Tugasan TTM 309

Tugasan 2

INPUT & OUTPUT MANAGEMENT

• Managing input & output in Windows XP involves many operating system componets.
• User-mode processes interact with an enviroment subsystem and not directly with kernel-mode componets.
• The enviroment subsystem pass input & output request to the input & output manager,which interacts with devices drivers to handle such request.
• Sereval device drivers,organized into a driver stack,cooperate to fulfill an input & output request.
• The plug and play manager dynamicaly recognizes when new devices are added to the system and allocates and deallocates resources,such as input & output ports or DMA channels, to them.
• The power manger administers the operating system’s power mangement policy.
• The power policy detemines whether to power down devices to conserve energy or keep them fully powered for high responsiveness.

 Elaborate the concept of buffering 

• Buffer overflow weakness is one of the many disadvantages of this type of security computer
• Buffer overflow attacks occur when the excessive Attacker provide input on the plan on the run
• Buffee overflow results from the weakness of the programming language c, c + +, fortran, and assembly, which does not automatically check the limit input when the program is executed
• The program is so complex, sehinnga programmers themselves do not know the weaknesses of the program
• Relies on external data to control the program
• Buffer is provided at the memory allocation, such as arrays or pointers in C. in the language C and C + +, there is no automatic restrictions on buffernya, where users can write through the input buffer. For example:

int main () {
int buffer [10];
buffer [20] = 10;
}

• Program in C above is a valid program, and each compiler to compile without error
• A process is a program in execution.

Recognize spooling technique

• In computer science, spooling refers to a process of transferring data by placing it in a temporary working area where another program may access it for processing at a later point in time.
• The normal English verb "spool" can refer to the action of a storage device that incorporates a physical spool or reel, such as a tape drive.
• Spooling refers to copying files in parallel with other work.
• The most common use is in reading files used by a job into or writing them from a buffer on a magnetic tape or a disk.
• Spooling is useful because devices access data at different rates. The buffer provides a waiting station where data can rest while the slower device catches up.
• This temporary working area would normally be a file or storage device.
• The most common spooling application is print spooling: documents formatted for printing are stored onto a buffer (usually an area on a disk) by a fast processor and retrieved and printed by a relatively slower printer at its own rate.
• Spooler or print management software may allow priorities to be assigned to jobs, notify users when they have printed, distribute jobs among several printers, allow stationery to be changed or select it automatically, generate banner pages to identify and separate print jobs, etc.

• The temporary storage area to which E-mail is delivered by a Mail Transfer Agent and in which it waits to be picked up by a Mail User Agent is sometimes called a mail spool.

Tugasan 3..

Also referred to as simply a file system or file system.

• The system that an operating system or program uses to organize and keep track of files.
• For example, a hierarchical file system is one that uses directories to organize files into a tree structure.
• Although the operating system provides its own file management system, you can buy separate file management systems.
• These systems interact smoothly with the operating system but provide more features, such as improved backup procedures and stricter file protection.
File Sharing

• Sharing of files on multi-user systems is desirable
• Sharing may be done through a protection scheme
• On distributed systems, files may be shared across a network
• Network File System (NFS) is a common distributed file-sharing method

Directory Structure

• A collection of nodes containing information about all files.
• Both the directory structure and the files reside on disk.
• Backups of these two structures are kept on tapes

File Mapping

• File mapping is the association of a file's contents with a portion of the virtual address space of a process.
• The system creates a file mapping object (also known as a section object) to maintain this association.
• A file view is the portion of virtual address space that a process uses to access the file's contents.
• File mapping allows the process to use both random input and output (I/O) and sequential I/O.
• It also allows the process to work efficiently with a large data file, such as a database, without having to map the whole file into memory.
• Multiple processes can also use memory-mapped files to share data.
• Processes read from and write to the file view using pointers, just as they would with dynamically allocated memory.
• The use of file mapping improves efficiency because the file resides on disk, but the file view resides in memory.
• Processes can also manipulate the file view with the Virtual Protect function.