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112 lines
4.6 KiB
HTML
112 lines
4.6 KiB
HTML
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<head>
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<title>Patching (Debugging with GDB)</title>
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<meta name="description" content="Patching (Debugging with GDB)">
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<meta name="keywords" content="Patching (Debugging with GDB)">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Altering.html#Altering" rel="up" title="Altering">
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<link href="Compiling-and-Injecting-Code.html#Compiling-and-Injecting-Code" rel="next" title="Compiling and Injecting Code">
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<link href="Calling.html#Calling" rel="prev" title="Calling">
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<a name="Patching"></a>
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<div class="header">
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<p>
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Next: <a href="Compiling-and-Injecting-Code.html#Compiling-and-Injecting-Code" accesskey="n" rel="next">Compiling and Injecting Code</a>, Previous: <a href="Calling.html#Calling" accesskey="p" rel="prev">Calling</a>, Up: <a href="Altering.html#Altering" accesskey="u" rel="up">Altering</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Patching-Programs"></a>
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<h3 class="section">17.6 Patching Programs</h3>
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<a name="index-patching-binaries"></a>
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<a name="index-writing-into-executables"></a>
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<a name="index-writing-into-corefiles"></a>
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<p>By default, <small>GDB</small> 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>
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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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</p>
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<dl compact="compact">
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<dd><a name="index-set-write"></a>
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</dd>
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<dt><code>set write on</code></dt>
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<dt><code>set write off</code></dt>
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<dd><p>If you specify ‘<samp>set write on</samp>’, <small>GDB</small> 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), <small>GDB</small> opens them read-only.
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</p>
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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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</p>
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</dd>
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<dt><code>show write</code></dt>
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<dd><a name="index-show-write"></a>
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<p>Display whether executable files and core files are opened for writing
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as well as reading.
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</p></dd>
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</dl>
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</body>
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</html>
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