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