Vito Sansevero
de194af8bc
admin.js, gallery.js and metadata.html each carried a copy of the PNG chunk walker that reads ComfyUI's tEXt/iTXt entries (admin.js had two until the shadowed one was removed). web/js/png-metadata.js is now the only parser: it checks the signature, bounds-checks every chunk so a truncated file or a bogus length cannot throw, decodes tEXt as Latin-1 and iTXt as UTF-8, skips compressed zTXt/iTXt payloads instead of decoding them as garbage, and stops at IEND. The three page-level parsePNGMetadata functions delegate to it.
103 lines
4.4 KiB
JavaScript
103 lines
4.4 KiB
JavaScript
// Run with: node --test tests/js/
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const test = require("node:test");
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const assert = require("node:assert/strict");
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const { parsePngTextChunks, PNG_SIGNATURE } = require("../../web/js/png-metadata.js");
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const SIGNATURE = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
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function u32(n) {
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return [(n >>> 24) & 0xff, (n >>> 16) & 0xff, (n >>> 8) & 0xff, n & 0xff];
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}
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/** A chunk with a dummy CRC (the parser does not verify it). */
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function chunk(type, dataBytes) {
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return [...u32(dataBytes.length), ...Buffer.from(type, "latin1"), ...dataBytes, 0, 0, 0, 0];
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}
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const IHDR = chunk("IHDR", [...u32(1), ...u32(1), 8, 6, 0, 0, 0]);
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const IEND = chunk("IEND", []);
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function tEXt(keyword, text) {
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return chunk("tEXt", [...Buffer.from(keyword, "latin1"), 0, ...Buffer.from(text, "latin1")]);
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}
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function iTXt(keyword, text, { compressed = false } = {}) {
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return chunk("iTXt", [
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...Buffer.from(keyword, "latin1"), 0,
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compressed ? 1 : 0, 0, // compression flag, compression method
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0, // empty language tag
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0, // empty translated keyword
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...Buffer.from(text, "utf8"),
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]);
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}
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function png(...chunks) {
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return Uint8Array.from([...SIGNATURE, ...IHDR, ...chunks.flat(), ...IEND]);
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}
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test("exports the PNG signature", () => {
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assert.deepEqual([...PNG_SIGNATURE], SIGNATURE);
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});
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test("reads a tEXt chunk written by ComfyUI", () => {
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const bytes = png(tEXt("prompt", '{"a":1}'));
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assert.deepEqual(parsePngTextChunks(bytes), { prompt: '{"a":1}' });
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});
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test("reads several text chunks and an uncompressed iTXt chunk with UTF-8 text", () => {
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const bytes = png(tEXt("prompt", '{"a":1}'), iTXt("workflow", '{"b":"日本語 🙂"}'), tEXt("Software", "ComfyUI"));
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assert.deepEqual(parsePngTextChunks(bytes), {
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prompt: '{"a":1}',
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workflow: '{"b":"日本語 🙂"}',
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Software: "ComfyUI",
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});
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});
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test("tEXt is Latin-1, so byte 0xE9 is an e-acute", () => {
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const bytes = png(chunk("tEXt", [...Buffer.from("Comment", "latin1"), 0, 0xe9]));
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assert.deepEqual(parsePngTextChunks(bytes), { Comment: "é" });
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});
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test("skips compressed iTXt and zTXt payloads instead of returning garbage", () => {
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const zTXt = chunk("zTXt", [...Buffer.from("Comment", "latin1"), 0, 0, 0x78, 0x9c, 1, 2, 3]);
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const bytes = png(iTXt("workflow", "zzz", { compressed: true }), zTXt, tEXt("prompt", "ok"));
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assert.deepEqual(parsePngTextChunks(bytes), { prompt: "ok" });
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});
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test("ignores non-text chunks and a text chunk without a NUL separator", () => {
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const bytes = png(chunk("IDAT", [1, 2, 3]), chunk("tEXt", [...Buffer.from("nonul", "latin1")]), tEXt("k", "v"));
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assert.deepEqual(parsePngTextChunks(bytes), { k: "v" });
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});
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test("accepts an ArrayBuffer as well as a Uint8Array", () => {
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const bytes = png(tEXt("prompt", "x"));
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assert.deepEqual(parsePngTextChunks(bytes.buffer.slice(bytes.byteOffset, bytes.byteOffset + bytes.byteLength)), { prompt: "x" });
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});
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test("returns {} for garbage, empty and non-PNG input", () => {
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assert.deepEqual(parsePngTextChunks(new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12])), {});
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assert.deepEqual(parsePngTextChunks(new Uint8Array(0)), {});
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assert.deepEqual(parsePngTextChunks(Uint8Array.from(Buffer.from("GIF89a....................", "latin1"))), {});
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assert.deepEqual(parsePngTextChunks(null), {});
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assert.deepEqual(parsePngTextChunks("not bytes"), {});
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});
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test("a file truncated inside a text chunk yields only the chunks that were complete", () => {
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const full = png(tEXt("prompt", "first"), tEXt("workflow", "second-second-second"));
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const cutInsideSecond = full.subarray(0, full.length - IEND.length - 6);
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assert.deepEqual(parsePngTextChunks(cutInsideSecond), { prompt: "first" });
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const cutInsideFirst = full.subarray(0, SIGNATURE.length + IHDR.length + 10);
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assert.deepEqual(parsePngTextChunks(cutInsideFirst), {});
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});
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test("a chunk whose declared length overruns the file is ignored", () => {
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const bogus = [...u32(0x7fffffff), ...Buffer.from("tEXt", "latin1"), ...Buffer.from("k\0v", "latin1")];
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const bytes = Uint8Array.from([...SIGNATURE, ...IHDR, ...tEXt("ok", "1"), ...bogus]);
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assert.deepEqual(parsePngTextChunks(bytes), { ok: "1" });
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});
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test("stops at IEND even if bytes follow it", () => {
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const bytes = Uint8Array.from([...png(tEXt("a", "1")), ...tEXt("b", "2")]);
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assert.deepEqual(parsePngTextChunks(bytes), { a: "1" });
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});
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