Category:Special-purpose file systems
This category has the following 5 subcategories, out of 5 total.
This category has the following 5 subcategories, out of 5 total.
1. Device file – In Unix-like operating systems, a device file or special file is an interface for a device driver that appears in a file system as if it were an ordinary file. There are also special files in MS-DOS, OS/2, and Microsoft Windows and they allow software to interact with a device driver using standard input/output system calls, which simplifies many tasks and unifies user-space I/O mechanisms. Device files often provide simple interfaces to peripheral devices such as printers and serial ports, finally, device files are useful for accessing system resources that have no connection with any actual device such as data sinks and random number generators. MS-DOS borrowed the concept of files from Unix but renamed them devices. Because early versions of MS-DOS did not support a directory hierarchy and this means that certain file names were reserved for devices, and should not be used to name new files or directories. The reserved names themselves were chosen to be compatible with special handling of PIP command in CP/M. There were two kinds of devices in MS-DOS, Block Devices and Character Devices, PIPE, MAILSLOT, and MUP are other standard Windows devices. There are two kinds of device files in Unix-like operating systems, known as character special files. The difference between them lies in how data written to them and read them is processed by the operating system. These together can be called device files in contrast to named pipes. Device nodes correspond to resources that an operating systems kernel has already allocated, Unix identifies those resources by a major number and a minor number, both stored as part of the structure of a node. The assignment of numbers occurs uniquely in different operating systems. Generally, the major number identifies the driver and the minor number identifies a particular device that the driver controls, in this case. However, in the presence of number allocation, this may not be the case. As with other file types, the computer system accesses device nodes using standard system calls. Character special files or character devices provide unbuffered, direct access to the hardware device and they do not necessarily allow programs to read or write single characters at a time, that is up to the device in question. The character device for a disk, for example, will normally require that all reads and writes are aligned to block boundaries. Block special files or block devices provide buffered access to hardware devices, unlike character devices, block devices will always allow the programmer to read or write a block of any size and any alignment
2. Encrypting File System – The Encrypting File System on Microsoft Windows is a feature introduced in version 3.0 of NTFS that provides filesystem-level encryption. The technology enables files to be encrypted to protect confidential data from attackers with physical access to the computer. EFS is available in all versions of Windows developed for environments from Windows 2000 onwards. By default, no files are encrypted, but encryption can be enabled by users on a per-file, per-directory, some EFS settings can also be mandated via Group Policy in Windows domain environments. Cryptographic file system implementations for other operating systems are available, see also the list of cryptographic file systems. When an operating system is running on a system without file encryption, access to files normally goes through OS-controlled user authentication, however, if an attacker gains physical access to the computer, this barrier can be easily circumvented. The most widely accepted solution to this is to store the files encrypted on the physical media, however, the cryptography keys for EFS are in practice protected by the user account password, and are therefore susceptible to most password attacks. In other words, the encryption of a file is only as strong as the password to unlock the decryption key, EFS works by encrypting a file with a bulk symmetric key, also known as the File Encryption Key, or FEK. It uses an encryption algorithm because it takes less time to encrypt and decrypt large amounts of data than if an asymmetric key cipher is used. The symmetric encryption algorithm used will vary depending on the version and configuration of the operating system, see Algorithms used by Windows version below. The FEK is then encrypted with a key that is associated with the user who encrypted the file. To decrypt the file, the EFS component driver uses the key that matches the EFS digital certificate to decrypt the symmetric key that is stored in the $EFS stream. The EFS component driver uses the symmetric key to decrypt the file. Because the encryption & decryption operations are performed at a layer below NTFS, it is transparent to the user, folders whose contents are to be encrypted by the file system are marked with an encryption attribute. When encrypted files are moved within an NTFS volume, the files remain encrypted, however, there are a number of occasions in which the file could be decrypted without the user explicitly asking Windows to do so. Files and folders are decrypted before being copied to a formatted with another file system. Finally, when encrypted files are copied over the network using the SMB/CIFS protocol, the most significant way of preventing the decryption-on-copy is using backup applications that are aware of the Raw APIs. Backup applications that have implemented these Raw APIs will simply copy the encrypted file stream, in other words, the files are copied in encrypted form, and are not decrypted during backup
3. WBFS – WBFS, or Wii Backup File System, is a file system developed by Wii homebrew coder Waninkoko. It uses Waninkokos cIOS and works by creating a WBFS partition on a SD or USB device, a Wii homebrew application may then be run to dump a Wii game to the partition. The titles may then be launched using a Wii USB loader, although there is no way to natively load a WBFS partition in a PC environment, they can be run in a Wii emulator, such as Dolphin. There are also several applications, such as WBFS managers, that allow the transfer of ISO image files to a WBFS formatted drive. This can allow some smaller games to go from a 4.7 GB ISO file to less than a hundred megabytes as any unused space on the disk will be filled by this padding data