Editing Binary File Descriptor library (section)

== Design ==

BFD works by presenting a common abstract view of object files. An object file has a "header" with descriptive info; a variable number of "sections" that each has a name, some attributes, and a block of data; a [[symbol table]]; [[Relocation (computer science)|relocation]] entries; and so forth.

Internally, BFD translates the data from the abstract view into the details of the  bit/byte layout required by the target [[Central processing unit|processor]] and file format. Its key services include handling [[byte order]] differences, such as between a [[little-endian]] host and [[big-endian]] target, correct conversion between [[32-bit]] and [[64-bit]] data, and details of [[Memory address|address]] arithmetic specified by relocation entries.

BFD<ref>[https://ftp.gnu.org/old-gnu/Manuals/bfd-2.9.1/html_chapter/bfd_1.html BFD specification]</ref> library can be logically divided into two parts. The front-end and the back-end. The front-end gives a common interface independent of underlying object file view. Users will be interacting with the object files with this interface. Even if the layout of the object files are not known to the user, the user would still be able to use the interface. This hiding of the detail is done with the help of the back-end. The back-end implements how the front-end interface interacts with the object files layout. Whenever a new object files type is introduced the back-end needs to register the type and implement it if it needs to be supported by the BFD application.

Although BFD was originally designed to be a generic library usable by a wide variety of tools, the frequent need to tinker with the API to accommodate new systems' capabilities has tended to limit its use;<ref>{{cite mailing list |url= http://lists.debian.org/debian-devel/2005/05/msg01086.html |title= Re: depending on shared libbfd from binutils-dev |date= 2005-05-22 |access-date=2011-04-03 |mailing-list= debian-devel |last= Langasek|first= Steve |language= en }}</ref><ref>{{cite mailing list |url= http://lists.fedoraproject.org/pipermail/packaging/2010-June/007154.html |title= binutils once more|date= 2010-06-04 |access-date=2011-04-03 |mailing-list= Fedora-packaging |last= Kuratomi |first= Toshio |language= en }}</ref><ref>{{cite mailing list |url= http://www.sourceware.org/ml/binutils/2003-09/msg00216.html|title= Re: FreeBSD 4.6 - binutils 2.14 installs useless libbfd|date= 2003-09-12|access-date=2011-04-03 |mailing-list= binutils|last= Taylor|first= Ian |language= en }}</ref> BFD's main clients are the [[GNU Assembler]] (GAS), [[GNU Linker]] (GLD),<ref>{{cite web |url=https://sourceware.org/binutils/docs/ld/Overview.html |title=GNU ld manual - 1. Overview |publisher=[[GNU Project]]}} See also: {{cite web |url=https://sourceware.org/binutils/docs/ld/BFD.html |title=GNU ld manual - 7. BFD}}</ref> and other [[GNU Binary Utilities]] ("binutils") tools, and the [[GNU Debugger]] (GDB). As a result, BFD is not distributed separately, but is always included with releases of binutils and GDB. Nevertheless, BFD is a critical component in the use of GNU tools for [[embedded system]]s development.

The BFD library can be used to read the structured data out of a [[core dump]].