mirror of
https://git.coom.tech/fuckjannies/lolipiss.git
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132 lines
4.3 KiB
TypeScript
132 lines
4.3 KiB
TypeScript
import { Buffer } from "buffer";
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import type { EmbeddedFile, ImageProcessor } from "./main";
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import { PNGDecoder, PNGEncoder } from "./png";
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import { decodeCoom3Payload } from "./utils";
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const CUM3 = Buffer.from("doo\0" + "m");
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const BufferReadStream = (b: Buffer) => {
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const ret = new ReadableStream<Buffer>({
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pull(cont) {
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cont.enqueue(b);
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cont.close();
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}
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});
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return ret;
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};
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const extract = async (png: Buffer) => {
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const reader = BufferReadStream(png).getReader();
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const sneed = new PNGDecoder(reader);
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const ret: EmbeddedFile[] = [];
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try {
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for await (const [name, chunk, crc, offset] of sneed.chunks()) {
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let buff: Buffer;
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switch (name) {
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// should exist at the beginning of file to signal decoders if the file indeed has an embedded chunk
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case 'tEXt':
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buff = await chunk();
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if (buff.slice(4, 4 + CUM3.length).equals(CUM3)) {
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const k = await decodeCoom3Payload(buff.slice(4 + CUM3.length));
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ret.push(...k.filter(e => e).map(e => e as EmbeddedFile));
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}
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break;
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case 'IDAT':
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// eslint-disable-next-line no-fallthrough
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case 'IEND':
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return ret;
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// eslint-disable-next-line no-fallthrough
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default:
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break;
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}
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}
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} catch (e) {
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console.error(e);
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} finally {
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reader.releaseLock();
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}
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};
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const buildChunk = (tag: string, data: Buffer) => {
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const ret = Buffer.alloc(data.byteLength + 4);
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ret.write(tag.slice(0, 4), 0);
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data.copy(ret, 4);
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return ret;
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};
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export const BufferWriteStream = () => {
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let b = Buffer.from([]);
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const ret = new WritableStream<Buffer>({
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write(chunk) {
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b = Buffer.concat([b, chunk]);
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}
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});
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return [ret, () => b] as [WritableStream<Buffer>, () => Buffer];
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};
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export const inject_data = async (container: File, injb: Buffer) => {
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let magic = false;
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const [writestream, extract] = BufferWriteStream();
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const encoder = new PNGEncoder(writestream);
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const decoder = new PNGDecoder(container.stream().getReader());
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for await (const [name, chunk, crc, offset] of decoder.chunks()) {
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if (magic && name != "IDAT")
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break;
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if (!magic && name == "IDAT") {
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await encoder.insertchunk(["tEXt", async () => buildChunk("tEXt", Buffer.concat([CUM3, injb])), () => Promise.resolve(0), 0]);
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magic = true;
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}
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await encoder.insertchunk([name, chunk, crc, offset]);
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}
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await encoder.insertchunk(["IEND",
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async () => Promise.resolve(buildChunk("IEND", Buffer.from([]))),
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async () => Promise.resolve(0),
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0]);
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return extract();
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};
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const inject = async (container: File, links: string[]) => {
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const injb = Buffer.from(links.join(' '));
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return inject_data(container, injb);
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};
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const has_embed = async (png: Buffer) => {
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const reader = BufferReadStream(png).getReader();
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const sneed = new PNGDecoder(reader);
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try {
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for await (const [name, chunk, crc, offset] of sneed.chunks()) {
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let buff: Buffer;
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switch (name) {
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// should exist at the beginning of file to signal decoders if the file indeed has an embedded chunk
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case 'tEXt':
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buff = await chunk();
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if (buff.slice(4, 4 + CUM3.length).equals(CUM3))
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return true;
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break;
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case 'IDAT':
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// eslint-disable-next-line no-fallthrough
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case 'IEND':
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return false; // Didn't find tExt Chunk; Definite no
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// eslint-disable-next-line no-fallthrough
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default:
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break;
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}
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}
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// stream ended on chunk boundary, so no unexpected EOF was fired, need more data anyway
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} catch (e) {
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return; // possibly unexpected EOF, need more data to decide
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} finally {
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reader.releaseLock();
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}
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};
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export default {
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extract,
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has_embed,
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inject,
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match: fn => !!fn.match(/\.png$/)
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} as ImageProcessor;
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