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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, 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). 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();
+};