Improve openssl-pkcs7-read + example for p7b

The input shall be a string data.

Basic example along with the error cases.

Author: vjardin

reference/openssl/functions/openssl-pkcs7-read.xml

@@ -10,7 +10,7 @@
   &reftitle.description;
   <methodsynopsis>
    <type>bool</type><methodname>openssl_pkcs7_read</methodname>
-   <methodparam><type>string</type><parameter>input_filename</parameter></methodparam>
+   <methodparam><type>string</type><parameter>data</parameter></methodparam>
    <methodparam><type>array</type><parameter role="reference">certificates</parameter></methodparam>
   </methodsynopsis>
   <para>
@@ -25,18 +25,18 @@
   &reftitle.parameters;
   <variablelist>
    <varlistentry>
-    <term><parameter>input_filename</parameter></term>
+    <term><parameter>data</parameter></term>
     <listitem>
      <para>
-      
+      The string of data you wish to parse (p7b format).
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>certificates</parameter></term>
     <listitem>
      <para>
-      
+      The array of PEM certificates from the p7b input data.
      </para>
     </listitem>
    </varlistentry>
@@ -50,6 +50,46 @@
   </para>
  </refsect1>
 
+ <refsect1 role="examples">
+  &reftitle.examples;
+  <para>
+   <example>
+    <title>Get a PEM array from a P7B file</title>
+    <programlisting role="php">
+<![CDATA[
+<?php
+
+$file = 'certs.p7b';
+
+$f = file_get_contents($file);
+$p7 = array();
+$r = openssl_pkcs7_read($f, $p7);
+
+if ($r === false) {
+    printf("ERROR: %s is not a proper p7b file".PHP_EOL, $file);
+        for($e = openssl_error_string(), $i = 0; $e; $e = openssl_error_string(), $i++)
+            printf("SSL l%d: %s".PHP_EOL, $i, $e);
+    exit(1);
+}
+
+print_r($p7);
+?>
+]]>
+    </programlisting>
+   </example>
+
+  </para>
+ </refsect1>
+
+ <refsect1 role="seealso">
+  &reftitle.seealso;
+  <para>
+   <simplelist>
+    <member><function>openssl_csr_sign</function></member>
+   </simplelist>
+  </para>
+ </refsect1>
+
 
 </refentry>
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