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86 lines
3.2 KiB
Plaintext
86 lines
3.2 KiB
Plaintext
/* 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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#include "nsISupports.idl"
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interface nsIEventTarget;
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interface nsIInputStreamLengthCallback;
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/**
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* Note: Instead of using these interfaces directly, consider to use
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* InputStreamLengthHelper class.
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*/
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[uuid(452d059f-9a9c-4434-8839-e10d1405647c)]
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interface nsIInputStreamLength : nsISupports
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{
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/**
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* Returns the total length of the stream if known. Otherwise it returns -1.
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* This is different than calling available() which returns the number of
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* bytes ready to be read from the stream.
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* -1 is a valid value for a stream that doesn't know its length. For
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* instance, a pipe stream could return such value.
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*
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* It could throw NS_BASE_STREAM_WOULD_BLOCK if the inputStream is
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* non-blocking. If this happens, you should use
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* nsIAsyncInputStreamLength::asyncLengthWait().
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*
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* If the stream has already been read (read()/readSegments()/close()/seek()
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* methods has been called), length() returns NS_ERROR_NOT_AVAILABLE.
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*
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* This is not an attribute because a stream can change its length. For
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* instance, if the stream is a file inputStream and the underlying OS file
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* changes, its length will change as well.
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*/
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long long length();
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};
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[uuid(b63f9ecf-4668-44a3-93bd-72dbc65a6125)]
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interface nsIAsyncInputStreamLength : nsISupports
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{
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/**
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* If the stream is non-blocking, nsIInputStreamLength::length() can return
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* NS_BASE_STREAM_WOULD_BLOCK. The caller must then wait for the stream to
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* know its length.
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*
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* If the stream implements nsIAsyncInputStreamLength, then the caller can
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* use this interface to request an asynchronous notification when the
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* stream's length becomes known (via the AsyncLengthWait method).
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* If the length is already known, the aCallback will be still called
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* asynchronously.
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*
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* If the stream has already been read (read()/readSegments()/close()/seek()
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* methods has been called), length() returns NS_ERROR_NOT_AVAILABLE.
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*
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* @param aCallback
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* This object is notified when the length becomes known. This
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* parameter may be null to clear an existing callback.
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* @param aEventTarget
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* Specify that the notification must be delivered to a specific event
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* target.
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*/
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void asyncLengthWait(in nsIInputStreamLengthCallback aCallback,
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in nsIEventTarget aEventTarget);
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};
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/**
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* This is a companion interface for
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* nsIAsyncInputStreamLength::asyncLengthWait.
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*/
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[function, uuid(9c0c13b9-1b33-445d-8adb-a8a7866a6c06)]
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interface nsIInputStreamLengthCallback : nsISupports
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{
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/**
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* Called to inform what the total length of the stream is.
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*
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* @param aStream
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* The stream whose asyncLengthWait method was called.
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* @param aLength
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* The stream's length. It can be -1 if the stream doesn't know its
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* length. For instance, this can happen for a pipe inputStream.
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*/
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void onInputStreamLengthReady(in nsIAsyncInputStreamLength aStream,
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in long long aLength);
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};
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