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Hooking
In computer programming, the term hooking covers a range of techniques used to alter or augment the behaviour of an operating system, of applications, or of other software components by intercepting function calls or messages or events passed between software components. Code that handles such intercepted function calls, events or messages is called a hook. Hooking is used for many purposes, including debugging and extending functionality. Examples might include intercepting keyboard or mouse event messages before they reach an application, or intercepting operating system calls in order to monitor behavior or modify the function of an application or other component. It is also widely used in benchmarking programs, for example frame rate measuring in 3D games, where the output and input is done through hooking. Hooking can also be used by malicious code. For example, rootkits, pieces of software that try to make themselves invisible by faking the output of API calls that woul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms (usually in a chosen programming language, commonly referred to as coding). The source code of a program is written in one or more languages that are intelligible to programmers, rather than machine code, which is directly executed by the central processing unit. The purpose of programming is to find a sequence of instructions that will automate the performance of a task (which can be as complex as an operating system) on a computer, often for solving a given problem. Proficient programming thus usually requires expertise in several different subjects, including knowledge of the application domain, specialized algorit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrapper Library
Wrapper libraries (or library wrappers) consist of a thin layer of code (a "shim") which translates a library's existing interface into a compatible interface. This is done for several reasons: * To refine a poorly designed or complicated interface * Allow code to work together which otherwise cannot (e.g. incompatible data formats) * Enable cross language and/or runtime interoperability Wrapper libraries can be implemented using the adapter, façade, and to a lesser extent, proxy design patterns. Structure and implementation The specific way in which a wrapper library is implemented is highly specific to the environment it is being written in and the scenarios which it intends to address. This is especially true in the case when cross language/runtime interoperability is a consideration. Example The following provides a general illustration of a common wrapper library implementation. In this example, a C++ interface acts as a "wrapper" around a C-language interface. C in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Executable
In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instructions", as opposed to a data file that must be interpreted ( parsed) by a program to be meaningful. The exact interpretation depends upon the use. "Instructions" is traditionally taken to mean machine code instructions for a physical CPU. In some contexts, a file containing scripting instructions (such as bytecode) may also be considered executable. Generation of executable files Executable files can be hand-coded in machine language, although it is far more convenient to develop software as source code in a high-level language that can be easily understood by humans. In some cases, source code might be specified in assembly language instead, which remains human-readable while being closely associated with machine code instructions. The high-level language is comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt Vector
An interrupt vector table (IVT) is a data structure that associates a list of interrupt handlers with a list of interrupt requests in a table of interrupt vectors. Each entry of the interrupt vector table, called an interrupt vector, is the address of an interrupt handler. While the concept is common across processor architectures, IVTs may be implemented in architecture-specific fashions. For example, a dispatch table is one method of implementing an interrupt vector table. Background Most processors have an interrupt vector table, including chips from Intel, AMD, Infineon, Microchip Atmel, NXP, ARM etc. Interrupt handlers Handling methods An interrupt vector table is used in the three most popular methods of finding the starting address of the interrupt service routine: "Predefined" The "predefined" method loads the program counter (PC) directly with the address of some entry inside the interrupt vector table. The jump table itself contains executable code. While in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shared Library
In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and subroutines, classes, values or type specifications. In IBM's OS/360 and its successors they are referred to as partitioned data sets. A library is also a collection of implementations of behavior, written in terms of a language, that has a well-defined interface by which the behavior is invoked. For instance, people who want to write a higher-level program can use a library to make system calls instead of implementing those system calls over and over again. In addition, the behavior is provided for reuse by multiple independent programs. A program invokes the library-provided behavior via a mechanism of the language. For example, in a simple imperative language such as C, the behavior in a library is invoked by using C's normal functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NetFilter
Netfilter is a framework provided by the Linux kernel that allows various networking-related operations to be implemented in the form of customized handlers. Netfilter offers various functions and operations for packet filtering, network address translation, and port translation, which provide the functionality required for directing packets through a network and prohibiting packets from reaching sensitive locations within a network. Netfilter represents a set of hooks inside the Linux kernel, allowing specific kernel modules to register callback functions with the kernel's networking stack. Those functions, usually applied to the traffic in the form of filtering and modification rules, are called for every packet that traverses the respective hook within the networking stack. History Rusty Russell started the ''netfilter/iptables project'' in 1998; he had also authored the project's predecessor, ipchains. As the project grew, he founded the ''Netfilter Core Team'' (or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (operating System)
The kernel is a computer program at the core of a computer's operating system and generally has complete control over everything in the system. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the utilization of common resources e.g. CPU & cache usage, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usually loaded into a separate area of memory, which is protected from access by applicatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mouse (computing)
A computer mouse (plural mice, sometimes mouses) is a hand-held pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface of a computer. The first public demonstration of a mouse controlling a computer system was in 1968. Mice originally used two separate wheels to track movement across a surface: one in the X-dimension and one in the Y. Later, the standard design shifted to utilize a ball rolling on a surface to detect motion. Most modern mice use optical sensors that have no moving parts. Though originally all mice were connected to a computer by a cable, many modern mice are cordless, relying on short-range radio communication with the connected system. In addition to moving a cursor, computer mice have one or more buttons to allow operations such as the selection of a menu item on a display. Mice often also feat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keyboard (computing)
A computer keyboard is a peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or keys to act as mechanical levers or electronic switches. Replacing early punched cards and paper tape technology, interaction via teleprinter-style keyboards have been the main input method for computers since the 1970s, supplemented by the computer mouse since the 1980s. Keyboard keys (buttons) typically have a set of characters engraved or printed on them, and each press of a key typically corresponds to a single written symbol. However, producing some symbols may require pressing and holding several keys simultaneously or in sequence. While most keys produce characters (letters, numbers or symbols), other keys (such as the escape key) can prompt the computer to execute system commands. In a modern computer, the interpretation of key presses is generally left to the software: the information sent to the computer, the scan code, tells it only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menu (computing)
In user interface design, a menu is a list of options or commands presented to the user of a computer or embedded system. A menu may either be a system's entire user interface, or only part of a more complex one. Navigation A user chooses an option from a menu by using an input device. Some input methods require linear navigation: the user must move a cursor or otherwise pass from one menu item to another until reaching the selection. On a computer terminal, a reverse video bar may serve as the cursor. Touch user interfaces and menus that accept codes to select menu options without navigation are two examples of non-linear interfaces. Some of the input devices used in menu interfaces are touchscreens, keyboards, mice, remote controls, and microphones. In a voice-activated system, such as interactive voice response, a microphone sends a recording of the user's voice to a speech recognition system, which translates it to a command. Types of menus A computer using a com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scrollbar
A scrollbar is an interaction technique or widget (GUI), widget in which continuous text, pictures, or any other content can be Scrolling, scrolled in a predetermined direction (up, down, left, or right) on a computer display, window (computing), window, or viewport so that all of the content can be viewed, even if only a fraction of the content can be seen on a device's screen at one time. It offers a solution to the problem of Web navigation, navigation to a known or unknown location within a two-dimensional information space. It was also known as a handle in the very first GUIs. They are present in a wide range of electronic devices including computers, graphing calculators, mobile phones, and portable media players. The user interacts with the scrollbar elements using some method of direct action, the scrollbar translates that action into scrolling commands, and the user receives feedback through a visual updating of both the scrollbar elements and the scrolled content. Althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dialog Box
The dialog box (also called dialogue box (non-U.S. English), message box or simply dialog) is a graphical control element in the form of a small window that communicates information to the user and prompts them for a response. Dialog boxes are classified as " modal" or "modeless", depending on whether they block interaction with the software that initiated the dialog. The type of dialog box displayed is dependent upon the desired user interaction. The simplest type of dialog box is the alert, which displays a message and may require an acknowledgment that the message has been read, usually by clicking "OK", or a decision as to whether or not an action should proceed, by clicking "OK" or "Cancel". Alerts are also used to display a "termination notice"—sometimes requesting confirmation that the notice has been read—in the event of either an intentional closing or unintentional closing (" crash") of an application or the operating system. (E.g., "Gedit has encounte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
