gecko-dev/xpcom/io/nsIBinaryInputStream.idl

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsIInputStream.idl"

/**
 * This interface allows consumption of primitive data types from a "binary
 * stream" containing untagged, big-endian binary data, i.e. as produced by an
 * implementation of nsIBinaryOutputStream.  This might be used, for example,
 * to implement network protocols or to read from architecture-neutral disk
 * files, i.e. ones that can be read and written by both big-endian and
 * little-endian platforms.
 *
 * @See nsIBinaryOutputStream
 */

[scriptable, uuid(899b826b-2eb3-469c-8b31-4c29f5d341a6)]
interface nsIBinaryInputStream : nsIInputStream {
    void setInputStream(in nsIInputStream aInputStream);
    
    /**
     * Read 8-bits from the stream.
     *
     * @return that byte to be treated as a boolean.
     */
    boolean readBoolean();

    uint8_t read8();
    uint16_t read16();
    uint32_t read32();
    uint64_t read64();

    float readFloat();
    double readDouble();

    /**
     * Read an 8-bit pascal style string from the stream.
     * 32-bit length field, followed by length 8-bit chars.
     */
    ACString readCString();

    /**
     * Read an 16-bit pascal style string from the stream.
     * 32-bit length field, followed by length PRUnichars.
     */
    AString readString();

    /**
     * Read an opaque byte array from the stream.
     *
     * @param aLength the number of bytes that must be read.
     *
     * @throws NS_ERROR_FAILURE if it can't read aLength bytes
     */
    void readBytes(in uint32_t aLength,
                   [size_is(aLength), retval] out string aString);

    /**
     * Read an opaque byte array from the stream, storing the results
     * as an array of PRUint8s.
     *
     * @param aLength the number of bytes that must be read.
     *
     * @throws NS_ERROR_FAILURE if it can't read aLength bytes
     */
    void readByteArray(in uint32_t aLength,
                       [array, size_is(aLength), retval] out uint8_t aBytes);

    /**
     * Read opaque bytes from the stream, storing the results in an ArrayBuffer.
     *
     * @param aLength the number of bytes that must be read
     * @param aArrayBuffer the arraybuffer in which to store the results
     * Note: passing view.buffer, where view is an ArrayBufferView of an
     *       ArrayBuffer, is not valid unless view.byteOffset == 0.
     *
     * @return The number of bytes actually read into aArrayBuffer.
     */
    [implicit_jscontext]
    unsigned long readArrayBuffer(in uint32_t aLength, in jsval aArrayBuffer);
};

%{C++

#ifdef MOZILLA_INTERNAL_API
#include "nsString.h"

inline nsresult
NS_ReadOptionalCString(nsIBinaryInputStream* aStream, nsACString& aResult)
{
    bool nonnull;
    nsresult rv = aStream->ReadBoolean(&nonnull);
    if (NS_SUCCEEDED(rv)) {
        if (nonnull)
            rv = aStream->ReadCString(aResult);
        else
            aResult.Truncate();
    }
    return rv;
}

inline nsresult
NS_ReadOptionalString(nsIBinaryInputStream* aStream, nsAString& aResult)
{
    bool nonnull;
    nsresult rv = aStream->ReadBoolean(&nonnull);
    if (NS_SUCCEEDED(rv)) {
        if (nonnull)
            rv = aStream->ReadString(aResult);
        else
            aResult.Truncate();
    }
    return rv;
}
#endif

%}