The Tor Browser: xpcom/io/nsIOutputStream.idl@97036ab72558 (annotated)

xpcom/io/nsIOutputStream.idl@97036ab72558 (annotated)

xpcom/io/nsIOutputStream.idl

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "nsISupports.idl"
 interface nsIOutputStream;
 interface nsIInputStream;
 %{C++
 /**
  * The signature for the reader function passed to WriteSegments. This
  * is the "provider" of data that gets written into the stream's buffer.
  *
  * @param aOutStream stream being written to
  * @param aClosure opaque parameter passed to WriteSegments
  * @param aToSegment pointer to memory owned by the output stream
  * @param aFromOffset amount already written (since WriteSegments was called)
  * @param aCount length of toSegment
  * @param aReadCount number of bytes written
  *
  * Implementers should return the following:
  *
  * @throws <any-error> if not interested in providing any data
  *
  * Errors are never passed to the caller of WriteSegments.
  */
 typedef NS_CALLBACK(nsReadSegmentFun)(nsIOutputStream *aOutStream,
                                       void *aClosure,
                                       char *aToSegment,
                                       uint32_t aFromOffset,
                                       uint32_t aCount,
                                       uint32_t *aReadCount);
 %}
 native nsReadSegmentFun(nsReadSegmentFun);
 /**
  * nsIOutputStream
  *
  * An interface describing a writable stream of data.  An output stream may be
  * "blocking" or "non-blocking" (see the IsNonBlocking method).  A blocking
  * output stream may suspend the calling thread in order to satisfy a call to
  * Close, Flush, Write, WriteFrom, or WriteSegments.  A non-blocking output
  * stream, on the other hand, must not block the calling thread of execution.
  *
  * NOTE: blocking output streams are often written to on a background thread to
  * avoid locking up the main application thread.  For this reason, it is
  * generally the case that a blocking output stream should be implemented using
  * thread- safe AddRef and Release.
  */
 [scriptable, uuid(0d0acd2a-61b4-11d4-9877-00c04fa0cf4a)]
 interface nsIOutputStream : nsISupports
 {
     /**
      * Close the stream. Forces the output stream to flush any buffered data.
      *
      * @throws NS_BASE_STREAM_WOULD_BLOCK if unable to flush without blocking
      *   the calling thread (non-blocking mode only)
      */
     void close();
     /**
      * Flush the stream.
      *
      * @throws NS_BASE_STREAM_WOULD_BLOCK if unable to flush without blocking
      *   the calling thread (non-blocking mode only)
      */
     void flush();
     /**
      * Write data into the stream.
      *
      * @param aBuf the buffer containing the data to be written
      * @param aCount the maximum number of bytes to be written
      *
      * @return number of bytes written (may be less than aCount)
      *
      * @throws NS_BASE_STREAM_WOULD_BLOCK if writing to the output stream would
      *   block the calling thread (non-blocking mode only)
      * @throws <other-error> on failure
      */
     unsigned long write(in string aBuf, in unsigned long aCount);
     /**
      * Writes data into the stream from an input stream.
      *
      * @param aFromStream the stream containing the data to be written
      * @param aCount the maximum number of bytes to be written
      *
      * @return number of bytes written (may be less than aCount)
      *
      * @throws NS_BASE_STREAM_WOULD_BLOCK if writing to the output stream would
      *    block the calling thread (non-blocking mode only)
      * @throws <other-error> on failure
      *
      * NOTE: This method is defined by this interface in order to allow the
      * output stream to efficiently copy the data from the input stream into
      * its internal buffer (if any). If this method was provided as an external
      * facility, a separate char* buffer would need to be used in order to call
      * the output stream's other Write method.
      */
     unsigned long writeFrom(in nsIInputStream aFromStream,
                             in unsigned long aCount);
     /**
      * Low-level write method that has access to the stream's underlying buffer.
      * The reader function may be called multiple times for segmented buffers.
      * WriteSegments is expected to keep calling the reader until either there
      * is nothing left to write or the reader returns an error.  WriteSegments
      * should not call the reader with zero bytes to provide.
      *
      * @param aReader the "provider" of the data to be written
      * @param aClosure opaque parameter passed to reader
      * @param aCount the maximum number of bytes to be written
      *
      * @return number of bytes written (may be less than aCount)
      *
      * @throws NS_BASE_STREAM_WOULD_BLOCK if writing to the output stream would
      *    block the calling thread (non-blocking mode only)
      * @throws NS_ERROR_NOT_IMPLEMENTED if the stream has no underlying buffer
      * @throws <other-error> on failure
      *
      * NOTE: this function may be unimplemented if a stream has no underlying
      * buffer (e.g., socket output stream).
      */
     [noscript] unsigned long writeSegments(in nsReadSegmentFun aReader,
                                            in voidPtr aClosure,
                                            in unsigned long aCount);
     /**
      * @return true if stream is non-blocking
      *
      * NOTE: writing to a blocking output stream will block the calling thread
      * until all given data can be consumed by the stream.
      *
      * NOTE: a non-blocking output stream may implement nsIAsyncOutputStream to
      * provide consumers with a way to wait for the stream to accept more data
      * once its write method is unable to accept any data without blocking.
      */
     boolean isNonBlocking();
 };

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