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102 lines
4.0 KiB
HTML
<html lang="en">
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<head>
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<title>Writing Symbols - Untitled</title>
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<meta name="generator" content="makeinfo 4.7">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Symbols.html#Symbols" title="Symbols">
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<link rel="prev" href="Reading-Symbols.html#Reading-Symbols" title="Reading Symbols">
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<link rel="next" href="Mini-Symbols.html#Mini-Symbols" title="Mini Symbols">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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This file documents the BFD library.
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Copyright (C) 1991, 2000, 2001, 2003, 2006, 2007 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.1 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``GNU General Public License'' and ``Funding
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Free Software'', the Front-Cover texts being (a) (see below), and with
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the Back-Cover Texts being (b) (see below). A copy of the license is
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included in the section entitled ``GNU Free Documentation License''.
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development.-->
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</head>
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<body>
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<div class="node">
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<p>
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<a name="Writing-Symbols"></a>Next: <a rel="next" accesskey="n" href="Mini-Symbols.html#Mini-Symbols">Mini Symbols</a>,
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Previous: <a rel="previous" accesskey="p" href="Reading-Symbols.html#Reading-Symbols">Reading Symbols</a>,
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Up: <a rel="up" accesskey="u" href="Symbols.html#Symbols">Symbols</a>
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<hr><br>
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</div>
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<h4 class="subsection">2.7.2 Writing symbols</h4>
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<p>Writing of a symbol table is automatic when a BFD open for
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writing is closed. The application attaches a vector of
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pointers to pointers to symbols to the BFD being written, and
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fills in the symbol count. The close and cleanup code reads
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through the table provided and performs all the necessary
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operations. The BFD output code must always be provided with an
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“owned” symbol: one which has come from another BFD, or one
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which has been created using <code>bfd_make_empty_symbol</code>. Here is an
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example showing the creation of a symbol table with only one element:
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<pre class="example"> #include "bfd.h"
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int main (void)
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{
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bfd *abfd;
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asymbol *ptrs[2];
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asymbol *new;
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abfd = bfd_openw ("foo","a.out-sunos-big");
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bfd_set_format (abfd, bfd_object);
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new = bfd_make_empty_symbol (abfd);
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new->name = "dummy_symbol";
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new->section = bfd_make_section_old_way (abfd, ".text");
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new->flags = BSF_GLOBAL;
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new->value = 0x12345;
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ptrs[0] = new;
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ptrs[1] = 0;
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bfd_set_symtab (abfd, ptrs, 1);
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bfd_close (abfd);
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return 0;
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}
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./makesym
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nm foo
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00012345 A dummy_symbol
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</pre>
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<p>Many formats cannot represent arbitrary symbol information; for
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instance, the <code>a.out</code> object format does not allow an
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arbitrary number of sections. A symbol pointing to a section
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which is not one of <code>.text</code>, <code>.data</code> or <code>.bss</code> cannot
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be described.
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</body></html>
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