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ipcMessageWriter.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 ipcMessageWriter_h__
00040 #define ipcMessageWriter_h__
00041 
00042 #include "prtypes.h"
00043 
00044 //*****************************************************************************
00045 // ipcMessageWriter
00046 //
00047 // Creates a block of memory and resizes it in order to hold writes. The
00048 // block will be freed when this object is destroyed. Bytes are written in
00049 // native endianess, as ipcMessageReader reads them in native endianess.
00050 //*****************************************************************************   
00051 
00052 class ipcMessageWriter
00053 {
00054 public:
00055                   ipcMessageWriter(PRUint32 initialCapacity) :
00056                     mBuf(NULL),
00057                     mBufPtr(NULL), mBufEnd(NULL),
00058                     mCapacity(0),
00059                     mError(PR_FALSE)
00060                   {
00061                     EnsureCapacity(initialCapacity);
00062                   }
00063                   
00064                   ~ipcMessageWriter();
00065 
00066                   // Returns PR_TRUE if an error has occured at any point
00067                   // during the lifetime of this object, due to the buffer
00068                   // not being able to be grown to the required size.
00069   PRBool          HasError()
00070                   { return mError; }
00071 
00072   void            PutInt8(PRUint8 val);
00073   void            PutInt16(PRUint16 val);
00074   void            PutInt32(PRUint32 val);  
00075   PRUint32        PutBytes(const void* src, PRUint32 n);
00076 
00077                   // Returns the beginning of the buffer. Do not free this.
00078   PRUint8*        GetBuffer()
00079                   { return mBuf; }
00080 
00081   PRInt32         GetSize()
00082                   { return mBufPtr - mBuf; }
00083 
00084 private:
00085   PRBool          EnsureCapacity(PRInt32 sizeNeeded)
00086                   {
00087                     return (mBuf && ((mBufPtr + sizeNeeded) <= mBufEnd)) ?
00088                       PR_TRUE : GrowCapacity(sizeNeeded);
00089                   }
00090   PRBool          GrowCapacity(PRInt32 sizeNeeded);
00091 
00092 private:
00093   PRUint8         *mBuf;
00094   PRUint8         *mBufPtr, *mBufEnd;
00095   PRInt32         mCapacity;
00096   PRBool          mError;
00097 };
00098 
00099 #endif // ipcMessageWriter_h__