folder/Maildir: Store only relative filename components

MaildirFolder.messagelist[*]['filename'] was storing the absolute file
paths for all stored emails. While this is convenient, it wastes much
space, as the folder prefix is always the same and it is known to the
MaildirFolder. Just 40 chars in a folder with 100k mails waste >4MB of
space. Adapt the few locations where we need the full path to construct
it dynamically.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

offlineimap/folder/Maildir.py

@@ -185,27 +185,32 @@ class MaildirFolder(BaseFolder):
         return self.messagelist
 
     def getmessage(self, uid):
+        """Return the content of the message"""
         filename = self.messagelist[uid]['filename']
-        file = open(filename, 'rt')
+        filepath = os.path.join(self.getfullname(), filename)
+        file = open(filepath, 'rt')
         retval = file.read()
         file.close()
+        #TODO: WHY are we replacing \r\n with \n here? And why do we
+        #      read it as text?
         return retval.replace("\r\n", "\n")
 
     def getmessagetime( self, uid ):
         filename = self.messagelist[uid]['filename']
-        st = os.stat(filename)
+        filepath = os.path.join(self.getfullname(), filename)
+        st = os.stat(filepath)
         return st.st_mtime
 
     def savemessage(self, uid, content, flags, rtime):
         # This function only ever saves to tmp/,
         # but it calls savemessageflags() to actually save to cur/ or new/.
-        self.ui.debug('maildir', 'savemessage: called to write with flags %s and content %s' % \
+        self.ui.debug('maildir', 'savemessage: called to write with flags %s '
-                 (repr(flags), repr(content)))
+                      'and content %s' % (repr(flags), repr(content)))
         if uid < 0:
             # We cannot assign a new uid.
             return uid
         if uid in self.messagelist:
-            # We already have it.
+            # We already have it, just update flags.
             self.savemessageflags(uid, flags)
             return uid
 
@@ -231,7 +236,8 @@ class MaildirFolder(BaseFolder):
             else:
                 break
         tmpmessagename = messagename.split(',')[0]
-        self.ui.debug('maildir', 'savemessage: using temporary name %s' % tmpmessagename)
+        self.ui.debug('maildir', 'savemessage: using temporary name %s' %\
+                          tmpmessagename)
         file = open(os.path.join(tmpdir, tmpmessagename), "wt")
         file.write(content)
 
@@ -239,10 +245,10 @@ class MaildirFolder(BaseFolder):
         file.flush()
         if self.dofsync:
             os.fsync(file.fileno())
-
         file.close()
+
         if rtime != None:
-            os.utime(os.path.join(tmpdir,tmpmessagename), (rtime,rtime))
+            os.utime(os.path.join(tmpdir, tmpmessagename), (rtime, rtime))
         self.ui.debug('maildir', 'savemessage: moving from %s to %s' % \
                  (tmpmessagename, messagename))
         if tmpmessagename != messagename: # then rename it
@@ -259,7 +265,8 @@ class MaildirFolder(BaseFolder):
                 pass
 
         self.messagelist[uid] = {'uid': uid, 'flags': [],
-                                 'filename': os.path.join(tmpdir, messagename)}
+                                 'filename': os.path.join('tmp', messagename)}
+        # savemessageflags moves msg to 'cur' or 'new' as appropriate
         self.savemessageflags(uid, flags)
         self.ui.debug('maildir', 'savemessage: returning uid %d' % uid)
         return uid
@@ -269,14 +276,14 @@ class MaildirFolder(BaseFolder):
 
     def savemessageflags(self, uid, flags):
         oldfilename = self.messagelist[uid]['filename']
-        newpath, newname = os.path.split(oldfilename)
+        dir_prefix, newname = os.path.split(oldfilename)
         tmpdir = os.path.join(self.getfullname(), 'tmp')
         if 'S' in flags:
             # If a message has been seen, it goes into the cur
-            # directory.  CR debian#152482, [complete.org #4]
+            # directory.  CR debian#152482
-            newpath = os.path.join(self.getfullname(), 'cur')
+            dir_prefix = 'cur'
         else:
-            newpath = os.path.join(self.getfullname(), 'new')
+            dir_prefix = 'new'
         infostr = ':'
         infomatch = re.search('(:.*)$', newname)
         if infomatch:                   # If the info string is present..
@@ -287,15 +294,16 @@ class MaildirFolder(BaseFolder):
         infostr += '2,' + ''.join(flags)
         newname += infostr
         
-        newfilename = os.path.join(newpath, newname)
+        newfilename = os.path.join(dir_prefix, newname)
         if (newfilename != oldfilename):
-            os.rename(oldfilename, newfilename)
+            os.rename(os.path.join(self.getfullname(), oldfilename),
+                      os.path.join(self.getfullname(), newfilename))
             self.messagelist[uid]['flags'] = flags
             self.messagelist[uid]['filename'] = newfilename
 
         # By now, the message had better not be in tmp/ land!
         final_dir, final_name = os.path.split(self.messagelist[uid]['filename'])
-        assert final_dir != tmpdir
+        assert final_dir != 'tmp'
 
     def deletemessage(self, uid):
         """Unlinks a message file from the Maildir.
@@ -309,13 +317,16 @@ class MaildirFolder(BaseFolder):
             return
 
         filename = self.messagelist[uid]['filename']
+        filepath = os.path.join(self.getfullname(), filename)
         try:
-            os.unlink(filename)
+            os.unlink(filepath)
         except OSError:
             # Can't find the file -- maybe already deleted?
             newmsglist = self._scanfolder()
             if uid in newmsglist:       # Nope, try new filename.
-                os.unlink(newmsglist[uid]['filename'])
+                filename = newmsglist[uid]['filename']
+                filepath = os.path.join(self.getfullname(), filename)
+                os.unlink(filepath)
             # Yep -- return.
         del(self.messagelist[uid])