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/* -*- 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 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 <other-error> 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 <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). This failure
* means no bytes were transferred.
* @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). This failure
* means no bytes were transferred.
* @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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