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<title>White paper: Libgtop Reference Manual</title>
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<div class="chapter">
<div class="titlepage"><div><div><h1 class="title">
<a name="libgtop-white-paper"></a>White paper</h1></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="sect1"><a href="libgtop-white-paper.html#libgtop-white-paper-introduction">Introduction</a></span></dt>
<dt><span class="sect1"><a href="libgtop-white-paper-overview.html">Overview</a></span></dt>
<dt><span class="sect2"><a href="libgtop-white-paper-overview.html#libgtop-white-paper-overview-design">Interface Design: Things that need to be considered</a></span></dt>
<dt><span class="sect2"><a href="libgtop-white-paper-overview.html#libgtop-white-paper-overview-server">Server Implementation: The LibGTop "server"</a></span></dt>
<div class="sect1">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="libgtop-white-paper-introduction"></a>Introduction</h2></div></div></div>
<p>Many modern UNIX systems like Solaris, BSD or Digitial Unix 
      only allow priviledged processes to read information like CPU and 
      Memory Usage or information about running processes.</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p>
      BSD, for instance, doesn't have any other way to get those data than reading
      directly from @file{/dev/kmem} and you need to be in the @code{kmem} group to
      be able to read this.</p></li>
<li class="listitem"><p>
      Other systems, like Digital Unix, allow all users to get things like CPU and
      Memory statistics, but only root may read information about any process other
      than the current one (you may not even get information about your own processes
      if you're not root).</p></li>
<li class="listitem"><p>
      Linux has a very nice @file{/proc} filesystem, but reading and parsing
      @file{/proc} is very slow and inefficient.</p></li>
<li class="listitem"><p>
      Solaris is a bit better, but you still need to be in the @code{sys} group or
      even root to get some data.</p></li>
      Because of this system utilities like @code{ps}, @code{uptime} or @code{top}
      often are setgid kmem or setuid root. Usually, they're also very specific to
      the system they're written for and not easily portable to other systems without
      a lot of work.</p>
      This, of cause, becomes a problem for graphical tools like @code{gtop} - making
      a GTK+ program setgid or even setuid would be a security hole as big as you can
      drive the entire X11 source code through. For the GNOME project, we also needed
      some kind of library which provides all the required information in a portable
      since there's more than just one single program that wants to use them - for
      instance @code{gtop} and the @code{multiload}, @code{cpumemusage} and
      @code{netload} panel applets.</p>
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