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<a name="Object-Size-Checking-1"></a>
<h3 class="section">12.2 Object Size Checking</h3>
<p>Object Size Checking is a feature which wraps certain functions with checks
to prevent buffer overflows.  These are enabled when compiling with
optimization (<code>-O1</code> and higher) and <code>_FORTIFY_SOURCE</code> defined
to 1, or for stricter checks, to 2.
</p>
<a name="index-list-of-overflow-protected-functions"></a>
<p>The following functions use object size checking to detect buffer overflows
when enabled:
</p>
<div class="example">
<pre class="example"><em>String functions:</em>
</pre><pre class="example">bcopy           memmove         strcpy
bzero           mempcpy         strcat
explicit_bzero  memset          strncat
memcpy          stpcpy          strncpy

</pre><pre class="example"><em>Wide Character String functions:</em>
</pre><pre class="example">fgetws          wcrtomb         wcsrtombs
fgetws_unlocked wcscat          wmemcpy
mbsnrtowcs      wcscpy          wmemmove
mbsrtowcs       wcsncat         wmempcpy
wcpcpy          wcsncpy         wmemset
wcpncpy         wcsnrtombs

</pre><pre class="example"><em>Stdio functions:</em>
</pre><pre class="example">fgets           fread_unlocked  sprintf
fgets_unlocked  gets            vsnprintf
fread           snprintf        vsprintf

</pre><pre class="example"><em>Stdlib functions:</em>
</pre><pre class="example">mbstowcs        wcstombs        wctomb

</pre><pre class="example"><em>System functions:</em>
</pre><pre class="example">getcwd          read            ttyname_r
pread           readlink

</pre></div>


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