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156 lines
7.7 KiB
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<META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.7.4">
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<TITLE>phpgwapi - VFS Class: Relativity</TITLE>
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<LINK HREF="vfs-5.html" REL=next>
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<LINK HREF="vfs-3.html" REL=previous>
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<LINK HREF="vfs.html#toc4" REL=contents>
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<A HREF="vfs-5.html">Next</A>
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<A HREF="vfs.html#toc4">Contents</A>
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<H2><A NAME="sec:relativity"></A> <A NAME="s4">4.</A> <A HREF="vfs.html#toc4">Relativity</A></H2>
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<P>Ok, just one last thing before we get into relativity. You will notice
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throughout the examples the use of $fakebase. $phpgw->vfs>fakebase
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is by default "/home". The old VFS was hard-coded to use "/home", but the naming
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choice for this is now up to administrators. See the "Notes - Fakebase directory"
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section for more information. Throughout the rest of this document, you will
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see $fakebase used in calls to the VFS, and /home used in actual paths.
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<EM>You should always use $fakebase when making applications. </EM>I suggest
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doing $fakebase = $phpgw->vfs->fakebase; right off the
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bat to keep things neater.</P>
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<H2><A NAME="ss4.1">4.1</A> <A HREF="vfs.html#toc4.1">What is it and how does it work?</A>
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</H2>
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<P>One of the design challenges for a Virtual File System is to try to figure
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out whether the calling application is referring to a file inside or outside
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the virtual root, and if inside, exactly where. To solve this problem, the
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phpGroupWare VFS uses RELATIVE defines that are used in bitmasks passed to
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each function. The result is that any set of different relativities can be
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used in combination with each other. Let's look at a few examples. Say you
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want to move "logo.png" from the user's home directory to the current directory.</P>
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<P>
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<PRE>
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$phpgw->vfs->mv ("logo.png", "", array (RELATIVE_USER, RELATIVE_ALL));
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</PRE>
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</P>
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<P>RELATIVE_USER means relative to the user's home directory. RELATIVE_ALL
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means relative to the current directory, as set by cd () and as reported by
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pwd (). So if the current directory was "$fakebase/my_group/project1",
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the call to mv () would be processed as:</P>
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<P>
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<PRE>
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MOVE "$fakebase/jason/logo.png" TO "$fakebase/my_group/project1/logo.png"
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</PRE>
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</P>
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<P>and the actual file system call would be:</P>
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<P>
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<PRE>
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rename ("/var/www/phpgroupware/files/home/jason/logo.php", "/var/www/phpgroupware/files/home/my_group/project1/logo.png");
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</PRE>
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</P>
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<P>Those used to the old VFS will note that you do not have to translate the
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path beforehand. Let's look at another example. Suppose you were moving an
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email attachment stored in phpGroupWare's temporary directory to the "attachments"
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directory within the user's home directory (we're assuming the attachments
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directory exists). Note that the temporary directory is <EM>outside</EM> the virtual
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root.</P>
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<P>
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<PRE>
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$phpgw->vfs->mv ("$phpgw_info[server][temp_dir]/$randomdir/$randomfile", "attachments/actual_name.ext", array (RELATIVE_NONE|VFS_REAL, RELATIVE_USER));
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</PRE>
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</P>
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<P>$randomdir and $randomfile are what the directory and file
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might be called before they are given a proper name by the user, which is actual_name.ext
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in this example. RELATIVE_NONE is the define for using full path names. However,
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RELATIVE_NONE is still relative to the virtual root, so we pass along VFS_REAL
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as well, to say that the file is <EM>outside</EM> the virtual root, somewhere else in
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the file system. Once again, RELATIVE_USER means relative to the user's home
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directory. So the actual file system call might look like this (keep in mind
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that $randomdir and $randomfile are just random strings):</P>
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<P>
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<PRE>
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rename ("/var/www/phpgroupware/tmp/0ak5adftgh7/jX42sC9M", "/var/www/phpgroupware/files/home/jason/attachments/actual_name.ext");
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</PRE>
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</P>
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<P>Of course you don't have to know that, nor should you be concerned with
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it; you can take it for granted that the VFS will translate the paths correctly.
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Let's take a look at one more example, this time using the RELATIVE_USER_APP
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define. RELATIVE_USER_APP is used to store quasi-hidden application files,
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similar to the Unix convention of ~/.appname. It simply appends .appname
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to the user's home directory. For example, if you were making an HTML editor
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application named htmledit, and wanted to keep a backup file in case something
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goes wrong, you would use RELATIVE_USER_APP to store it:</P>
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<P>
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<PRE>
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$phpgw->vfs->write ("file.name~", array (RELATIVE_USER_APP), $contents);
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</PRE>
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</P>
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<P>This assumes that ~/.htmledit exists of course. The backup file "file.name~"
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would then be written in $fakebase/jason/.htmledit/file.name~.
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Note that storing files like this might not be as good of a solution as storing
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them in the temporary directory or in the database. But it is there in case
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you need it.</P>
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<H2><A NAME="sec:relatives_complete_list"></A> <A NAME="ss4.2">4.2</A> <A HREF="vfs.html#toc4.2">Complete List</A>
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</H2>
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<P>Here is the complete list of RELATIVE defines, and what they do:</P>
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<P>
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<DL>
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<DT><B>RELATIVE_ROOT</B><DD><P>Don't translate the path at all. Just prepends a /.
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You'll probably want to use RELATIVE_NONE though, which handles both virtual
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and real files.</P>
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<DT><B>RELATIVE_USER</B><DD><P>User's home directory</P>
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<DT><B>RELATIVE_CURR_USER</B><DD><P>Current user's home directory. If the current
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directory is $fakebase/my_group/project1, this will return is $fakebase/my_group</P>
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<DT><B>RELATIVE_USER_APP</B><DD><P>Append .appname to the user's home directory, where
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appname is the current application's appname</P>
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<DT><B>RELATIVE_PATH</B><DD><P>DO NOT USE. Relative to the current directory, used
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in RELATIVE_ALL</P>
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<DT><B>RELATIVE_NONE</B><DD><P>Not relative to anything. Use this with VFS_REAL for
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files outside the virtual root. Note that using RELATIVE_NONE by itself still
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means relative to the virtual root</P>
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<DT><B>RELATIVE_CURRENT</B><DD><P>An alias for the currently set RELATIVE define,
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or RELATIVE_ALL if none is set (see the Defaults section)</P>
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<DT><B>VFS_REAL</B><DD><P>File is outside of the virtual root. Usually used with RELATIVE_NONE</P>
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<DT><B>RELATIVE_ALL</B><DD><P>Relative to the current directory. Use RELATIVE_ALL<EM></EM>instead of RELATIVE_PATH</P>
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</DL>
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</P>
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<H2><A NAME="sec:relatives_defaults"></A> <A NAME="ss4.3">4.3</A> <A HREF="vfs.html#toc4.3">Defaults</A>
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</H2>
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<P>You might be thinking to yourself that passing along RELATIVE defines with
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every VFS call is overkill, especially if your application always uses the
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same relativity. The default RELATIVE define for all VFS calls is RELATIVE_CURRENT.
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RELATIVE_CURRENT itself defaults to RELATIVE_ALL (relative to the current path),
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<EM>unless</EM> your application sets a specific relativity. If your application requires
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most of the work to be done outside of the virtual root, you may wish to set
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RELATIVE_CURRENT to RELATIVE_NONE|VFS_REAL. set_relative () is the function
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to do this. For example:</P>
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<P>
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<PRE>
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$phpgw->vfs->set_relative (RELATIVE_NONE|VFS_REAL);
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$phpgw->vfs->read ("/etc/passwd");
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$phpgw->vfs->cp ("/usr/include/stdio.h", "/tmp/stdio.h");
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$phpgw->vfs->cp ("/usr/share/pixmaps/yes.xpm", "icons/yes.xpm", array (RELATIVE_CURRENT, RELATIVE_USER));
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</PRE>
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</P>
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<P>You should notice that no relativity array is needed in the other calls
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that refer to files outside the virtual root, but one is needed for calls that
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include files inside the virtual root. Any RELATIVE define can be set as the
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default and works in the same fashion. To retrieve the currently set define,
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use get_relative (). Note that the relativity is reset after each page request;
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that is, it's good only for the life of the current page loading, and is not
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stored in session management.</P>
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