nstdlib-nightly/lib/internal/fs/streams.mjs

Node.js standard library converted to runtime-agnostic ES modules.

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/internal/fs/streams.js

import { codes as __codes__ } from "nstdlib/lib/internal/errors";
import { deprecate, kEmptyObject } from "nstdlib/lib/internal/util";
import {
  validateBoolean,
  validateFunction,
  validateInteger,
} from "nstdlib/lib/internal/validators";
import { errorOrDestroy } from "nstdlib/lib/internal/streams/destroy";
import * as fs from "nstdlib/lib/fs";
import { kRef, kUnref, FileHandle } from "nstdlib/lib/internal/fs/promises";
import { Buffer } from "nstdlib/lib/buffer";
import {
  copyObject,
  getOptions,
  getValidatedFd,
  validatePath,
} from "nstdlib/lib/internal/fs/utils";
import { Readable, Writable, finished } from "nstdlib/lib/stream";
import { toPathIfFileURL } from "nstdlib/lib/internal/url";

const {
  ERR_INVALID_ARG_TYPE,
  ERR_METHOD_NOT_IMPLEMENTED,
  ERR_OUT_OF_RANGE,
  ERR_STREAM_DESTROYED,
  ERR_SYSTEM_ERROR,
} = __codes__;
const kIoDone = Symbol("kIoDone");
const kIsPerformingIO = Symbol("kIsPerformingIO");

const kFs = Symbol("kFs");
const kHandle = Symbol("kHandle");

function _construct(callback) {
  const stream = this;
  if (typeof stream.fd === "number") {
    callback();
    return;
  }

  if (stream.open !== openWriteFs && stream.open !== openReadFs) {
    // Backwards compat for monkey patching open().
    const orgEmit = stream.emit;
    stream.emit = function (...args) {
      if (args[0] === "open") {
        this.emit = orgEmit;
        callback();
        ReflectApply(orgEmit, this, args);
      } else if (args[0] === "error") {
        this.emit = orgEmit;
        callback(args[1]);
      } else {
        ReflectApply(orgEmit, this, args);
      }
    };
    stream.open();
  } else {
    stream[kFs].open(stream.path, stream.flags, stream.mode, (er, fd) => {
      if (er) {
        callback(er);
      } else {
        stream.fd = fd;
        callback();
        stream.emit("open", stream.fd);
        stream.emit("ready");
      }
    });
  }
}

// This generates an fs operations structure for a FileHandle
const FileHandleOperations = (handle) => {
  return {
    open: (path, flags, mode, cb) => {
      throw new ERR_METHOD_NOT_IMPLEMENTED("open()");
    },
    close: (fd, cb) => {
      handle[kUnref]();
      Promise.prototype.then.call(handle.close(), () => cb(), cb);
    },
    fsync: (fd, cb) => {
      Promise.prototype.then.call(handle.sync(), () => cb(), cb);
    },
    read: (fd, buf, offset, length, pos, cb) => {
      Promise.prototype.then.call(
        handle.read(buf, offset, length, pos),
        (r) => cb(null, r.bytesRead, r.buffer),
        (err) => cb(err, 0, buf),
      );
    },
    write: (fd, buf, offset, length, pos, cb) => {
      Promise.prototype.then.call(
        handle.write(buf, offset, length, pos),
        (r) => cb(null, r.bytesWritten, r.buffer),
        (err) => cb(err, 0, buf),
      );
    },
    writev: (fd, buffers, pos, cb) => {
      Promise.prototype.then.call(
        handle.writev(buffers, pos),
        (r) => cb(null, r.bytesWritten, r.buffers),
        (err) => cb(err, 0, buffers),
      );
    },
  };
};

function close(stream, err, cb) {
  if (!stream.fd) {
    cb(err);
  } else if (stream.flush) {
    stream[kFs].fsync(stream.fd, (flushErr) => {
      _close(stream, err || flushErr, cb);
    });
  } else {
    _close(stream, err, cb);
  }
}

function _close(stream, err, cb) {
  stream[kFs].close(stream.fd, (er) => {
    cb(er || err);
  });
  stream.fd = null;
}

function importFd(stream, options) {
  if (typeof options.fd === "number") {
    // When fd is a raw descriptor, we must keep our fingers crossed
    // that the descriptor won't get closed, or worse, replaced with
    // another one
    // https://github.com/nodejs/node/issues/35862
    stream[kFs] = options.fs || fs;
    return options.fd;
  } else if (
    typeof options.fd === "object" &&
    options.fd instanceof FileHandle
  ) {
    // When fd is a FileHandle we can listen for 'close' events
    if (options.fs) {
      // FileHandle is not supported with custom fs operations
      throw new ERR_METHOD_NOT_IMPLEMENTED("FileHandle with fs");
    }
    stream[kHandle] = options.fd;
    stream[kFs] = FileHandleOperations(stream[kHandle]);
    stream[kHandle][kRef]();
    options.fd.on("close", Function.prototype.bind.call(stream.close, stream));
    return options.fd.fd;
  }

  throw new ERR_INVALID_ARG_TYPE(
    "options.fd",
    ["number", "FileHandle"],
    options.fd,
  );
}

function ReadStream(path, options) {
  if (!(this instanceof ReadStream)) return new ReadStream(path, options);

  // A little bit bigger buffer and water marks by default
  options = copyObject(getOptions(options, kEmptyObject));
  if (options.highWaterMark === undefined) options.highWaterMark = 64 * 1024;

  if (options.autoDestroy === undefined) {
    options.autoDestroy = false;
  }

  if (options.fd == null) {
    this.fd = null;
    this[kFs] = options.fs || fs;
    validateFunction(this[kFs].open, "options.fs.open");

    // Path will be ignored when fd is specified, so it can be falsy
    this.path = toPathIfFileURL(path);
    this.flags = options.flags === undefined ? "r" : options.flags;
    this.mode = options.mode === undefined ? 0o666 : options.mode;

    validatePath(this.path);
  } else {
    this.fd = getValidatedFd(importFd(this, options));
  }

  options.autoDestroy =
    options.autoClose === undefined ? true : options.autoClose;

  validateFunction(this[kFs].read, "options.fs.read");

  if (options.autoDestroy) {
    validateFunction(this[kFs].close, "options.fs.close");
  }

  this.start = options.start;
  this.end = options.end;
  this.pos = undefined;
  this.bytesRead = 0;
  this[kIsPerformingIO] = false;

  if (this.start !== undefined) {
    validateInteger(this.start, "start", 0);

    this.pos = this.start;
  }

  if (this.end === undefined) {
    this.end = Infinity;
  } else if (this.end !== Infinity) {
    validateInteger(this.end, "end", 0);

    if (this.start !== undefined && this.start > this.end) {
      throw new ERR_OUT_OF_RANGE(
        "start",
        `<= "end" (here: ${this.end})`,
        this.start,
      );
    }
  }

  ReflectApply(Readable, this, [options]);
}
Object.setPrototypeOf(ReadStream.prototype, Readable.prototype);
Object.setPrototypeOf(ReadStream, Readable);

Object.defineProperty(ReadStream.prototype, "autoClose", {
  __proto__: null,
  get() {
    return this._readableState.autoDestroy;
  },
  set(val) {
    this._readableState.autoDestroy = val;
  },
});

const openReadFs = deprecate(
  function () {
    // Noop.
  },
  "ReadStream.prototype.open() is deprecated",
  "DEP0135",
);
ReadStream.prototype.open = openReadFs;

ReadStream.prototype._construct = _construct;

ReadStream.prototype._read = function (n) {
  n =
    this.pos !== undefined
      ? Math.min(this.end - this.pos + 1, n)
      : Math.min(this.end - this.bytesRead + 1, n);

  if (n <= 0) {
    this.push(null);
    return;
  }

  const buf = Buffer.allocUnsafeSlow(n);

  this[kIsPerformingIO] = true;
  this[kFs].read(this.fd, buf, 0, n, this.pos, (er, bytesRead, buf) => {
    this[kIsPerformingIO] = false;

    // Tell ._destroy() that it's safe to close the fd now.
    if (this.destroyed) {
      this.emit(kIoDone, er);
      return;
    }

    if (er) {
      errorOrDestroy(this, er);
    } else if (bytesRead > 0) {
      if (this.pos !== undefined) {
        this.pos += bytesRead;
      }

      this.bytesRead += bytesRead;

      if (bytesRead !== buf.length) {
        // Slow path. Shrink to fit.
        // Copy instead of slice so that we don't retain
        // large backing buffer for small reads.
        const dst = Buffer.allocUnsafeSlow(bytesRead);
        buf.copy(dst, 0, 0, bytesRead);
        buf = dst;
      }

      this.push(buf);
    } else {
      this.push(null);
    }
  });
};

ReadStream.prototype._destroy = function (err, cb) {
  // Usually for async IO it is safe to close a file descriptor
  // even when there are pending operations. However, due to platform
  // differences file IO is implemented using synchronous operations
  // running in a thread pool. Therefore, file descriptors are not safe
  // to close while used in a pending read or write operation. Wait for
  // any pending IO (kIsPerformingIO) to complete (kIoDone).
  if (this[kIsPerformingIO]) {
    this.once(kIoDone, (er) => close(this, err || er, cb));
  } else {
    close(this, err, cb);
  }
};

ReadStream.prototype.close = function (cb) {
  if (typeof cb === "function") finished(this, cb);
  this.destroy();
};

Object.defineProperty(ReadStream.prototype, "pending", {
  __proto__: null,
  get() {
    return this.fd === null;
  },
  configurable: true,
});

function WriteStream(path, options) {
  if (!(this instanceof WriteStream)) return new WriteStream(path, options);

  options = copyObject(getOptions(options, kEmptyObject));

  // Only buffers are supported.
  options.decodeStrings = true;

  if (options.fd == null) {
    this.fd = null;
    this[kFs] = options.fs || fs;
    validateFunction(this[kFs].open, "options.fs.open");

    // Path will be ignored when fd is specified, so it can be falsy
    this.path = toPathIfFileURL(path);
    this.flags = options.flags === undefined ? "w" : options.flags;
    this.mode = options.mode === undefined ? 0o666 : options.mode;

    validatePath(this.path);
  } else {
    this.fd = getValidatedFd(importFd(this, options));
  }

  options.autoDestroy =
    options.autoClose === undefined ? true : options.autoClose;

  if (!this[kFs].write && !this[kFs].writev) {
    throw new ERR_INVALID_ARG_TYPE(
      "options.fs.write",
      "function",
      this[kFs].write,
    );
  }

  if (this[kFs].write) {
    validateFunction(this[kFs].write, "options.fs.write");
  }

  if (this[kFs].writev) {
    validateFunction(this[kFs].writev, "options.fs.writev");
  }

  if (options.autoDestroy) {
    validateFunction(this[kFs].close, "options.fs.close");
  }

  this.flush = options.flush;
  if (this.flush == null) {
    this.flush = false;
  } else {
    validateBoolean(this.flush, "options.flush");
    validateFunction(this[kFs].fsync, "options.fs.fsync");
  }

  // It's enough to override either, in which case only one will be used.
  if (!this[kFs].write) {
    this._write = null;
  }
  if (!this[kFs].writev) {
    this._writev = null;
  }

  this.start = options.start;
  this.pos = undefined;
  this.bytesWritten = 0;
  this[kIsPerformingIO] = false;

  if (this.start !== undefined) {
    validateInteger(this.start, "start", 0);

    this.pos = this.start;
  }

  ReflectApply(Writable, this, [options]);

  if (options.encoding) this.setDefaultEncoding(options.encoding);
}
Object.setPrototypeOf(WriteStream.prototype, Writable.prototype);
Object.setPrototypeOf(WriteStream, Writable);

Object.defineProperty(WriteStream.prototype, "autoClose", {
  __proto__: null,
  get() {
    return this._writableState.autoDestroy;
  },
  set(val) {
    this._writableState.autoDestroy = val;
  },
});

const openWriteFs = deprecate(
  function () {
    // Noop.
  },
  "WriteStream.prototype.open() is deprecated",
  "DEP0135",
);
WriteStream.prototype.open = openWriteFs;

WriteStream.prototype._construct = _construct;

function writeAll(data, size, pos, cb, retries = 0) {
  this[kFs].write(this.fd, data, 0, size, pos, (er, bytesWritten, buffer) => {
    // No data currently available and operation should be retried later.
    if (er?.code === "EAGAIN") {
      er = null;
      bytesWritten = 0;
    }

    if (this.destroyed || er) {
      return cb(er || new ERR_STREAM_DESTROYED("write"));
    }

    this.bytesWritten += bytesWritten;

    retries = bytesWritten ? 0 : retries + 1;
    size -= bytesWritten;
    pos += bytesWritten;

    // Try writing non-zero number of bytes up to 5 times.
    if (retries > 5) {
      cb(new ERR_SYSTEM_ERROR("write failed"));
    } else if (size) {
      writeAll.call(this, buffer.slice(bytesWritten), size, pos, cb, retries);
    } else {
      cb();
    }
  });
}

function writevAll(chunks, size, pos, cb, retries = 0) {
  this[kFs].writev(this.fd, chunks, this.pos, (er, bytesWritten, buffers) => {
    // No data currently available and operation should be retried later.
    if (er?.code === "EAGAIN") {
      er = null;
      bytesWritten = 0;
    }

    if (this.destroyed || er) {
      return cb(er || new ERR_STREAM_DESTROYED("writev"));
    }

    this.bytesWritten += bytesWritten;

    retries = bytesWritten ? 0 : retries + 1;
    size -= bytesWritten;
    pos += bytesWritten;

    // Try writing non-zero number of bytes up to 5 times.
    if (retries > 5) {
      cb(new ERR_SYSTEM_ERROR("writev failed"));
    } else if (size) {
      writevAll.call(
        this,
        [Buffer.concat(buffers).slice(bytesWritten)],
        size,
        pos,
        cb,
        retries,
      );
    } else {
      cb();
    }
  });
}

WriteStream.prototype._write = function (data, encoding, cb) {
  this[kIsPerformingIO] = true;
  writeAll.call(this, data, data.length, this.pos, (er) => {
    this[kIsPerformingIO] = false;
    if (this.destroyed) {
      // Tell ._destroy() that it's safe to close the fd now.
      cb(er);
      return this.emit(kIoDone, er);
    }

    cb(er);
  });

  if (this.pos !== undefined) this.pos += data.length;
};

WriteStream.prototype._writev = function (data, cb) {
  const len = data.length;
  const chunks = new Array(len);
  let size = 0;

  for (let i = 0; i < len; i++) {
    const chunk = data[i].chunk;

    chunks[i] = chunk;
    size += chunk.length;
  }

  this[kIsPerformingIO] = true;
  writevAll.call(this, chunks, size, this.pos, (er) => {
    this[kIsPerformingIO] = false;
    if (this.destroyed) {
      // Tell ._destroy() that it's safe to close the fd now.
      cb(er);
      return this.emit(kIoDone, er);
    }

    cb(er);
  });

  if (this.pos !== undefined) this.pos += size;
};

WriteStream.prototype._destroy = function (err, cb) {
  // Usually for async IO it is safe to close a file descriptor
  // even when there are pending operations. However, due to platform
  // differences file IO is implemented using synchronous operations
  // running in a thread pool. Therefore, file descriptors are not safe
  // to close while used in a pending read or write operation. Wait for
  // any pending IO (kIsPerformingIO) to complete (kIoDone).
  if (this[kIsPerformingIO]) {
    this.once(kIoDone, (er) => close(this, err || er, cb));
  } else {
    close(this, err, cb);
  }
};

WriteStream.prototype.close = function (cb) {
  if (cb) {
    if (this.closed) {
      process.nextTick(cb);
      return;
    }
    this.on("close", cb);
  }

  // If we are not autoClosing, we should call
  // destroy on 'finish'.
  if (!this.autoClose) {
    this.on("finish", this.destroy);
  }

  // We use end() instead of destroy() because of
  // https://github.com/nodejs/node/issues/2006
  this.end();
};

// There is no shutdown() for files.
WriteStream.prototype.destroySoon = WriteStream.prototype.end;

Object.defineProperty(WriteStream.prototype, "pending", {
  __proto__: null,
  get() {
    return this.fd === null;
  },
  configurable: true,
});

export { ReadStream };
export { WriteStream };