/*

* 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;

	}