<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 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: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept xml:lang="en" id="GUID-D91DC379-947A-52CB-A154-7922AF334527"><title>How to retrieve drive and volume information</title><prolog><metadata><keywords/></metadata></prolog><conbody><p>The class <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita"><apiname>RFs</apiname></xref> provides a number of functions that extract drive and volume information. </p> <p>The <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-23B14094-0526-5BB2-8CCB-E25558F452F4">FileSystemSubType()</xref> function returns the sub type of a drive. This information can be used to warn a user if they try to use a volume that is not of the correct format. </p> <p>The volume information supplied by <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-35712294-BF6D-5ADF-A717-67B949F02EC3">VolumeIOParam()</xref> is particularly useful as it allows you to get specific properties for a volume. This includes the block size of the underlying media for read/write operations, allowing your application to access data on the underlying media in the most efficient way. For example: </p> <ul><li id="GUID-519C820E-DDF3-574C-9FF0-C16E805C38E4"><p>Applications that download from a local or network connection to transfer files, for example, bluetooth beaming, HTTP, FTP, may be able to improve their performance by knowing the recommended block and cluster sizes. </p> </li> <li id="GUID-555B3946-64CA-52BC-96AC-12034ACC0483"><p>For Multimedia source data, reading in optimal sized blocks may help to achieve a consistent read speed. </p> </li> </ul> <ul><li id="GUID-F9366D6D-E5CA-58EC-B28F-7219AB43F61A"><p> <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-83B63D4E-65E5-5DC6-8C4B-CD3A26165B6D">Drive information</xref>  </p> <ul><li id="GUID-3E51BA09-FB64-54C7-9FD6-F05E43FC9DB5"><p> <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-BF5C8B94-7600-555F-B9F7-DFAE390B4EE3">DriveList()</xref> </p> </li> <li id="GUID-58D7E17C-9D24-551C-AD21-BA234395C0E5"><p> <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-57F650DF-4144-586F-81E5-B1386202A27B">Drive()</xref>  </p> </li> <li id="GUID-241A56DC-B1B5-57A7-8A03-11CC9F11D523"><p> <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-23B14094-0526-5BB2-8CCB-E25558F452F4">FileSystemSubType()</xref> </p> </li> </ul> </li> <li id="GUID-16335B02-EF2C-51C8-AC1E-8F596085D896"><p> <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-43EFDCEC-A390-56F6-A4C0-A8150E188E05">Volume information</xref>  </p> <ul><li id="GUID-50F492F4-FBF5-50CA-A318-C7758C1999E1"><p> <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-8F14799F-6F60-5C64-AC8D-4083CE06E6A2">Volume()</xref>  </p> </li> <li id="GUID-746C70D5-F301-5F99-B8B6-31E1AB1D42EE"><p> <xref href="GUID-D91DC379-947A-52CB-A154-7922AF334527.dita#GUID-D91DC379-947A-52CB-A154-7922AF334527/GUID-35712294-BF6D-5ADF-A717-67B949F02EC3">VolumeIOParam()</xref> </p> </li> </ul> </li> </ul> <section id="GUID-83B63D4E-65E5-5DC6-8C4B-CD3A26165B6D"><title>Drive information</title> <p id="GUID-BF5C8B94-7600-555F-B9F7-DFAE390B4EE3"><b> DriveList()</b> </p> <p> <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-384A86BF-EB47-3525-9614-D474977AF991"><apiname>RFs::DriveList()</apiname></xref> retrieves an array of drives. The drive list consists of an array of 26 bytes. Array index zero corresponds to drive A, one equals B and so on. If the value of an array member is 1 the corresponding drive exists. If this drive is able to contain removable media then use <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-51CDDF8D-3F18-398D-A477-B81948C10872"><apiname>RFs::Drive</apiname></xref> to test for its presence. </p> <p>The following code prints each drive in the drive list as a letter, followed by the hex value of the integer indicating the drive's attributes. </p> <codeblock id="GUID-78C60DB6-8AA1-598C-80F8-98163898ED7D" xml:space="preserve">TDriveList drivelist;

TChar driveLetter; 

TInt driveNumber; 

_LIT(KDrive,"%c: %02x ");

User::LeaveIfError(fsSession.DriveList(drivelist)); 

for(driveNumber=EDriveA;driveNumber<=EDriveZ;driveNumber++) 

{ 

    if (drivelist[driveNumber]) 

    {

        User::LeaveIfError(fsSession.DriveToChar(driveNumber,driveLetter));

        console->Printf(KDrive, TUint(driveLetter), drivelist[driveNumber]); 

    }

}</codeblock> <p id="GUID-57F650DF-4144-586F-81E5-B1386202A27B"><b>Drive()</b> </p> <p> <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-BAB41D5B-A8B2-31D0-8A45-931112D1F5D3"><apiname>RFs::Drive()</apiname></xref> retrieves the attributes of the drive specified with <xref href="GUID-4D883FA4-115C-3425-8A34-B00D1D4BBCF9.dita"><apiname>TDriveInfo</apiname></xref>. The following example loops through all possible drives, a-z, and prints a message if a drive is flash-based. </p> <codeblock id="GUID-8711C4BC-225A-5824-A920-09696CD59E06" xml:space="preserve">TChar driveLetter; 

TDriveInfo driveInfo; 

TInt driveNumber;

_LIT(KFlash,"Drive %c is flash\n"); 

for (driveNumber=EDriveA; driveNumber<=EDriveZ; driveNumber++) 

{

    fsSession.Drive(driveInfo, driveNumber); 

    if (driveInfo.iDriveAtt == KDriveAbsent) 

        continue; 

    if (driveInfo.iType == EMediaFlash) 

    {

        User::LeaveIfError(fsSession.DriveToChar(driveNumber, driveLetter));

        console->Printf(KFlash, driveLetter); 

    }

}</codeblock> <p id="GUID-23B14094-0526-5BB2-8CCB-E25558F452F4"><b>FileSystemSubType()</b> </p> <p>To retrieve the sub type of the volume use <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-00404432-7095-3461-A669-9009A91BD45C"><apiname>RFs::FileSystemSubType()</apiname></xref>. Pass this function a drive number and a <xref href="GUID-F3E8BB64-554E-3A9A-A7FA-A5C935A644FD.dita"><apiname>TFSName</apiname></xref> for the sub type. For example, the sub type can be 'FAT16' of the Fat file system. </p> <p> <b>Note</b>: For file systems that do not have a sub type, for example a ROM file system, the name of the file system is returned, in this case 'ROM'. </p> <codeblock id="GUID-7BB4BAAD-95C3-57D2-8BDB-C4698FEB4748" xml:space="preserve">TChar driveLetter;

TFSName name;

TInt driveNumber;

_LIT(KSubType,"Drive %c is Sub Type: %S\n"); 

for (driveNumber=EDriveA; driveNumber<=EDriveZ; driveNumber++) 

{

    TInt err = fsSession.FileSystemSubType(driveNumber, name); 

    if (err != KErrNone)

        continue; 

    User::LeaveIfError(fsSession.DriveToChar(driveNumber, driveLetter));

    console->Printf(KSubType, driveLetter, &name);

}</codeblock> </section> <section id="GUID-43EFDCEC-A390-56F6-A4C0-A8150E188E05"><title>Volume information</title> <p id="GUID-8F14799F-6F60-5C64-AC8D-4083CE06E6A2"><b>Volume()</b> </p> <p>Use <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-52EFB8B0-E175-328F-AB1B-EACD03104A15"><apiname>RFs::Volume()</apiname></xref> to get the volume information, with a <xref href="GUID-F7AECD65-6C3C-3056-847A-FD49BB2E927F.dita"><apiname>TVolumeInfo</apiname></xref> object. The information returned includes a <xref href="GUID-4D883FA4-115C-3425-8A34-B00D1D4BBCF9.dita"><apiname>TDriveInfo</apiname></xref> object with the volume name, its unique ID, size and the amount of free space. </p> <p>The following example prints out the names of volumes: </p> <codeblock id="GUID-2C806466-0FC6-5AB3-A1C1-1655323DCEB3" xml:space="preserve">TChar driveLetter;

TVolumeInfo volumeInfo; 

TInt driveNumber;

_LIT(KVolName,"Volume name: %S\n"); 

for (driveNumber=EDriveA; driveNumber<=EDriveZ; driveNumber++) 

{

    TInt err = fsSession.Volume(volumeInfo, driveNumber); 

    if (err != KErrNone)

        continue; 

    User::LeaveIfError(fsSession.DriveToChar(driveNumber, driveLetter));

    console->Printf(KVolName, &volumeInfo.iName);

}</codeblock> <p>Note: Use the return value from <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-52EFB8B0-E175-328F-AB1B-EACD03104A15"><apiname>RFs::Volume()</apiname></xref> to test whether a volume is present in the drive, a value of <xref href="GUID-51298FCE-7857-39F8-BFAB-49AF5556D0CC.dita"><apiname>KErrNotReady</apiname></xref> indicates that there is no volume present. </p> <p id="GUID-35712294-BF6D-5ADF-A717-67B949F02EC3"><b> VolumeIOParam()</b> </p> <p>Use <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-DE5542A5-18ED-3F68-9012-DEE13619DCA2"><apiname>RFs::VolumeIOParam</apiname></xref> to retrieve volume information, with a <xref href="GUID-FA2892FC-4554-3E1D-93AD-593DFA4FB6F7.dita"><apiname>TVolumeIOParamInfo</apiname></xref> object. The object returns the recommended sizes for read and write operations on memory and buffers. </p> <codeblock id="GUID-8618DED6-7771-5495-B109-3B629BFC006C" xml:space="preserve">TChar driveLetter;

TVolumeIOParamInfo volumeparamInfo; 

TInt driveNumber;

_LIT(KRecWriteSize,"Drive %c's recommended write size: %d\n"); 

for (driveNumber=EDriveA; driveNumber<=EDriveZ; driveNumber++) 

{

    TInt err = fsSession.VolumeIOParam(driveNumber, volumeparamInfo); 

    if (err != KErrNone)

        continue; 

    User::LeaveIfError(fsSession.DriveToChar(driveNumber, driveLetter));

    console->Printf(KRecWriteSize, driveLetter, &volumeparamInfo.iRecWriteBufSize);