From 0e911833009282b0c8d345904a581a0d627247f7 Mon Sep 17 00:00:00 2001 From: Alexandru Ardelean Date: Tue, 25 Oct 2016 17:39:16 +0300 Subject: [PATCH] json_pointer: add first revision Signed-off-by: Alexandru Ardelean --- CMakeLists.txt | 2 + Makefile.am | 2 + json-c.vcproj | 6 ++ json-c.vcxproj | 2 + json-c.vcxproj.filters | 6 ++ json.h | 1 + json_pointer.c | 239 +++++++++++++++++++++++++++++++++++++++++ json_pointer.h | 69 ++++++++++++ 8 files changed, 327 insertions(+) create mode 100644 json_pointer.c create mode 100644 json_pointer.h diff --git a/CMakeLists.txt b/CMakeLists.txt index 39ffe24..77a9558 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -32,6 +32,7 @@ set(JSON_C_HEADERS ./json_inttypes.h ./json_object.h ./json_object_private.h + ./json_pointer.h ./json_tokener.h ./json_util.h ./linkhash.h @@ -44,6 +45,7 @@ set(JSON_C_SOURCES ./arraylist.c ./debug.c ./json_object.c + ./json_pointer.c ./json_tokener.c ./json_util.c ./linkhash.c diff --git a/Makefile.am b/Makefile.am index 8f7af38..58452fc 100644 --- a/Makefile.am +++ b/Makefile.am @@ -27,6 +27,7 @@ libjson_cinclude_HEADERS = \ json_object.h \ json_object_iterator.h \ json_object_private.h \ + json_pointer.h \ json_tokener.h \ json_util.h \ json_visit.h \ @@ -43,6 +44,7 @@ libjson_c_la_SOURCES = \ json_c_version.c \ json_object.c \ json_object_iterator.c \ + json_pointer.c \ json_tokener.c \ json_util.c \ json_visit.c \ diff --git a/json-c.vcproj b/json-c.vcproj index 184aa83..796856e 100644 --- a/json-c.vcproj +++ b/json-c.vcproj @@ -108,6 +108,9 @@ copy json_config.h.win32 json_config.h"/> + + @@ -143,6 +146,9 @@ copy json_config.h.win32 json_config.h"/> + + diff --git a/json-c.vcxproj b/json-c.vcxproj index d0f1e98..02e0c2d 100644 --- a/json-c.vcxproj +++ b/json-c.vcxproj @@ -133,6 +133,7 @@ copy json_config.h.win32 json_config.h + @@ -146,6 +147,7 @@ copy json_config.h.win32 json_config.h + diff --git a/json-c.vcxproj.filters b/json-c.vcxproj.filters index 7861064..cc13355 100644 --- a/json-c.vcxproj.filters +++ b/json-c.vcxproj.filters @@ -27,6 +27,9 @@ Source Files + + Source Files + Source Files @@ -59,6 +62,9 @@ Header Files + + Header Files + Header Files diff --git a/json.h b/json.h index e198f5d..dca0df5 100644 --- a/json.h +++ b/json.h @@ -22,6 +22,7 @@ extern "C" { #include "arraylist.h" #include "json_util.h" #include "json_object.h" +#include "json_pointer.h" #include "json_tokener.h" #include "json_object_iterator.h" #include "json_c_version.h" diff --git a/json_pointer.c b/json_pointer.c new file mode 100644 index 0000000..f06aed0 --- /dev/null +++ b/json_pointer.c @@ -0,0 +1,239 @@ +/* + * Copyright (c) 2016 Alexandru Ardelean. + * + * This is free software; you can redistribute it and/or modify + * it under the terms of the MIT license. See COPYING for details. + * + */ + +#include "config.h" + +#include +#include +#include +#include +#include + +#include "json_pointer.h" + +/** + * JavaScript Object Notation (JSON) Pointer + * RFC 6901 - https://tools.ietf.org/html/rfc6901 + */ + +static void string_replace_all_occurrences_with_char(char *s, const char *occur, char repl_char) +{ + int slen = strlen(s); + int skip = strlen(occur) - 1; /* length of the occurence, minus the char we're replacing */ + char *p = s; + while ((p = strstr(p, occur))) { + *p = repl_char; + p++; + slen -= skip; + memcpy(p, (p + skip), slen - (p - s) + 1); /* includes null char too */ + } +} + +static int is_valid_index(struct json_object *jo, const char *path, int32_t *idx) +{ + int i, len = strlen(path); + /* this code-path optimizes a bit, for when we reference the 0-9 index range in a JSON array + and because leading zeros not allowed */ + if (len == 1) { + if (isdigit(path[0])) { + *idx = (path[0] - '0'); + goto check_oob; + } + errno = EINVAL; + return 0; + } + /* leading zeros not allowed per RFC */ + if (path[0] == '0') { + errno = EINVAL; + return 0; + } + /* RFC states base-10 decimals */ + for (i = 0; i < len; i++) { + if (!isdigit(path[i])) { + errno = EINVAL; + return 0; + } + } + + *idx = strtol(path, NULL, 10); + if (*idx < 0) { + errno = EINVAL; + return 0; + } +check_oob: + len = json_object_array_length(jo); + if (*idx >= len) { + errno = ENOENT; + return 0; + } + + return 1; +} + +static int json_pointer_get_single_path(struct json_object *obj, char *path, struct json_object **value) +{ + if (json_object_is_type(obj, json_type_array)) { + int32_t idx; + if (!is_valid_index(obj, path, &idx)) + return -1; + obj = json_object_array_get_idx(obj, idx); + if (obj) { + if (value) + *value = obj; + return 0; + } + /* Entry not found */ + errno = ENOENT; + return -1; + } + + /* RFC states that we first must eval all ~1 then all ~0 */ + string_replace_all_occurrences_with_char(path, "~1", '/'); + string_replace_all_occurrences_with_char(path, "~0", '~'); + + if (!json_object_object_get_ex(obj, path, value)) { + errno = ENOENT; + return -1; + } + + return 0; +} + +static int json_pointer_set_single_path( + struct json_object *parent, + const char *path, + struct json_object *value) +{ + if (json_object_is_type(parent, json_type_array)) { + int32_t idx; + /* RFC (Chapter 4) states that '-' may be used to add new elements to an array */ + if (path[0] == '-' && path[1] == '\0') + return json_object_array_add(parent, value); + if (!is_valid_index(parent, path, &idx)) + return -1; + return json_object_array_put_idx(parent, idx, value); + } + + /* path replacements should have been done in json_pointer_get_single_path(), + and we should still be good here */ + if (json_object_is_type(parent, json_type_object)) + return json_object_object_add(parent, path, value); + + /* Getting here means that we tried to "dereference" a primitive JSON type (like string, int, bool). + i.e. add a sub-object to it */ + errno = ENOENT; + return -1; +} + +static int json_pointer_get_recursive( + struct json_object *obj, + char *path, + struct json_object **value) +{ + char *endp; + int rc; + + /* All paths (on each recursion level must have a leading '/' */ + if (path[0] != '/') { + errno = EINVAL; + return -1; + } + path++; + + endp = strchr(path, '/'); + if (endp) + *endp = '\0'; + + /* If we err-ed here, return here */ + if ((rc = json_pointer_get_single_path(obj, path, &obj))) + return rc; + + if (endp) { + *endp = '/'; /* Put the slash back, so that the sanity check passes on next recursion level */ + return json_pointer_get_recursive(obj, endp, value); + } + + /* We should be at the end of the recursion here */ + if (value) + *value = obj; + + return 0; +} + +int json_pointer_get(struct json_object *obj, const char *path, struct json_object **res) +{ + char *path_copy = NULL; + int rc; + + if (!obj || !path) { + errno = EINVAL; + return -1; + } + + if (path[0] == '\0') { + if (res) + *res = obj; + return 0; + } + + /* pass a working copy to the recursive call */ + if (!(path_copy = strdup(path))) { + errno = ENOMEM; + return -1; + } + rc = json_pointer_get_recursive(obj, path_copy, res); + free(path_copy); + + return rc; +} + +int json_pointer_set(struct json_object **obj, const char *path, struct json_object *value) +{ + const char *endp; + char *path_copy = NULL; + struct json_object *set = NULL; + int rc; + + if (!obj || !path) { + errno = EINVAL; + return -1; + } + + if (path[0] == '\0') { + json_object_put(*obj); + *obj = value; + return 0; + } + + if (path[0] != '/') { + errno = EINVAL; + return -1; + } + + /* If there's only 1 level to set, stop here */ + if ((endp = strrchr(path, '/')) == path) { + path++; + return json_pointer_set_single_path(*obj, path, value); + } + + /* pass a working copy to the recursive call */ + if (!(path_copy = strdup(path))) { + errno = ENOMEM; + return -1; + } + path_copy[endp - path] = '\0'; + rc = json_pointer_get_recursive(*obj, path_copy, &set); + free(path_copy); + + if (rc) + return rc; + + endp++; + return json_pointer_set_single_path(set, endp, value); +} + diff --git a/json_pointer.h b/json_pointer.h new file mode 100644 index 0000000..d661b7b --- /dev/null +++ b/json_pointer.h @@ -0,0 +1,69 @@ +/* + * Copyright (c) 2016 Alexadru Ardelean. + * + * This is free software; you can redistribute it and/or modify + * it under the terms of the MIT license. See COPYING for details. + * + */ + +#ifndef _json_pointer_h_ +#define _json_pointer_h_ + +#include "json_object.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * Retrieves a JSON sub-object from inside another JSON object + * using the JSON pointer notation as defined in RFC 6901 + * https://tools.ietf.org/html/rfc6901 + * + * The returned JSON sub-object is equivalent to parsing manually the + * 'obj' JSON tree ; i.e. it's not a new object that is created, but rather + * a pointer inside the JSON tree. + * + * Internally, this is equivalent to doing a series of 'json_object_object_get()' + * and 'json_object_array_get_idx()' along the given 'path'. + * + * @param obj the json_object instance/tree from where to retrieve sub-objects + * @param path a (RFC6901) string notation for the sub-object to retrieve + * @param res a pointer where to store a reference to the json_object + * associated with the given path + * + * @return negative if an error (or not found), or 0 if succeeded + */ +int json_pointer_get(struct json_object *obj, const char *path, struct json_object **res); + +/** + * Sets JSON object 'value' in the 'obj' tree at the location specified + * by the 'path'. 'path' is JSON pointer notation as defined in RFC 6901 + * https://tools.ietf.org/html/rfc6901 + * + * Note that 'obj' is a double pointer, mostly for the "" (empty string) + * case, where the entire JSON object would be replaced by 'value'. + * In the case of the "" path, the object at '*obj' will have it's refcount + * decremented with 'json_object_put()' and the 'value' object will be assigned to it. + * + * For other cases (JSON sub-objects) ownership of 'value' will be transferred into + * '*obj' via 'json_object_object_add()' & 'json_object_array_put_idx()', so the + * only time the refcount should be decremented for 'value' is when the return value of + * 'json_pointer_set()' is negative (meaning the 'value' object did not get set into '*obj'). + * + * That also implies that 'json_pointer_set()' does not do any refcount incrementing. + * (Just that single decrement that was mentioned above). + * + * @param obj the json_object instance/tree to which to add a sub-object + * @param path a (RFC6901) string notation for the sub-object to set in the tree + * @param value object to set at path + * + * @return negative if an error (or not found), or 0 if succeeded + */ +int json_pointer_set(struct json_object **obj, const char *path, struct json_object *value); + +#ifdef __cplusplus +} +#endif + +#endif -- 2.50.0