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code-server/packages/server/src/fill.ts
2019-02-07 13:11:01 -06:00

156 lines
3.7 KiB
TypeScript

import * as fs from "fs";
import * as util from "util";
import { isCli } from "./constants";
const oldAccess = fs.access;
const existsWithinBinary = (path: fs.PathLike): Promise<boolean> => {
return new Promise<boolean>((resolve): void => {
if (typeof path === "number") {
if (path < 0) {
return resolve(true);
}
}
oldAccess(path, fs.constants.F_OK, (err) => {
const exists = !err;
const es = fs.existsSync(path);
const res = !exists && es;
resolve(res);
});
});
};
export const fillFs = (): void => {
/**
* Refer to https://github.com/nexe/nexe/blob/master/src/fs/patch.ts
* For impls
*/
if (!isCli) {
throw new Error("Should not fill FS when not in CLI");
}
interface FD {
readonly path: string;
position: number;
}
let lastFd = Number.MIN_SAFE_INTEGER;
const fds = new Map<number, FD>();
const replaceNative = <T extends keyof typeof fs>(propertyName: T, func: (callOld: () => void, ...args: any[]) => any, customPromisify?: (...args: any[]) => Promise<any>): void => {
const oldFunc = (<any>fs)[propertyName];
fs[propertyName] = (...args: any[]) => {
try {
return func(() => {
return oldFunc(...args);
}, ...args);
} catch (ex) {
return oldFunc(...args);
}
};
if (customPromisify) {
(<any>fs[propertyName])[util.promisify.custom] = customPromisify;
}
};
replaceNative("access", (callNative, path, mode, callback) => {
existsWithinBinary(path).then((exists) => {
if (!exists) {
return callNative();
}
return callback();
});
});
replaceNative("exists", (callOld, path, callback) => {
existsWithinBinary(path).then((exists) => {
if (exists) {
return callback(true);
}
return callOld();
});
}, (path) => new Promise((res) => fs.exists(path, res)));
replaceNative("open", (callOld, path: fs.PathLike, flags: string | Number, mode: any, callback: any) => {
existsWithinBinary(path).then((exists) => {
if (!exists) {
return callOld();
}
if (typeof mode === "function") {
callback = mode;
mode = undefined;
}
if (path === process.execPath) {
return callOld();
}
const fd = lastFd++;
fds.set(fd, {
path: path.toString(),
position: 0,
});
callback(undefined, fd);
});
});
replaceNative("close", (callOld, fd: number, callback) => {
if (!fds.has(fd)) {
return callOld();
}
fds.delete(fd);
callback();
});
replaceNative("read", (callOld, fd: number, buffer: Buffer, offset: number, length: number, position: number | null, callback?: (err: NodeJS.ErrnoException, bytesRead: number, buffer: Buffer) => void, ) => {
if (!fds.has(fd)) {
return callOld();
}
const fileDesc = fds.get(fd)!;
/**
* `readFile` is filled within nexe, but `read` is not
* https://github.com/nexe/nexe/blob/master/src/fs/patch.ts#L199
* We can simulate a real _read_ by reading the entire file.
* Efficiency can be improved here by storing the entire file in memory
* until it has been closed.
*/
return fs.readFile(fileDesc.path, (err, rb) => {
if (err) {
return callOld();
}
rb = rb.slice(position || fileDesc.position);
const sliced = rb.slice(0, length);
if (position === null) {
fileDesc.position += sliced.byteLength;
}
buffer.set(sliced, offset);
if (callback) {
callback(undefined!, sliced.byteLength, buffer);
}
});
}, (fd: number, buffer: Buffer, offset: number, length: number, position: number | null): Promise<{
bytesRead: number;
buffer: Buffer;
}> => {
return new Promise((res, rej) => {
fs.read(fd, buffer, offset, length, position, (err, bytesRead, buffer) => {
if (err) {
return rej(err);
}
res({
bytesRead,
buffer,
});
});
});
});
};