From b23c98dd390db79e2243b0a7015d008b2f3f45f9 Mon Sep 17 00:00:00 2001
From: Brandon Liu <bdon@bdon.org>
Date: Thu, 22 Dec 2022 21:56:03 +0800
Subject: [PATCH] javascript: fix tile id overflow for z > 15 and error
 assertions in tests.

---
 js/index.ts        | 27 ++++++++++++-------
 js/test/v3.test.ts | 64 ++++++++++++++++++++++++++++------------------
 2 files changed, 57 insertions(+), 34 deletions(-)

diff --git a/js/index.ts b/js/index.ts
index 57d2181..18338d2 100644
--- a/js/index.ts
+++ b/js/index.ts
@@ -70,43 +70,50 @@ function rotate(n: number, xy: number[], rx: number, ry: number): void {
 }
 
 function idOnLevel(z: number, pos: number): [number, number, number] {
-	const n = 1 << z;
+	const n = Math.pow(2, z);
 	let rx = pos;
 	let ry = pos;
 	let t = pos;
 	const xy = [0, 0];
 	let s = 1;
 	while (s < n) {
-		rx = 1 & ((t / 2) >> 0);
+		rx = 1 & (t / 2);
 		ry = 1 & (t ^ rx);
 		rotate(s, xy, rx, ry);
 		xy[0] += s * rx;
 		xy[1] += s * ry;
-		t = (t / 4) >> 0;
+		t = t / 4;
 		s *= 2;
 	}
 	return [z, xy[0], xy[1]];
 }
 
 export function zxyToTileId(z: number, x: number, y: number): number {
+	if (z > 26) {
+		throw Error("Tile zoom level exceeds max safe number limit (26)");
+	}
+	if (x > Math.pow(2, z) - 1 || y > Math.pow(2, z) - 1) {
+		throw Error("tile x/y outside zoom level bounds");
+	}
+
 	let acc = 0;
 	let tz = 0;
 	while (tz < z) {
-		acc += (0x1 << tz) * (0x1 << tz);
+		acc += Math.pow(2, tz) * Math.pow(2, tz);
 		tz++;
 	}
-	const n = 1 << z;
+	const n = Math.pow(2, z);
 	let rx = 0;
 	let ry = 0;
 	let d = 0;
 	const xy = [x, y];
-	let s = (n / 2) >> 0;
+	let s = n / 2;
 	while (s > 0) {
 		rx = (xy[0] & s) > 0 ? 1 : 0;
 		ry = (xy[1] & s) > 0 ? 1 : 0;
 		d += s * s * ((3 * rx) ^ ry);
 		rotate(s, xy, rx, ry);
-		s = (s / 2) >> 0;
+		s = s / 2;
 	}
 	return acc + d;
 }
@@ -114,14 +121,16 @@ export function zxyToTileId(z: number, x: number, y: number): number {
 export function tileIdToZxy(i: number): [number, number, number] {
 	let acc = 0;
 	let z = 0;
-	for (;;) {
+
+	for (let z = 0; z < 27; z++) {
 		const num_tiles = (0x1 << z) * (0x1 << z);
 		if (acc + num_tiles > i) {
 			return idOnLevel(z, i - acc);
 		}
 		acc += num_tiles;
-		z++;
 	}
+
+	throw Error("Tile zoom level exceeds max safe number limit (26)");
 }
 
 export interface Entry {
diff --git a/js/test/v3.test.ts b/js/test/v3.test.ts
index 369afee..5a9e900 100644
--- a/js/test/v3.test.ts
+++ b/js/test/v3.test.ts
@@ -64,6 +64,34 @@ test("a lot of tiles", () => {
 	}
 });
 
+test("tile extremes", () => {
+	for (var z = 0; z < 27; z++) {
+		const dim = Math.pow(2, z) - 1;
+		const tl = tileIdToZxy(zxyToTileId(z, 0, 0));
+		assert.deepEqual([z, 0, 0], tl);
+		const tr = tileIdToZxy(zxyToTileId(z, dim, 0));
+		assert.deepEqual([z, dim, 0], tr);
+		const bl = tileIdToZxy(zxyToTileId(z, 0, dim));
+		assert.deepEqual([z, 0, dim], bl);
+		const br = tileIdToZxy(zxyToTileId(z, dim, dim));
+		assert.deepEqual([z, dim, dim], br);
+	}
+});
+
+test("invalid tiles", () => {
+	assert.throws(() => {
+		tileIdToZxy(Number.MAX_SAFE_INTEGER);
+	});
+
+	assert.throws(() => {
+		zxyToTileId(27,0,0);
+	});
+
+	assert.throws(() => {
+		zxyToTileId(0,1,1);
+	});
+});
+
 test("tile search for missing entry", () => {
 	const entries: Entry[] = [];
 	assert.strictEqual(findTile(entries, 101), null);
@@ -185,34 +213,25 @@ test("getUint64", async () => {
 test("cache check against empty", async () => {
 	const source = new TestNodeFileSource("test/data/empty.pmtiles", "1");
 	const cache = new SharedPromiseCache();
-	try {
+	assert.rejects(async () => {
 		await cache.getHeader(source);
-		assert.fail("Should have thrown");
-	} catch (e) {
-		assert.ok(e instanceof Error);
-	}
+	});
 });
 
 test("cache check magic number", async () => {
 	const source = new TestNodeFileSource("test/data/invalid.pmtiles", "1");
 	const cache = new SharedPromiseCache();
-	try {
+	assert.rejects(async () => {
 		await cache.getHeader(source);
-		assert.fail("Should have thrown");
-	} catch (e) {
-		assert.ok(e instanceof Error);
-	}
+	});
 });
 
 test("cache check future spec version", async () => {
 	const source = new TestNodeFileSource("test/data/invalid_v4.pmtiles", "1");
 	const cache = new SharedPromiseCache();
-	try {
+	assert.rejects(async () => {
 		await cache.getHeader(source);
-		assert.fail("Should have thrown");
-	} catch (e) {
-		assert.ok(e instanceof Error);
-	}
+	});
 });
 
 test("cache getDirectory", async () => {
@@ -276,17 +295,15 @@ test("etags are part of key", async () => {
 
 	source.etag = "etag_2";
 
-	try {
+	assert.rejects(async () => {
 		await cache.getDirectory(
 			source,
 			header.rootDirectoryOffset,
 			header.rootDirectoryLength,
 			header
 		);
-		assert.fail("Should have thrown");
-	} catch (e) {
-		assert.ok(e instanceof EtagMismatch);
-	}
+	})
+
 	cache.invalidate(source, "etag_2");
 	header = await cache.getHeader(source);
 	assert.ok(
@@ -311,17 +328,14 @@ test("soft failure on etag weirdness", async () => {
 
 	source.etag = "etag_2";
 
-	try {
+	assert.rejects(async () => {
 		await cache.getDirectory(
 			source,
 			header.rootDirectoryOffset,
 			header.rootDirectoryLength,
 			header
 		);
-		assert.fail("Should have thrown");
-	} catch (e) {
-		assert.ok(e instanceof EtagMismatch);
-	}
+	})
 
 	source.etag = "etag_1";
 	cache.invalidate(source, "etag_2");