[incubator-ponymail-foal] branch master updated: add back mboxo file in the right place

[hu...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

humbedooh pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-ponymail-foal.git


The following commit(s) were added to refs/heads/master by this push:
     new 63392e7  add back mboxo file in the right place
63392e7 is described below

commit 63392e76b9c28c4ecccc1b6204786e9aecbea4b9
Author: Daniel Gruno <hu...@apache.org>
AuthorDate: Wed Aug 26 13:41:29 2020 +0200

    add back mboxo file in the right place
---
 tools/plugins/mboxo_patch.py | 97 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)

diff --git a/tools/plugins/mboxo_patch.py b/tools/plugins/mboxo_patch.py
new file mode 100644
index 0000000..a577567
--- /dev/null
+++ b/tools/plugins/mboxo_patch.py
@@ -0,0 +1,97 @@
+# -*- coding: utf-8 -*-
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Byte stream reader to process mboxo style mailbox files.
+These are not currently handled by the Python email package.
+
+It replaces any occurrence of b'\n>From ' with b'\nFrom '
+
+The class handles matching across read boundaries.
+
+To use:
+
+from mboxo_patch import MboxoFactory
+...
+messages = mailbox.mbox(filename, MboxoFactory)
+
+N.B.
+To simplify the code, the MboxoReader class changes the
+size parameter to 7 if (and only if): 0 <= size < 7
+The return byte buffer can thus be larger than expected.
+However this is only a theoretical possibility
+as the mailbox code uses a size of 8192 (or None)
+
+"""
+import mailbox
+
+FROM_MANGLED  =b'\n>From '
+FROM_MANGLED_LEN=len(FROM_MANGLED)
+FROM_UNMANGLED=b'\nFrom '
+# We want to match the 7 bytes b'\n>From ' in the input stream
+# However this can be split over multiple reads.
+# The split can occur anywhere after the leading b'\n'
+# and the trailing b' '. If we match any of these
+# we keep the trailing part of the buffer for next time
+# The following are all the possible prefixes for a split:
+FROMS=(FROM_MANGLED[:-1],
+       FROM_MANGLED[:-2],
+       FROM_MANGLED[:-3],
+       FROM_MANGLED[:-4],
+       FROM_MANGLED[:-5],
+       FROM_MANGLED[:-6],
+       )
+
+class MboxoReader(mailbox._PartialFile): # pylint: disable=W0212
+    def __init__(self, f, start=None, stop=None):
+        self.remain=0 # number of bytes to keep for next read
+        super().__init__(f._file, start=f._start, stop=f._stop) # pylint: disable=W0212
+
+    # Override the read method to provide mboxo filtering
+    def _read(self, size, read_method):
+        # get the next chunk, resetting if necessary
+        if self.remain != 0:
+            super().seek(whence=1, offset=-self.remain)
+        # if size is None or negative, then read returns everything.
+        # in which case there is no need to wory about matching across reads
+        limited_read = size and size >= 0
+        # ensure we get enough to match successfully when refilling
+        if limited_read and size < FROM_MANGLED_LEN:
+            size = FROM_MANGLED_LEN
+        buff = super()._read(size, read_method)
+        bufflen=len(buff)
+        # did we get anything new?
+        if limited_read and bufflen > self.remain:
+            # is there a potential cross-boundary match?
+            if buff.endswith(FROMS):
+                # yes, work out what to keep
+                # N.B. rindex will fail if it cannot find the LF;
+                # this should be impossible
+                self.remain=bufflen - buff.rindex(b'\n')
+            else:
+                # don't need to keep anything back
+                self.remain=0
+        else:
+            # EOF
+            self.remain=0
+        # we cannot use -0 to mean end of array...
+        end = bufflen if self.remain == 0 else -self.remain
+        # exclude the potential split match from the return
+        return buff[:end].replace(FROM_MANGLED, FROM_UNMANGLED)
+
+class MboxoFactory(mailbox.mboxMessage):
+    def __init__(self, message=None):
+        super().__init__(message=MboxoReader(message))