зеркало из https://github.com/mozilla/gecko-dev.git
230 строки
9.1 KiB
C++
230 строки
9.1 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsStreamUtils_h__
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#define nsStreamUtils_h__
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#include "nsStringFwd.h"
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#include "nsIInputStream.h"
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class nsIOutputStream;
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class nsIInputStreamCallback;
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class nsIOutputStreamCallback;
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class nsIEventTarget;
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/**
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* A "one-shot" proxy of the OnInputStreamReady callback. The resulting
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* proxy object's OnInputStreamReady function may only be called once! The
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* proxy object ensures that the real notify object will be free'd on the
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* thread corresponding to the given event target regardless of what thread
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* the proxy object is destroyed on.
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*
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* This function is designed to be used to implement AsyncWait when the
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* aTarget parameter is non-null.
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*/
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extern nsresult
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NS_NewInputStreamReadyEvent(nsIInputStreamCallback **aEvent,
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nsIInputStreamCallback *aNotify,
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nsIEventTarget *aTarget);
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/**
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* A "one-shot" proxy of the OnOutputStreamReady callback. The resulting
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* proxy object's OnOutputStreamReady function may only be called once! The
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* proxy object ensures that the real notify object will be free'd on the
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* thread corresponding to the given event target regardless of what thread
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* the proxy object is destroyed on.
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*
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* This function is designed to be used to implement AsyncWait when the
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* aTarget parameter is non-null.
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*/
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extern nsresult
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NS_NewOutputStreamReadyEvent(nsIOutputStreamCallback **aEvent,
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nsIOutputStreamCallback *aNotify,
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nsIEventTarget *aTarget);
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/* ------------------------------------------------------------------------- */
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enum nsAsyncCopyMode {
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NS_ASYNCCOPY_VIA_READSEGMENTS,
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NS_ASYNCCOPY_VIA_WRITESEGMENTS
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};
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/**
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* This function is called when the async copy process completes. The reported
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* status is NS_OK on success and some error code on failure.
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*/
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typedef void (* nsAsyncCopyCallbackFun)(void *closure, nsresult status);
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/**
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* This function asynchronously copies data from the source to the sink. All
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* data transfer occurs on the thread corresponding to the given event target.
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* A null event target is not permitted.
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*
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* The copier handles blocking or non-blocking streams transparently. If a
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* stream operation returns NS_BASE_STREAM_WOULD_BLOCK, then the stream will
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* be QI'd to nsIAsync{In,Out}putStream and its AsyncWait method will be used
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* to determine when to resume copying.
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*
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* Source and sink are closed by default when copying finishes or when error
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* occurs. Caller can prevent closing source or sink by setting aCloseSource
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* or aCloseSink to false.
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*
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* Caller can obtain aCopierCtx to be able to cancel copying.
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*/
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extern nsresult
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NS_AsyncCopy(nsIInputStream *aSource,
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nsIOutputStream *aSink,
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nsIEventTarget *aTarget,
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nsAsyncCopyMode aMode = NS_ASYNCCOPY_VIA_READSEGMENTS,
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PRUint32 aChunkSize = 4096,
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nsAsyncCopyCallbackFun aCallbackFun = nullptr,
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void *aCallbackClosure = nullptr,
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bool aCloseSource = true,
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bool aCloseSink = true,
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nsISupports **aCopierCtx = nullptr);
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/**
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* This function cancels copying started by function NS_AsyncCopy.
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*
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* @param aCopierCtx
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* Copier context returned by NS_AsyncCopy.
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* @param aReason
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* A failure code indicating why the operation is being canceled.
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* It is an error to pass a success code.
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*/
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extern nsresult
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NS_CancelAsyncCopy(nsISupports *aCopierCtx, nsresult aReason);
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/**
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* This function copies all of the available data from the stream (up to at
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* most aMaxCount bytes) into the given buffer. The buffer is truncated at
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* the start of the function.
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*
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* If an error occurs while reading from the stream or while attempting to
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* resize the buffer, then the corresponding error code is returned from this
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* function, and any data that has already been read will be returned in the
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* output buffer. This allows one to use this function with a non-blocking
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* input stream that may return NS_BASE_STREAM_WOULD_BLOCK if it only has
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* partial data available.
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*
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* @param aSource
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* The input stream to read.
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* @param aMaxCount
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* The maximum number of bytes to consume from the stream. Pass the
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* value PR_UINT32_MAX to consume the entire stream. The number of
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* bytes actually read is given by the length of aBuffer upon return.
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* @param aBuffer
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* The string object that will contain the stream data upon return.
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* Note: The data copied to the string may contain null bytes and may
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* contain non-ASCII values.
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*/
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extern nsresult
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NS_ConsumeStream(nsIInputStream *aSource, PRUint32 aMaxCount,
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nsACString &aBuffer);
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/**
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* This function tests whether or not the input stream is buffered. A buffered
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* input stream is one that implements readSegments. The test for this is to
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* simply call readSegments, without actually consuming any data from the
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* stream, to verify that it functions.
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*
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* NOTE: If the stream is non-blocking and has no data available yet, then this
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* test will fail. In that case, we return false even though the test is not
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* really conclusive.
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*
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* @param aInputStream
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* The input stream to test.
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*/
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extern bool
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NS_InputStreamIsBuffered(nsIInputStream *aInputStream);
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/**
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* This function tests whether or not the output stream is buffered. A
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* buffered output stream is one that implements writeSegments. The test for
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* this is to simply call writeSegments, without actually writing any data into
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* the stream, to verify that it functions.
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*
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* NOTE: If the stream is non-blocking and has no available space yet, then
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* this test will fail. In that case, we return false even though the test is
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* not really conclusive.
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*
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* @param aOutputStream
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* The output stream to test.
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*/
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extern bool
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NS_OutputStreamIsBuffered(nsIOutputStream *aOutputStream);
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/**
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* This function is intended to be passed to nsIInputStream::ReadSegments to
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* copy data from the nsIInputStream into a nsIOutputStream passed as the
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* aClosure parameter to the ReadSegments function.
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*
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* @see nsIInputStream.idl for a description of this function's parameters.
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*/
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extern NS_METHOD
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NS_CopySegmentToStream(nsIInputStream *aInputStream, void *aClosure,
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const char *aFromSegment, PRUint32 aToOffset,
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PRUint32 aCount, PRUint32 *aWriteCount);
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/**
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* This function is intended to be passed to nsIInputStream::ReadSegments to
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* copy data from the nsIInputStream into a character buffer passed as the
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* aClosure parameter to the ReadSegments function. The character buffer
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* must be at least as large as the aCount parameter passed to ReadSegments.
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*
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* @see nsIInputStream.idl for a description of this function's parameters.
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*/
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extern NS_METHOD
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NS_CopySegmentToBuffer(nsIInputStream *aInputStream, void *aClosure,
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const char *aFromSegment, PRUint32 aToOffset,
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PRUint32 aCount, PRUint32 *aWriteCount);
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/**
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* This function is intended to be passed to nsIOutputStream::WriteSegments to
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* copy data into the nsIOutputStream from a character buffer passed as the
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* aClosure parameter to the WriteSegments function.
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*
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* @see nsIOutputStream.idl for a description of this function's parameters.
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*/
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extern NS_METHOD
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NS_CopySegmentToBuffer(nsIOutputStream *aOutputStream, void *aClosure,
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char *aToSegment, PRUint32 aFromOffset,
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PRUint32 aCount, PRUint32 *aReadCount);
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/**
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* This function is intended to be passed to nsIInputStream::ReadSegments to
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* discard data from the nsIInputStream. This can be used to efficiently read
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* data from the stream without actually copying any bytes.
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*
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* @see nsIInputStream.idl for a description of this function's parameters.
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*/
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extern NS_METHOD
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NS_DiscardSegment(nsIInputStream *aInputStream, void *aClosure,
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const char *aFromSegment, PRUint32 aToOffset,
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PRUint32 aCount, PRUint32 *aWriteCount);
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/**
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* This function is intended to be passed to nsIInputStream::ReadSegments to
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* adjust the aInputStream parameter passed to a consumer's WriteSegmentFun.
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* The aClosure parameter must be a pointer to a nsWriteSegmentThunk object.
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* The mStream and mClosure members of that object will be passed to the mFun
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* function, with the remainder of the parameters being what are passed to
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* NS_WriteSegmentThunk.
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*
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* This function comes in handy when implementing ReadSegments in terms of an
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* inner stream's ReadSegments.
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*/
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extern NS_METHOD
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NS_WriteSegmentThunk(nsIInputStream *aInputStream, void *aClosure,
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const char *aFromSegment, PRUint32 aToOffset,
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PRUint32 aCount, PRUint32 *aWriteCount);
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struct nsWriteSegmentThunk {
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nsIInputStream *mStream;
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nsWriteSegmentFun mFun;
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void *mClosure;
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};
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#endif // !nsStreamUtils_h__
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