mingw/info/gdb/Patching.html

   1 <html lang="en">
   2 <head>
   3 <title>Debugging with GDB</title>
   4 <meta http-equiv="Content-Type" content="text/html">
   5 <meta name="description" content="Debugging with GDB">
   6 <meta name="generator" content="makeinfo 4.3">
   7 <link href="http://www.gnu.org/software/texinfo/" rel="generator-home">
   8 </head>
   9 <body>
  10 <div class="node">
  11 <p>
  12 Node:<a name="Patching">Patching</a>,
  13 Previous:<a rel="previous" accesskey="p" href="Calling.html#Calling">Calling</a>,
  14 Up:<a rel="up" accesskey="u" href="Altering.html#Altering">Altering</a>
  15 <hr><br>
  16 </div>
  17
  18 <h3 class="section">Patching programs</h3>
  19
  20    <p>By default, GDB opens the file containing your program's
  21 executable code (or the corefile) read-only.  This prevents accidental
  22 alterations to machine code; but it also prevents you from intentionally
  23 patching your program's binary.
  24
  25    <p>If you'd like to be able to patch the binary, you can specify that
  26 explicitly with the <code>set write</code> command.  For example, you might
  27 want to turn on internal debugging flags, or even to make emergency
  28 repairs.
  29
  30      <dl>
  31 <dt><code>set write on</code>
  32      <dd><dt><code>set write off</code>
  33      <dd>If you specify <code>set write on</code>, GDB opens executable and
  34 core files for both reading and writing; if you specify <code>set write
  35 off</code> (the default), GDB opens them read-only.
  36
  37      <p>If you have already loaded a file, you must load it again (using the
  38 <code>exec-file</code> or <code>core-file</code> command) after changing <code>set
  39 write</code>, for your new setting to take effect.
  40
  41      <br><dt><code>show write</code>
  42      <dd>Display whether executable files and core files are opened for writing
  43 as well as reading.
  44 </dl>
  45
  46    </body></html>
  47