Concept

Handle (computing)

In computer programming, a handle is an abstract reference to a resource that is used when application software references blocks of memory or objects that are managed by another system like a database or an operating system. A resource handle can be an opaque identifier, in which case it is often an integer number (often an array index in an array or "table" that is used to manage that type of resource), or it can be a pointer that allows access to further information. Common resource handles include s, network sockets, database connections, process identifiers (PIDs), and job IDs. PIDs and job IDs are explicitly visible integers; while file descriptors and sockets (which are often implemented as a form of file descriptor) are represented as integers, they are typically considered opaque. In traditional implementations, file descriptors are indices into a (per-process) , thence a (system-wide) . While a pointer contains the address of the item to which it refers, a handle is an abstraction of a reference which is managed externally; its opacity allows the referent to be relocated in memory by the system without invalidating the handle, which is impossible with pointers. The extra layer of indirection also increases the control that the managing system has over the operations performed on the referent. Typically the handle is an index or a pointer into a global array of tombstones. A handle leak is a type of software bug that occurs when a computer program asks for a handle to a resource but does not free the handle when it is no longer used; this is a form of resource leak, similar to a memory leak for a pointer to memory. In secure computing terms, because access to a resource via a handle is mediated by another system, a handle functions as a capability: it not only identifies an object, but also associates access rights. For example, while a filename is forgeable (it is just a guessable identifier), a handle is given to a user by an external system, and thus represents not just identity, but also granted access.

Official source

https://en.wikipedia.org/wiki/Handle_(computing)

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related courses (1)

MATH-661: Advanced Scientific Programming in Python

This seminar teaches the participants to use advanced Python concepts for writing easier to read, more flexible and faster code. It teaches concepts in a hands-on and tangible fashion, providing examp

Related publications (1)

Compilation Techniques for Incremental Collection Processing

Many map-reduce frameworks as well as NoSQL systems rely on collection programming as their interface of choice due to its rich semantics along with an easily parallelizable set of primitives. Unfortunately, the potential of collection programming is not ...

EPFL2017

Related concepts (5)

In computer programming, an opaque pointer is a special case of an opaque data type, a data type declared to be a pointer to a record or data structure of some unspecified type. Opaque pointers are present in several programming languages including Ada, C, C++, D and Modula-2. If the language is strongly typed, programs and procedures that have no other information about an opaque pointer type T can still declare variables, arrays, and record fields of type T, assign values of that type, and compare those values for equality.

C file input/output

The C programming language provides many standard library functions for input and output. These functions make up the bulk of the C standard library . The functionality descends from a "portable I/O package" written by Mike Lesk at Bell Labs in the early 1970s, and officially became part of the Unix operating system in Version 7. The I/O functionality of C is fairly low-level by modern standards; C abstracts all file operations into operations on streams of bytes, which may be "input streams" or "output streams".

Reference (computer science)

In computer programming, a reference is a value that enables a program to indirectly access a particular data, such as a variable's value or a record, in the computer's memory or in some other storage device. The reference is said to refer to the datum, and accessing the datum is called dereferencing the reference. A reference is distinct from the datum itself. A reference is an abstract data type and may be implemented in many ways. Typically, a reference refers to data stored in memory on a given system, and its internal value is the memory address of the data, i.