/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ /* ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (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.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is mozilla.org code. * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1998 * the Initial Developer. All Rights Reserved. * * Contributor(s): * Warren Harris * Darin Fisher * * Alternatively, the contents of this file may be used under the terms of * either of the GNU General Public License Version 2 or later (the "GPL"), * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ #include "nsISupports.idl" interface nsIInputStream; %{C++ /** * The signature of the writer function passed to ReadSegments. This * is the "consumer" of data that gets read from the stream's buffer. * * @param aInStream stream being read * @param aClosure opaque parameter passed to ReadSegments * @param aFromSegment pointer to memory owned by the input stream. This is * where the writer function should start consuming data. * @param aToOffset amount of data already consumed by this writer during this * ReadSegments call. This is also the sum of the aWriteCount * returns from this writer over the previous invocations of * the writer by this ReadSegments call. * @param aCount Number of bytes available to be read starting at aFromSegment * @param [out] aWriteCount number of bytes read by this writer function call * * Implementers should return the following: * * @return NS_OK and (*aWriteCount > 0) if consumed some data * @return if not interested in consuming any data * * Errors are never passed to the caller of ReadSegments. * * NOTE: returning NS_OK and (*aWriteCount = 0) has undefined behavior. * * @status FROZEN */ typedef NS_CALLBACK(nsWriteSegmentFun)(nsIInputStream *aInStream, void *aClosure, const char *aFromSegment, PRUint32 aToOffset, PRUint32 aCount, PRUint32 *aWriteCount); %} native nsWriteSegmentFun(nsWriteSegmentFun); /** * nsIInputStream * * An interface describing a readable stream of data. An input stream may be * "blocking" or "non-blocking" (see the IsNonBlocking method). A blocking * input stream may suspend the calling thread in order to satisfy a call to * Close, Available, Read, or ReadSegments. A non-blocking input stream, on * the other hand, must not block the calling thread of execution. * * NOTE: blocking input streams are often read on a background thread to avoid * locking up the main application thread. For this reason, it is generally * the case that a blocking input stream should be implemented using thread- * safe AddRef and Release. * * @status FROZEN */ [scriptable, uuid(fa9c7f6c-61b3-11d4-9877-00c04fa0cf4a)] interface nsIInputStream : nsISupports { /** * Close the stream. This method causes subsequent calls to Read and * ReadSegments to return 0 bytes read to indicate end-of-file. Any * subsequent calls to Available should throw NS_BASE_STREAM_CLOSED. */ void close(); /** * Determine number of bytes available in the stream. A non-blocking * stream that does not yet have any data to read should return 0 bytes * from this method (i.e., it must not throw the NS_BASE_STREAM_WOULD_BLOCK * exception). * * In addition to the number of bytes available in the stream, this method * also informs the caller of the current status of the stream. A stream * that is closed will throw an exception when this method is called. That * enables the caller to know the condition of the stream before attempting * to read from it. If a stream is at end-of-file, but not closed, then * this method should return 0 bytes available. * * @return number of bytes currently available in the stream, or * PR_UINT32_MAX if the size of the stream exceeds PR_UINT32_MAX. * * @throws NS_BASE_STREAM_CLOSED if the stream is closed normally or at * end-of-file * @throws if the stream is closed due to some error * condition */ unsigned long available(); /** * Read data from the stream. * * @param aBuf the buffer into which the data is to be read * @param aCount the maximum number of bytes to be read * * @return number of bytes read (may be less than aCount). * @return 0 if reached end-of-file * * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would * block the calling thread (non-blocking mode only) * @throws on failure * * NOTE: this method should not throw NS_BASE_STREAM_CLOSED. */ [noscript] unsigned long read(in charPtr aBuf, in unsigned long aCount); /** * Low-level read method that provides access to the stream's underlying * buffer. The writer function may be called multiple times for segmented * buffers. ReadSegments is expected to keep calling the writer until * either there is nothing left to read or the writer returns an error. * ReadSegments should not call the writer with zero bytes to consume. * * @param aWriter the "consumer" of the data to be read * @param aClosure opaque parameter passed to writer * @param aCount the maximum number of bytes to be read * * @return number of bytes read (may be less than aCount) * @return 0 if reached end-of-file (or if aWriter refused to consume data) * * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would * block the calling thread (non-blocking mode only) * @throws NS_ERROR_NOT_IMPLEMENTED if the stream has no underlying buffer * @throws on failure * * NOTE: this function may be unimplemented if a stream has no underlying * buffer (e.g., socket input stream). * * NOTE: this method should not throw NS_BASE_STREAM_CLOSED. */ [noscript] unsigned long readSegments(in nsWriteSegmentFun aWriter, in voidPtr aClosure, in unsigned long aCount); /** * @return true if stream is non-blocking * * NOTE: reading from a blocking input stream will block the calling thread * until at least one byte of data can be extracted from the stream. * * NOTE: a non-blocking input stream may implement nsIAsyncInputStream to * provide consumers with a way to wait for the stream to have more data * once its read method is unable to return any data without blocking. */ boolean isNonBlocking(); };