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| <a name="Writing-the-symbol-table"></a> |
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| Previous: <a href="Relocating-the-section-contents.html#Relocating-the-section-contents" accesskey="p" rel="prev">Relocating the section contents</a>, Up: <a href="Performing-the-Final-Link.html#Performing-the-Final-Link" accesskey="u" rel="up">Performing the Final Link</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="BFD-Index.html#BFD-Index" title="Index" rel="index">Index</a>]</p> |
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| <hr> |
| <a name="Writing-the-symbol-table-1"></a> |
| <h4 class="subsubsection">2.17.3.3 Writing the symbol table</h4> |
| <p>The <code>_bfd_final_link</code> function must gather all the symbols |
| in the input files and write them out. It must also write out |
| all the symbols in the global hash table. This must be |
| controlled by the <code>strip</code> and <code>discard</code> fields of the |
| <code>bfd_link_info</code> structure. |
| </p> |
| <p>The local symbols of the input files will not have been |
| entered into the linker hash table. The <code>_bfd_final_link</code> |
| routine must consider each input file and include the symbols |
| in the output file. It may be convenient to do this when |
| looking through the <code>link_order</code> structures, or it may be |
| done by stepping through the <code>input_bfds</code> list. |
| </p> |
| <p>The <code>_bfd_final_link</code> routine must also traverse the global |
| hash table to gather all the externally visible symbols. It |
| is possible that most of the externally visible symbols may be |
| written out when considering the symbols of each input file, |
| but it is still necessary to traverse the hash table since the |
| linker script may have defined some symbols that are not in |
| any of the input files. |
| </p> |
| <p>The <code>strip</code> field of the <code>bfd_link_info</code> structure |
| controls which symbols are written out. The possible values |
| are listed in <code>bfdlink.h</code>. If the value is <code>strip_some</code>, |
| then the <code>keep_hash</code> field of the <code>bfd_link_info</code> |
| structure is a hash table of symbols to keep; each symbol |
| should be looked up in this hash table, and only symbols which |
| are present should be included in the output file. |
| </p> |
| <p>If the <code>strip</code> field of the <code>bfd_link_info</code> structure |
| permits local symbols to be written out, the <code>discard</code> field |
| is used to further controls which local symbols are included |
| in the output file. If the value is <code>discard_l</code>, then all |
| local symbols which begin with a certain prefix are discarded; |
| this is controlled by the <code>bfd_is_local_label_name</code> entry point. |
| </p> |
| <p>The a.out backend handles symbols by calling |
| <code>aout_link_write_symbols</code> on each input BFD and then |
| traversing the global hash table with the function |
| <code>aout_link_write_other_symbol</code>. It builds a string table |
| while writing out the symbols, which is written to the output |
| file at the end of <code>NAME(aout,final_link)</code>. |
| </p> |
| <a name="index-bfd_005flink_005fsplit_005fsection"></a> |
| <a name="bfd_005flink_005fsplit_005fsection"></a> |
| <h4 class="subsubsection">2.17.3.4 <code>bfd_link_split_section</code></h4> |
| <p><strong>Synopsis</strong> |
| </p><div class="example"> |
| <pre class="example">bfd_boolean bfd_link_split_section (bfd *abfd, asection *sec); |
| </pre></div> |
| <p><strong>Description</strong><br> |
| Return nonzero if <var>sec</var> should be split during a |
| reloceatable or final link. |
| </p><div class="example"> |
| <pre class="example">#define bfd_link_split_section(abfd, sec) \ |
| BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec)) |
| |
| </pre></div> |
| |
| <a name="index-bfd_005fsection_005falready_005flinked"></a> |
| <a name="bfd_005fsection_005falready_005flinked"></a> |
| <h4 class="subsubsection">2.17.3.5 <code>bfd_section_already_linked</code></h4> |
| <p><strong>Synopsis</strong> |
| </p><div class="example"> |
| <pre class="example">bfd_boolean bfd_section_already_linked (bfd *abfd, |
| asection *sec, |
| struct bfd_link_info *info); |
| </pre></div> |
| <p><strong>Description</strong><br> |
| Check if <var>data</var> has been already linked during a reloceatable |
| or final link. Return TRUE if it has. |
| </p><div class="example"> |
| <pre class="example">#define bfd_section_already_linked(abfd, sec, info) \ |
| BFD_SEND (abfd, _section_already_linked, (abfd, sec, info)) |
| |
| </pre></div> |
| |
| <a name="index-bfd_005fgeneric_005fdefine_005fcommon_005fsymbol"></a> |
| <a name="bfd_005fgeneric_005fdefine_005fcommon_005fsymbol"></a> |
| <h4 class="subsubsection">2.17.3.6 <code>bfd_generic_define_common_symbol</code></h4> |
| <p><strong>Synopsis</strong> |
| </p><div class="example"> |
| <pre class="example">bfd_boolean bfd_generic_define_common_symbol |
| (bfd *output_bfd, struct bfd_link_info *info, |
| struct bfd_link_hash_entry *h); |
| </pre></div> |
| <p><strong>Description</strong><br> |
| Convert common symbol <var>h</var> into a defined symbol. |
| Return TRUE on success and FALSE on failure. |
| </p><div class="example"> |
| <pre class="example">#define bfd_define_common_symbol(output_bfd, info, h) \ |
| BFD_SEND (output_bfd, _bfd_define_common_symbol, (output_bfd, info, h)) |
| |
| </pre></div> |
| |
| <a name="index-bfd_005ffind_005fversion_005ffor_005fsym"></a> |
| <a name="bfd_005ffind_005fversion_005ffor_005fsym"></a> |
| <h4 class="subsubsection">2.17.3.7 <code>bfd_find_version_for_sym</code></h4> |
| <p><strong>Synopsis</strong> |
| </p><div class="example"> |
| <pre class="example">struct bfd_elf_version_tree * bfd_find_version_for_sym |
| (struct bfd_elf_version_tree *verdefs, |
| const char *sym_name, bfd_boolean *hide); |
| </pre></div> |
| <p><strong>Description</strong><br> |
| Search an elf version script tree for symbol versioning |
| info and export / don’t-export status for a given symbol. |
| Return non-NULL on success and NULL on failure; also sets |
| the output ‘<samp>hide</samp>’ boolean parameter. |
| </p> |
| <a name="index-bfd_005fhide_005fsym_005fby_005fversion"></a> |
| <a name="bfd_005fhide_005fsym_005fby_005fversion"></a> |
| <h4 class="subsubsection">2.17.3.8 <code>bfd_hide_sym_by_version</code></h4> |
| <p><strong>Synopsis</strong> |
| </p><div class="example"> |
| <pre class="example">bfd_boolean bfd_hide_sym_by_version |
| (struct bfd_elf_version_tree *verdefs, const char *sym_name); |
| </pre></div> |
| <p><strong>Description</strong><br> |
| Search an elf version script tree for symbol versioning |
| info for a given symbol. Return TRUE if the symbol is hidden. |
| </p> |
| |
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