i.e. after the json_object is deleted)
247  *
248  * Note: Objects created by parsing strings may have custom serializers set
249  * which expect the userdata to contain specific data (due to use of
250  * json_object_new_double_s()). In this case, json_object_set_serialiser() with
251  * NULL as to_string_func should be used instead to set the userdata and reset
252  * the serializer to its default value.
253  *
254  * @param jso the object to set the userdata for
255  * @param userdata an optional opaque cookie
256  * @param user_delete an optional function from freeing userdata
257  */
258 JSON_EXPORT void json_object_set_userdata(json_object *jso, void *userdata,
259                                           json_object_delete_fn *user_delete);
260 
261 /**
262  * Set a custom serialization function to be used when this particular object
263  * is converted to a string by json_object_to_json_string.
264  *
265  * If custom userdata is already set on this object, any existing user_delete
266  * function is called before the new one is set.
267  *
268  * If to_string_func is NULL the default behaviour is reset (but the userdata
269  * and user_delete fields are still set).
270  *
271  * The userdata parameter is optional and may be passed as NULL. It can be used
272  * to provide additional data for to_string_func to use. This parameter may
273  * be NULL even if user_delete is non-NULL.
274  *
275  * The user_delete parameter is optional and may be passed as NULL, even if
276  * the userdata parameter is non-NULL.  It will be called just before the
277  * json_object is deleted, after it's reference count goes to zero
278  * (see json_object_put()).
279  * If this is not provided, it is up to the caller to free the userdata at
280  * an appropriate time. (i.e. after the json_object is deleted)
281  *
282  * Note that the userdata is the same as set by json_object_set_userdata(), so
283  * care must be taken not to overwrite the value when both a custom serializer
284  * and json_object_set_userdata() are used.
285  *
286  * @param jso the object to customize
287  * @param to_string_func the custom serialization function
288  * @param userdata an optional opaque cookie
289  * @param user_delete an optional function from freeing userdata
290  */
291 JSON_EXPORT void json_object_set_serializer(json_object *jso,
292                                             json_object_to_json_string_fn *to_string_func,
293                                             void *userdata, json_object_delete_fn *user_delete);
294 
295 #ifdef __clang__
296 /*
297  * Clang doesn't pay attention to the parameters defined in the
298  * function typedefs used here, so turn off spurious doc warnings.
299  * {
300  */
301 #pragma clang diagnostic push
302 #pragma clang diagnostic ignored "-Wdocumentation"
303 #endif
304 
305 /**
306  * Simply call free on the userdata pointer.
307  * Can be used with json_object_set_serializer().
308  *
309  * @param jso unused
310  * @param userdata the pointer that is passed to free().
311  */
312 JSON_EXPORT json_object_delete_fn json_object_free_userdata;
313 
314 /**
315  * Copy the jso->_userdata string over to pb as-is.
316  * Can be used with json_object_set_serializer().
317  *
318  * @param jso The object whose _userdata is used.
319  * @param pb The destination buffer.
320  * @param level Ignored.
321  * @param flags Ignored.
322  */
323 JSON_EXPORT json_object_to_json_string_fn json_object_userdata_to_json_string;
324 
325 #ifdef __clang__
326 /* } */
327 #pragma clang diagnostic pop
328 #endif
329 
330 /* object type methods */
331 
332 /** Create a new empty object with a reference count of 1.  The caller of
333  * this object initially has sole ownership.  Remember, when using
334  * json_object_object_add or json_object_array_put_idx, ownership will
335  * transfer to the object/array.  Call json_object_get if you want to maintain
336  * shared ownership or also add this object as a child of multiple objects or
337  * arrays.  Any ownerships you acquired but did not transfer must be released
338  * through json_object_put.
339  *
340  * @returns a json_object of type json_type_object
341  */
342 JSON_EXPORT struct json_object *json_object_new_object(void);
343 
344 /** Get the hashtable of a json_object of type json_type_object
345  * @param obj the json_object instance
346  * @returns a linkhash
347  */
348 JSON_EXPORT struct lh_table *json_object_get_object(const struct json_object *obj);
349 
350 /** Get the size of an object in terms of the number of fields it has.
351  * @param obj the json_object whose length to return
352  */
353 JSON_EXPORT int json_object_object_length(const struct json_object *obj);
354 
355 /** Get the sizeof (struct json_object).
356  * @returns a size_t with the sizeof (struct json_object)
357  */
358 JSON_C_CONST_FUNCTION(JSON_EXPORT size_t json_c_object_sizeof(void));
359 
360 /** Add an object field to a json_object of type json_type_object
361  *
362  * The reference count of `val` will *not* be incremented, in effect
363  * transferring ownership that object to `obj`, and thus `val` will be
364  * freed when `obj` is.  (i.e. through `json_object_put(obj)`)
365  *
366  * If you want to retain a reference to the added object, independent
367  * of the lifetime of obj, you must increment the refcount with
368  * `json_object_get(val)` (and later release it with json_object_put()).
369  *
370  * Since ownership transfers to `obj`, you must make sure
371  * that you do in fact have ownership over `val`.  For instance,
372  * json_object_new_object() will give you ownership until you transfer it,
373  * whereas json_object_object_get() does not.
374  *
375  * Any previous object stored under `key` in `obj` will have its refcount
376  * decremented, and be freed normally if that drops to zero.
377  *
378  * @param obj the json_object instance
379  * @param key the object field name (a private copy will be duplicated)
380  * @param val a json_object or NULL member to associate with the given field
381  *
382  * @return On success, <code>0</code> is returned.
383  *      On error, a negative value is returned.
384  */
385 JSON_EXPORT int json_object_object_add(struct json_object *obj, const char *key,
386                                        struct json_object *val);
387 
388 /** Add an object field to a json_object of type json_type_object
389  *
390  * The semantics are identical to json_object_object_add, except that an
391  * additional flag fields gives you more control over some detail aspects
392  * of processing. See the description of JSON_C_OBJECT_ADD_* flags for more
393  * details.
394  *
395  * @param obj the json_object instance
396  * @param key the object field name (a private copy will be duplicated)
397  * @param val a json_object or NULL member to associate with the given field
398  * @param opts process-modifying options. To specify multiple options, use
399  *             (OPT1|OPT2)
400  */
401 JSON_EXPORT int json_object_object_add_ex(struct json_object *obj, const char *const key,
402                                           struct json_object *const val, const unsigned opts);
403 
404 /** Get the json_object associate with a given object field.
405  * Deprecated/discouraged: used json_object_object_get_ex instead.
406  *
407  * This returns NULL if the field is found but its value is null, or if
408  *  the field is not found, or if obj is not a json_type_object.  If you
409  *  need to distinguish between these cases, use json_object_object_get_ex().
410  *
411  * *No* reference counts will be changed.  There is no need to manually adjust
412  * reference counts through the json_object_put/json_object_get methods unless
413  * you need to have the child (value) reference maintain a different lifetime
414  * than the owning parent (obj). Ownership of the returned value is retained
415  * by obj (do not do json_object_put unless you have done a json_object_get).
416  * If you delete the value from obj (json_object_object_del) and wish to access
417  * the returned reference afterwards, make sure you have first gotten shared
418  * ownership through json_object_get (& don't forget to do a json_object_put
419  * or transfer ownership to prevent a memory leak).
420  *
421  * @param obj the json_object instance
422  * @param key the object field name
423  * @returns the json_object associated with the given field name
424  */
425 JSON_EXPORT struct json_object *json_object_object_get(const struct json_object *obj,
426                                                        const char *key);
427 
428 /** Get the json_object associated with a given object field.
429  *
430  * This returns true if the key is found, false in all other cases (including
431  * if obj isn't a json_type_object).
432  *
433  * *No* reference counts will be changed.  There is no need to manually adjust
434  * reference counts through the json_object_put/json_object_get methods unless
435  * you need to have the child (value) reference maintain a different lifetime
436  * than the owning parent (obj).  Ownership of value is retained by obj.
437  *
438  * @param obj the json_object instance
439  * @param key the object field name
440  * @param value a pointer where to store a reference to the json_object
441  *              associated with the given field name.
442  *
443  *              It is safe to pass a NULL value.
444  * @returns whether or not the key exists
445  */
446 JSON_EXPORT json_bool json_object_object_get_ex(const struct json_object *obj, const char *key,
447                                                 struct json_object **value);
448 
449 /** Delete the given json_object field
450  *
451  * The reference count will be decremented for the deleted object.  If there
452  * are no more owners of the value represented by this key, then the value is
453  * freed.  Otherwise, the reference to the value will remain in memory.
454  *
455  * @param obj the json_object instance
456  * @param key the object field name
457  */
458 JSON_EXPORT void json_object_object_del(struct json_object *obj, const char *key);
459 
460 /**
461  * Iterate through all keys and values of an object.
462  *
463  * Adding keys to the object while iterating is NOT allowed.
464  *
465  * Deleting an existing key, or replacing an existing key with a
466  * new value IS allowed.
467  *
468  * @param obj the json_object instance
469  * @param key the local name for the char* key variable defined in the body
470  * @param val the local name for the json_object* object variable defined in
471  *            the body
472  */
473 #if defined(__GNUC__) && !defined(__STRICT_ANSI__) && __STDC_VERSION__ >= 199901L
474 
475 #define json_object_object_foreach(obj, key, val)                                \
476         char *key = NULL;                                                        \
477         struct json_object *val __attribute__((__unused__)) = NULL;              \
478         for (struct lh_entry *entry##key = json_object_get_object(obj)->head,    \
479                              *entry_next##key = NULL;                            \
480              ({                                                                  \
481                      if (entry##key)                                             \
482                      {                                                           \
483                              key = (char *)lh_entry_k(entry##key);               \
484                              val = (struct json_object *)lh_entry_v(entry##key); \
485                              entry_next##key = entry##key->next;                 \
486                      };                                                          \
487                      entry##key;                                                 \
488              });                                                                 \
489              entry##key = entry_next##key)
490 
491 #else /* ANSI C or MSC */
492 
493 #define json_object_object_foreach(obj, key, val)                              \
494         char *key = NULL;                                                      \
495         struct json_object *val = NULL;                                        \
496         struct lh_entry *entry##key;                                           \
497         struct lh_entry *entry_next##key = NULL;                               \
498         for (entry##key = json_object_get_object(obj)->head;                   \
499              (entry##key ? (key = (char *)lh_entry_k(entry##key),              \
500                            val = (struct json_object *)lh_entry_v(entry##key), \
501                            entry_next##key = entry##key->next, entry##key)     \
502                          : 0);                                                 \
503              entry##key = entry_next##key)
504 
505 #endif /* defined(__GNUC__) && !defined(__STRICT_ANSI__) && __STDC_VERSION__ >= 199901L */
506 
507 /** Iterate through all keys and values of an object (ANSI C Safe)
508  * @param obj the json_object instance
509  * @param iter the object iterator, use type json_object_iter
510  */
511 #define json_object_object_foreachC(obj, iter)                                                  \
512         for (iter.entry = json_object_get_object(obj)->head;                                    \
513              (iter.entry ? (iter.key = (char *)lh_entry_k(iter.entry),                          \
514                            iter.val = (struct json_object *)lh_entry_v(iter.entry), iter.entry) \
515                          : 0);                                                                  \
516              iter.entry = iter.entry->next)
517 
518 /* Array type methods */
519 
520 /** Create a new empty json_object of type json_type_array
521  * with 32 slots allocated.
522  * If you know the array size you'll need ahead of time, use
523  * json_object_new_array_ext() instead.
524  * @see json_object_new_array_ext()
525  * @see json_object_array_shrink()
526  * @returns a json_object of type json_type_array
527  */
528 JSON_EXPORT struct json_object *json_object_new_array(void);
529 
530 /** Create a new empty json_object of type json_type_array
531  * with the desired number of slots allocated.
532  * @see json_object_array_shrink()
533  * @param initial_size the number of slots to allocate
534  * @returns a json_object of type json_type_array
535  */
536 JSON_EXPORT struct json_object *json_object_new_array_ext(int initial_size);
537 
538 /** Get the arraylist of a json_object of type json_type_array
539  * @param obj the json_object instance
540  * @returns an arraylist
541  */
542 JSON_EXPORT struct array_list *json_object_get_array(const struct json_object *obj);
543 
544 /** Get the length of a json_object of type json_type_array
545  * @param obj the json_object instance
546  * @returns an int
547  */
548 JSON_EXPORT size_t json_object_array_length(const struct json_object *obj);
549 
550 /** Sorts the elements of jso of type json_type_array
551 *
552 * Pointers to the json_object pointers will be passed as the two arguments
553 * to sort_fn
554 *
555 * @param jso the json_object instance
556 * @param sort_fn a sorting function
557 */
558 JSON_EXPORT void json_object_array_sort(struct json_object *jso,
559                                         int (*sort_fn)(const void *, const void *));
560 
561 /** Binary search a sorted array for a specified key object.
562  *
563  * It depends on your compare function what's sufficient as a key.
564  * Usually you create some dummy object with the parameter compared in
565  * it, to identify the right item you're actually looking for.
566  *
567  * @see json_object_array_sort() for hints on the compare function.
568  *
569  * @param key a dummy json_object with the right key
570  * @param jso the array object we're searching
571  * @param sort_fn the sort/compare function
572  *
573  * @return the wanted json_object instance
574  */
575 JSON_EXPORT struct json_object *
576 json_object_array_bsearch(const struct json_object *key, const struct json_object *jso,
577                           int (*sort_fn)(const void *, const void *));
578 
579 /** Add an element to the end of a json_object of type json_type_array
580  *
581  * The reference count will *not* be incremented. This is to make adding
582  * fields to objects in code more compact. If you want to retain a reference
583  * to an added object you must wrap the passed object with json_object_get
584  *
585  * @param obj the json_object instance
586  * @param val the json_object to be added
587  */
588 JSON_EXPORT int json_object_array_add(struct json_object *obj, struct json_object *val);
589 
590 /** Insert or replace an element at a specified index in an array (a json_object of type json_type_array)
591  *
592  * The reference count will *not* be incremented. This is to make adding
593  * fields to objects in code more compact. If you want to retain a reference
594  * to an added object you must wrap the passed object with json_object_get
595  *
596  * The reference count of a replaced object will be decremented.
597  *
598  * The array size will be automatically be expanded to the size of the
599  * index if the index is larger than the current size.
600  *
601  * @param obj the json_object instance
602  * @param idx the index to insert the element at
603  * @param val the json_object to be added
604  */
605 JSON_EXPORT int json_object_array_put_idx(struct json_object *obj, size_t idx,
606                                           struct json_object *val);
607 
608 /** Get the element at specified index of array `obj` (which must be a json_object of type json_type_array)
609  *
610  * *No* reference counts will be changed, and ownership of the returned
611  * object remains with `obj`.  See json_object_object_get() for additional
612  * implications of this behavior.
613  *
614  * Calling this with anything other than a json_type_array will trigger
615  * an assert.
616  *
617  * @param obj the json_object instance
618  * @param idx the index to get the element at
619  * @returns the json_object at the specified index (or NULL)
620  */
621 JSON_EXPORT struct json_object *json_object_array_get_idx(const struct json_object *obj,
622                                                           size_t idx);
623 
624 /** Delete an elements from a specified index in an array (a json_object of type json_type_array)
625  *
626  * The reference count will be decremented for each of the deleted objects.  If there
627  * are no more owners of an element that is being deleted, then the value is
628  * freed.  Otherwise, the reference to the value will remain in memory.
629  *
630  * @param obj the json_object instance
631  * @param idx the index to start deleting elements at
632  * @param count the number of elements to delete
633  * @returns 0 if the elements were successfully deleted
634  */
635 JSON_EXPORT int json_object_array_del_idx(struct json_object *obj, size_t idx, size_t count);
636 
637 /**
638  * Shrink the internal memory allocation of the array to just
639  * enough to fit the number of elements in it, plus empty_slots.
640  *
641  * @param jso the json_object instance, must be json_type_array
642  * @param empty_slots the number of empty slots to leave allocated
643  */
644 JSON_EXPORT int json_object_array_shrink(struct json_object *jso, int empty_slots);
645 
646 /* json_bool type methods */
647 
648 /** Create a new empty json_object of type json_type_boolean
649  * @param b a json_bool 1 or 0
650  * @returns a json_object of type json_type_boolean
651  */
652 JSON_EXPORT struct json_object *json_object_new_boolean(json_bool b);
653 
654 /** Get the json_bool value of a json_object
655  *
656  * The type is coerced to a json_bool if the passed object is not a json_bool.
657  * integer and double objects will return 0 if there value is zero
658  * or 1 otherwise. If the passed object is a string it will return
659  * 1 if it has a non zero length. If any other object type is passed
660  * 1 will be returned if the object is not NULL.
661  *
662  * @param obj the json_object instance
663  * @returns a json_bool
664  */
665 JSON_EXPORT json_bool json_object_get_boolean(const struct json_object *obj);
666 
667 /** Set the json_bool value of a json_object
668  *
669  * The type of obj is checked to be a json_type_boolean and 0 is returned
670  * if it is not without any further actions. If type of obj is json_type_boolean
671  * the object value is changed to new_value
672  *
673  * @param obj the json_object instance
674  * @param new_value the value to be set
675  * @returns 1 if value is set correctly, 0 otherwise
676  */
677 JSON_EXPORT int json_object_set_boolean(struct json_object *obj, json_bool new_value);
678 
679 /* int type methods */
680 
681 /** Create a new empty json_object of type json_type_int
682  * Note that values are stored as 64-bit values internally.
683  * To ensure the full range is maintained, use json_object_new_int64 instead.
684  * @param i the integer
685  * @returns a json_object of type json_type_int
686  */
687 JSON_EXPORT struct json_object *json_object_new_int(int32_t i);
688 
689 /** Create a new empty json_object of type json_type_int
690  * @param i the integer
691  * @returns a json_object of type json_type_int
692  */
693 JSON_EXPORT struct json_object *json_object_new_int64(int64_t i);
694 
695 /** Create a new empty json_object of type json_type_uint
696  * @param i the integer
697  * @returns a json_object of type json_type_uint
698  */
699 JSON_EXPORT struct json_object *json_object_new_uint64(uint64_t i);
700 
701 /** Get the int value of a json_object
702  *
703  * The type is coerced to a int if the passed object is not a int.
704  * double objects will return their integer conversion. Strings will be
705  * parsed as an integer. If no conversion exists then 0 is returned
706  * and errno is set to EINVAL. null is equivalent to 0 (no error values set)
707  *
708  * Note that integers are stored internally as 64-bit values.
709  * If the value of too big or too small to fit into 32-bit, INT32_MAX or
710  * INT32_MIN are returned, respectively.
711  *
712  * @param obj the json_object instance
713  * @returns an int
714  */
715 JSON_EXPORT int32_t json_object_get_int(const struct json_object *obj);
716 
717 /** Set the int value of a json_object
718  *
719  * The type of obj is checked to be a json_type_int and 0 is returned
720  * if it is not without any further actions. If type of obj is json_type_int
721  * the object value is changed to new_value
722  *
723  * @param obj the json_object instance
724  * @param new_value the value to be set
725  * @returns 1 if value is set correctly, 0 otherwise
726  */
727 JSON_EXPORT int json_object_set_int(struct json_object *obj, int new_value);
728 
729 /** Increment a json_type_int object by the given amount, which may be negative.
730  *
731  * If the type of obj is not json_type_int then 0 is returned with no further
732  * action taken.
733  * If the addition would result in a overflow, the object value
734  * is set to INT64_MAX.
735  * If the addition would result in a underflow, the object value
736  * is set to INT64_MIN.
737  * Neither overflow nor underflow affect the return value.
738  *
739  * @param obj the json_object instance
740  * @param val the value to add
741  * @returns 1 if the increment succeded, 0 otherwise
742  */
743 JSON_EXPORT int json_object_int_inc(struct json_object *obj, int64_t val);
744 
745 /** Get the int value of a json_object
746  *
747  * The type is coerced to a int64 if the passed object is not a int64.
748  * double objects will return their int64 conversion. Strings will be
749  * parsed as an int64. If no conversion exists then 0 is returned.
750  *
751  * NOTE: Set errno to 0 directly before a call to this function to determine
752  * whether or not conversion was successful (it does not clear the value for
753  * you).
754  *
755  * @param obj the json_object instance
756  * @returns an int64
757  */
758 JSON_EXPORT int64_t json_object_get_int64(const struct json_object *obj);
759 
760 /** Get the uint value of a json_object
761  *
762  * The type is coerced to a uint64 if the passed object is not a uint64.
763  * double objects will return their uint64 conversion. Strings will be
764  * parsed as an uint64. If no conversion exists then 0 is returned.
765  *
766  * NOTE: Set errno to 0 directly before a call to this function to determine
767  * whether or not conversion was successful (it does not clear the value for
768  * you).
769  *
770  * @param obj the json_object instance
771  * @returns an uint64
772  */
773 JSON_EXPORT uint64_t json_object_get_uint64(const struct json_object *obj);
774 
775 /** Set the int64_t value of a json_object
776  *
777  * The type of obj is checked to be a json_type_int and 0 is returned
778  * if it is not without any further actions. If type of obj is json_type_int
779  * the object value is changed to new_value
780  *
781  * @param obj the json_object instance
782  * @param new_value the value to be set
783  * @returns 1 if value is set correctly, 0 otherwise
784  */
785 JSON_EXPORT int json_object_set_int64(struct json_object *obj, int64_t new_value);
786 
787 /** Set the uint64_t value of a json_object
788  *
789  * The type of obj is checked to be a json_type_uint and 0 is returned
790  * if it is not without any further actions. If type of obj is json_type_uint
791  * the object value is changed to new_value
792  *
793  * @param obj the json_object instance
794  * @param new_value the value to be set
795  * @returns 1 if value is set correctly, 0 otherwise
796  */
797 JSON_EXPORT int json_object_set_uint64(struct json_object *obj, uint64_t new_value);
798 
799 /* double type methods */
800 
801 /** Create a new empty json_object of type json_type_double
802  *
803  * @see json_object_double_to_json_string() for how to set a custom format string.
804  *
805  * @param d the double
806  * @returns a json_object of type json_type_double
807  */
808 JSON_EXPORT struct json_object *json_object_new_double(double d);
809 
810 /**
811  * Create a new json_object of type json_type_double, using
812  * the exact serialized representation of the value.
813  *
814  * This allows for numbers that would otherwise get displayed
815  * inefficiently (e.g. 12.3 => "12.300000000000001") to be
816  * serialized with the more convenient form.
817  *
818  * Notes:
819  *
820  * This is used by json_tokener_parse_ex() to allow for
821  * an exact re-serialization of a parsed object.
822  *
823  * The userdata field is used to store the string representation, so it
824  * can't be used for other data if this function is used.
825  *
826  * A roughly equivalent sequence of calls, with the difference being that
827  *  the serialization function won't be reset by json_object_set_double(), is:
828  * @code
829  *   jso = json_object_new_double(d);
830  *   json_object_set_serializer(jso, json_object_userdata_to_json_string,
831  *       strdup(ds), json_object_free_userdata);
832  * @endcode
833  *
834  * @param d the numeric value of the double.
835  * @param ds the string representation of the double.  This will be copied.
836  */
837 JSON_EXPORT struct json_object *json_object_new_double_s(double d, const char *ds);
838 
839 /**
840  * Set a global or thread-local json-c option, depending on whether
841  *  JSON_C_OPTION_GLOBAL or JSON_C_OPTION_THREAD is passed.
842  * Thread-local options default to undefined, and inherit from the global
843  *  value, even if the global value is changed after the thread is created.
844  * Attempting to set thread-local options when threading is not compiled in
845  *  will result in an error.  Be sure to check the return value.
846  *
847  * double_format is a "%g" printf format, such as "%.20g"
848  *
849  * @return -1 on errors, 0 on success.
850  */
851 JSON_EXPORT int json_c_set_serialization_double_format(const char *double_format,
852                                                        int global_or_thread);
853 
854 /** Serialize a json_object of type json_type_double to a string.
855  *
856  * This function isn't meant to be called directly. Instead, you can set a
857  * custom format string for the serialization of this double using the
858  * following call (where "%.17g" actually is the default):
859  *
860  * @code
861  *   jso = json_object_new_double(d);
862  *   json_object_set_serializer(jso, json_object_double_to_json_string,
863  *       "%.17g", NULL);
864  * @endcode
865  *
866  * @see printf(3) man page for format strings
867  *
868  * @param jso The json_type_double object that is serialized.
869  * @param pb The destination buffer.
870  * @param level Ignored.
871  * @param flags Ignored.
872  */
873 JSON_EXPORT int json_object_double_to_json_string(struct json_object *jso, struct printbuf *pb,
874                                                   int level, int flags);
875 
876 /** Get the double floating point value of a json_object
877  *
878  * The type is coerced to a double if the passed object is not a double.
879  * integer objects will return their double conversion. Strings will be
880  * parsed as a double. If no conversion exists then 0.0 is returned and
881  * errno is set to EINVAL. null is equivalent to 0 (no error values set)
882  *
883  * If the value is too big to fit in a double, then the value is set to
884  * the closest infinity with errno set to ERANGE. If strings cannot be
885  * converted to their double value, then EINVAL is set & NaN is returned.
886  *
887  * Arrays of length 0 are interpreted as 0 (with no error flags set).
888  * Arrays of length 1 are effectively cast to the equivalent object and
889  * converted using the above rules.  All other arrays set the error to
890  * EINVAL & return NaN.
891  *
892  * NOTE: Set errno to 0 directly before a call to this function to
893  * determine whether or not conversion was successful (it does not clear
894  * the value for you).
895  *
896  * @param obj the json_object instance
897  * @returns a double floating point number
898  */
899 JSON_EXPORT double json_object_get_double(const struct json_object *obj);
900 
901 /** Set the double value of a json_object
902  *
903  * The type of obj is checked to be a json_type_double and 0 is returned
904  * if it is not without any further actions. If type of obj is json_type_double
905  * the object value is changed to new_value
906  *
907  * If the object was created with json_object_new_double_s(), the serialization
908  * function is reset to the default and the cached serialized value is cleared.
909  *
910  * @param obj the json_object instance
911  * @param new_value the value to be set
912  * @returns 1 if value is set correctly, 0 otherwise
913  */
914 JSON_EXPORT int json_object_set_double(struct json_object *obj, double new_value);
915 
916 /* string type methods */
917 
918 /** Create a new empty json_object of type json_type_string
919  *
920  * A copy of the string is made and the memory is managed by the json_object
921  *
922  * @param s the string
923  * @returns a json_object of type json_type_string
924  * @see json_object_new_string_len()
925  */
926 JSON_EXPORT struct json_object *json_object_new_string(const char *s);
927 
928 /** Create a new empty json_object of type json_type_string and allocate
929  * len characters for the new string.
930  *
931  * A copy of the string is made and the memory is managed by the json_object
932  *
933  * @param s the string
934  * @param len max length of the new string
935  * @returns a json_object of type json_type_string
936  * @see json_object_new_string()
937  */
938 JSON_EXPORT struct json_object *json_object_new_string_len(const char *s, const int len);
939 
940 /** Get the string value of a json_object
941  *
942  * If the passed object is of type json_type_null (i.e. obj == NULL),
943  * NULL is returned.
944  *
945  * If the passed object of type json_type_string, the string contents
946  * are returned.
947  *
948  * Otherwise the JSON representation of the object is returned.
949  *
950  * The returned string memory is managed by the json_object and will
951  * be freed when the reference count of the json_object drops to zero.
952  *
953  * @param obj the json_object instance
954  * @returns a string or NULL
955  */
956 JSON_EXPORT const char *json_object_get_string(struct json_object *obj);
957 
958 /** Get the string length of a json_object
959  *
960  * If the passed object is not of type json_type_string then zero
961  * will be returned.
962  *
963  * @param obj the json_object instance
964  * @returns int
965  */
966 JSON_EXPORT int json_object_get_string_len(const struct json_object *obj);
967 
968 /** Set the string value of a json_object with zero terminated strings
969  * equivalent to json_object_set_string_len (obj, new_value, strlen(new_value))
970  * @returns 1 if value is set correctly, 0 otherwise
971  */
972 JSON_EXPORT int json_object_set_string(json_object *obj, const char *new_value);
973 
974 /** Set the string value of a json_object str
975  *
976  * The type of obj is checked to be a json_type_string and 0 is returned
977  * if it is not without any further actions. If type of obj is json_type_string
978  * the object value is changed to new_value
979  *
980  * @param obj the json_object instance
981  * @param new_value the value to be set; Since string length is given in len this need not be zero terminated
982  * @param len the length of new_value
983  * @returns 1 if value is set correctly, 0 otherwise
984  */
985 JSON_EXPORT int json_object_set_string_len(json_object *obj, const char *new_value, int len);
986 
987 /** This method exists only to provide a complementary function
988  * along the lines of the other json_object_new_* functions.
989  * It always returns NULL, and it is entirely acceptable to simply use NULL directly.
990  */
991 JSON_EXPORT struct json_object *json_object_new_null(void);
992 
993 /** Check if two json_object's are equal
994  *
995  * If the passed objects are equal 1 will be returned.
996  * Equality is defined as follows:
997  * - json_objects of different types are never equal
998  * - json_objects of the same primitive type are equal if the
999  *   c-representation of their value is equal
1000  * - json-arrays are considered equal if all values at the same
1001  *   indices are equal (same order)
1002  * - Complex json_objects are considered equal if all
1003  *   contained objects referenced by their key are equal,
1004  *   regardless their order.
1005  *
1006  * @param obj1 the first json_object instance
1007  * @param obj2 the second json_object instance
1008  * @returns whether both objects are equal or not
1009  */
1010 JSON_EXPORT int json_object_equal(struct json_object *obj1, struct json_object *obj2);
1011 
1012 /**
1013  * Perform a shallow copy of src into *dst as part of an overall json_object_deep_copy().
1014  *
1015  * If src is part of a containing object or array, parent will be non-NULL,
1016  * and key or index will be provided.
1017  * When shallow_copy is called *dst will be NULL, and must be non-NULL when it returns.
1018  * src will never be NULL.
1019  *
1020  * If shallow_copy sets the serializer on an object, return 2 to indicate to
1021  *  json_object_deep_copy that it should not attempt to use the standard userdata
1022  *  copy function.
1023  *
1024  * @return On success 1 or 2, -1 on errors
1025  */
1026 typedef int(json_c_shallow_copy_fn)(json_object *src, json_object *parent, const char *key,
1027                                     size_t index, json_object **dst);
1028 
1029 /**
1030  * The default shallow copy implementation for use with json_object_deep_copy().
1031  * This simply calls the appropriate json_object_new_<type>() function and
1032  * copies over the serializer function (_to_json_string internal field of
1033  * the json_object structure) but not any _userdata or _user_delete values.
1034  *
1035  * If you're writing a custom shallow_copy function, perhaps because you're using
1036  * your own custom serializer, you can call this first to create the new object
1037  * before customizing it with json_object_set_serializer().
1038  *
1039  * @return 1 on success, -1 on errors, but never 2.
1040  */
1041 JSON_EXPORT json_c_shallow_copy_fn json_c_shallow_copy_default;
1042 
1043 /**
1044  * Copy the contents of the JSON object.
1045  * The destination object must be initialized to NULL,
1046  * to make sure this function won't overwrite an existing JSON object.
1047  *
1048  * This does roughly the same thing as
1049  * `json_tokener_parse(json_object_get_string(src))`.
1050  *
1051  * @param src source JSON object whose contents will be copied
1052  * @param dst pointer to the destination object where the contents of `src`;
1053  *            make sure this pointer is initialized to NULL
1054  * @param shallow_copy an optional function to copy individual objects, needed
1055  *                     when custom serializers are in use.  See also
1056  *                     json_object set_serializer.
1057  *
1058  * @returns 0 if the copy went well, -1 if an error occured during copy
1059  *          or if the destination pointer is non-NULL
1060  */
1061 
1062 JSON_EXPORT int json_object_deep_copy(struct json_object *src, struct json_object **dst,
1063                                       json_c_shallow_copy_fn *shallow_copy);
1064 #ifdef __cplusplus
1065 }
1066 #endif
1067 
1068 #endif
1069 

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