/*

 * Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).

 * All rights reserved.

 * This component and the accompanying materials are made available

 * under the terms of the License "Eclipse Public License v1.0"

 * which accompanies this distribution, and is available

 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

 *

 * Initial Contributors:

 * Nokia Corporation - initial contribution.

 *

 * Contributors:

 *

 * Description: 

 * Common security functions

 *

 */

 /**

  @file

 */

 #include "securityutils.h"

 #include <f32file.h>

 // Extracts the next sub-dir name, i.e. "directory1" for "directory1\directory2\...". As a second parameter, returns the remaining path without the leading slash 

 // Return ETrue iff a directory was found in the path

  TBool GetNextDirNameL(const TPtrC& aPath, TPtrC& aNextDir, TPtrC& aRemainingPath)

 	{

 	TInt nextSlashPos = aPath.Locate('\\');

 	if (nextSlashPos < 0)

 		return EFalse;

 	aNextDir.Set(aPath.Left(nextSlashPos));

 	TPtrC remainingPath = nextSlashPos <  aPath.Length() - 1 ? aPath.Mid(nextSlashPos + 1) : TPtrC();

 	aRemainingPath.Set(remainingPath);

 	return ETrue;

 	}

 TCapabilitySet PrivateModificationRequiredCapabilitiesL(const TDesC& aPrivateSubPath, TSecureId aClientSid)

 	{

 	TPtrC privateSubDirName;

 	TPtrC remainingSubPath;

 	TBool nextDirAvailable = GetNextDirNameL(aPrivateSubPath, privateSubDirName, remainingSubPath);

 	// Filter out paths which do not have a /private/<SID> form - require TCB for them

 	// First, filter out files directly under the /private directory

 	if (!nextDirAvailable)

 		return TCapabilitySet(ECapabilityTCB);

 	if (privateSubDirName.Length() != 8)

 		return TCapabilitySet(ECapabilityTCB); // Filter out sub-dir names which do not have 8 bytes, i.e. do not represent a SID

 	TLex hexConverter(privateSubDirName);

 	TUint32 foundSecureIdInt;

 	if (hexConverter.Val(foundSecureIdInt, EHex) != KErrNone)

 		return TCapabilitySet(ECapabilityTCB); // Filter out paths which do not have a <secureId> subdir under private

 	TSecureId foundSecureId(foundSecureIdInt);

 	if (foundSecureId != aClientSid) // Check whether this the client's SID

 		{

 		TPtrC nextSubPath; // Check for /private/<SID>/import directories

 		TPtrC nextSubDir;

 		if (!GetNextDirNameL(remainingSubPath, nextSubDir, nextSubPath) || nextSubDir.CompareF(_L("import")) != 0)

 			{

 			// If not an import directory, require TCB or AllFiles

 			TCapabilitySet ret(ECapabilityTCB);

 			ret.AddCapability(ECapabilityAllFiles);

 			return ret;			

 			}

 		}

 	TCapabilitySet emptySet;

 	emptySet.SetEmpty();

 	return emptySet;

 	}

 EXPORT_C TCapabilitySet SecCommonUtils::FileModificationRequiredCapabilitiesL(const TDesC& aFileName, TSecureId aClientSid)

 	{

 	TCapabilitySet emptySet;

 	emptySet.SetEmpty();	

 	// TParsePtrC is unusable, since it panics on incorrect paths. We have to use TParse and create a temporary buffer for it (as there's no TParseC)

 	RBuf tempbuf;

 	tempbuf.CreateL(aFileName);

 	tempbuf.CleanupClosePushL();

 	TParse pathParse;

 	if (pathParse.Set(tempbuf, NULL, NULL) != KErrNone)

 		{

 		CleanupStack::PopAndDestroy(&tempbuf);

 		// Path failed to parse - require TCB, as it is the only capability which allows modification anywhere on the FS

 		// (and we do not know where on the FS this file is)

 		return TCapabilitySet(ECapabilityTCB); 

 		}

 	CleanupStack::PopAndDestroy(&tempbuf);

 	// check for wild cards (such as * or ?) in paths 

     if(pathParse.IsWild())

         return TCapabilitySet(ECapabilityTCB);

 	// check for relative paths

     if(aFileName.Find(_L("..")) != KErrNotFound)

         return TCapabilitySet(ECapabilityTCB);

     TPtrC pathTmp = pathParse.Path();

     if (pathTmp.Length() <= 1) // The should be at least one directory - otherwise there's nothing to check

     	return emptySet;

     // Get the first directory name    

     TPtrC path = pathTmp.Mid(1); // Remove the leading slash

     TPtrC firstDirName;

     TPtrC remainingPath;

     TBool nextDirAvailable = GetNextDirNameL(path, firstDirName, remainingPath);

     __ASSERT_ALWAYS(nextDirAvailable, User::Invariant()); // There should be at least one directory if the Path() was not empty

     // For 'sys' or 'resource', require TCB

     if (firstDirName.CompareF(_L("sys")) == 0 || firstDirName.CompareF(_L("resource")) == 0)

     	return TCapabilitySet(ECapabilityTCB);

     if (firstDirName.CompareF(_L("private")) == 0)

     	return PrivateModificationRequiredCapabilitiesL(remainingPath, aClientSid);

     // If the directory name is not 'private', 'resource' or 'sys', no capabilities are required

 	return emptySet;

 	}