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Subject svn commit: r1761274 - /httpd/httpd/branches/2.4.x/docs/manual/expr.xml
Date Sat, 17 Sep 2016 20:41:07 GMT
Author: covener
Date: Sat Sep 17 20:41:07 2016
New Revision: 1761274

Merge r1761272 from trunk:

expand third common in the expression functions doc

Explain some risks at looking at per-request environment variables
set by other modules within <If>.


Modified: httpd/httpd/branches/2.4.x/docs/manual/expr.xml
--- httpd/httpd/branches/2.4.x/docs/manual/expr.xml (original)
+++ httpd/httpd/branches/2.4.x/docs/manual/expr.xml Sat Sep 17 20:41:07 2016
@@ -464,7 +464,7 @@ listfunction ::= listfuncname "<strong>(
     <table border="1" style="zebra">
     <columnspec><column width=".2"/><column width=".4"/><column width=".4"/></columnspec>
-    <tr><th>Name</th><th>Description</th><th>Restricted</th></tr>
+    <tr><th>Name</th><th>Description</th><th>Special
     <tr><td><code>req</code>, <code>http</code></td>
         <td>Get HTTP request header; header names may be added to the Vary
             header, see below</td><td></td></tr>
@@ -475,15 +475,15 @@ listfunction ::= listfuncname "<strong>(
         <td>Get HTTP response header</td><td></td></tr>
         <td>Lookup request environment variable (as a shortcut,
-        <code>v</code> can be used too to access
-        variables).</td><td></td></tr>
+        <code>v</code> can also be used to access variables). 
+        <td>ordering</td></tr>
         <td>Lookup operating system environment variable</td><td></td></tr>
-        <td>Lookup request note</td><td></td></tr>
+        <td>Lookup request note</td><td>ordering</td></tr>
         <td>Return first match of <code>note</code>, <code>reqenv</code>,
-            <code>osenv</code></td><td></td></tr>
+            <code>osenv</code></td><td>ordering</td></tr>
         <td>Convert string to lower case</td><td></td></tr>
@@ -506,15 +506,39 @@ listfunction ::= listfuncname "<strong>(
         <td>Read contents from a file (including line endings, when present)
-        </td><td>yes</td></tr>
+        </td><td>restricted</td></tr>
+    <tr><td><code>filemod</code></td>
+        <td>Return last modification time of a file (or 0 if file does not exist
+            or is not regular file)</td><td>restricted</td></tr>
         <td>Return size of a file (or 0 if file does not exist or is not
-            regular file)</td><td>yes</td></tr>
+            regular file)</td><td>restricted</td></tr>
-    <p>The functions marked as "restricted" are not available in some modules
-    like <module>mod_include</module>.</p>
+    <p>The functions marked as "restricted" in the final column are not 
+    available in some modules like <module>mod_include</module>.</p>
+    <p>The functions marked as "ordering" in the final column require some
+    consideration for the ordering of different components of the server,
+    especially when the function is used within the 
+    &lt;<directive module="core">If</directive>&gt; directive which is
+    evaluated relatively early.</p>
+    <note>
+    <title>Environment variable ordering</title>
+    When environment variables are looked up within an 
+    &lt;<directive module="core">If</directive>&gt; condition, it's important

+    to consider how extremely early in request processing that this 
+    resolution occurs. As a guideline, any directive defined outside of virtual host 
+    context (directory, location, htaccess) is not likely to have yet had a 
+    chance to execute. <directive module="mod_setenvif">SetEnvIf</directive>
+    in virtual host scope is one directive that runs prior to this resolution
+    <br/>
+    <br/>
+    When <code>reqenv</code> is used outside of &lt;<directive module="core"
+    >If</directive>&gt;, the resolution will generally occur later, but the

+    exact timing depends on the directive the expression has been used within.
+    </note>
     <p>When the functions <code>req</code> or <code>http</code>
are used,
     the header name will automatically be added to the Vary header of the

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