Class RResourceFile

class RResourceFile;

Description

Accesses a resource file and reads the resource data into a buffer.

Interpretation of the data is achieved using the TResourceReader class.

RResourceFile instance behaviour when some problem occurs - it panics. Or asserts, if the used method is not "L" method.

Expected behaviour when assignment operator or copy constructor is called: The class doesn't have assignment operator and copy constructor, so the compiler generated ones will be used. The heap buffers used by the source class instance will be shared with the destination class instance.

Expected behaviour when the RResourceFile instance is about to be destroyed: The class doesn't have destructor so compiler generated one will be used. Always call Close() to free allocated by the instance resources.

Members

Defined in RResourceFile:
AllocReadL(), AllocReadLC(), Close(), ConfirmSignatureL(), ConfirmSignatureL(), Offset(), OpenL(), OpenL(), OwnsResourceId(), OwnsResourceIdL(), RResourceFile(), ReadL(), SignatureL(), UidType()

See also:

• TResourceReader

IMPORT_C RResourceFile();

Description

Constructs a default resource file object.

IMPORT_C void Close();

Description

Closes the resource file reader. This function is called after finishing reading all resources.

IMPORT_C void OpenL(RFs &aFs, const TDesC &aName);

Description

Opens the resource file reader.

The resource file reader must be opened before reading resources or checking the signature of the resource file. This function initially closes the resource-file object if it is currently open. If a leave occurs during the function, the object is reverted to its closed state.

Parameters

RFs &aFs Handle to a file server session. const TDesC &aName File to open as a resource file

Leave codes

The function leaves if the named file cannot be opened or the header record at the beginning of the file cannot be read.

Panic codes

If the file is corrupted - the method will panic in debug mode.

IMPORT_C TUidType UidType() const;

Pre-Condition

OpenL() has been called successfully.

Description

Retrieve the UID tuple of the opened resource file.

Return value

TUidType The UIDs of the loaded resource file.

Panic codes

If the file is not opened or class data members initialization fails - the method will panic always.

IMPORT_C void ReadL(TDes8 &aDes, TInt aResourceId) const;

Description

Reads a resource specified by resource id into the specified descriptor.

The descriptor must be long enough to contain the entire resource

The search for the resource uses the following algorithm:

A resource id in the range 1 to 4095 is looked up in this resource file. The function leaves if there is no matching resource.

If the resource id is greater than 4095, then the most significant 20 bits of the resource id is treated as an offset and the least significant 12 bits is treated as the real resource id. If the offset matches the offset value defined for this file, then the resource is looked up in this resource file using the real resource id (i.e. the least significant 12 bits). If the offset does not match, then the function leaves.

Note, do not call this function until a call to ConfirmSignatureL() has completed successfully.

Parameters

TDes8 &aDes On return, contains the resource that has been read. The function leaves if the descriptor is not long enough to contain the entire resource. TInt aResourceId The numeric id of the resource to be read.

Leave codes

The function leaves if this resource id is not in this resource file.

Panic codes

If the file is corrupted - the method will panic in debug mode.

IMPORT_C HBufC8 *AllocReadL(TInt aResourceId) const;

Description

Reads a resource into a heap descriptor and returns a pointer to that descriptor.

A heap descriptor of appropriate length is allocated for the resource. Ownership of the heap descriptor passes to the caller who must destroy it when it is no longer needed.

The search for the resource uses the following algorithm:

A resource id in the range 1 to 4095 is looked up in this resource file. The function leaves if there is no matching resource.

If the resource id is greater than 4095, then the most significant 20 bits of the resource id is treated as an offset and the least significant 12 bits is treated as the real resource id. If the offset matches the offset value defined for this file, then the resource is looked up in this resource file using the real resource id (i.e. the least significant 12 bits). If the offset does not match, then the function leaves.

Note, do not call this function until a call to ConfirmSignatureL() has completed successfully.

Parameters

TInt aResourceId The numeric id of the resource to be read.

Return value

HBufC8 * Pointer to an 8 bit heap descriptor containing the resource.

Leave codes

KErrNotFound - there is no resource with aResourceId in the file.

Panic codes

If the file is corrupted - the method will panic in debug mode.

See also:

• RResourceFile::Offset()

IMPORT_C HBufC8 *AllocReadLC(TInt aResourceId) const;

Description

Reads a resource into a heap descriptor, returns a pointer to that descriptor and pushes the pointer onto the cleanup stack.

A heap descriptor of appropriate length is allocated for the resource. Ownership of the heap descriptor passes to the caller who must destroy it and pop its pointer off the cleanup stack when it is no longer needed.

The search for the resource uses the following algorithm:

A resource id in the range 1 to 4095 is looked up in this resource file. The function leaves if there is no matching resource.

If the resource id is greater than 4095, then the most significant 20 bits of the resource id is treated as an offset and the least significant 12 bits is treated as the real resource id. If the offset matches the offset value defined for this file, then the resource is looked up in this resource file using the real resource id (i.e. the least significant 12 bits). If the offset does not match, then the function leaves.

Note, do not call this function until a call to ConfirmSignatureL() has completed successfully.

Parameters

TInt aResourceId The numeric id of the resource to be read.

Return value

HBufC8 * Pointer to a heap descriptor containing the resource.

Leave codes

KErrNotFound - there is no resource with aResourceId in the file.

Panic codes

If the file is corrupted - the method will panic in debug mode.

See also:

• RResourceFile::Offset()

IMPORT_C void ConfirmSignatureL(TInt aSignature);

Description

Initialises the offset value from the first resource.

The function assumes that the first resource in the file consists of two 32-bit integers. The first integer contains the version number and the second is a self-referencing link whose value is the offset for the resources in the file, plus 1.This function must be called before calling Offset(), AllocReadL(), AllocReadLC() or ReadL().

Parameters

TInt aSignature This argument value is not used by the function.

Leave codes

KErrCorrupt - wrong size of the first resource in the file. Probably the file is corrupted.

Panic codes

If the file is corrupted - the method will panic in debug mode.

IMPORT_C void ConfirmSignatureL();

Description

Initialises the offset value from the first resource.

The function tests to catch cases where the first resource is not an RSS_SIGNATURE. It assumes that the first resource in the file consists of two 32-bit integers. The first integer contains the version number and the second is a self-referencing link whose value is the offset for the resources in the file, plus 1.This function must be called before calling Offset(), AllocReadL(), AllocReadLC() or ReadL().

Leave codes

KErrCorrupt - wrong size of the first resource in the file. Probably the file is corrupted.

Panic codes

If the file is corrupted - the method will panic in debug mode.

IMPORT_C TInt SignatureL() const;

Description

Returns this resource file's version number.

The function assumes that the first resource in the file consists of two 32-bit integers. The first integer contains the version number.

Return value

TInt The version number.

Leave codes

KErrCorrupt Wrong size of the first resource in the file. Probably the file is corrupted.

Panic codes

If the file is corrupted - the method will panic in debug mode.

See also:

• RResourceFile::ConfirmSignatureL()

IMPORT_C TBool OwnsResourceId(TInt aResourceId) const;

Description

Tests whether the resource file owns the specified resource id.

The resource file owns the resource id if the most significant 20 bits of the resource id are zero or match the offset value as returned from a call to the Offset() member function.

Parameters

TInt aResourceId The resource id to test or if the resource id is not out of range.

Return value

TBool True, if the resource file owns the id, false otherwise.

IMPORT_C TBool OwnsResourceIdL(TInt aResourceId) const;

Description

Tests whether the resource file owns the specified resource id.

The resource file owns the resource id if the most significant 20 bits of the resource id are zero or match the offset value as returned from a call to the Offset() member function or if the resource id is not out of range.

Parameters

TInt aResourceId The resource id to test.

Return value

TBool True, if the resource file owns the id, false otherwise.

Panic codes

If the file is corrupted - the method will panic in debug mode.

IMPORT_C void OpenL(RFs &aFs, const TDesC &aName, TUint aFileOffset, TInt aFileSize);

Description

Opens the resource file reader.

The resource file reader must be opened before reading resources or checking the signature of the resource file. This function initially closes the resource-file object if it is currently open. If a leave occurs during the function, the object is reverted to its closed state.

Parameters

RFs &aFs Handle to a file server session const TDesC &aName File to open as a resource file TUint aFileOffset Resource file section offset from the beginning of the file. TInt aFileSize Resource file section size.

Leave codes

Function leaves if the named file cannot be opened or the header record at the beginning of the file cannot be read.

Panic codes

If the file is corrupted - the method will panic in debug mode.

inline TInt Offset() const;

Description

Returns the offset value defined for this resource file.

This function must not be called until a call to ConfirmSignatureL() has completed successfully, otherwise the value returned by this function may be meaningless.

Return value

TInt The offset value defined for this resource file.

See also:

• RResourceFile::ConfirmSignatureL()