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fix(core): reject malformed array path indexes #327

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26 changes: 26 additions & 0 deletions packages/core/src/state-store.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,32 @@ describe("createStateStore", () => {
expect(store.getSnapshot()).toEqual({ x: 1 });
});

it.each(["1foo", "01", "1.5", "-1", "999999999999999999999"])(
"set ignores invalid array index %s",
(index) => {
const store = createStateStore({ items: ["a", "b", "c"] });
const snapshot = store.getSnapshot();
const listener = vi.fn();
store.subscribe(listener);

store.set(`/items/${index}`, "x");

expect(store.getSnapshot()).toBe(snapshot);
expect(store.getSnapshot().items).toEqual(["a", "b", "c"]);
expect(listener).not.toHaveBeenCalled();
},
);

it("preserves unsafe numeric tokens as object keys", () => {
const store = createStateStore({ obj: {} });

store.set("/obj/999999999999999999999/name", "value");

expect(store.getSnapshot()).toEqual({
obj: { "999999999999999999999": { name: "value" } },
});
});

it("update notifies subscribers once", () => {
const store = createStateStore({});
const listener = vi.fn();
Expand Down
59 changes: 46 additions & 13 deletions packages/core/src/state-store.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,17 @@ import {
type StateStore,
} from "./types";

function isNumericIndex(segment: string): boolean {
return /^(0|[1-9]\d*)$/.test(segment);
}

function parseArrayIndex(segment: string): number | undefined {
if (!isNumericIndex(segment)) return undefined;

const index = Number(segment);
return Number.isSafeInteger(index) ? index : undefined;
}

/**
* Immutably set a value at a JSON Pointer path using structural sharing.
* Only objects along the path are shallow-cloned; untouched branches keep
Expand All @@ -23,24 +34,36 @@ export function immutableSetByPath(

for (let i = 0; i < segments.length - 1; i++) {
const seg = segments[i]!;
const child = current[seg];
let key: string | number = seg;
if (Array.isArray(current)) {
const index = parseArrayIndex(seg);
if (index === undefined) return root;
key = index;
}

const nextSeg = segments[i + 1];
const nextIndex =
nextSeg === undefined ? undefined : parseArrayIndex(nextSeg);

const child = current[key];
if (Array.isArray(child)) {
current[seg] = [...child];
current[key] = [...child];
} else if (child !== null && typeof child === "object") {
current[seg] = { ...(child as Record<string, unknown>) };
current[key] = { ...(child as Record<string, unknown>) };
} else {
const nextSeg = segments[i + 1];
current[seg] = nextSeg !== undefined && /^\d+$/.test(nextSeg) ? [] : {};
current[key] = nextIndex !== undefined ? [] : {};
}
current = current[seg] as Record<string, unknown>;
current = current[key] as Record<string, unknown>;
}

const lastSeg = segments[segments.length - 1]!;
if (Array.isArray(current)) {
if (lastSeg === "-") {
(current as unknown[]).push(value);
} else {
(current as unknown[])[parseInt(lastSeg, 10)] = value;
const index = parseArrayIndex(lastSeg);
if (index === undefined) return root;
(current as unknown[])[index] = value;
}
} else {
current[lastSeg] = value;
Expand Down Expand Up @@ -73,7 +96,9 @@ export function createStateStore(initialState: StateModel = {}): StateStore {

set(path: string, value: unknown): void {
if (getByPath(state, path) === value) return;
state = immutableSetByPath(state, path, value);
const next = immutableSetByPath(state, path, value);
if (next === state) return;
state = next;
notify();
},

Expand All @@ -82,8 +107,11 @@ export function createStateStore(initialState: StateModel = {}): StateStore {
let next = state;
for (const [path, value] of Object.entries(updates)) {
if (getByPath(next, path) !== value) {
next = immutableSetByPath(next, path, value);
changed = true;
const updated = immutableSetByPath(next, path, value);
if (updated !== next) {
next = updated;
changed = true;
}
}
}
if (!changed) return;
Expand Down Expand Up @@ -139,16 +167,21 @@ export function createStoreAdapter(config: StoreAdapterConfig): StateStore {
set(path: string, value: unknown): void {
const current = config.getSnapshot();
if (getByPath(current, path) === value) return;
config.setSnapshot(immutableSetByPath(current, path, value));
const next = immutableSetByPath(current, path, value);
if (next === current) return;
config.setSnapshot(next);
},

update(updates: Record<string, unknown>): void {
let next = config.getSnapshot();
let changed = false;
for (const [path, value] of Object.entries(updates)) {
if (getByPath(next, path) !== value) {
next = immutableSetByPath(next, path, value);
changed = true;
const updated = immutableSetByPath(next, path, value);
if (updated !== next) {
next = updated;
changed = true;
}
}
}
if (!changed) return;
Expand Down
51 changes: 51 additions & 0 deletions packages/core/src/types.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -215,6 +215,57 @@ describe("JSON Pointer escaping (RFC 6901)", () => {
});
});

describe("JSON Patch array indexes (RFC 6902)", () => {
it.each(["1foo", "01", "1.5", "-1"])(
"rejects invalid array index %s",
(index) => {
const source = { items: ["a", "b", "c"] };
expect(getByPath(source, `/items/${index}`)).toBeUndefined();

const setData: Record<string, unknown> = { items: ["a", "b", "c"] };
setByPath(setData, `/items/${index}`, "x");
expect(setData.items).toEqual(["a", "b", "c"]);
expect(Object.keys(setData.items as unknown[])).toEqual(["0", "1", "2"]);

const addData: Record<string, unknown> = { items: ["a", "b", "c"] };
addByPath(addData, `/items/${index}`, "x");
expect(addData.items).toEqual(["a", "b", "c"]);

const removeData: Record<string, unknown> = { items: ["a", "b", "c"] };
removeByPath(removeData, `/items/${index}`);
expect(removeData.items).toEqual(["a", "b", "c"]);
},
);

it("accepts canonical array indexes", () => {
const data: Record<string, unknown> = { items: ["a", "b", "c"] };
setByPath(data, "/items/0", "first");
setByPath(data, "/items/2", "last");
expect(data.items).toEqual(["first", "b", "last"]);
});

it("preserves invalid-index-shaped keys on objects", () => {
const data = { items: { "01": "object key" } };
expect(getByPath(data, "/items/01")).toBe("object key");
});

it("treats unsafe numeric tokens as object keys when creating containers", () => {
const setData: Record<string, unknown> = {};
setByPath(setData, "/items/999999999999999999999", "x");
expect(setData).toEqual({ items: { "999999999999999999999": "x" } });

const addData: Record<string, unknown> = {};
addByPath(addData, "/items/999999999999999999999", "x");
expect(addData).toEqual({ items: { "999999999999999999999": "x" } });

const nestedData: Record<string, unknown> = { obj: {} };
setByPath(nestedData, "/obj/999999999999999999999/name", "value");
expect(nestedData).toEqual({
obj: { "999999999999999999999": { name: "value" } },
});
});
});

// =============================================================================
// addByPath (RFC 6902 "add" semantics)
// =============================================================================
Expand Down
42 changes: 28 additions & 14 deletions packages/core/src/types.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -298,7 +298,8 @@ export function getByPath(obj: unknown, path: string): unknown {
}

if (Array.isArray(current)) {
const index = parseInt(segment, 10);
const index = parseArrayIndex(segment);
if (index === undefined) return undefined;
current = current[index];
} else if (typeof current === "object") {
current = (current as Record<string, unknown>)[segment];
Expand Down Expand Up @@ -348,7 +349,14 @@ function joinStatePath(basePath: string, childPath: string): string {
* Check if a string is a numeric index
*/
function isNumericIndex(str: string): boolean {
return /^\d+$/.test(str);
return /^(0|[1-9]\d*)$/.test(str);
}

function parseArrayIndex(str: string): number | undefined {
if (!isNumericIndex(str)) return undefined;

const index = Number(str);
return Number.isSafeInteger(index) ? index : undefined;
}

/**
Expand All @@ -369,12 +377,13 @@ export function setByPath(
for (let i = 0; i < segments.length - 1; i++) {
const segment = segments[i]!;
const nextSegment = segments[i + 1];
const nextIsNumeric =
nextSegment !== undefined &&
(isNumericIndex(nextSegment) || nextSegment === "-");
const nextArrayIndex =
nextSegment === undefined ? undefined : parseArrayIndex(nextSegment);
const nextIsNumeric = nextArrayIndex !== undefined || nextSegment === "-";

if (Array.isArray(current)) {
const index = parseInt(segment, 10);
const index = parseArrayIndex(segment);
if (index === undefined) return;
if (current[index] === undefined || typeof current[index] !== "object") {
current[index] = nextIsNumeric ? [] : {};
}
Expand All @@ -392,7 +401,8 @@ export function setByPath(
if (lastSegment === "-") {
current.push(value);
} else {
const index = parseInt(lastSegment, 10);
const index = parseArrayIndex(lastSegment);
if (index === undefined) return;
current[index] = value;
}
} else {
Expand All @@ -419,12 +429,13 @@ export function addByPath(
for (let i = 0; i < segments.length - 1; i++) {
const segment = segments[i]!;
const nextSegment = segments[i + 1];
const nextIsNumeric =
nextSegment !== undefined &&
(isNumericIndex(nextSegment) || nextSegment === "-");
const nextArrayIndex =
nextSegment === undefined ? undefined : parseArrayIndex(nextSegment);
const nextIsNumeric = nextArrayIndex !== undefined || nextSegment === "-";

if (Array.isArray(current)) {
const index = parseInt(segment, 10);
const index = parseArrayIndex(segment);
if (index === undefined) return;
if (current[index] === undefined || typeof current[index] !== "object") {
current[index] = nextIsNumeric ? [] : {};
}
Expand All @@ -442,7 +453,8 @@ export function addByPath(
if (lastSegment === "-") {
current.push(value);
} else {
const index = parseInt(lastSegment, 10);
const index = parseArrayIndex(lastSegment);
if (index === undefined) return;
current.splice(index, 0, value);
}
} else {
Expand All @@ -466,7 +478,8 @@ export function removeByPath(obj: Record<string, unknown>, path: string): void {
const segment = segments[i]!;

if (Array.isArray(current)) {
const index = parseInt(segment, 10);
const index = parseArrayIndex(segment);
if (index === undefined) return;
if (current[index] === undefined || typeof current[index] !== "object") {
return; // path does not exist
}
Expand All @@ -481,7 +494,8 @@ export function removeByPath(obj: Record<string, unknown>, path: string): void {

const lastSegment = segments[segments.length - 1]!;
if (Array.isArray(current)) {
const index = parseInt(lastSegment, 10);
const index = parseArrayIndex(lastSegment);
if (index === undefined) return;
if (index >= 0 && index < current.length) {
current.splice(index, 1);
}
Expand Down