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<a name="Searching-Memory"></a>
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<p>
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<hr>
<a name="Search-Memory"></a>
<h3 class="section">10.22 Search Memory</h3>
<a name="index-searching-memory"></a>
<p>Memory can be searched for a particular sequence of bytes with the
<code>find</code> command.
</p>
<dl compact="compact">
<dd><a name="index-find"></a>
</dd>
<dt><code>find <span class="roman">[</span>/<var>sn</var><span class="roman">]</span> <var>start_addr</var>, +<var>len</var>, <var>val1</var> <span class="roman">[</span>, <var>val2</var>, …<span class="roman">]</span></code></dt>
<dt><code>find <span class="roman">[</span>/<var>sn</var><span class="roman">]</span> <var>start_addr</var>, <var>end_addr</var>, <var>val1</var> <span class="roman">[</span>, <var>val2</var>, …<span class="roman">]</span></code></dt>
<dd><p>Search memory for the sequence of bytes specified by <var>val1</var>, <var>val2</var>,
etc. The search begins at address <var>start_addr</var> and continues for either
<var>len</var> bytes or through to <var>end_addr</var> inclusive.
</p></dd>
</dl>
<p><var>s</var> and <var>n</var> are optional parameters.
They may be specified in either order, apart or together.
</p>
<dl compact="compact">
<dt><span class="roman"><var>s</var>, search query size</span></dt>
<dd><p>The size of each search query value.
</p>
<dl compact="compact">
<dt><code>b</code></dt>
<dd><p>bytes
</p></dd>
<dt><code>h</code></dt>
<dd><p>halfwords (two bytes)
</p></dd>
<dt><code>w</code></dt>
<dd><p>words (four bytes)
</p></dd>
<dt><code>g</code></dt>
<dd><p>giant words (eight bytes)
</p></dd>
</dl>
<p>All values are interpreted in the current language.
This means, for example, that if the current source language is C/C<tt>++</tt>
then searching for the string “hello” includes the trailing ’\0’.
The null terminator can be removed from searching by using casts,
e.g.: ‘<samp>{char[5]}"hello"</samp>’.
</p>
<p>If the value size is not specified, it is taken from the
value’s type in the current language.
This is useful when one wants to specify the search
pattern as a mixture of types.
Note that this means, for example, that in the case of C-like languages
a search for an untyped 0x42 will search for ‘<samp>(int) 0x42</samp>’
which is typically four bytes.
</p>
</dd>
<dt><span class="roman"><var>n</var>, maximum number of finds</span></dt>
<dd><p>The maximum number of matches to print. The default is to print all finds.
</p></dd>
</dl>
<p>You can use strings as search values. Quote them with double-quotes
(<code>"</code>).
The string value is copied into the search pattern byte by byte,
regardless of the endianness of the target and the size specification.
</p>
<p>The address of each match found is printed as well as a count of the
number of matches found.
</p>
<p>The address of the last value found is stored in convenience variable
‘<samp>$_</samp>’.
A count of the number of matches is stored in ‘<samp>$numfound</samp>’.
</p>
<p>For example, if stopped at the <code>printf</code> in this function:
</p>
<div class="smallexample">
<pre class="smallexample">void
hello ()
{
static char hello[] = "hello-hello";
static struct { char c; short s; int i; }
__attribute__ ((packed)) mixed
= { 'c', 0x1234, 0x87654321 };
printf ("%s\n", hello);
}
</pre></div>
<p>you get during debugging:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) find &hello[0], +sizeof(hello), "hello"
0x804956d <hello.1620+6>
1 pattern found
(gdb) find &hello[0], +sizeof(hello), 'h', 'e', 'l', 'l', 'o'
0x8049567 <hello.1620>
0x804956d <hello.1620+6>
2 patterns found.
(gdb) find &hello[0], +sizeof(hello), {char[5]}"hello"
0x8049567 <hello.1620>
0x804956d <hello.1620+6>
2 patterns found.
(gdb) find /b1 &hello[0], +sizeof(hello), 'h', 0x65, 'l'
0x8049567 <hello.1620>
1 pattern found
(gdb) find &mixed, +sizeof(mixed), (char) 'c', (short) 0x1234, (int) 0x87654321
0x8049560 <mixed.1625>
1 pattern found
(gdb) print $numfound
$1 = 1
(gdb) print $_
$2 = (void *) 0x8049560
</pre></div>
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