[Proftpd-docs] www.proftpd.org/docs/howto FTP.html,1.2,1.3

[TJ S. <cas...@us...>]

Update of /cvsroot/pdd/www.proftpd.org/docs/howto
In directory sfp-cvs-1.v30.ch3.sourceforge.com:/tmp/cvs-serv10577

Modified Files:
	FTP.html 
Log Message:

Updated website copy of FTP howto.


Index: FTP.html
===================================================================
RCS file: /cvsroot/pdd/www.proftpd.org/docs/howto/FTP.html,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -d -r1.2 -r1.3
--- FTP.html	12 Oct 2012 15:23:16 -0000	1.2
+++ FTP.html	27 Dec 2012 18:30:08 -0000	1.3
@@ -337,7 +337,7 @@
 <pre>
   SITE MKDIR /path/to/some/dir/that/is/not/there/
 </pre>
-    Supported by the <code>mod_site_misc</code> module.
+    Supported by the <a href="../contrib/mod_site_misc.html"><code>mod_site_misc</code></a> module.
   </li>
 
   <p>
@@ -350,7 +350,7 @@
 <pre>
   SITE RMDIR /path/to/some/dir/with/files/
 </pre>
-    Supported by the <code>mod_site_misc</code> module.
+    Supported by the <a href="../contrib/mod_site_misc.html"><code>mod_site_misc</code></a> module.
   </li>
 
   <p>
@@ -362,7 +362,7 @@
 <pre>
   SITE SYMLINK src dest
 </pre>
-    Supported by the <code>mod_site_misc</code> module.
+    Supported by the <a href="../contrib/mod_site_misc.html"><code>mod_site_misc</code></a> module.
   </li>
 
   <p>
@@ -373,9 +373,8 @@
 <pre>
   SITE UTIME 200412312359 /path/to/some/file.txt
 </pre>
-    Supported by the <code>mod_site_misc</code> module.
+    Supported by the <a href="../contrib/mod_site_misc.html"><code>mod_site_misc</code></a> module.
   </li>
-
 </ul>
 
 <p>
@@ -408,6 +407,57 @@
   </li>
 </ul>
 
+<p><a name="FAQ">
+<b>Frequently Asked Questions</b>
+
+<p><a name="MoveDirectoriesAcrossDevices">
+<font color=red>Question</font>: I can use the <code>RNFR</code> and
+<code>RNTO</code> commands to <i>move</i> a file, even across different
+disks/mount points.  And I can use <code>RNFR</code>/<code>RNTO</code> to move
+a directory, <b>but</b> I <b>cannot</b> move a directory across different
+disks/mount points.  Is this a bug?<br>
+<font color=blue>Answer</font>: No, it is not a bug.  Why not?  Ultimately,
+it is because the FTP specifications do not guarantee (or even <i>discuss</i>)
+that an FTP implementation must support renaming of directories across
+mount points.
+<p>
+
+<p>
+ProFTPD implements the <code>RNFR</code>/<code>RNTO</code> functionality
+by using the <code>rename(2)</code> system call.  And <code>rename(2)</code>
+is documented to <b>not</b> work across mount points.
+
+<p>
+"But then why does it work when I rename a file across mount points?" you
+ask.  Good question.  The answer is that for <b>files only</b>, ProFTPD
+detects the <code>rename(2)</code> error for renaming across mount points,
+and then <i>copies</i> the file in question to the new location, deleting
+the old location when the copy completes successfully.
+
+<p>
+"Great!" you say, "Now do the same thing for directories!" Unfortunately, for
+directories, the answer is not that simple.  Here are some things to consider
+when copying directories: what if the directory contains sockets, FIFOs,
+devices, and other irregular file types which cannot be easily copied/moved?
+Should copying/moving of directories automatically use root privileges in
+order to preserve the ownership on files that do not belong to the logged-in
+user?  What if the copying/deleting of files fails in the midde: what should
+then happen to the copied (and remaining) files/directories?
+
+<p>
+Since there are no easy answers as yet to the above questions, ProFTPD now
+detects the <code>rename(2)</code> error for renaming across mount points
+for a <b>directory</b>, and rejects the <code>RNTO</code> command, showing
+something like:
+<pre>
+  RNFR directory
+  350 File or directory exists, ready for destination name
+  RNTO /other/mount/directory
+  550 Rename /other/mount/directory: Is a directory
+</pre>
+That "Is a directory" error indicates that ProFTPD cannot rename a directory
+across the mount points you requested.  (That particular error message can,
+and will, be made more informative.)
 
 <p>
 <hr>