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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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<refentry id='shadow.3'>
  <!--  $Id: shadow.3.xml,v 1.9 2005/06/20 08:42:12 kloczek Exp $ -->
  <refmeta>
    <refentrytitle>shadow</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>
  <refnamediv id='name'>
    <refname>shadow</refname>
    <refpurpose>encrypted password file routines</refpurpose>
  </refnamediv>
  
  <refsect1 id='syntax'>
    <title>SYNTAX</title>
    <para><emphasis remap='B'>#include &lt;shadow.h&gt;</emphasis>
    </para>
    
    <para><emphasis remap='B'>struct spwd *getspent();</emphasis>
    </para>
    
    <para><emphasis remap='B'>struct spwd *getspnam(char</emphasis>
      <emphasis remap='I'>*name</emphasis><emphasis remap='B'>);</emphasis>
    </para>
    
    <para><emphasis remap='B'>void setspent();</emphasis>
    </para>
    
    <para><emphasis remap='B'>void endspent();</emphasis>
    </para>
    
    <para><emphasis remap='B'>struct spwd *fgetspent(FILE</emphasis>
      <emphasis remap='I'>*fp</emphasis><emphasis remap='B'>);</emphasis>
    </para>
    
    <para><emphasis remap='B'>struct spwd *sgetspent(char</emphasis>
      <emphasis remap='I'>*cp</emphasis><emphasis remap='B'>);</emphasis>
    </para>
    
    <para><emphasis remap='B'>int putspent(struct spwd</emphasis>
      <emphasis remap='I'>*p,</emphasis>
      <emphasis remap='B'>FILE</emphasis>
      <emphasis remap='I'>*fp</emphasis><emphasis remap='B'>);</emphasis>
    </para>
    
    <para><emphasis remap='B'>int lckpwdf();</emphasis>
    </para>
    
    <para><emphasis remap='B'>int ulckpwdf();</emphasis>
    </para>
  </refsect1>
  
  <refsect1 id='description'>
    <title>DESCRIPTION</title>
    <para><emphasis remap='I'>shadow</emphasis> manipulates the contents of
      the shadow password file, <filename>/etc/shadow</filename>.
      The structure in the <emphasis remap='I'>#include</emphasis> file is:
    </para>
    <programlisting>struct spwd {
      char			*sp_namp; /* user login name */
      char			*sp_pwdp; /* encrypted password */
      long int		sp_lstchg; /* last password change */
      long int		sp_min; /* days until change allowed. */
      long int		sp_max; /* days before change required */
      long int		sp_warn; /* days warning for expiration */
      long int		sp_inact; /* days before account inactive */
      long int		sp_expire; /* date when account expires */
      unsigned long int	sp_flag; /* reserved for future use */
}
    </programlisting>
    <para>The meanings of each field are:</para>
    <itemizedlist mark='bullet'>
      <listitem>
        <para>sp_namp - pointer to null-terminated user name</para>
      </listitem>
      <listitem>
        <para>sp_pwdp - pointer to null-terminated password</para>
      </listitem>
      <listitem>
        <para>sp_lstchg - days since Jan 1, 1970 password was last changed</para>
      </listitem>
      <listitem>
        <para>sp_min - days before which password may not be changed</para>
      </listitem>
      <listitem>
        <para>sp_max - days after which password must be changed</para>
      </listitem>
      <listitem>
         <para>sp_warn - days before password is to expire that user is warned of
	   pending password expiration
	 </para>
      </listitem>
      <listitem>
        <para>sp_inact - days after password expires that account is considered
          inactive and disabled
	</para>
      </listitem>
      <listitem>
        <para>sp_expire - days since Jan 1, 1970 when account will be disabled</para>
      </listitem>
      <listitem>
        <para>sp_flag - reserved for future use</para>
      </listitem>
    </itemizedlist>
        
  </refsect1>
  
  <refsect1 id='description2'>
    <title>DESCRIPTION</title>
    <para><emphasis remap='B'>getspent</emphasis>, <emphasis
      remap='B'>getspname</emphasis> <emphasis
      remap='B'>fgetspent</emphasis>, and <emphasis
      remap='B'>sgetspent</emphasis> each return a pointer to a <emphasis
      remap='B'>struct spwd</emphasis>. <emphasis
      remap='B'>getspent</emphasis> returns the next entry from the file,
      and <emphasis remap='B'>fgetspent</emphasis> returns the next entry
      from the given stream, which is assumed to be a file of the proper
      format. <emphasis remap='B'>sgetspent</emphasis> returns a pointer to
      a <emphasis remap='B'>struct spwd</emphasis> using the provided string
      as input. <emphasis remap='B'>getspnam</emphasis> searches from the
      current position in the file for an entry matching <emphasis
      remap='B'>name</emphasis>.
    </para>
    <para><emphasis remap='B'>setspent</emphasis> and <emphasis
      remap='B'>endspent</emphasis> may be used to begin and end,
      respectively, access to the shadow password file.
    </para>
    <para>The <emphasis remap='B'>lckpwdf</emphasis> and <emphasis
      remap='B'>ulckpwdf</emphasis> routines should be used to insure
      exclusive access to the <filename>/etc/shadow</filename> file. 
      <emphasis remap='B'>lckpwdf</emphasis> attempts to acquire a lock
      using <emphasis remap='B'>pw_lock</emphasis> for up to 15 seconds. It
      continues by attempting to acquire a second lock using <emphasis
      remap='B'>spw_lock</emphasis> for the remainder of the initial 15
      seconds. Should either attempt fail after a total of 15 seconds,
      <emphasis remap='B'>lckpwdf</emphasis> returns -1. When both locks are
      acquired 0 is returned.
    </para>
  </refsect1>
  
  <refsect1 id='diagnostics'>
    <title>DIAGNOSTICS</title>
    <para>Routines return NULL if no more entries are available or if an
      error occurs during processing. Routines which have <emphasis
      remap='B'>int</emphasis> as the return value return 0 for success and
      -1 for failure.
    </para>
  </refsect1>
  
  <refsect1 id='caveats'>
    <title>CAVEATS</title>
    <para>These routines may only be used by the super user as access to the
      shadow password file is restricted.
    </para>
  </refsect1>
  
  <refsect1 id='files'>
    <title>FILES</title>
    <variablelist>
      <varlistentry>
        <term><filename>/etc/shadow</filename></term>
        <listitem>secure user account information</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
  
  <refsect1 id='see_also'>
    <title>SEE ALSO</title>
    <para><citerefentry>
        <refentrytitle>getpwent</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>shadow</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>
    </para>
  </refsect1>
  
  <refsect1 id='author'>
    <title>AUTHOR</title>
    <para>Julianne Frances Haugh (jockgrrl@ix.netcom.com)</para>
  </refsect1>
</refentry>
