2002-11-16 Klee Dienes <kdienes@apple.com>

[deliverable/binutils-gdb.git] / bfd / doc / bfd.texinfo

\input texinfo.tex
@setfilename bfd.info
@c Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1997, 2000
@c Free Software Foundation, Inc.
@c 
@tex
% NOTE LOCAL KLUGE TO AVOID TOO MUCH WHITESPACE
\global\long\def\example{%
\begingroup
\let\aboveenvbreak=\par
\let\afterenvbreak=\par
\parskip=0pt
\lisp}
\global\long\def\Eexample{%
\Elisp
\endgroup
\vskip -\parskip% to cancel out effect of following \par
}
@end tex
@synindex fn cp

@ifinfo
@format
START-INFO-DIR-ENTRY
* Bfd: (bfd).                   The Binary File Descriptor library.
END-INFO-DIR-ENTRY
@end format
@end ifinfo

@ifinfo
This file documents the BFD library.

Copyright (C) 1991, 2000, 2001 Free Software Foundation, Inc.

      Permission is granted to copy, distribute and/or modify this document
      under the terms of the GNU Free Documentation License, Version 1.1
      or any later version published by the Free Software Foundation;
      with no Invariant Sections, with no Front-Cover Texts, and with no
      Back-Cover Texts.  A copy of the license is included in the
      section entitled "GNU Free Documentation License".

@ignore
Permission is granted to process this file through Tex and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore
@end ifinfo
@iftex
@c@finalout
@setchapternewpage on
@c@setchapternewpage odd
@settitle LIB BFD, the Binary File Descriptor Library
@titlepage
@title{libbfd}
@subtitle{The Binary File Descriptor Library}
@sp 1
@subtitle First Edition---BFD version < 3.0  % Since no product is stable berfore version 3.0 :-)
@subtitle Original Document Created: April 1991
@author {Steve Chamberlain}
@author {Cygnus Support}
@page

@tex
\def\$#1${{#1}}  % Kluge: collect RCS revision info without $...$
\xdef\manvers{\1.5}  % For use in headers, footers too
{\parskip=0pt
\hfill Free Software Foundation\par
\hfill sac\@www.gnu.org\par
\hfill {\it BFD}, \manvers\par
\hfill \TeX{}info \texinfoversion\par
}
\global\parindent=0pt % Steve likes it this way
@end tex

@vskip 0pt plus 1filll
Copyright @copyright{} 1991, 2001 Free Software Foundation, Inc.

      Permission is granted to copy, distribute and/or modify this document
      under the terms of the GNU Free Documentation License, Version 1.1
      or any later version published by the Free Software Foundation;
      with no Invariant Sections, with no Front-Cover Texts, and with no
      Back-Cover Texts.  A copy of the license is included in the
      section entitled "GNU Free Documentation License".

@end titlepage
@end iftex

@node Top, Overview, (dir), (dir)
@ifinfo
This file documents the binary file descriptor library libbfd.
@end ifinfo

@menu
* Overview::			Overview of BFD
* BFD front end::		BFD front end
* BFD back ends::		BFD back ends
* GNU Free Documentation License::  GNU Free Documentation License
* Index::			Index
@end menu

@node Overview, BFD front end, Top, Top
@chapter Introduction
@cindex BFD
@cindex what is it?
BFD is a package which allows applications to use the
same routines to operate on object files whatever the object file
format.  A new object file format can be supported simply by
creating a new BFD back end and adding it to the library.

BFD is split into two parts: the front end, and the back ends (one for
each object file format).
@itemize @bullet
@item The front end of BFD provides the interface to the user. It manages
memory and various canonical data structures. The front end also
decides which back end to use and when to call back end routines.
@item The back ends provide BFD its view of the real world. Each back
end provides a set of calls which the BFD front end can use to maintain
its canonical form. The back ends also may keep around information for
their own use, for greater efficiency.
@end itemize
@menu
* History::			History
* How It Works::		How It Works
* What BFD Version 2 Can Do::	What BFD Version 2 Can Do
@end menu

@node History, How It Works, Overview, Overview
@section History

One spur behind BFD was the desire, on the part of the GNU 960 team at
Intel Oregon, for interoperability of applications on their COFF and
b.out file formats.  Cygnus was providing GNU support for the team, and
was contracted to provide the required functionality.

The name came from a conversation David Wallace was having with Richard
Stallman about the library: RMS said that it would be quite hard---David
said ``BFD''.  Stallman was right, but the name stuck.

At the same time, Ready Systems wanted much the same thing, but for
different object file formats: IEEE-695, Oasys, Srecords, a.out and 68k
coff.

BFD was first implemented by members of Cygnus Support; Steve
Chamberlain (@code{sac@@cygnus.com}), John Gilmore
(@code{gnu@@cygnus.com}), K.  Richard Pixley (@code{rich@@cygnus.com})
and David Henkel-Wallace (@code{gumby@@cygnus.com}).



@node How It Works, What BFD Version 2 Can Do, History, Overview
@section How To Use BFD

To use the library, include @file{bfd.h} and link with @file{libbfd.a}.	

BFD provides a common interface to the parts of an object file
for a calling application. 

When an application sucessfully opens a target file (object, archive, or
whatever), a pointer to an internal structure is returned. This pointer
points to a structure called @code{bfd}, described in
@file{bfd.h}.  Our convention is to call this pointer a BFD, and
instances of it within code @code{abfd}.  All operations on
the target object file are applied as methods to the BFD.  The mapping is
defined within @code{bfd.h} in a set of macros, all beginning
with @samp{bfd_} to reduce namespace pollution.

For example, this sequence does what you would probably expect:
return the number of sections in an object file attached to a BFD
@code{abfd}. 

@lisp
@c @cartouche
#include "bfd.h"

unsigned int number_of_sections(abfd)
bfd *abfd;
@{
  return bfd_count_sections(abfd);
@}
@c @end cartouche
@end lisp

The abstraction used within BFD is that an object file has:

@itemize @bullet
@item
a header,
@item
a number of sections containing raw data (@pxref{Sections}),
@item
a set of relocations (@pxref{Relocations}), and
@item
some symbol information (@pxref{Symbols}).
@end itemize
@noindent
Also, BFDs opened for archives have the additional attribute of an index
and contain subordinate BFDs. This approach is fine for a.out and coff,
but loses efficiency when applied to formats such as S-records and
IEEE-695.

@node What BFD Version 2 Can Do,  , How It Works, Overview
@section What BFD Version 2 Can Do
@include bfdsumm.texi

@node BFD front end, BFD back ends, Overview, Top
@chapter BFD front end
@include bfdt.texi
@include bfdio.texi

@menu
* Memory Usage::
* Initialization::
* Sections::
* Symbols::
* Archives::
* Formats::
* Relocations::
* Core Files::
* Targets::
* Architectures::
* Opening and Closing::
* Internal::
* File Caching::
* Linker Functions::
* Hash Tables::
@end menu

@node Memory Usage, Initialization, BFD front end, BFD front end
@section Memory usage
BFD keeps all of its internal structures in obstacks. There is one obstack
per open BFD file, into which the current state is stored. When a BFD is
closed, the obstack is deleted, and so everything which has been
allocated by BFD for the closing file is thrown away.

BFD does not free anything created by an application, but pointers into
@code{bfd} structures become invalid on a @code{bfd_close}; for example,
after a @code{bfd_close} the vector passed to
@code{bfd_canonicalize_symtab} is still around, since it has been
allocated by the application, but the data that it pointed to are
lost.

The general rule is to not close a BFD until all operations dependent
upon data from the BFD have been completed, or all the data from within
the file has been copied. To help with the management of memory, there
is a function (@code{bfd_alloc_size}) which returns the number of bytes
in obstacks associated with the supplied BFD. This could be used to
select the greediest open BFD, close it to reclaim the memory, perform
some operation and reopen the BFD again, to get a fresh copy of the data
structures.

@node Initialization, Sections, Memory Usage, BFD front end
@include  init.texi

@node Sections, Symbols, Initialization, BFD front end
@include  section.texi

@node Symbols, Archives, Sections, BFD front end
@include  syms.texi

@node Archives, Formats, Symbols, BFD front end
@include  archive.texi

@node Formats, Relocations, Archives, BFD front end
@include  format.texi

@node Relocations, Core Files, Formats, BFD front end
@include  reloc.texi

@node Core Files, Targets, Relocations, BFD front end
@include  core.texi

@node Targets, Architectures, Core Files, BFD front end
@include  targets.texi

@node Architectures, Opening and Closing, Targets, BFD front end
@include  archures.texi

@node Opening and Closing, Internal, Architectures, BFD front end
@include  opncls.texi

@node Internal, File Caching, Opening and Closing, BFD front end
@include  libbfd.texi

@node File Caching, Linker Functions, Internal, BFD front end
@include  cache.texi

@node Linker Functions, Hash Tables, File Caching, BFD front end
@include  linker.texi

@node Hash Tables, , Linker Functions, BFD front end
@include  hash.texi

@node BFD back ends, GNU Free Documentation License, BFD front end, Top
@chapter BFD back ends
@menu
* What to Put Where::
* aout ::	a.out backends
* coff ::	coff backends
* elf  ::	elf backends
* mmo  ::	mmo backend
@ignore
* oasys ::	oasys backends
* ieee ::	ieee backend
* srecord ::	s-record backend
@end ignore
@end menu
@node What to Put Where, aout, BFD back ends, BFD back ends
All of BFD lives in one directory.

@node aout, coff, What to Put Where, BFD back ends
@include  aoutx.texi

@node coff, elf, aout, BFD back ends
@include  coffcode.texi

@node elf, mmo, coff, BFD back ends
@include  elf.texi
@c Leave this out until the file has some actual contents...
@c @include  elfcode.texi

@node mmo,  , elf, BFD back ends
@include  mmo.texi

@node GNU Free Documentation License, Index, BFD back ends, Top
@chapter GNU Free Documentation License
@cindex GNU Free Documentation License

                GNU Free Documentation License
                
                   Version 1.1, March 2000

 Copyright (C) 2000  Free Software Foundation, Inc.
  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.


0. PREAMBLE

The purpose of this License is to make a manual, textbook, or other
written document "free" in the sense of freedom: to assure everyone
the effective freedom to copy and redistribute it, with or without
modifying it, either commercially or noncommercially.  Secondarily,
this License preserves for the author and publisher a way to get
credit for their work, while not being considered responsible for
modifications made by others.

This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.

We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.


1. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work that contains a
notice placed by the copyright holder saying it can be distributed
under the terms of this License.  The "Document", below, refers to any
such manual or work.  Any member of the public is a licensee, and is
addressed as "you".

A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.

A "Secondary Section" is a named appendix or a front-matter section of
the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall subject
(or to related matters) and contains nothing that could fall directly
within that overall subject.  (For example, if the Document is in part a
textbook of mathematics, a Secondary Section may not explain any
mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.

The "Invariant Sections" are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.

The "Cover Texts" are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.

A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, whose contents can be viewed and edited directly and
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup has been designed to thwart or discourage
subsequent modification by readers is not Transparent.  A copy that is
not "Transparent" is called "Opaque".

Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format, SGML
or XML using a publicly available DTD, and standard-conforming simple
HTML designed for human modification.  Opaque formats include
PostScript, PDF, proprietary formats that can be read and edited only
by proprietary word processors, SGML or XML for which the DTD and/or
processing tools are not generally available, and the
machine-generated HTML produced by some word processors for output
purposes only.

The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, "Title Page" means
the text near the most prominent appearance of the work's title,
preceding the beginning of the body of the text.


2. VERBATIM COPYING

You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and
you may publicly display copies.


3. COPYING IN QUANTITY

If you publish printed copies of the Document numbering more than 100,
and the Document's license notice requires Cover Texts, you must enclose
the copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.

If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a publicly-accessible computer-network location containing a complete
Transparent copy of the Document, free of added material, which the
general network-using public has access to download anonymously at no
charge using public-standard network protocols.  If you use the latter
option, you must take reasonably prudent steps, when you begin
distribution of Opaque copies in quantity, to ensure that this
Transparent copy will remain thus accessible at the stated location
until at least one year after the last time you distribute an Opaque
copy (directly or through your agents or retailers) of that edition to
the public.

It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.


4. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:

A. Use in the Title Page (and on the covers, if any) a title distinct
   from that of the Document, and from those of previous versions
   (which should, if there were any, be listed in the History section
   of the Document).  You may use the same title as a previous version
   if the original publisher of that version gives permission.
B. List on the Title Page, as authors, one or more persons or entities
   responsible for authorship of the modifications in the Modified
   Version, together with at least five of the principal authors of the
   Document (all of its principal authors, if it has less than five).
C. State on the Title page the name of the publisher of the
   Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications
   adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license notice
   giving the public permission to use the Modified Version under the
   terms of this License, in the form shown in the Addendum below.
G. Preserve in that license notice the full lists of Invariant Sections
   and required Cover Texts given in the Document's license notice.
H. Include an unaltered copy of this License.
I. Preserve the section entitled "History", and its title, and add to
   it an item stating at least the title, year, new authors, and
   publisher of the Modified Version as given on the Title Page.  If
   there is no section entitled "History" in the Document, create one
   stating the title, year, authors, and publisher of the Document as
   given on its Title Page, then add an item describing the Modified
   Version as stated in the previous sentence.
J. Preserve the network location, if any, given in the Document for
   public access to a Transparent copy of the Document, and likewise
   the network locations given in the Document for previous versions
   it was based on.  These may be placed in the "History" section.
   You may omit a network location for a work that was published at
   least four years before the Document itself, or if the original
   publisher of the version it refers to gives permission.
K. In any section entitled "Acknowledgements" or "Dedications",
   preserve the section's title, and preserve in the section all the
   substance and tone of each of the contributor acknowledgements
   and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document,
   unaltered in their text and in their titles.  Section numbers
   or the equivalent are not considered part of the section titles.
M. Delete any section entitled "Endorsements".  Such a section
   may not be included in the Modified Version.
N. Do not retitle any existing section as "Endorsements"
   or to conflict in title with any Invariant Section.

If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version's license notice.
These titles must be distinct from any other section titles.

You may add a section entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.

You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version.  Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity.  If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.


5. COMBINING DOCUMENTS

You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice.

The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy.  If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections entitled "History"
in the various original documents, forming one section entitled
"History"; likewise combine any sections entitled "Acknowledgements",
and any sections entitled "Dedications".  You must delete all sections
entitled "Endorsements."


6. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in
the collection, provided that you follow the rules of this License for
verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute
it individually under this License, provided you insert a copy of this
License into the extracted document, and follow this License in all
other respects regarding verbatim copying of that document.


7. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, does not as a whole count as a Modified Version
of the Document, provided no compilation copyright is claimed for the
compilation.  Such a compilation is called an "aggregate", and this
License does not apply to the other self-contained works thus compiled
with the Document, on account of their being thus compiled, if they
are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one quarter
of the entire aggregate, the Document's Cover Texts may be placed on
covers that surround only the Document within the aggregate.
Otherwise they must appear on covers around the whole aggregate.


8. TRANSLATION

Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections.  You may include a
translation of this License provided that you also include the
original English version of this License.  In case of a disagreement
between the translation and the original English version of this
License, the original English version will prevail.


9. TERMINATION

You may not copy, modify, sublicense, or distribute the Document except
as expressly provided for under this License.  Any other attempt to
copy, modify, sublicense or distribute the Document is void, and will
automatically terminate your rights under this License.  However,
parties who have received copies, or rights, from you under this
License will not have their licenses terminated so long as such
parties remain in full compliance.


10. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time.  Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.  See
http://www.gnu.org/copyleft/.

Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License "or any later version" applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation.  If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation.


ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:

@smallexample
    Copyright (c)  YEAR  YOUR NAME.
    Permission is granted to copy, distribute and/or modify this document
    under the terms of the GNU Free Documentation License, Version 1.1
    or any later version published by the Free Software Foundation;
    with the Invariant Sections being LIST THEIR TITLES, with the
    Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
    A copy of the license is included in the section entitled "GNU
    Free Documentation License".
@end smallexample

If you have no Invariant Sections, write "with no Invariant Sections"
instead of saying which ones are invariant.  If you have no
Front-Cover Texts, write "no Front-Cover Texts" instead of
"Front-Cover Texts being LIST"; likewise for Back-Cover Texts.

If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.

@node Index,  , GNU Free Documentation License , Top
@unnumbered Index
@printindex cp

@tex
% I think something like @colophon should be in texinfo.  In the
% meantime:
\long\def\colophon{\hbox to0pt{}\vfill
\centerline{The body of this manual is set in}
\centerline{\fontname\tenrm,}
\centerline{with headings in {\bf\fontname\tenbf}}
\centerline{and examples in {\tt\fontname\tentt}.}
\centerline{{\it\fontname\tenit\/} and}
\centerline{{\sl\fontname\tensl\/}}
\centerline{are used for emphasis.}\vfill}
\page\colophon
% Blame: doc@cygnus.com, 28mar91.
@end tex

@contents
@bye