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ipcMessageReader.h
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00001 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
00002 /* ***** BEGIN LICENSE BLOCK *****
00003  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
00004  *
00005  * The contents of this file are subject to the Mozilla Public License Version
00006  * 1.1 (the "License"); you may not use this file except in compliance with
00007  * the License. You may obtain a copy of the License at
00008  * http://www.mozilla.org/MPL/
00009  *
00010  * Software distributed under the License is distributed on an "AS IS" basis,
00011  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
00012  * for the specific language governing rights and limitations under the
00013  * License.
00014  *
00015  * The Original Code is Mozilla IPC.
00016  *
00017  * The Initial Developer of the Original Code is
00018  * Netscape Communications Corporation.
00019  * Portions created by the Initial Developer are Copyright (C) 2003
00020  * the Initial Developer. All Rights Reserved.
00021  *
00022  * Contributor(s):
00023  *   Conrad Carlen <ccarlen@netscape.com>
00024  *
00025  * Alternatively, the contents of this file may be used under the terms of
00026  * either the GNU General Public License Version 2 or later (the "GPL"), or
00027  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
00028  * in which case the provisions of the GPL or the LGPL are applicable instead
00029  * of those above. If you wish to allow use of your version of this file only
00030  * under the terms of either the GPL or the LGPL, and not to allow others to
00031  * use your version of this file under the terms of the MPL, indicate your
00032  * decision by deleting the provisions above and replace them with the notice
00033  * and other provisions required by the GPL or the LGPL. If you do not delete
00034  * the provisions above, a recipient may use your version of this file under
00035  * the terms of any one of the MPL, the GPL or the LGPL.
00036  *
00037  * ***** END LICENSE BLOCK ***** */
00038 
00039 #ifndef ipcMessageReader_h__
00040 #define ipcMessageReader_h__
00041 
00042 #include "prtypes.h"
00043 
00044 //*****************************************************************************
00045 // ipcMessageReader
00046 //
00047 // Reads from a const buffer supplied to it. Does not take ownership of the
00048 // buffer. Bytes are read in native endianess, as ipcMessageWriter writes them
00049 // in native endianess.
00050 //*****************************************************************************   
00051 
00052 class ipcMessageReader
00053 {
00054 public:
00055                   ipcMessageReader(const PRUint8* inBuffer, PRUint32 bufferSize) :
00056                     mBuf(inBuffer), mBufEnd(inBuffer + bufferSize),
00057                     mBufPtr(mBuf),
00058                     mError(PR_FALSE)
00059                   { }
00060                   
00061                   ~ipcMessageReader()
00062                   { }
00063 
00064                   // Returns PR_TRUE if an error has occured at any point
00065                   // during the lifetime of this object. Any read operation
00066                   // will safely return 0 on an error condition.
00067   PRBool          HasError()
00068                   { return mError; }
00069   
00070   PRUint8         GetInt8();
00071   PRUint16        GetInt16();
00072   PRUint32        GetInt32();
00073   PRInt32         GetBytes(void* destBuffer, PRInt32 n);
00074   
00075                   // Returns data at the current read position.
00076   const PRUint8*  GetPtr()
00077                   { return mBufPtr; }
00078 
00079                   // Returns PR_TRUE if the new position is within the buffer.
00080                   // Returns PR_FALSE and sets error state if not.
00081   PRBool          AdvancePtr(PRInt32 n);
00082       
00083 private:
00084   const PRUint8   *mBuf, *mBufEnd;
00085   const PRUint8   *mBufPtr;
00086   PRBool          mError;
00087 };
00088 
00089 #endif // ipcMessageReader_h__