6c7eed7580
Fresh history cut from cynarAI/evoo antigravity-handoff/project-timeline (Voice First + project timeline). Brand docs/titles as evOo; keep @rakazo/* packages as tech debt. Excludes node_modules, caches, secrets, voice blobs.
63 lines
2.2 KiB
TypeScript
63 lines
2.2 KiB
TypeScript
import { PNG } from "pngjs";
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const PNG_SIGNATURE = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
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export const MAX_PNG_SCREENSHOT_BYTES = 15 * 1024 * 1024;
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const MAX_SCREENSHOT_DIMENSION = 10_000;
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const MAX_SCREENSHOT_PIXELS = 50_000_000;
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export function validatePngScreenshot(buffer: Buffer, source: string): void {
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if (buffer.length === 0 || buffer.length > MAX_PNG_SCREENSHOT_BYTES) {
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throw new Error(`Invalid screenshot size for ${source}`);
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}
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if (buffer.length < 24 || !buffer.subarray(0, 8).equals(PNG_SIGNATURE)) {
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throw new Error(`Screenshot is not a PNG image: ${source}`);
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}
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const width = buffer.readUInt32BE(16);
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const height = buffer.readUInt32BE(20);
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if (
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width === 0 ||
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height === 0 ||
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width > MAX_SCREENSHOT_DIMENSION ||
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height > MAX_SCREENSHOT_DIMENSION ||
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width * height > MAX_SCREENSHOT_PIXELS
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) {
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throw new Error(`Invalid PNG dimensions for ${source}: ${width}x${height}`);
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}
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assertCompleteChunkStream(buffer, source);
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try {
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const decoded = PNG.sync.read(buffer, { checkCRC: true });
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if (decoded.width !== width || decoded.height !== height) {
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throw new Error("decoded dimensions do not match IHDR");
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}
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} catch (error) {
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const detail = error instanceof Error ? error.message : String(error);
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throw new Error(`Invalid PNG screenshot ${source}: ${detail}`);
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}
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}
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function assertCompleteChunkStream(buffer: Buffer, source: string): void {
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let offset = PNG_SIGNATURE.length;
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let chunkIndex = 0;
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while (offset < buffer.length) {
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if (offset + 12 > buffer.length) throw new Error(`Truncated PNG screenshot: ${source}`);
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const length = buffer.readUInt32BE(offset);
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const type = buffer.toString("ascii", offset + 4, offset + 8);
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const chunkEnd = offset + 12 + length;
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if (chunkEnd > buffer.length) throw new Error(`Truncated PNG screenshot: ${source}`);
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if (chunkIndex === 0 && (type !== "IHDR" || length !== 13)) {
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throw new Error(`Invalid PNG header for ${source}`);
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}
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if (type === "IEND") {
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if (length !== 0 || chunkEnd !== buffer.length) {
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throw new Error(`Invalid PNG end for ${source}`);
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}
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return;
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}
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offset = chunkEnd;
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chunkIndex += 1;
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}
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throw new Error(`PNG screenshot is missing IEND: ${source}`);
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}
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