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<h1 id="glibc"><a class="header" href="#glibc">glibc</a></h1>
<h2 id="malloc-tracer-mtrace3"><a class="header" href="#malloc-tracer-mtrace3">malloc tracer <a href="http://man7.org/linux/man-pages/man3/mtrace.3.html"><code>mtrace(3)</code></a></a></h2>
<p>Trace memory allocation and de-allocation to detect memory leaks.
Need to call <code>mtrace(3)</code> to install the tracing hooks.</p>
<p>If we can't modify the binary to call <code>mtrace</code> we can create a small shared
library and pre-load it.</p>
<pre><code class="language-c">// libmtrace.c
#include <mcheck.h>
__attribute__((constructor)) static void init_mtrace() { mtrace(); }
</code></pre>
<p>Compile as:</p>
<pre><code class="language-bash">gcc -shared -fPIC -o libmtrace.so libmtrace.c
</code></pre>
<p>To generate the trace file run:</p>
<pre><code class="language-bash">export MALLOC_TRACE=<file>
LD_PRELOAD=./libmtrace.so <binary>
</code></pre>
<p><strong>Note</strong>: If <code>MALLOC_TRACE</code> is not set <code>mtrace</code> won't install tracing hooks.</p>
<p>To get the results of the trace file:</p>
<pre><code class="language-bash">mtrace <binary> $MALLOC_TRACE
</code></pre>
<h2 id="malloc-check-mallopt3"><a class="header" href="#malloc-check-mallopt3">malloc check <a href="http://man7.org/linux/man-pages/man3/mallopt.3.html"><code>mallopt(3)</code></a></a></h2>
<p>Configure action when glibc detects memory error.</p>
<pre><code class="language-bash">export MALLOC_CHECK_=<N>
</code></pre>
<p>Useful values:</p>
<pre><code class="language-markdown">1 print detailed error & continue
3 print detailed error + stack trace + memory mappings & abort
7 print simple error message + stack trace + memory mappings & abort
</code></pre>
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