Limit msg body length in debug output

We were outputting full message bodies to the debug log (often stderr),
and then again (as they go over the imaplib2 wire, imaplib logs
everything too). Not only is quite a privacy issue when sending in debug
logs but it can also freeze a console for quite some time. Plus it
bloats debug logs A LOT.

Only output the first and last 100 bytes of each message body to the
debug log (we still get the full body from imaplib2 logging). This
limits privacy issues when handing the log to someone else, but usually
still contains all the interesting bits that we want to see in a log.

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

offlineimap/folder/IMAP.py

@@ -203,17 +203,32 @@ class IMAPFolder(BaseFolder):
         try:
             imapobj.select(self.getfullname(), readonly = 1)
             res_type, data = imapobj.uid('fetch', '%d' % uid, '(BODY.PEEK[])')
+            assert res_type == 'OK', "Fetching message with UID '%d' failed" % uid
+            # data looks now e.g. [('320 (UID 17061 BODY[]
+            # {2565}','msgbody....')]  we only asked for one message,
+            # and that msg is in data[0]. msbody is in [0][1]
+
+            #NB & TODO: When the message on the IMAP server has been
+            #deleted in the mean time, it will respond with an 'OK'
+            #res_type, but it will simply not send any data. This will
+            #lead to a crash in the below line. We need urgently to
+            #detect this, protect from this and need to think about what
+            #to return in this case. Probably returning `None` in this
+            #case would be good. But we need to make sure that all
+            #Backends behave the same, and that we actually check the
+            #return value and behave accordingly.
+            data = data[0][1].replace("\r\n", "\n")
+
+            if len(data)>200:
+                dbg_output = "%s...%s" % (str(data)[:150],
+                                          str(data)[-50:])
+            else:
+                dbg_output = data
+            self.ui.debug('imap', "Returned object from fetching %d: '%s'" %
+                          (uid, dbg_output))
         finally:
             self.imapserver.releaseconnection(imapobj)
-        assert res_type == 'OK', "Fetching message with UID '%d' failed" % uid
+        return data
-        # data looks now e.g. [('320 (UID 17061 BODY[]
-        # {2565}','msgbody....')]  we only asked for one message,
-        # and that msg is in data[0]. msbody is in [0][1]
-        data = data[0][1]
-        self.ui.debug('imap', '%s bytes returned from fetching %d: %s...%s' % \
-                          (len(data), uid, data[0:100], data[-100:]))
-        return data.replace("\r\n", "\n")
-
 
     def getmessagetime(self, uid):
         return self.messagelist[uid]['time']
@@ -410,21 +425,24 @@ class IMAPFolder(BaseFolder):
 
             # get the date of the message file, so we can pass it to the server.
             date = self.getmessageinternaldate(content, rtime)
-            self.ui.debug('imap', 'savemessage: using date %s' % date)
-
             content = re.sub("(?<!\r)\n", "\r\n", content)
 
             if not use_uidplus:
                 # insert a random unique header that we can fetch later
                 (headername, headervalue) = self.generate_randomheader(content)
-                self.ui.debug('imap', 'savemessage: new headers are: %s: %s' % \
+                self.ui.debug('imap', 'savemessage: new header is: %s: %s' % \
                              (headername, headervalue))
                 content = self.savemessage_addheader(content, headername,
                                                      headervalue)    
-            self.ui.debug('imap', 'savemessage: content is: ' + repr(content))
+            if len(content)>200:
+                dbg_output = "%s...%s" % (content[:150],
+                                          content[-50:])
+            else:
+                dbg_output = content
+
+            self.ui.debug('imap', "savemessage: date: %s, content: '%s'" %
+                          (date, dbg_output))
 
-            # TODO: - append could raise a ValueError if the date is not in
-            #         valid format...?
             (typ,dat) = imapobj.append(self.getfullname(),
                                        imaputil.flagsmaildir2imap(flags),
                                        date, content)