"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">

<book id="index" xmlns:xi="http://www.w3.org/2003/XInclude">

  <bookinfo>

    <title>Libgtop Reference Manual</title>

    <releaseinfo>for libgtop <xi:include href="version.xml"/></releaseinfo>

    <authorgroup>

      <author>

	<firstname>Martin </firstname>

	<surname>Baulig</surname>

	<affiliation>

	  <address>

	    <email>martin@home-of-linux.org</email>

	  </address>

	</affiliation>

      </author>

      <author>

	<firstname>Germán</firstname>

	<surname>Poó-Caamaño</surname>

	<affiliation>

	  <address>

	    <email>gpoo@ubiobio.cl</email>

	  </address>

	</affiliation>

      </author>

    </authorgroup>

    <legalnotice>

      <para>Permission is granted to copy, distribute and/or modify

      this document under the terms of the <citetitle>GNU Free

      Documentation License</citetitle>, Version 1.1 or any later

      version published by the Free Software Foundation with no

      Invariant Sections, no Front-Cover Texts, and no Back-Cover

      Texts. You may obtain a copy of the <citetitle>GNU Free

      Documentation License</citetitle> from the Free Software

      Foundation by visiting 

      url="http://www.fsf.org">their Web site</ulink> or by writing

      to: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

      Boston, MA 02110-1301, USA.</para>

      <para>Many of the names used by companies to distinguish their

      products and services are claimed as trademarks. Where those

      names appear in any GNOME documentation, and those trademarks

      are made aware to the members of the GNOME Documentation

      Project, the names have been printed in caps or initial

      caps.</para>

    </legalnotice>

    <abstract>

      <para>

      LibGTop is a library to get system specific data such as CPU and 

      Memory Usage and information about running Processes.</para>

      <para>On Systems like Solaris or Digital Unix where you need special

      privileges to get those data, it uses a setuid/setgid server to do 

      so.</para>

      <para>Even if LibGTop is a part of the GNOME desktop environment

      (@uref{http://www.gnome.org}), the main interface of LibGTop is totally

      independent from any particular desktop environment, so you can also

      use it as a standalone library in any piece of GPLed software.</para>

      <para>This manual documents the interfaces of the libgtop

      library and has some short notes to help get you up to speed

      with using the library.</para>

    </abstract>

  </bookinfo>

  <chapter id="libgtop-white-paper">

    <title>White paper</title>

    <sect1 id="libgtop-white-paper-introduction">

      <title>Introduction</title>

      <para>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.</para>

      <itemizedlist>

      <listitem><para>

      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.</para></listitem>

      <listitem><para>

      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).</para></listitem>

      <listitem><para>

      Linux has a very nice @file{/proc} filesystem, but reading and parsing

      @file{/proc} is very slow and inefficient.</para></listitem>

      <listitem><para>

      Solaris is a bit better, but you still need to be in the @code{sys} group or

      even root to get some data.</para></listitem>

      </itemizedlist>

      <para>

      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.</para>

      <para>

      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.</para>

    </sect1>

    <sect1 id="libgtop-white-paper-overview">

      <title>Overview</title>

      <para>This section should give you a short overview on how LibGTop

      was developed, which things needed to be considered and how it 

      works.</para>

      <sect2 id="libgtop-white-paper-overview-design">

      <title>Interface Design: Things that need to be considered</title>

      <para>

At the very beginning, it was necessary to collect all the data the library part

should provide and put them into some C structures. This was not that easiy as it

might sound since LibGTop should be portable to any modern UNIX system with a common

library part on all those systems, but the data that should be returned vary from

system to system. For instance some systems support shared memory, but some others

may not.</para>

      <para>

The header files where we define these C structures (which are system-independent) are

shared between client and server. This way we can call the system dependent code

directly where we do not need any special privileges to do so.</para>

      <para>

All of those structures contain a @code{flags} member which is interpreted as a bit

mask and tells the caller of the library functions which of the fields in the returned

structure are valid and which are not.</para>

      </sect2>

      <sect2 id="libgtop-white-paper-overview-server">

      <title>Server Implementation: The LibGTop "server"</title>

      <para>

The LibGTop @dfn{server} is a setgid/setuid binary which contains all the system

dependent code which needs special privileges. It is only build if it's required

on the current system (for instance, the Linux kernel provides all the required

data via its @file{/proc} filesystem so we do not need the server at all) and it

only contains the @dfn{features} which need privileges.</para>

      <para>

Whenever we do not need any privileges to get all the data for some of the requested

structures (here called @dfn{features}) the library calls the sysdeps code directly

rather than using the server.</para>

      </sect2>

    </sect1>

  </chapter>

  <chapter id="libgtop-lib">

    <title>Libgtop Library Reference</title>

    <para>This section contains the API reference for libgtop.  All

    the public interfaces are documented here.</para>

    <xi:include href="xml/glibtop.xml"/>

    <xi:include href="xml/close.xml"/>

    <xi:include href="xml/command.xml"/>

    <xi:include href="xml/glibtop-server.xml"/>

    <xi:include href="xml/netload.xml"/>

    <xi:include href="xml/ppp.xml"/>

    <xi:include href="xml/shm_limits.xml"/>

    <xi:include href="xml/uptime.xml"/>

    <xi:include href="xml/netlist.xml"/>

    <xi:include href="xml/open.xml"/>

    <xi:include href="xml/parameter.xml"/>

    <xi:include href="xml/procargs.xml"/>

    <xi:include href="xml/procmem.xml"/>

    <xi:include href="xml/procopenfiles.xml"/>

    <xi:include href="xml/procsegment.xml"/>

    <xi:include href="xml/procsignal.xml"/>

    <xi:include href="xml/sysdeps.xml"/>

    <xi:include href="xml/procstate.xml"/>

    <xi:include href="xml/procuid.xml"/>

    <xi:include href="xml/proctime.xml"/>

    <xi:include href="xml/signal.xml"/>

    <xi:include href="xml/procmap.xml"/>

    <xi:include href="xml/sysinfo.xml"/>

    <xi:include href="xml/union.xml"/>

    <xi:include href="xml/version.xml"/>

    <xi:include href="xml/proclist.xml"/>

    <xi:include href="xml/sem_limits.xml"/>

    <xi:include href="xml/prockernel.xml"/>

    <xi:include href="xml/fsusage.xml"/>

    <xi:include href="xml/loadavg.xml"/>

    <xi:include href="xml/mem.xml"/>

    <xi:include href="xml/mountlist.xml"/>

    <xi:include href="xml/msg_limits.xml"/>

    <xi:include href="xml/cpu.xml"/>

    <xi:include href="xml/swap.xml"/>

  </chapter>

</book>