--- /dev/null
+/*
+ * Copyright (c) 2021 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 <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include "json_patch.h"
+#include "json_object_private.h"
+
+/**
+ * JavaScript Object Notation (JSON) Patch
+ * RFC 6902 - https://tools.ietf.org/html/rfc6902
+ */
+
+static int json_patch_apply_test(struct json_object **res,
+ struct json_object *patch_elem,
+ const char *path)
+{
+ struct json_object *value1, *value2;
+
+ if (!json_object_object_get_ex(patch_elem, "value", &value1)) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ /* errno should be set by json_pointer_get() */
+ if (json_pointer_get(*res, path, &value2))
+ return -1;
+
+ if (!json_object_equal(value1, value2)) {
+ json_object_put(*res);
+ *res = NULL;
+ errno = ENOENT;
+ return -1;
+ }
+
+ return 0;
+}
+
+static int __json_patch_apply_remove(struct json_pointer_get_result *jpres)
+{
+ if (json_object_is_type(jpres->parent, json_type_array)) {
+ return json_object_array_del_idx(jpres->parent, jpres->id.index, 1);
+ } else if (jpres->parent && jpres->id.key) {
+ json_object_object_del(jpres->parent, jpres->id.key);
+ return 0;
+ } else {
+ return json_object_put(jpres->obj);
+ }
+}
+
+static int json_patch_apply_remove(struct json_object **res, const char *path)
+{
+ struct json_pointer_get_result jpres;
+
+ if (json_pointer_get_internal(*res, path, &jpres))
+ return -1;
+
+ return __json_patch_apply_remove(&jpres);
+}
+
+static int json_object_array_insert_idx_cb(struct json_object *parent, size_t idx,
+ struct json_object *value, void *priv)
+{
+ int *add = priv;
+
+ if (idx > json_object_array_length(parent))
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
+ if (*add)
+ return json_object_array_insert_idx(parent, idx, value);
+ else
+ return json_object_array_put_idx(parent, idx, value);
+}
+
+static int json_patch_apply_add_replace(struct json_object **res,
+ struct json_object *patch_elem,
+ const char *path, int add)
+{
+ struct json_object *value;
+ int rc;
+
+ if (!json_object_object_get_ex(patch_elem, "value", &value)) {
+ errno = EINVAL;
+ return -1;
+ }
+ /* if this is a replace op, then we need to make sure it exists before replacing */
+ if (!add && json_pointer_get(*res, path, NULL)) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ rc = json_pointer_set_with_array_cb(res, path, json_object_get(value),
+ json_object_array_insert_idx_cb, &add);
+ if (rc)
+ json_object_put(value);
+
+ return rc;
+}
+
+static int json_object_array_move_cb(struct json_object *parent, size_t idx,
+ struct json_object *value, void *priv)
+{
+ struct json_pointer_get_result *from = priv;
+ size_t len = json_object_array_length(parent);
+
+ /**
+ * If it's the same array parent, it means that we removed
+ * and element from it, so the length is temporarily reduced
+ * by 1, which means that if we try to move an element to
+ * the last position, we need to check the current length + 1
+ */
+ if (parent == from->parent)
+ len++;
+
+ if (idx > len)
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
+ return json_object_array_insert_idx(parent, idx, value);
+}
+
+static int json_patch_apply_move_copy(struct json_object **res,
+ struct json_object *patch_elem,
+ const char *path, int move)
+{
+ json_pointer_array_set_cb array_set_cb;
+ struct json_pointer_get_result from;
+ struct json_object *jfrom;
+ const char *from_s;
+ size_t from_s_len;
+ int rc;
+
+ if (!json_object_object_get_ex(patch_elem, "from", &jfrom)) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ from_s = json_object_get_string(jfrom);
+
+ from_s_len = strlen(from_s);
+ if (strncmp(from_s, path, from_s_len) == 0) {
+ /**
+ * If lengths match, it's a noop, if they don't,
+ * then we're trying to move a parent under a child
+ * which is not allowed as per RFC 6902 section 4.4
+ * The "from" location MUST NOT be a proper prefix of the "path"
+ * location; i.e., a location cannot be moved into one of its children.
+ */
+ if (from_s_len == strlen(path))
+ return 0;
+ errno = EINVAL;
+ return -1;
+ }
+
+ rc = json_pointer_get_internal(*res, from_s, &from);
+ if (rc)
+ return rc;
+
+ json_object_get(from.obj);
+
+ if (!move) {
+ array_set_cb = json_object_array_insert_idx_cb;
+ } else {
+ rc = __json_patch_apply_remove(&from);
+ if (rc < 0) {
+ json_object_put(from.obj);
+ return rc;
+ }
+ array_set_cb = json_object_array_move_cb;
+ }
+
+ rc = json_pointer_set_with_array_cb(res, path, from.obj, array_set_cb, &from);
+ if (rc)
+ json_object_put(from.obj);
+
+ return rc;
+}
+
+int json_patch_apply(struct json_object *base, struct json_object *patch,
+ struct json_object **res)
+{
+ size_t i;
+ int rc = 0;
+
+ if (!base || !json_object_is_type(patch, json_type_array)) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ /* errno should be set inside json_object_deep_copy() */
+ if (json_object_deep_copy(base, res, NULL) < 0)
+ return -1;
+
+ /* Go through all operations ; apply them on res */
+ for (i = 0; i < json_object_array_length(patch); i++) {
+ struct json_object *jop, *jpath;
+ struct json_object *patch_elem = json_object_array_get_idx(patch, i);
+ const char *op, *path;
+ if (!json_object_object_get_ex(patch_elem, "op", &jop)) {
+ errno = EINVAL;
+ rc = -1;
+ break;
+ }
+ op = json_object_get_string(jop);
+ json_object_object_get_ex(patch_elem, "path", &jpath);
+ path = json_object_get_string(jpath);
+
+ if (!strcmp(op, "test"))
+ rc = json_patch_apply_test(res, patch_elem, path);
+ else if (!strcmp(op, "remove"))
+ rc = json_patch_apply_remove(res, path);
+ else if (!strcmp(op, "add"))
+ rc = json_patch_apply_add_replace(res, patch_elem, path, 1);
+ else if (!strcmp(op, "replace"))
+ rc = json_patch_apply_add_replace(res, patch_elem, path, 0);
+ else if (!strcmp(op, "move"))
+ rc = json_patch_apply_move_copy(res, patch_elem, path, 1);
+ else if (!strcmp(op, "copy"))
+ rc = json_patch_apply_move_copy(res, patch_elem, path, 0);
+ else {
+ errno = EINVAL;
+ rc = -1;
+ break;
+ }
+ if (rc < 0)
+ break;
+ }
+
+ if (rc < 0) {
+ json_object_put(*res);
+ *res = NULL;
+ }
+
+ return rc;
+}
projects / thirdparty / json-c.git / commitdiff
