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lightning-sunbird  0.9+nobinonly
ipcMessageReader.cpp
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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 #include "ipcMessageReader.h"
00040 #include <string.h>
00041 
00042 //*****************************************************************************
00043 // ipcMessageReader
00044 //*****************************************************************************   
00045 
00046 PRUint8 ipcMessageReader::GetInt8()
00047 {
00048   if (mBufPtr < mBufEnd)
00049     return *mBufPtr++;
00050   mError = PR_TRUE;
00051   return 0;
00052 }
00053 
00054 // GetInt16 and GetInt32 go to pains to avoid unaligned memory accesses that
00055 // are larger than a byte. On some platforms, that causes a performance penalty.
00056 // On other platforms, Tru64 for instance, it's an error.
00057 
00058 PRUint16 ipcMessageReader::GetInt16()
00059 {
00060   if (mBufPtr + sizeof(PRUint16) <= mBufEnd) {
00061     PRUint8 temp[2] = { mBufPtr[0], mBufPtr[1] };
00062     mBufPtr += sizeof(PRUint16);
00063     return *(PRUint16*)temp;
00064   }
00065   mError = PR_TRUE;
00066   return 0;
00067 }
00068 
00069 PRUint32 ipcMessageReader::GetInt32()
00070 {
00071   if (mBufPtr + sizeof(PRUint32) <= mBufEnd) {
00072     PRUint8 temp[4] = { mBufPtr[0], mBufPtr[1], mBufPtr[2], mBufPtr[3] };
00073     mBufPtr += sizeof(PRUint32);
00074     return *(PRUint32*)temp;
00075   }
00076   mError = PR_TRUE;
00077   return 0;
00078 }
00079 
00080 PRInt32 ipcMessageReader::GetBytes(void* destBuffer, PRInt32 n)
00081 {
00082   if (mBufPtr + n <= mBufEnd) {
00083     memcpy(destBuffer, mBufPtr, n);
00084     mBufPtr += n;
00085     return n;
00086   }
00087   mError = PR_TRUE;
00088   return 0;
00089 }
00090 
00091 PRBool ipcMessageReader::AdvancePtr(PRInt32 n)
00092 {
00093   const PRUint8 *newPtr = mBufPtr + n;
00094   if (newPtr >= mBuf && newPtr <= mBufEnd) {
00095     mBufPtr = newPtr;
00096     return PR_TRUE;
00097   }
00098   mError = PR_TRUE;
00099   return PR_FALSE;
00100 }