| 1 | \input texinfo.tex |
| 2 | @setfilename bfd.info |
| 3 | @c Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1997, 2000, |
| 4 | @c 2001, 2002, 2003, 2006, 2007, 2008, 2009, 2013 |
| 5 | @c Free Software Foundation, Inc. |
| 6 | @c |
| 7 | @synindex fn cp |
| 8 | |
| 9 | @ifnottex |
| 10 | @dircategory Software development |
| 11 | @direntry |
| 12 | * Bfd: (bfd). The Binary File Descriptor library. |
| 13 | @end direntry |
| 14 | @end ifnottex |
| 15 | |
| 16 | @copying |
| 17 | This file documents the BFD library. |
| 18 | |
| 19 | Copyright @copyright{} 1991, 2000, 2001, 2003, 2006, 2007, 2008, 2013 |
| 20 | Free Software Foundation, Inc. |
| 21 | |
| 22 | Permission is granted to copy, distribute and/or modify this document |
| 23 | under the terms of the GNU Free Documentation License, Version 1.3 or |
| 24 | any later version published by the Free Software Foundation; with the |
| 25 | Invariant Sections being ``GNU General Public License'' and ``Funding |
| 26 | Free Software'', the Front-Cover texts being (a) (see below), and with |
| 27 | the Back-Cover Texts being (b) (see below). A copy of the license is |
| 28 | included in the section entitled ``GNU Free Documentation License''. |
| 29 | |
| 30 | (a) The FSF's Front-Cover Text is: |
| 31 | |
| 32 | A GNU Manual |
| 33 | |
| 34 | (b) The FSF's Back-Cover Text is: |
| 35 | |
| 36 | You have freedom to copy and modify this GNU Manual, like GNU |
| 37 | software. Copies published by the Free Software Foundation raise |
| 38 | funds for GNU development. |
| 39 | @end copying |
| 40 | @iftex |
| 41 | @c@finalout |
| 42 | @setchapternewpage on |
| 43 | @c@setchapternewpage odd |
| 44 | @settitle LIB BFD, the Binary File Descriptor Library |
| 45 | @titlepage |
| 46 | @title{libbfd} |
| 47 | @subtitle{The Binary File Descriptor Library} |
| 48 | @sp 1 |
| 49 | @subtitle First Edition---BFD version < 3.0 % Since no product is stable before version 3.0 :-) |
| 50 | @subtitle Original Document Created: April 1991 |
| 51 | @author {Steve Chamberlain} |
| 52 | @author {Cygnus Support} |
| 53 | @page |
| 54 | |
| 55 | @tex |
| 56 | \def\$#1${{#1}} % Kluge: collect RCS revision info without $...$ |
| 57 | \xdef\manvers{1.5} % For use in headers, footers too |
| 58 | {\parskip=0pt |
| 59 | \hfill Free Software Foundation\par |
| 60 | \hfill sac\@www.gnu.org\par |
| 61 | \hfill {\it BFD}, \manvers\par |
| 62 | \hfill \TeX{}info \texinfoversion\par |
| 63 | } |
| 64 | \global\parindent=0pt % Steve likes it this way |
| 65 | @end tex |
| 66 | |
| 67 | @vskip 0pt plus 1filll |
| 68 | Copyright @copyright{} 1991, 2001, 2003, 2006, 2008, 2013 |
| 69 | Free Software Foundation, Inc. |
| 70 | |
| 71 | Permission is granted to copy, distribute and/or modify this document |
| 72 | under the terms of the GNU Free Documentation License, Version 1.3 |
| 73 | or any later version published by the Free Software Foundation; |
| 74 | with no Invariant Sections, with no Front-Cover Texts, and with no |
| 75 | Back-Cover Texts. A copy of the license is included in the |
| 76 | section entitled ``GNU Free Documentation License''. |
| 77 | |
| 78 | @end titlepage |
| 79 | @end iftex |
| 80 | @contents |
| 81 | |
| 82 | @node Top, Overview, (dir), (dir) |
| 83 | @ifinfo |
| 84 | This file documents the binary file descriptor library libbfd. |
| 85 | @end ifinfo |
| 86 | |
| 87 | @menu |
| 88 | * Overview:: Overview of BFD |
| 89 | * BFD front end:: BFD front end |
| 90 | * BFD back ends:: BFD back ends |
| 91 | * GNU Free Documentation License:: GNU Free Documentation License |
| 92 | * BFD Index:: BFD Index |
| 93 | @end menu |
| 94 | |
| 95 | @node Overview, BFD front end, Top, Top |
| 96 | @chapter Introduction |
| 97 | @cindex BFD |
| 98 | @cindex what is it? |
| 99 | BFD is a package which allows applications to use the |
| 100 | same routines to operate on object files whatever the object file |
| 101 | format. A new object file format can be supported simply by |
| 102 | creating a new BFD back end and adding it to the library. |
| 103 | |
| 104 | BFD is split into two parts: the front end, and the back ends (one for |
| 105 | each object file format). |
| 106 | @itemize @bullet |
| 107 | @item The front end of BFD provides the interface to the user. It manages |
| 108 | memory and various canonical data structures. The front end also |
| 109 | decides which back end to use and when to call back end routines. |
| 110 | @item The back ends provide BFD its view of the real world. Each back |
| 111 | end provides a set of calls which the BFD front end can use to maintain |
| 112 | its canonical form. The back ends also may keep around information for |
| 113 | their own use, for greater efficiency. |
| 114 | @end itemize |
| 115 | @menu |
| 116 | * History:: History |
| 117 | * How It Works:: How It Works |
| 118 | * What BFD Version 2 Can Do:: What BFD Version 2 Can Do |
| 119 | @end menu |
| 120 | |
| 121 | @node History, How It Works, Overview, Overview |
| 122 | @section History |
| 123 | |
| 124 | One spur behind BFD was the desire, on the part of the GNU 960 team at |
| 125 | Intel Oregon, for interoperability of applications on their COFF and |
| 126 | b.out file formats. Cygnus was providing GNU support for the team, and |
| 127 | was contracted to provide the required functionality. |
| 128 | |
| 129 | The name came from a conversation David Wallace was having with Richard |
| 130 | Stallman about the library: RMS said that it would be quite hard---David |
| 131 | said ``BFD''. Stallman was right, but the name stuck. |
| 132 | |
| 133 | At the same time, Ready Systems wanted much the same thing, but for |
| 134 | different object file formats: IEEE-695, Oasys, Srecords, a.out and 68k |
| 135 | coff. |
| 136 | |
| 137 | BFD was first implemented by members of Cygnus Support; Steve |
| 138 | Chamberlain (@code{sac@@cygnus.com}), John Gilmore |
| 139 | (@code{gnu@@cygnus.com}), K. Richard Pixley (@code{rich@@cygnus.com}) |
| 140 | and David Henkel-Wallace (@code{gumby@@cygnus.com}). |
| 141 | |
| 142 | |
| 143 | |
| 144 | @node How It Works, What BFD Version 2 Can Do, History, Overview |
| 145 | @section How To Use BFD |
| 146 | |
| 147 | To use the library, include @file{bfd.h} and link with @file{libbfd.a}. |
| 148 | |
| 149 | BFD provides a common interface to the parts of an object file |
| 150 | for a calling application. |
| 151 | |
| 152 | When an application successfully opens a target file (object, archive, or |
| 153 | whatever), a pointer to an internal structure is returned. This pointer |
| 154 | points to a structure called @code{bfd}, described in |
| 155 | @file{bfd.h}. Our convention is to call this pointer a BFD, and |
| 156 | instances of it within code @code{abfd}. All operations on |
| 157 | the target object file are applied as methods to the BFD. The mapping is |
| 158 | defined within @code{bfd.h} in a set of macros, all beginning |
| 159 | with @samp{bfd_} to reduce namespace pollution. |
| 160 | |
| 161 | For example, this sequence does what you would probably expect: |
| 162 | return the number of sections in an object file attached to a BFD |
| 163 | @code{abfd}. |
| 164 | |
| 165 | @example |
| 166 | @c @cartouche |
| 167 | #include "bfd.h" |
| 168 | |
| 169 | unsigned int number_of_sections (abfd) |
| 170 | bfd *abfd; |
| 171 | @{ |
| 172 | return bfd_count_sections (abfd); |
| 173 | @} |
| 174 | @c @end cartouche |
| 175 | @end example |
| 176 | |
| 177 | The abstraction used within BFD is that an object file has: |
| 178 | |
| 179 | @itemize @bullet |
| 180 | @item |
| 181 | a header, |
| 182 | @item |
| 183 | a number of sections containing raw data (@pxref{Sections}), |
| 184 | @item |
| 185 | a set of relocations (@pxref{Relocations}), and |
| 186 | @item |
| 187 | some symbol information (@pxref{Symbols}). |
| 188 | @end itemize |
| 189 | @noindent |
| 190 | Also, BFDs opened for archives have the additional attribute of an index |
| 191 | and contain subordinate BFDs. This approach is fine for a.out and coff, |
| 192 | but loses efficiency when applied to formats such as S-records and |
| 193 | IEEE-695. |
| 194 | |
| 195 | @node What BFD Version 2 Can Do, , How It Works, Overview |
| 196 | @section What BFD Version 2 Can Do |
| 197 | @include bfdsumm.texi |
| 198 | |
| 199 | @node BFD front end, BFD back ends, Overview, Top |
| 200 | @chapter BFD Front End |
| 201 | @include bfdt.texi |
| 202 | @include bfdio.texi |
| 203 | |
| 204 | @menu |
| 205 | * Memory Usage:: |
| 206 | * Initialization:: |
| 207 | * Sections:: |
| 208 | * Symbols:: |
| 209 | * Archives:: |
| 210 | * Formats:: |
| 211 | * Relocations:: |
| 212 | * Core Files:: |
| 213 | * Targets:: |
| 214 | * Architectures:: |
| 215 | * Opening and Closing:: |
| 216 | * Internal:: |
| 217 | * File Caching:: |
| 218 | * Linker Functions:: |
| 219 | * Hash Tables:: |
| 220 | @end menu |
| 221 | |
| 222 | @node Memory Usage, Initialization, BFD front end, BFD front end |
| 223 | @section Memory Usage |
| 224 | BFD keeps all of its internal structures in obstacks. There is one obstack |
| 225 | per open BFD file, into which the current state is stored. When a BFD is |
| 226 | closed, the obstack is deleted, and so everything which has been |
| 227 | allocated by BFD for the closing file is thrown away. |
| 228 | |
| 229 | BFD does not free anything created by an application, but pointers into |
| 230 | @code{bfd} structures become invalid on a @code{bfd_close}; for example, |
| 231 | after a @code{bfd_close} the vector passed to |
| 232 | @code{bfd_canonicalize_symtab} is still around, since it has been |
| 233 | allocated by the application, but the data that it pointed to are |
| 234 | lost. |
| 235 | |
| 236 | The general rule is to not close a BFD until all operations dependent |
| 237 | upon data from the BFD have been completed, or all the data from within |
| 238 | the file has been copied. To help with the management of memory, there |
| 239 | is a function (@code{bfd_alloc_size}) which returns the number of bytes |
| 240 | in obstacks associated with the supplied BFD. This could be used to |
| 241 | select the greediest open BFD, close it to reclaim the memory, perform |
| 242 | some operation and reopen the BFD again, to get a fresh copy of the data |
| 243 | structures. |
| 244 | |
| 245 | @node Initialization, Sections, Memory Usage, BFD front end |
| 246 | @include init.texi |
| 247 | |
| 248 | @node Sections, Symbols, Initialization, BFD front end |
| 249 | @include section.texi |
| 250 | |
| 251 | @node Symbols, Archives, Sections, BFD front end |
| 252 | @include syms.texi |
| 253 | |
| 254 | @node Archives, Formats, Symbols, BFD front end |
| 255 | @include archive.texi |
| 256 | |
| 257 | @node Formats, Relocations, Archives, BFD front end |
| 258 | @include format.texi |
| 259 | |
| 260 | @node Relocations, Core Files, Formats, BFD front end |
| 261 | @include reloc.texi |
| 262 | |
| 263 | @node Core Files, Targets, Relocations, BFD front end |
| 264 | @include core.texi |
| 265 | |
| 266 | @node Targets, Architectures, Core Files, BFD front end |
| 267 | @include targets.texi |
| 268 | |
| 269 | @node Architectures, Opening and Closing, Targets, BFD front end |
| 270 | @include archures.texi |
| 271 | |
| 272 | @node Opening and Closing, Internal, Architectures, BFD front end |
| 273 | @include opncls.texi |
| 274 | |
| 275 | @node Internal, File Caching, Opening and Closing, BFD front end |
| 276 | @include libbfd.texi |
| 277 | |
| 278 | @node File Caching, Linker Functions, Internal, BFD front end |
| 279 | @include cache.texi |
| 280 | |
| 281 | @node Linker Functions, Hash Tables, File Caching, BFD front end |
| 282 | @include linker.texi |
| 283 | |
| 284 | @node Hash Tables, , Linker Functions, BFD front end |
| 285 | @include hash.texi |
| 286 | |
| 287 | @node BFD back ends, GNU Free Documentation License, BFD front end, Top |
| 288 | @chapter BFD back ends |
| 289 | @menu |
| 290 | * What to Put Where:: |
| 291 | * aout :: a.out backends |
| 292 | * coff :: coff backends |
| 293 | * elf :: elf backends |
| 294 | * mmo :: mmo backend |
| 295 | @ignore |
| 296 | * oasys :: oasys backends |
| 297 | * ieee :: ieee backend |
| 298 | * srecord :: s-record backend |
| 299 | @end ignore |
| 300 | @end menu |
| 301 | @node What to Put Where, aout, BFD back ends, BFD back ends |
| 302 | @section What to Put Where |
| 303 | All of BFD lives in one directory. |
| 304 | |
| 305 | @node aout, coff, What to Put Where, BFD back ends |
| 306 | @include aoutx.texi |
| 307 | |
| 308 | @node coff, elf, aout, BFD back ends |
| 309 | @include coffcode.texi |
| 310 | |
| 311 | @node elf, mmo, coff, BFD back ends |
| 312 | @include elf.texi |
| 313 | @c Leave this out until the file has some actual contents... |
| 314 | @c @include elfcode.texi |
| 315 | |
| 316 | @node mmo, , elf, BFD back ends |
| 317 | @include mmo.texi |
| 318 | |
| 319 | @node GNU Free Documentation License, BFD Index, BFD back ends, Top |
| 320 | @include fdl.texi |
| 321 | |
| 322 | @node BFD Index, , GNU Free Documentation License, Top |
| 323 | @unnumbered BFD Index |
| 324 | @printindex cp |
| 325 | |
| 326 | @tex |
| 327 | % I think something like @@colophon should be in texinfo. In the |
| 328 | % meantime: |
| 329 | \long\def\colophon{\hbox to0pt{}\vfill |
| 330 | \centerline{The body of this manual is set in} |
| 331 | \centerline{\fontname\tenrm,} |
| 332 | \centerline{with headings in {\bf\fontname\tenbf}} |
| 333 | \centerline{and examples in {\tt\fontname\tentt}.} |
| 334 | \centerline{{\it\fontname\tenit\/} and} |
| 335 | \centerline{{\sl\fontname\tensl\/}} |
| 336 | \centerline{are used for emphasis.}\vfill} |
| 337 | \page\colophon |
| 338 | % Blame: doc@@cygnus.com, 28mar91. |
| 339 | @end tex |
| 340 | |
| 341 | @bye |