eio-read.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->

<refentry xml:id="function.eio-read" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>eio_read</refname>
  <refpurpose>Read from a file descriptor at given offset</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>resource</type><methodname>eio_read</methodname>
   <methodparam><type>mixed</type><parameter>fd</parameter></methodparam>
   <methodparam><type>int</type><parameter>length</parameter></methodparam>
   <methodparam><type>int</type><parameter>offset</parameter></methodparam>
   <methodparam><type>int</type><parameter>pri</parameter></methodparam>
   <methodparam><type>callable</type><parameter>callback</parameter></methodparam>
   <methodparam
   choice="opt"><type>mixed</type><parameter>data</parameter><initializer>NULL</initializer></methodparam>
  </methodsynopsis>
  <para>
   <function>eio_read</function> reads up to <parameter>length</parameter>
   bytes from <parameter>fd</parameter> file descriptor at
   <parameter>offset</parameter>. The read bytes are stored in
   <parameter>result</parameter> argument of <parameter>callback</parameter>.
  </para>

 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>fd</parameter></term>
    <listitem>
     <para>
     Stream, Socket resource, or numeric file descriptor
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>length</parameter></term>
    <listitem>
     <para>
     Maximum number of bytes to read.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>offset</parameter></term>
    <listitem>
     <para>
     Offset within the file.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>pri</parameter></term>
    <listitem>
    &eio.request.pri.values;
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>callback</parameter></term>
    <listitem>
     &eio.callback.proto;
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>data</parameter></term>
    <listitem>
     <para>
     Arbitrary variable passed to <parameter>callback</parameter>.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
  <function>eio_read</function> stores read bytes in
  <parameter>result</parameter> argument of <parameter>callback</parameter>
  function.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title><function>eio_read</function> example</title>
   <programlisting role="php">
<![CDATA[
<?php
// Open a temporary file and write some bytes there
$temp_filename = "eio-temp-file.tmp";
$fp = fopen($temp_filename, "w");
fwrite($fp, "1234567890");
fclose($fp);

/* Is called when eio_read() is done */
function my_read_cb($data, $result) {
    global $temp_filename;

 // Output read bytes
    var_dump($result);

 // Close file
    eio_close($data);
    eio_event_loop();

 // Remove temporary file
    @unlink($temp_filename);
}

/* Is called when eio_open() is done */
function my_file_opened_callback($data, $result) {
 // $result should contain the file descriptor
    if ($result > 0) {
  // Read 5 bytes starting from third
        eio_read($result, 5, 2, EIO_PRI_DEFAULT, "my_read_cb", $result);
        eio_event_loop();
    } else {
  // eio_open() failed
        unlink($data);
    }
}

// Open the file for reading and writing
eio_open($temp_filename, EIO_O_RDWR, NULL,
    EIO_PRI_DEFAULT, "my_file_opened_callback", $temp_filename);
eio_event_loop();
?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
<![CDATA[
string(5) "34567"
]]>
   </screen>
  </example>
 </refsect1>


 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><function>eio_open</function></member>
   <member><function>eio_write</function></member>
   <member><function>eio_close</function></member>
   <member><function>eio_event_loop</function></member>
  </simplelist>
 </refsect1>

</refentry>

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