1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/io/nsIInputStream.idl Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,147 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#include "nsISupports.idl"
1.10 +
1.11 +interface nsIInputStream;
1.12 +
1.13 +%{C++
1.14 +/**
1.15 + * The signature of the writer function passed to ReadSegments. This
1.16 + * is the "consumer" of data that gets read from the stream's buffer.
1.17 + *
1.18 + * @param aInStream stream being read
1.19 + * @param aClosure opaque parameter passed to ReadSegments
1.20 + * @param aFromSegment pointer to memory owned by the input stream. This is
1.21 + * where the writer function should start consuming data.
1.22 + * @param aToOffset amount of data already consumed by this writer during this
1.23 + * ReadSegments call. This is also the sum of the aWriteCount
1.24 + * returns from this writer over the previous invocations of
1.25 + * the writer by this ReadSegments call.
1.26 + * @param aCount Number of bytes available to be read starting at aFromSegment
1.27 + * @param [out] aWriteCount number of bytes read by this writer function call
1.28 + *
1.29 + * Implementers should return the following:
1.30 + *
1.31 + * @return NS_OK and (*aWriteCount > 0) if consumed some data
1.32 + * @return <any-error> if not interested in consuming any data
1.33 + *
1.34 + * Errors are never passed to the caller of ReadSegments.
1.35 + *
1.36 + * NOTE: returning NS_OK and (*aWriteCount = 0) has undefined behavior.
1.37 + */
1.38 +typedef NS_CALLBACK(nsWriteSegmentFun)(nsIInputStream *aInStream,
1.39 + void *aClosure,
1.40 + const char *aFromSegment,
1.41 + uint32_t aToOffset,
1.42 + uint32_t aCount,
1.43 + uint32_t *aWriteCount);
1.44 +%}
1.45 +
1.46 +native nsWriteSegmentFun(nsWriteSegmentFun);
1.47 +
1.48 +/**
1.49 + * nsIInputStream
1.50 + *
1.51 + * An interface describing a readable stream of data. An input stream may be
1.52 + * "blocking" or "non-blocking" (see the IsNonBlocking method). A blocking
1.53 + * input stream may suspend the calling thread in order to satisfy a call to
1.54 + * Close, Available, Read, or ReadSegments. A non-blocking input stream, on
1.55 + * the other hand, must not block the calling thread of execution.
1.56 + *
1.57 + * NOTE: blocking input streams are often read on a background thread to avoid
1.58 + * locking up the main application thread. For this reason, it is generally
1.59 + * the case that a blocking input stream should be implemented using thread-
1.60 + * safe AddRef and Release.
1.61 + */
1.62 +[scriptable, uuid(53cdbc97-c2d7-4e30-b2c3-45b2ee79db18)]
1.63 +interface nsIInputStream : nsISupports
1.64 +{
1.65 + /**
1.66 + * Close the stream. This method causes subsequent calls to Read and
1.67 + * ReadSegments to return 0 bytes read to indicate end-of-file. Any
1.68 + * subsequent calls to Available should throw NS_BASE_STREAM_CLOSED.
1.69 + */
1.70 + void close();
1.71 +
1.72 + /**
1.73 + * Determine number of bytes available in the stream. A non-blocking
1.74 + * stream that does not yet have any data to read should return 0 bytes
1.75 + * from this method (i.e., it must not throw the NS_BASE_STREAM_WOULD_BLOCK
1.76 + * exception).
1.77 + *
1.78 + * In addition to the number of bytes available in the stream, this method
1.79 + * also informs the caller of the current status of the stream. A stream
1.80 + * that is closed will throw an exception when this method is called. That
1.81 + * enables the caller to know the condition of the stream before attempting
1.82 + * to read from it. If a stream is at end-of-file, but not closed, then
1.83 + * this method returns 0 bytes available. (Note: some nsIInputStream
1.84 + * implementations automatically close when eof is reached; some do not).
1.85 + *
1.86 + * @return number of bytes currently available in the stream.
1.87 + *
1.88 + * @throws NS_BASE_STREAM_CLOSED if the stream is closed normally.
1.89 + * @throws <other-error> if the stream is closed due to some error
1.90 + * condition
1.91 + */
1.92 + unsigned long long available();
1.93 +
1.94 + /**
1.95 + * Read data from the stream.
1.96 + *
1.97 + * @param aBuf the buffer into which the data is to be read
1.98 + * @param aCount the maximum number of bytes to be read
1.99 + *
1.100 + * @return number of bytes read (may be less than aCount).
1.101 + * @return 0 if reached end-of-file
1.102 + *
1.103 + * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
1.104 + * block the calling thread (non-blocking mode only)
1.105 + * @throws <other-error> on failure
1.106 + *
1.107 + * NOTE: this method should not throw NS_BASE_STREAM_CLOSED.
1.108 + */
1.109 + [noscript] unsigned long read(in charPtr aBuf, in unsigned long aCount);
1.110 +
1.111 + /**
1.112 + * Low-level read method that provides access to the stream's underlying
1.113 + * buffer. The writer function may be called multiple times for segmented
1.114 + * buffers. ReadSegments is expected to keep calling the writer until
1.115 + * either there is nothing left to read or the writer returns an error.
1.116 + * ReadSegments should not call the writer with zero bytes to consume.
1.117 + *
1.118 + * @param aWriter the "consumer" of the data to be read
1.119 + * @param aClosure opaque parameter passed to writer
1.120 + * @param aCount the maximum number of bytes to be read
1.121 + *
1.122 + * @return number of bytes read (may be less than aCount)
1.123 + * @return 0 if reached end-of-file (or if aWriter refused to consume data)
1.124 + *
1.125 + * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
1.126 + * block the calling thread (non-blocking mode only)
1.127 + * @throws NS_ERROR_NOT_IMPLEMENTED if the stream has no underlying buffer
1.128 + * @throws <other-error> on failure
1.129 + *
1.130 + * NOTE: this function may be unimplemented if a stream has no underlying
1.131 + * buffer (e.g., socket input stream).
1.132 + *
1.133 + * NOTE: this method should not throw NS_BASE_STREAM_CLOSED.
1.134 + */
1.135 + [noscript] unsigned long readSegments(in nsWriteSegmentFun aWriter,
1.136 + in voidPtr aClosure,
1.137 + in unsigned long aCount);
1.138 +
1.139 + /**
1.140 + * @return true if stream is non-blocking
1.141 + *
1.142 + * NOTE: reading from a blocking input stream will block the calling thread
1.143 + * until at least one byte of data can be extracted from the stream.
1.144 + *
1.145 + * NOTE: a non-blocking input stream may implement nsIAsyncInputStream to
1.146 + * provide consumers with a way to wait for the stream to have more data
1.147 + * once its read method is unable to return any data without blocking.
1.148 + */
1.149 + boolean isNonBlocking();
1.150 +};
