node_stream.js

/* Copyright 2012 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/* globals __non_webpack_require__ */

let fs = __non_webpack_require__('fs');
let http = __non_webpack_require__('http');
let https = __non_webpack_require__('https');
let url = __non_webpack_require__('url');

import {
  AbortException, assert, createPromiseCapability
} from '../shared/util';
import { validateRangeRequestCapabilities } from './network_utils';

const fileUriRegex = /^file:\/\/\/[a-zA-Z]:\//;

class PDFNodeStream {
  constructor(source) {
    this.source = source;
    this.url = url.parse(source.url);
    this.isHttp = this.url.protocol === 'http:' ||
                  this.url.protocol === 'https:';
    // Check if url refers to filesystem.
    this.isFsUrl = this.url.protocol === 'file:' || !this.url.host;
    this.httpHeaders = (this.isHttp && source.httpHeaders) || {};

    this._fullRequest = null;
    this._rangeRequestReaders = [];
  }

  getFullReader() {
    assert(!this._fullRequest);
    this._fullRequest = this.isFsUrl ?
      new PDFNodeStreamFsFullReader(this) :
      new PDFNodeStreamFullReader(this);
    return this._fullRequest;
  }

  getRangeReader(start, end) {
    let rangeReader = this.isFsUrl ?
      new PDFNodeStreamFsRangeReader(this, start, end) :
      new PDFNodeStreamRangeReader(this, start, end);
    this._rangeRequestReaders.push(rangeReader);
    return rangeReader;
  }

  cancelAllRequests(reason) {
    if (this._fullRequest) {
      this._fullRequest.cancel(reason);
    }

    let readers = this._rangeRequestReaders.slice(0);
    readers.forEach(function(reader) {
      reader.cancel(reason);
    });
  }
}

class BaseFullReader {
  constructor(stream) {
    this._url = stream.url;
    this._done = false;
    this._errored = false;
    this._reason = null;
    this.onProgress = null;
    let source = stream.source;
    this._contentLength = source.length; // optional
    this._loaded = 0;

    this._disableRange = source.disableRange || false;
    this._rangeChunkSize = source.rangeChunkSize;
    if (!this._rangeChunkSize && !this._disableRange) {
      this._disableRange = true;
    }

    this._isStreamingSupported = !source.disableStream;
    this._isRangeSupported = !source.disableRange;

    this._readableStream = null;
    this._readCapability = createPromiseCapability();
    this._headersCapability = createPromiseCapability();
  }

  get headersReady() {
    return this._headersCapability.promise;
  }

  get contentLength() {
    return this._contentLength;
  }

  get isRangeSupported() {
    return this._isRangeSupported;
  }

  get isStreamingSupported() {
    return this._isStreamingSupported;
  }

  read() {
    return this._readCapability.promise.then(() => {
      if (this._done) {
        return Promise.resolve({ value: undefined, done: true, });
      }
      if (this._errored) {
        return Promise.reject(this._reason);
      }

      let chunk = this._readableStream.read();
      if (chunk === null) {
        this._readCapability = createPromiseCapability();
        return this.read();
      }
      this._loaded += chunk.length;
      if (this.onProgress) {
        this.onProgress({
          loaded: this._loaded,
          total: this._contentLength,
        });
      }
      // Ensure that `read()` method returns ArrayBuffer.
      let buffer = new Uint8Array(chunk).buffer;
      return Promise.resolve({ value: buffer, done: false, });
    });
  }

  cancel(reason) {
    // Call `this._error()` method when cancel is called
    // before _readableStream is set.
    if (!this._readableStream) {
      this._error(reason);
      return;
    }
    this._readableStream.destroy(reason);
  }

  _error(reason) {
    this._errored = true;
    this._reason = reason;
    this._readCapability.resolve();
  }

  _setReadableStream(readableStream) {
    this._readableStream = readableStream;
    readableStream.on('readable', () => {
      this._readCapability.resolve();
    });

    readableStream.on('end', () => {
      // Destroy readable to minimize resource usage.
      readableStream.destroy();
      this._done = true;
      this._readCapability.resolve();
    });

    readableStream.on('error', (reason) => {
      this._error(reason);
    });

    // We need to stop reading when range is supported and streaming is
    // disabled.
    if (!this._isStreamingSupported && this._isRangeSupported) {
      this._error(new AbortException('streaming is disabled'));
    }

    // Destroy ReadableStream if already in errored state.
    if (this._errored) {
      this._readableStream.destroy(this._reason);
    }
  }
}

class BaseRangeReader {
  constructor(stream) {
    this._url = stream.url;
    this._done = false;
    this._errored = false;
    this._reason = null;
    this.onProgress = null;
    this._loaded = 0;
    this._readableStream = null;
    this._readCapability = createPromiseCapability();
    let source = stream.source;
    this._isStreamingSupported = !source.disableStream;
  }

  get isStreamingSupported() {
    return this._isStreamingSupported;
  }

  read() {
    return this._readCapability.promise.then(() => {
      if (this._done) {
        return Promise.resolve({ value: undefined, done: true, });
      }
      if (this._errored) {
        return Promise.reject(this._reason);
      }

      let chunk = this._readableStream.read();
      if (chunk === null) {
        this._readCapability = createPromiseCapability();
        return this.read();
      }
      this._loaded += chunk.length;
      if (this.onProgress) {
        this.onProgress({ loaded: this._loaded, });
      }
      // Ensure that `read()` method returns ArrayBuffer.
      let buffer = new Uint8Array(chunk).buffer;
      return Promise.resolve({ value: buffer, done: false, });
    });
  }

  cancel(reason) {
    // Call `this._error()` method when cancel is called
    // before _readableStream is set.
    if (!this._readableStream) {
      this._error(reason);
      return;
    }
    this._readableStream.destroy(reason);
  }

  _error(reason) {
    this._errored = true;
    this._reason = reason;
    this._readCapability.resolve();
  }

  _setReadableStream(readableStream) {
    this._readableStream = readableStream;
    readableStream.on('readable', () => {
      this._readCapability.resolve();
    });

    readableStream.on('end', () => {
      // Destroy readableStream to minimize resource usage.
      readableStream.destroy();
      this._done = true;
      this._readCapability.resolve();
    });

    readableStream.on('error', (reason) => {
      this._error(reason);
    });

    // Destroy readableStream if already in errored state.
    if (this._errored) {
      this._readableStream.destroy(this._reason);
    }
  }
}

function createRequestOptions(url, headers) {
  return {
    protocol: url.protocol,
    auth: url.auth,
    host: url.hostname,
    port: url.port,
    path: url.path,
    method: 'GET',
    headers,
  };
}

class PDFNodeStreamFullReader extends BaseFullReader {
  constructor(stream) {
    super(stream);

    let handleResponse = (response) => {
      this._headersCapability.resolve();
      this._setReadableStream(response);

      let { allowRangeRequests, suggestedLength, } =
      validateRangeRequestCapabilities({
        getResponseHeader: (name) => {
          // Make sure that headers name are in lower case, as mentioned
          // here: https://nodejs.org/api/http.html#http_message_headers.
          return this._readableStream.headers[name.toLowerCase()];
        },
        isHttp: stream.isHttp,
        rangeChunkSize: this._rangeChunkSize,
        disableRange: this._disableRange,
      });

      if (allowRangeRequests) {
        this._isRangeSupported = true;
      }
      // Setting right content length.
      this._contentLength = suggestedLength;
    };

    this._request = null;
    if (this._url.protocol === 'http:') {
      this._request = http.request(
        createRequestOptions(this._url, stream.httpHeaders),
        handleResponse);
    } else {
      this._request = https.request(
        createRequestOptions(this._url, stream.httpHeaders),
        handleResponse);
    }

    this._request.on('error', (reason) => {
      this._errored = true;
      this._reason = reason;
      this._headersCapability.reject(reason);
    });
    // Note: `request.end(data)` is used to write `data` to request body
    // and notify end of request. But one should always call `request.end()`
    // even if there is no data to write -- (to notify the end of request).
    this._request.end();
  }
}

class PDFNodeStreamRangeReader extends BaseRangeReader {
  constructor(stream, start, end) {
    super(stream);

    this._httpHeaders = {};
    for (let property in stream.httpHeaders) {
      let value = stream.httpHeaders[property];
      if (typeof value === 'undefined') {
        continue;
      }
      this._httpHeaders[property] = value;
    }
    this._httpHeaders['Range'] = `bytes=${start}-${end - 1}`;

    this._request = null;
    if (this._url.protocol === 'http:') {
      this._request = http.request(createRequestOptions(
        this._url, this._httpHeaders), (response) => {
          this._setReadableStream(response);
        });
    } else {
      this._request = https.request(createRequestOptions(
        this._url, this._httpHeaders), (response) => {
          this._setReadableStream(response);
        });
    }

    this._request.on('error', (reason) => {
      this._errored = true;
      this._reason = reason;
    });
    this._request.end();
  }
}

class PDFNodeStreamFsFullReader extends BaseFullReader {
  constructor(stream) {
    super(stream);

    let path = decodeURI(this._url.path);

    // Remove the extra slash to get right path from url like `file:///C:/`
    if (fileUriRegex.test(this._url.href)) {
      path = path.replace(/^\//, '');
    }

    fs.lstat(path, (error, stat) => {
      if (error) {
        this._errored = true;
        this._reason = error;
        this._headersCapability.reject(error);
        return;
      }
      // Setting right content length.
      this._contentLength = stat.size;

      this._setReadableStream(fs.createReadStream(path));
      this._headersCapability.resolve();
    });
  }
}

class PDFNodeStreamFsRangeReader extends BaseRangeReader {
  constructor(stream, start, end) {
    super(stream);

    let path = decodeURI(this._url.path);

    // Remove the extra slash to get right path from url like `file:///C:/`
    if (fileUriRegex.test(this._url.href)) {
      path = path.replace(/^\//, '');
    }

    this._setReadableStream(
      fs.createReadStream(path, { start, end: end - 1, }));
  }
}

export {
  PDFNodeStream,
};