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diff --git a/xpcom/io/nsStreamUtils.h b/xpcom/io/nsStreamUtils.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef nsStreamUtils_h__
+#define nsStreamUtils_h__
+
+#include "nsCOMPtr.h"
+#include "nsStringFwd.h"
+#include "nsIInputStream.h"
+#include "nsTArray.h"
+#include "nsIRunnable.h"
+
+class nsIAsyncInputStream;
+class nsIOutputStream;
+class nsIInputStreamCallback;
+class nsIOutputStreamCallback;
+class nsIEventTarget;
+
+/**
+ * A "one-shot" proxy of the OnInputStreamReady callback.  The resulting
+ * proxy object's OnInputStreamReady function may only be called once!  The
+ * proxy object ensures that the real notify object will be free'd on the
+ * thread corresponding to the given event target regardless of what thread
+ * the proxy object is destroyed on.
+ *
+ * This function is designed to be used to implement AsyncWait when the
+ * aTarget parameter is non-null.
+ *
+ * The optional aPriority parameter allows the input stream runnable events
+ * to be dispatched with a different priority than normal.
+ */
+extern already_AddRefed<nsIInputStreamCallback> NS_NewInputStreamReadyEvent(
+    const char* aName, nsIInputStreamCallback* aNotify, nsIEventTarget* aTarget,
+    uint32_t aPriority = nsIRunnablePriority::PRIORITY_NORMAL);
+
+/**
+ * A "one-shot" proxy of the OnOutputStreamReady callback.  The resulting
+ * proxy object's OnOutputStreamReady function may only be called once!  The
+ * proxy object ensures that the real notify object will be free'd on the
+ * thread corresponding to the given event target regardless of what thread
+ * the proxy object is destroyed on.
+ *
+ * This function is designed to be used to implement AsyncWait when the
+ * aTarget parameter is non-null.
+ */
+extern already_AddRefed<nsIOutputStreamCallback> NS_NewOutputStreamReadyEvent(
+    nsIOutputStreamCallback* aNotify, nsIEventTarget* aTarget);
+
+/* ------------------------------------------------------------------------- */
+
+enum nsAsyncCopyMode {
+  NS_ASYNCCOPY_VIA_READSEGMENTS,
+  NS_ASYNCCOPY_VIA_WRITESEGMENTS
+};
+
+/**
+ * This function is called when a new chunk of data has been copied.  The
+ * reported count is the size of the current chunk.
+ */
+typedef void (*nsAsyncCopyProgressFun)(void* closure, uint32_t count);
+
+/**
+ * This function is called when the async copy process completes.  The reported
+ * status is NS_OK on success and some error code on failure.
+ */
+typedef void (*nsAsyncCopyCallbackFun)(void* closure, nsresult status);
+
+/**
+ * This function asynchronously copies data from the source to the sink. All
+ * data transfer occurs on the thread corresponding to the given event target.
+ * A null event target is not permitted.
+ *
+ * The copier handles blocking or non-blocking streams transparently.  If a
+ * stream operation returns NS_BASE_STREAM_WOULD_BLOCK, then the stream will
+ * be QI'd to nsIAsync{In,Out}putStream and its AsyncWait method will be used
+ * to determine when to resume copying.
+ *
+ * Source and sink are closed by default when copying finishes or when error
+ * occurs. Caller can prevent closing source or sink by setting aCloseSource
+ * or aCloseSink to false.
+ *
+ * Caller can obtain aCopierCtx to be able to cancel copying.
+ */
+extern nsresult NS_AsyncCopy(
+    nsIInputStream* aSource, nsIOutputStream* aSink, nsIEventTarget* aTarget,
+    nsAsyncCopyMode aMode = NS_ASYNCCOPY_VIA_READSEGMENTS,
+    uint32_t aChunkSize = 4096, nsAsyncCopyCallbackFun aCallbackFun = nullptr,
+    void* aCallbackClosure = nullptr, bool aCloseSource = true,
+    bool aCloseSink = true, nsISupports** aCopierCtx = nullptr,
+    nsAsyncCopyProgressFun aProgressCallbackFun = nullptr);
+
+/**
+ * This function cancels copying started by function NS_AsyncCopy.
+ *
+ * @param aCopierCtx
+ *        Copier context returned by NS_AsyncCopy.
+ * @param aReason
+ *        A failure code indicating why the operation is being canceled.
+ *        It is an error to pass a success code.
+ */
+extern nsresult NS_CancelAsyncCopy(nsISupports* aCopierCtx, nsresult aReason);
+
+/**
+ * This function copies all of the available data from the stream (up to at
+ * most aMaxCount bytes) into the given buffer.  The buffer is truncated at
+ * the start of the function.
+ *
+ * If an error occurs while reading from the stream or while attempting to
+ * resize the buffer, then the corresponding error code is returned from this
+ * function, and any data that has already been read will be returned in the
+ * output buffer.  This allows one to use this function with a non-blocking
+ * input stream that may return NS_BASE_STREAM_WOULD_BLOCK if it only has
+ * partial data available.
+ *
+ * @param aSource
+ *        The input stream to read.
+ * @param aMaxCount
+ *        The maximum number of bytes to consume from the stream.  Pass the
+ *        value UINT32_MAX to consume the entire stream.  The number of
+ *        bytes actually read is given by the length of aBuffer upon return.
+ * @param aBuffer
+ *        The string object that will contain the stream data upon return.
+ *        Note: The data copied to the string may contain null bytes and may
+ *        contain non-ASCII values.
+ */
+extern nsresult NS_ConsumeStream(nsIInputStream* aSource, uint32_t aMaxCount,
+                                 nsACString& aBuffer);
+
+/**
+ * Just like the above, but consumes into an nsTArray<uint8_t>.
+ */
+extern nsresult NS_ConsumeStream(nsIInputStream* aSource, uint32_t aMaxCount,
+                                 nsTArray<uint8_t>& aBuffer);
+
+/**
+ * This function tests whether or not the input stream is buffered. A buffered
+ * input stream is one that implements readSegments.  The test for this is to
+ * 1/ check whether the input stream implements nsIBufferedInputStream;
+ * 2/ if not, call readSegments, without actually consuming any data from the
+ * stream, to verify that it functions.
+ *
+ * NOTE: If the stream is non-blocking and has no data available yet, then this
+ * test will fail.  In that case, we return false even though the test is not
+ * really conclusive.
+ *
+ * PERFORMANCE NOTE: If the stream does not implement nsIBufferedInputStream,
+ * calling readSegments may cause I/O. Therefore, you should avoid calling
+ * this function from the main thread.
+ *
+ * @param aInputStream
+ *        The input stream to test.
+ */
+extern bool NS_InputStreamIsBuffered(nsIInputStream* aInputStream);
+
+/**
+ * This function tests whether or not the output stream is buffered.  A
+ * buffered output stream is one that implements writeSegments.  The test for
+ * this is to:
+ * 1/ check whether the output stream implements nsIBufferedOutputStream;
+ * 2/ if not, call writeSegments, without actually writing any data into
+ * the stream, to verify that it functions.
+ *
+ * NOTE: If the stream is non-blocking and has no available space yet, then
+ * this test will fail.  In that case, we return false even though the test is
+ * not really conclusive.
+ *
+ * PERFORMANCE NOTE: If the stream does not implement nsIBufferedOutputStream,
+ * calling writeSegments may cause I/O. Therefore, you should avoid calling
+ * this function from the main thread.
+ *
+ * @param aOutputStream
+ *        The output stream to test.
+ */
+extern bool NS_OutputStreamIsBuffered(nsIOutputStream* aOutputStream);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * copy data from the nsIInputStream into a nsIOutputStream passed as the
+ * aClosure parameter to the ReadSegments function.
+ *
+ * @see nsIInputStream.idl for a description of this function's parameters.
+ */
+extern nsresult NS_CopySegmentToStream(nsIInputStream* aInputStream,
+                                       void* aClosure, const char* aFromSegment,
+                                       uint32_t aToOffset, uint32_t aCount,
+                                       uint32_t* aWriteCount);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * copy data from the nsIInputStream into a character buffer passed as the
+ * aClosure parameter to the ReadSegments function.  The character buffer
+ * must be at least as large as the aCount parameter passed to ReadSegments.
+ *
+ * @see nsIInputStream.idl for a description of this function's parameters.
+ */
+extern nsresult NS_CopySegmentToBuffer(nsIInputStream* aInputStream,
+                                       void* aClosure, const char* aFromSegment,
+                                       uint32_t aToOffset, uint32_t aCount,
+                                       uint32_t* aWriteCount);
+
+/**
+ * This function is intended to be passed to nsIOutputStream::WriteSegments to
+ * copy data into the nsIOutputStream from a character buffer passed as the
+ * aClosure parameter to the WriteSegments function.
+ *
+ * @see nsIOutputStream.idl for a description of this function's parameters.
+ */
+extern nsresult NS_CopyBufferToSegment(nsIOutputStream* aOutputStream,
+                                       void* aClosure, char* aToSegment,
+                                       uint32_t aFromOffset, uint32_t aCount,
+                                       uint32_t* aReadCount);
+
+/**
+ * This function is intended to be passed to nsIOutputStream::WriteSegments to
+ * copy data into the nsIOutputStream from a nsIInputStream passed as the
+ * aClosure parameter to the WriteSegments function.
+ *
+ * @see nsIOutputStream.idl for a description of this function's parameters.
+ */
+extern nsresult NS_CopyStreamToSegment(nsIOutputStream* aOutputStream,
+                                       void* aClosure, char* aToSegment,
+                                       uint32_t aFromOffset, uint32_t aCount,
+                                       uint32_t* aReadCount);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * discard data from the nsIInputStream.  This can be used to efficiently read
+ * data from the stream without actually copying any bytes.
+ *
+ * @see nsIInputStream.idl for a description of this function's parameters.
+ */
+extern nsresult NS_DiscardSegment(nsIInputStream* aInputStream, void* aClosure,
+                                  const char* aFromSegment, uint32_t aToOffset,
+                                  uint32_t aCount, uint32_t* aWriteCount);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * adjust the aInputStream parameter passed to a consumer's WriteSegmentFun.
+ * The aClosure parameter must be a pointer to a nsWriteSegmentThunk object.
+ * The mStream and mClosure members of that object will be passed to the mFun
+ * function, with the remainder of the parameters being what are passed to
+ * NS_WriteSegmentThunk.
+ *
+ * This function comes in handy when implementing ReadSegments in terms of an
+ * inner stream's ReadSegments.
+ */
+extern nsresult NS_WriteSegmentThunk(nsIInputStream* aInputStream,
+                                     void* aClosure, const char* aFromSegment,
+                                     uint32_t aToOffset, uint32_t aCount,
+                                     uint32_t* aWriteCount);
+
+struct MOZ_STACK_CLASS nsWriteSegmentThunk {
+  nsCOMPtr<nsIInputStream> mStream;
+  nsWriteSegmentFun mFun;
+  void* mClosure;
+};
+
+/**
+ * Read data from aInput and store in aDest.  A non-zero aKeep will keep that
+ * many bytes from aDest (from the end).  New data is appended after the kept
+ * bytes (if any).  aDest's new length on returning from this function is
+ * aKeep + aNewBytes and is guaranteed to be less than or equal to aDest's
+ * current capacity.
+ * @param aDest the array to fill
+ * @param aInput the stream to read from
+ * @param aKeep number of bytes to keep (0 <= aKeep <= aDest.Length())
+ * @param aNewBytes (out) number of bytes read from aInput or zero if Read()
+ *        failed
+ * @return the result from aInput->Read(...)
+ */
+extern nsresult NS_FillArray(FallibleTArray<char>& aDest,
+                             nsIInputStream* aInput, uint32_t aKeep,
+                             uint32_t* aNewBytes);
+
+/**
+ * Return true if the given stream can be directly cloned.
+ */
+extern bool NS_InputStreamIsCloneable(nsIInputStream* aSource);
+
+/**
+ * Clone the provided source stream in the most efficient way possible.  This
+ * first attempts to QI to nsICloneableInputStream to use Clone().  If that is
+ * not supported or its cloneable attribute is false, then a fallback clone is
+ * provided by copying the source to a pipe.  In this case the caller must
+ * replace the source stream with the resulting replacement stream.  The clone
+ * and the replacement stream are then cloneable using nsICloneableInputStream
+ * without duplicating memory.  This fallback clone using the pipe is only
+ * performed if a replacement stream parameter is also passed in.
+ * @param aSource         The input stream to clone.
+ * @param aCloneOut       Required out parameter to hold resulting clone.
+ * @param aReplacementOut Optional out parameter to hold stream to replace
+ *                        original source stream after clone.  If not
+ *                        provided then the fallback clone process is not
+ *                        supported and a non-cloneable source will result
+ *                        in failure.  Replacement streams are non-blocking.
+ * @return NS_OK on successful clone.  Error otherwise.
+ */
+extern nsresult NS_CloneInputStream(nsIInputStream* aSource,
+                                    nsIInputStream** aCloneOut,
+                                    nsIInputStream** aReplacementOut = nullptr);
+
+/*
+ * This function returns a non-blocking nsIAsyncInputStream. Internally,
+ * different approaches are used based on what |aSource| is and what it
+ * implements.
+ *
+ * Note that this component takes the owninship of aSource.
+ *
+ * If the |aSource| is already a non-blocking and async stream,
+ * |aAsyncInputStream| will be equal to |aSource|.
+ *
+ * Otherwise, if |aSource| is just non-blocking, NonBlockingAsyncInputStream
+ * class is used in order to make it async.
+ *
+ * The last step is to use nsIStreamTransportService and create a pipe in order
+ * to expose a non-blocking async inputStream and read |aSource| data from
+ * a separate thread.
+ *
+ * In case we need to create a pipe, |aCloseWhenDone| will be used to create the
+ * inputTransport, |aFlags|, |aSegmentSize|, |asegmentCount| will be used to
+ * open the inputStream. If true, the input stream will be closed after it has
+ * been read. Read more in nsITransport.idl.
+ */
+extern nsresult NS_MakeAsyncNonBlockingInputStream(
+    already_AddRefed<nsIInputStream> aSource,
+    nsIAsyncInputStream** aAsyncInputStream, bool aCloseWhenDone = true,
+    uint32_t aFlags = 0, uint32_t aSegmentSize = 0, uint32_t aSegmentCount = 0);
+
+#endif  // !nsStreamUtils_h__