Operating System Questions Medium
The file descriptor table is a data structure used by the operating system to manage and keep track of open files in a file system. It serves as a reference table that contains information about each open file, such as its file descriptor number, file position, access mode, and other relevant attributes.
The primary role of the file descriptor table is to provide a level of abstraction between the user and the underlying file system. When a file is opened by a process, the operating system assigns a unique file descriptor number to that file and creates an entry in the file descriptor table. This file descriptor number is then used by the process to perform various operations on the file, such as reading, writing, or seeking.
The file descriptor table allows the operating system to keep track of all open files in the system, ensuring that multiple processes can access the same file simultaneously without conflicts. It also helps in managing system resources efficiently by limiting the number of open files per process and providing a mechanism for releasing file descriptors when a file is closed.
Furthermore, the file descriptor table plays a crucial role in implementing file permissions and access control. Each entry in the table contains information about the access mode of the corresponding file, which determines the operations that can be performed on it. The operating system checks these access permissions before allowing a process to perform any file operation, ensuring data security and preventing unauthorized access.
In summary, the file descriptor table is a vital component of a file system, responsible for managing and organizing open files, providing a level of abstraction, facilitating concurrent access, managing system resources, and enforcing file permissions and access control.