shadow/man/shadow.3.xml

<?xml version="1.0" encoding="UTF-8"?>
<refentry id='shadow.3'>
  <!--  $Id: shadow.3.xml,v 1.22 2006/11/12 19:20:34 kloczek Exp $ -->
  <refmeta>
    <refentrytitle>shadow</refentrytitle>
    <manvolnum>3</manvolnum>
    <refmiscinfo class="sectdesc">Library Calls</refmiscinfo>
  </refmeta>
  <refnamediv id='name'>
    <refname>shadow</refname>
    <refname>getspnam</refname>
    <refpurpose>encrypted password file routines</refpurpose>
  </refnamediv>

  <refsect1 id='syntax'>
    <title>SYNTAX</title>
    <para>
      <emphasis>#include &lt;shadow.h&gt;</emphasis>
    </para>

    <para>
      <emphasis>struct spwd *getspent();</emphasis>
    </para>

    <para>
      <emphasis>struct spwd *getspnam(char</emphasis> <emphasis
      remap='I'>*name</emphasis><emphasis>);</emphasis>
    </para>

    <para>
      <emphasis>void setspent();</emphasis>
    </para>

    <para>
      <emphasis>void endspent();</emphasis>
    </para>

    <para>
      <emphasis>struct spwd *fgetspent(FILE</emphasis> <emphasis
      remap='I'>*fp</emphasis><emphasis>);</emphasis>
    </para>

    <para>
      <emphasis>struct spwd *sgetspent(char</emphasis> <emphasis
      remap='I'>*cp</emphasis><emphasis>);</emphasis>
    </para>

    <para>
      <emphasis>int putspent(struct spwd</emphasis> <emphasis
      remap='I'>*p,</emphasis> <emphasis>FILE</emphasis> <emphasis
      remap='I'>*fp</emphasis><emphasis>);</emphasis>
    </para>

    <para>
      <emphasis>int lckpwdf();</emphasis>
    </para>

    <para>
      <emphasis>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>getspent</emphasis>, <emphasis>getspname</emphasis>,
      <emphasis>fgetspent</emphasis>, and <emphasis>sgetspent</emphasis>
      each return a pointer to a <emphasis>struct spwd</emphasis>.
      <emphasis>getspent</emphasis> returns the next entry from the file,
      and <emphasis>fgetspent</emphasis> returns the next entry from the
      given stream, which is assumed to be a file of the proper format.
      <emphasis>sgetspent</emphasis> returns a pointer to a <emphasis>struct
      spwd</emphasis> using the provided string as input.
      <emphasis>getspnam</emphasis> searches from the current position in
      the file for an entry matching <emphasis>name</emphasis>.
    </para>

    <para>
      <emphasis>setspent</emphasis> and <emphasis>endspent</emphasis> may be
      used to begin and end, respectively, access to the shadow password
      file.
    </para>
    
    <para>
      The <emphasis>lckpwdf</emphasis> and <emphasis>ulckpwdf</emphasis>
      routines should be used to insure exclusive access to the
      <filename>/etc/shadow</filename> file.  <emphasis>lckpwdf</emphasis>
      attempts to acquire a lock using <emphasis>pw_lock</emphasis> for up
      to 15 seconds. It continues by attempting to acquire a second lock
      using <emphasis>spw_lock</emphasis> for the remainder of the initial
      15 seconds. Should either attempt fail after a total of 15 seconds,
      <emphasis>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>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 superuser 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>
	  <para>Secure user account information.</para>
	</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>
</refentry>