Optional aInstancePtr: objectA run time mechanism for interface discovery.
NS_OK if the interface is supported by the associated instance, NS_NOINTERFACE if it is not.
aInstancePtr must not be null.
[in] A requested interface IID
[out] A pointer to an interface pointer to receive the result.
Determine number of bytes available in the stream. A non-blocking stream that does not yet have any data to read should return 0 bytes from this method (i.e., it must not throw the NS_BASE_STREAM_WOULD_BLOCK exception).
In addition to the number of bytes available in the stream, this method also informs the caller of the current status of the stream. A stream that is closed will throw an exception when this method is called. That enables the caller to know the condition of the stream before attempting to read from it. If a stream is at end-of-file, but not closed, then this method returns 0 bytes available. (Note: some nsIInputStream implementations automatically close when eof is reached; some do not).
NOTE: Streams implementing nsIAsyncInputStream must automatically close when eof is reached, as otherwise it is impossible to distinguish between a stream waiting for more data and a stream at EOF using Available().
number of bytes currently available in the stream.
NS_BASE_STREAM_CLOSED if the stream is closed normally.
true if stream is non-blocking
NOTE: reading from a blocking input stream will block the calling thread until at least one byte of data can be extracted from the stream.
NOTE: a non-blocking input stream may implement nsIAsyncInputStream to provide consumers with a way to wait for the stream to have more data once its read method is unable to return any data without blocking.
Read data from the stream.
number of bytes read (may be less than aCount).
0 if reached end-of-file
NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would block the calling thread (non-blocking mode only)
NOTE: this method should not throw NS_BASE_STREAM_CLOSED.
the buffer into which the data is to be read
the maximum number of bytes to be read
Low-level read method that provides access to the stream's underlying buffer. The writer function may be called multiple times for segmented buffers. ReadSegments is expected to keep calling the writer until either there is nothing left to read or the writer returns an error. ReadSegments should not call the writer with zero bytes to consume.
number of bytes read (may be less than aCount)
0 if reached end-of-file (or if aWriter refused to consume data)
NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would block the calling thread (non-blocking mode only)
NS_ERROR_NOT_IMPLEMENTED if the stream has no underlying buffer
NOTE: this function may be unimplemented if a stream has no underlying buffer (e.g., socket input stream).
NOTE: this method should not throw NS_BASE_STREAM_CLOSED.
the "consumer" of the data to be read
opaque parameter passed to writer
the maximum number of bytes to be read
Check the current status of the stream. A stream that is closed will throw an exception when this method is called. That enables the caller to know the condition of the stream before attempting to read from it.
This method will not throw NS_BASE_STREAM_WOULD_BLOCK, even if the stream is an non-blocking stream with no data. A non-blocking stream that does not yet have any data to read should return NS_OK.
NOTE: Unlike available, his method should not block the calling thread (e.g. to query the state of a file descriptor), even when called on a blocking stream.
NS_BASE_STREAM_CLOSED if the stream closed normally
Generated using TypeDoc
nsIInputStream
An interface describing a readable stream of data. An input stream may be "blocking" or "non-blocking" (see the IsNonBlocking method). A blocking input stream may suspend the calling thread in order to satisfy a call to Close, Available, Read, or ReadSegments. A non-blocking input stream, on the other hand, must not block the calling thread of execution.
NOTE: blocking input streams are often read on a background thread to avoid locking up the main application thread. For this reason, it is generally the case that a blocking input stream should be implemented using thread- safe AddRef and Release.