gecko-dev/xpcom/io/nsStreamUtils.h

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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2002
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Darin Fisher <darin@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsStreamUtils_h__
#define nsStreamUtils_h__
#include "nsStringFwd.h"
#include "nsIInputStream.h"
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
* aEventTarget parameter is non-null.
*/
extern NS_COM nsresult
NS_NewInputStreamReadyEvent(nsIInputStreamCallback **aEvent,
nsIInputStreamCallback *aNotify,
nsIEventTarget *aEventTarget);
/**
* 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
* aEventTarget parameter is non-null.
*/
extern NS_COM nsresult
NS_NewOutputStreamReadyEvent(nsIOutputStreamCallback **aEvent,
nsIOutputStreamCallback *aNotify,
nsIEventTarget *aEventTarget);
/* ------------------------------------------------------------------------- */
enum nsAsyncCopyMode {
NS_ASYNCCOPY_VIA_READSEGMENTS,
NS_ASYNCCOPY_VIA_WRITESEGMENTS
};
/**
* 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.
*/
extern NS_COM nsresult
NS_AsyncCopy(nsIInputStream *aSource,
nsIOutputStream *aSink,
nsIEventTarget *aEventTarget,
nsAsyncCopyMode aMode = NS_ASYNCCOPY_VIA_READSEGMENTS,
PRUint32 aChunkSize = 4096,
nsAsyncCopyCallbackFun aCallbackFun = nsnull,
void *aCallbackClosure = nsnull);
/**
* 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 PR_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 NS_COM nsresult
NS_ConsumeStream(nsIInputStream *aSource, PRUint32 aMaxCount,
nsACString &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
* simply 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.
*
* @param aInputStream
* The input stream to test.
*/
extern NS_COM PRBool
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 simply 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.
*
* @param aOutputStream
* The output stream to test.
*/
extern NS_COM PRBool
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 NS_COM NS_METHOD
NS_CopySegmentToStream(nsIInputStream *aInputStream, void *aClosure,
const char *aFromSegment, PRUint32 aToOffset,
PRUint32 aCount, PRUint32 *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 NS_COM NS_METHOD
NS_CopySegmentToBuffer(nsIInputStream *aInputStream, void *aClosure,
const char *aFromSegment, PRUint32 aToOffset,
PRUint32 aCount, PRUint32 *aWriteCount);
/**
* 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 NS_COM NS_METHOD
NS_DiscardSegment(nsIInputStream *aInputStream, void *aClosure,
const char *aFromSegment, PRUint32 aToOffset,
PRUint32 aCount, PRUint32 *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 NS_COM NS_METHOD
NS_WriteSegmentThunk(nsIInputStream *aInputStream, void *aClosure,
const char *aFromSegment, PRUint32 aToOffset,
PRUint32 aCount, PRUint32 *aWriteCount);
struct nsWriteSegmentThunk {
nsIInputStream *mStream;
nsWriteSegmentFun mFun;
void *mClosure;
};
#endif // !nsStreamUtils_h__