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(Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> + <i class="fa fa-search"></i> + </button> + + </div> + + <h1 class="menu-title">Notes</h1> + + <div class="right-buttons"> + <a href="print.html" title="Print this book" aria-label="Print this book"> + <i id="print-button" class="fa fa-print"></i> + </a> + + </div> + </div> + </div> + + + <div id="search-wrapper" class="hidden"> + <form id="searchbar-outer" class="searchbar-outer"> + <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> + </form> + <div id="searchresults-outer" class="searchresults-outer hidden"> + <div id="searchresults-header" class="searchresults-header"></div> + <ul id="searchresults"> + </ul> + </div> + </div> + + + <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM --> + <script type="text/javascript"> + document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); + document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible'); + Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) { + link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1); + }); + </script> + + <div id="content" class="content"> + <main> + <h1><a class="header" href="#glibc" id="glibc">glibc</a></h1> +<h2><a class="header" href="#malloc-tracer-a-hrefhttpman7orglinuxman-pagesman3mtrace3htmlmtrace3a" id="malloc-tracer-a-hrefhttpman7orglinuxman-pagesman3mtrace3htmlmtrace3a">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><a class="header" href="#malloc-check-a-hrefhttpman7orglinuxman-pagesman3mallopt3htmlmallopt3a" id="malloc-check-a-hrefhttpman7orglinuxman-pagesman3mallopt3htmlmallopt3a">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> + + </main> + + <nav class="nav-wrapper" aria-label="Page navigation"> + <!-- Mobile navigation buttons --> + + <a rel="prev" href="c++.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> + <i class="fa fa-angle-left"></i> + </a> + + + + <a rel="next" href="gcc.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> + <i class="fa fa-angle-right"></i> + </a> + + + <div style="clear: both"></div> + </nav> + </div> + </div> + + <nav class="nav-wide-wrapper" aria-label="Page navigation"> + + <a href="c++.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> + <i class="fa fa-angle-left"></i> + </a> + + + + <a href="gcc.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> + <i class="fa fa-angle-right"></i> + </a> + + </nav> + + </div> + + + + + + + + + <script type="text/javascript"> + window.playpen_copyable = true; + </script> + + + + + + <script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script> + <script src="mark.min.js" type="text/javascript" charset="utf-8"></script> + <script src="searcher.js" type="text/javascript" charset="utf-8"></script> + + + <script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script> + <script src="highlight.js" type="text/javascript" charset="utf-8"></script> + <script src="book.js" type="text/javascript" charset="utf-8"></script> + + <!-- Custom JS scripts --> + + + + + </body> +</html> |