/* -*- 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 if not interested in providing any data * * Errors are never passed to the caller of WriteSegments. */ typedef nsresult (*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, builtinclass, uuid(0d0acd2a-61b4-11d4-9877-00c04fa0cf4a)] interface nsIOutputStream : nsISupports { /** * Close the stream. Forces the output stream to flush any buffered data. * Any subsequent calls to StreamStatus should throw NS_BASE_STREAM_CLOSED. * Succeeds without effect if already closed. * * @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(); /** * Check 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 write into it. * * This method will not throw NS_BASE_STREAM_WOULD_BLOCK, even if the stream * is a non-blocking stream with no available space. A non-blocking stream * which has not been closed, but has no available room should return NS_OK. * * NOTE: This method should not block the calling thread (e.g. to query the * state of a file descriptor), even when called on a blocking stream. * * @throws NS_BASE_STREAM_CLOSED if the stream closed normally * @throws if the stream closed with a different status */ void streamStatus(); /** * 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 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). This failure * means no bytes were transferred. * @throws 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). This failure * means no bytes were transferred. * @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 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(); };