fs-capacitor/dist/index.js

import { randomBytes } from "crypto";
import { read, open, closeSync, unlinkSync, write, close, unlink } from "fs";
import { tmpdir } from "os";
import { join } from "path";
import { Readable, Writable } from "stream";
import { EventEmitter } from "events";
export class ReadAfterDestroyedError extends Error {
}
export class ReadAfterReleasedError extends Error {
}
// Use a “proxy” event emitter configured to have an infinite maximum number of
// listeners to prevent Node.js max listeners exceeded warnings if many
// `fs-capacitor` `ReadStream` instances are created at the same time. See:
// https://github.com/mike-marcacci/fs-capacitor/issues/30
const processExitProxy = new EventEmitter();
processExitProxy.setMaxListeners(Infinity);
process.once("exit", () => processExitProxy.emit("exit"));
export class ReadStream extends Readable {
    constructor(writeStream, options) {
        super({
            highWaterMark: options === null || options === void 0 ? void 0 : options.highWaterMark,
            encoding: options === null || options === void 0 ? void 0 : options.encoding,
            autoDestroy: true,
        });
        this._pos = 0;
        this._writeStream = writeStream;
    }
    _read(n) {
        if (this.destroyed)
            return;
        if (typeof this._writeStream["_fd"] !== "number") {
            this._writeStream.once("ready", () => this._read(n));
            return;
        }
        // Using `allocUnsafe` here is OK because we return a slice the length of
        // `bytesRead`, and discard the rest. This prevents node from having to zero
        // out the entire allocation first.
        const buf = Buffer.allocUnsafe(n);
        read(this._writeStream["_fd"], buf, 0, n, this._pos, (error, bytesRead) => {
            if (error)
                this.destroy(error);
            // Push any read bytes into the local stream buffer.
            if (bytesRead) {
                this._pos += bytesRead;
                this.push(buf.slice(0, bytesRead));
                return;
            }
            // If there were no more bytes to read and the write stream is finished,
            // than this stream has reached the end.
            if (this._writeStream._writableState.finished) {
                this.push(null);
                return;
            }
            // Otherwise, wait for the write stream to add more data or finish.
            const retry = () => {
                this._writeStream.off("finish", retry);
                this._writeStream.off("write", retry);
                this._read(n);
            };
            this._writeStream.on("finish", retry);
            this._writeStream.on("write", retry);
        });
    }
}
export class WriteStream extends Writable {
    constructor(options) {
        super({
            highWaterMark: options === null || options === void 0 ? void 0 : options.highWaterMark,
            defaultEncoding: options === null || options === void 0 ? void 0 : options.defaultEncoding,
            autoDestroy: false,
        });
        this._fd = null;
        this._path = null;
        this._pos = 0;
        this._readStreams = new Set();
        this._released = false;
        this._cleanup = (callback) => {
            const fd = this._fd;
            const path = this._path;
            if (typeof fd !== "number" || typeof path !== "string") {
                callback(null);
                return;
            }
            // Close the file descriptor.
            close(fd, (closeError) => {
                // An error here probably means the fd was already closed, but we can
                // still try to unlink the file.
                unlink(path, (unlinkError) => {
                    // If we are unable to unlink the file, the operating system will
                    // clean up on next restart, since we use store thes in `os.tmpdir()`
                    this._fd = null;
                    // We avoid removing this until now in case an exit occurs while
                    // asyncronously cleaning up.
                    processExitProxy.off("exit", this._cleanupSync);
                    callback(unlinkError !== null && unlinkError !== void 0 ? unlinkError : closeError);
                });
            });
        };
        this._cleanupSync = () => {
            processExitProxy.off("exit", this._cleanupSync);
            if (typeof this._fd === "number")
                try {
                    closeSync(this._fd);
                }
                catch (error) {
                    // An error here probably means the fd was already closed, but we can
                    // still try to unlink the file.
                }
            try {
                if (this._path !== null) {
                    unlinkSync(this._path);
                }
            }
            catch (error) {
                // If we are unable to unlink the file, the operating system will clean
                // up on next restart, since we use store thes in `os.tmpdir()`
            }
        };
        // Generate a random filename.
        randomBytes(16, (error, buffer) => {
            var _a;
            if (error) {
                this.destroy(error);
                return;
            }
            this._path = join(((_a = options === null || options === void 0 ? void 0 : options.tmpdir) !== null && _a !== void 0 ? _a : tmpdir)(), `capacitor-${buffer.toString("hex")}.tmp`);
            // Create a file in the OS's temporary files directory.
            open(this._path, "wx+", 0o600, (error, fd) => {
                if (error) {
                    this.destroy(error);
                    return;
                }
                // Cleanup when the process exits or is killed.
                processExitProxy.once("exit", this._cleanupSync);
                this._fd = fd;
                this.emit("ready");
            });
        });
    }
    _final(callback) {
        if (typeof this._fd !== "number") {
            this.once("ready", () => this._final(callback));
            return;
        }
        callback();
    }
    _write(chunk, encoding, callback) {
        if (typeof this._fd !== "number") {
            this.once("ready", () => this._write(chunk, encoding, callback));
            return;
        }
        write(this._fd, chunk, 0, chunk.length, this._pos, (error) => {
            if (error) {
                callback(error);
                return;
            }
            // It's safe to increment `this._pos` after flushing to the filesystem
            // because node streams ensure that only one `_write()` is active at a
            // time. If this assumption is broken, the behavior of this library is
            // undefined, regardless of where this is incremented. Relocating this
            // to increment syncronously would result in correct file contents, but
            // the out-of-order writes would still open the potential for read streams
            // to scan positions that have not yet been written.
            this._pos += chunk.length;
            this.emit("write");
            callback();
        });
    }
    release() {
        this._released = true;
        if (this._readStreams.size === 0)
            this.destroy();
    }
    _destroy(error, callback) {
        // Destroy all attached read streams.
        for (const readStream of this._readStreams) {
            readStream.destroy(error || undefined);
        }
        // This capacitor is fully initialized.
        if (typeof this._fd === "number" && typeof this._path === "string") {
            this._cleanup((cleanupError) => callback(cleanupError !== null && cleanupError !== void 0 ? cleanupError : error));
            return;
        }
        // This capacitor has not yet finished initialization; if initialization
        // does complete, immediately clean up after.
        this.once("ready", () => {
            this._cleanup((cleanupError) => {
                if (cleanupError) {
                    this.emit("error", cleanupError);
                }
            });
        });
        callback(error);
    }
    createReadStream(options) {
        if (this.destroyed)
            throw new ReadAfterDestroyedError("A ReadStream cannot be created from a destroyed WriteStream.");
        if (this._released)
            throw new ReadAfterReleasedError("A ReadStream cannot be created from a released WriteStream.");
        const readStream = new ReadStream(this, options);
        this._readStreams.add(readStream);
        readStream.once("close", () => {
            this._readStreams.delete(readStream);
            if (this._released && this._readStreams.size === 0) {
                this.destroy();
            }
        });
        return readStream;
    }
}
export default {
    WriteStream,
    ReadStream,
    ReadAfterDestroyedError,
    ReadAfterReleasedError,
};
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