forked from mirrors/gecko-dev
105 lines
4.9 KiB
Text
105 lines
4.9 KiB
Text
/* 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 "nsIInputStream.idl"
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interface nsIInputStreamCallback;
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interface nsIEventTarget;
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/**
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* If an input stream is non-blocking, it may return NS_BASE_STREAM_WOULD_BLOCK
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* when read. The caller must then wait for the stream to have some data to
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* read. If the stream implements nsIAsyncInputStream, then the caller can use
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* this interface to request an asynchronous notification when the stream
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* becomes readable or closed (via the AsyncWait method).
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*
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* While this interface is almost exclusively used with non-blocking streams, it
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* is not necessary that nsIInputStream::isNonBlocking return true. Nor is it
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* necessary that a non-blocking nsIInputStream implementation also implement
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* nsIAsyncInputStream.
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*/
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[scriptable, uuid(a5f255ab-4801-4161-8816-277ac92f6ad1)]
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interface nsIAsyncInputStream : nsIInputStream
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{
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/**
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* This method closes the stream and sets its internal status. If the
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* stream is already closed, then this method is ignored. Once the stream
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* is closed, the stream's status cannot be changed. Any successful status
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* code passed to this method is treated as NS_BASE_STREAM_CLOSED, which
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* has an effect equivalent to nsIInputStream::close.
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*
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* NOTE: this method exists in part to support pipes, which have both an
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* input end and an output end. If the input end of a pipe is closed, then
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* writes to the output end of the pipe will fail. The error code returned
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* when an attempt is made to write to a "broken" pipe corresponds to the
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* status code passed in when the input end of the pipe was closed, which
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* greatly simplifies working with pipes in some cases.
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*
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* @param aStatus
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* The error that will be reported if this stream is accessed after
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* it has been closed.
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*/
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void closeWithStatus(in nsresult aStatus);
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/**
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* Asynchronously wait for the stream to be readable or closed. The
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* notification is one-shot, meaning that each asyncWait call will result
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* in exactly one notification callback. After the OnInputStreamReady event
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* is dispatched, the stream releases its reference to the
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* nsIInputStreamCallback object. It is safe to call asyncWait again from the
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* notification handler.
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*
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* This method may be called at any time (even if read has not been called).
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* In other words, this method may be called when the stream already has
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* data to read. It may also be called when the stream is closed and will NOT
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* result in an error return, e.g., NS_BASE_STREAM_CLOSED. If the stream is
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* already readable or closed when AsyncWait is called, then the
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* OnInputStreamReady event will be dispatched immediately. Otherwise, the
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* event will be dispatched when the stream becomes readable or closed.
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*
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* @param aCallback
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* This object is notified when the stream becomes ready. This
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* parameter may be null to clear an existing callback.
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* @param aFlags
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* This parameter specifies optional flags passed in to configure
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* the behavior of this method. Pass zero to specify no flags.
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* @param aRequestedCount
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* Wait until at least this many bytes can be read. This is only
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* a suggestion to the underlying stream; it may be ignored. The
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* caller may pass zero to indicate no preference.
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* @param aEventTarget
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* Specify NULL to receive notification on ANY thread (possibly even
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* recursively on the calling thread -- i.e., synchronously), or
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* specify that the notification be delivered to a specific event
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* target.
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*/
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void asyncWait(in nsIInputStreamCallback aCallback,
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in unsigned long aFlags,
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in unsigned long aRequestedCount,
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in nsIEventTarget aEventTarget);
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/**
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* If passed to asyncWait, this flag overrides the default behavior,
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* causing the OnInputStreamReady notification to be suppressed until the
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* stream becomes closed (either as a result of closeWithStatus/close being
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* called on the stream or possibly due to some error in the underlying
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* stream).
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*/
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const unsigned long WAIT_CLOSURE_ONLY = (1<<0);
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};
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/**
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* This is a companion interface for nsIAsyncInputStream::asyncWait.
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*/
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[function, scriptable, uuid(d1f28e94-3a6e-4050-a5f5-2e81b1fc2a43)]
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interface nsIInputStreamCallback : nsISupports
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{
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/**
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* Called to indicate that the stream is either readable or closed.
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*
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* @param aStream
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* The stream whose asyncWait method was called.
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*/
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void onInputStreamReady(in nsIAsyncInputStream aStream);
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};
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