rfshell.dll

This document describes the interface of the RFSHELL.DLL which can be used to easily add ReiserFS support for existing applications.

Overview

The RFSHELL.DLL has three C-style functions:

It is necessary to first find out which ReiserFS partitions are on the host system, thus the autodetect function. The other two functions are used to create an interface for the filesystem (you can access two or more reiserfs partitions at once).

Autodetecting partitions

Prototype

typedef void (WINAPI* LPFNFoundPartition)(LPCSTR lpszName);
void WINAPI FS_Autodetect( LPFNFoundPartition lpCallback );

Description

This function autodetects all reiserfs partitions on the local machine. For each partition found, it will call the callback specified as parameter lpCallback

Input

LPFNFoundPartition lpCallback - Pointer to a caller-provided function that looks like this:

void WINAPI FoundPartition(LPCSTR lpszName)
{
    // todo: add implementation
}

Output

None

Creating an instance of IFilesystem

Prototype

IFilesystem* WINAPI FS_CreateInstance( LPCSTR lpszName );

Description

This function creates an instance of IFilesystem for the reiserfs partition specified by lpszName. See below for a description of the IFilesystem interface.

Input

LPCSTR lpszName - Pointer to the name of a reiserfs partition.

Output

Pointer to a newly allocated IFilesystem or NULL if an error occured.

Destroying an instance of IFilesystem

Prototype

void WINAPI FS_DestroyInstance( IFilesystem* pFilesystem );

Description

This function destroys an instance of IFilesystem previously allocated using FS_CreateInstance

Input

IFilesystem* pFilesystem - Pointer to the IFilesystem.

Output

None

The IFilesystem interface

Overview

class IFilesystem : public IUnknown
{
public:
	virtual HANDLE OpenFile(LPCTSTR szFilename) const = 0;
	virtual void ReadFile(HANDLE hFile, LPVOID lpBuffer, DWORD NumberOfBytesToRead, DWORD& NumberOfBytesRead) const = 0;
	virtual void CloseFile(HANDLE hFile) const = 0;
	
	virtual HANDLE FindFirstFile(LPCTSTR szPath) const = 0;
	virtual bool FindNextFile(HANDLE hFind, UNIX_FILEINFO& FileInfo) const = 0;
	virtual void CloseFind(HANDLE hFind) const = 0;
};

IFilesystem::OpenFile

Prototype

HANDLE IFilesystem::OpenFile(LPCTSTR szFilename) const;

Description

This function opens a handle for the file specified by szFilename. Note that the file returned is readonly, because rfstool supports readonly-mode only.

Input

LPCTSTR szFilename - Name of a file on the local filesystem, e.g. /etc/fstab

Output

Handle for the file.

IFilesystem::ReadFile

Prototype

void IFilesystem::ReadFile(HANDLE hFile, LPVOID lpBuffer, DWORD NumberOfBytesToRead, DWORD& NumberOfBytesRead) const;

Description

This function reads data from a file. Note that due to implementation issues, in the current version of rfstool, the whole file is read to memory first.

Input

HANDLE hFile - Filehandle previously allocated by IFilesystem::OpenFile

LPVOID lpBuffer - Pointer to a BYTE buffer to receive the file data

DWORD NumberOfBytesToRead - Size of the Buffer pointed to by lpBuffer

DWORD& NumberOfBytesRead - Reference to a DWORD that will receive the number of bytes actually retrieved. This might be less than NumberOfBytesToRead, indicating end-of-file.

Output

None

IFilesystem::OpenFile

Prototype

void IFilesystem::CloseFile(HANDLE hFile) const;

Description

This function closes a handle for a file on a reiserfs partition. Do NOT call the Win32-CloseHandle API on handles returned from IFilesystem

Input

HANDLE hFile - Filehandle previously allocated by IFilesystem::OpenFile

Output

None

IFilesystem::FindFirstFile

Prototype

HANDLE IFilesystem::FindFirstFile(LPCTSTR szPath) const;

Description

This function opens a handle for a directory in szPath

Input

LPCTSTR szPath - Name of a directory the local filesystem, e.g. /usr/include

Output

Handle for the directory.

IFilesystem::FindNextFile

Prototype

bool IFilesystem::FindNextFile(HANDLE hFind, UNIX_FILEINFO& FileInfo) const;

Description

This function returns the description of the next file in the directory, or false if there are no more files in the directory.

Input

HANDLE hFind - Handle to a directory previously allocated by IFilesystem::FindFirstFile

UNIX_FILEINFO& FileInfo - Reference to a UNIX_FILEINFO structure describing the file. This structure looks like this:

struct UNIX_FILEINFO
{
	__u16	i_mode;		/* File mode (permissions)*/
	__u16	i_uid;		/* Low 16 bits of Owner Uid */
	__u16	i_gid;		/* Low 16 bits of Group Id */
	__u32	i_size;		/* Size in bytes */
	__s32	i_atime;	/* Access time */
	__s32	i_ctime;	/* Creation time */
	__s32	i_mtime;	/* Modification time */
	TCHAR szFileName[UNIX_FILENAME_LENGTH];
};

Output

If the function returns true, there are more files to check. If the function returns false, end of directory has been reached.

IFilesystem::CloseFind

Prototype

void IFilesystem::CloseFind(HANDLE hFind) const;

Description

This function closes a handle for a directory on a reiserfs partition. Do NOT call the Win32-CloseHandle API on handles returned from IFilesystem

Input

HANDLE hFind - Filehandle previously allocated by IFilesystem::FindFirstFile

Output

None

Appendix: The header IFilesystem.h

#ifndef IFILESYSTEM_H
#define IFILESYSTEM_H

typedef unsigned char __u8;
typedef unsigned short __u16;
typedef unsigned long __u32;

typedef char __s8;
typedef short __s16;
typedef long __s32;


#define UNIX_FILENAME_LENGTH 255

struct UNIX_FILEINFO
{
	__u16	i_mode;		/* File mode (permissions)*/
	__u16	i_uid;		/* Low 16 bits of Owner Uid */
	__u16	i_gid;		/* Low 16 bits of Group Id */
	__u32	i_size;		/* Size in bytes */
	__s32	i_atime;	/* Access time */
	__s32	i_ctime;	/* Creation time */
	__s32	i_mtime;	/* Modification time */
	TCHAR szFileName[UNIX_FILENAME_LENGTH];
};

class IFilesystem : public IUnknown
{
public:
	virtual HANDLE OpenFile(LPCTSTR szFilename) const = 0;
	virtual void ReadFile(HANDLE hFile, LPVOID lpBuffer, DWORD NumberOfBytesToRead, DWORD& NumberOfBytesRead) const = 0;
	virtual void CloseFile(HANDLE hFile) const = 0;
	
	virtual HANDLE FindFirstFile(LPCTSTR szPath) const = 0;
	virtual bool FindNextFile(HANDLE hFind, UNIX_FILEINFO& FileInfo) const = 0;
	virtual void CloseFind(HANDLE hFind) const = 0;
};

#ifdef __cplusplus
extern "C" {
#endif

typedef void (WINAPI* LPFNFoundPartition)(LPCSTR lpszName);

void WINAPI FS_Autodetect( LPFNFoundPartition lpCallback );
IFilesystem* WINAPI FS_CreateInstance( LPCSTR lpszName );
void WINAPI FS_DestroyInstance( IFilesystem* pFilesystem );

#ifdef __cplusplus
}
#endif

#endif // IFilesystem_H