78 lines
3.6 KiB
HTML
78 lines
3.6 KiB
HTML
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<title>Patching - Debugging with GDB</title>
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<link rel="up" href="Altering.html#Altering" title="Altering">
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<link rel="prev" href="Calling.html#Calling" title="Calling">
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<a name="Patching"></a>
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Next: <a rel="next" accesskey="n" href="Compiling-and-Injecting-Code.html#Compiling-and-Injecting-Code">Compiling and Injecting Code</a>,
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Previous: <a rel="previous" accesskey="p" href="Calling.html#Calling">Calling</a>,
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Up: <a rel="up" accesskey="u" href="Altering.html#Altering">Altering</a>
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<hr>
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</div>
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<h3 class="section">17.6 Patching Programs</h3>
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<p><a name="index-patching-binaries-1187"></a><a name="index-writing-into-executables-1188"></a><a name="index-writing-into-corefiles-1189"></a>
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By default, <span class="sc">gdb</span> opens the file containing your program's
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executable code (or the corefile) read-only. This prevents accidental
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alterations to machine code; but it also prevents you from intentionally
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patching your program's binary.
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<p>If you'd like to be able to patch the binary, you can specify that
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explicitly with the <code>set write</code> command. For example, you might
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want to turn on internal debugging flags, or even to make emergency
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repairs.
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<a name="index-set-write-1190"></a>
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<dl><dt><code>set write on</code><dt><code>set write off</code><dd>If you specify ‘<samp><span class="samp">set write on</span></samp>’, <span class="sc">gdb</span> opens executable and
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core files for both reading and writing; if you specify <kbd>set write
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off</kbd> (the default), <span class="sc">gdb</span> opens them read-only.
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<p>If you have already loaded a file, you must load it again (using the
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<code>exec-file</code> or <code>core-file</code> command) after changing <code>set
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write</code>, for your new setting to take effect.
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<br><dt><code>show write</code><dd><a name="index-show-write-1191"></a>Display whether executable files and core files are opened for writing
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as well as reading.
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</dl>
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</body></html>
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