meillo@0: .H0 "Work Report
meillo@0: .P
meillo@0: foo
meillo@0: .P
meillo@0: bar
meillo@0: 
meillo@12: .H1 "Removal of Code Relicts
meillo@0: .P
meillo@12: The code base of mmh originates in the late 70s, had been extensively
meillo@12: worked on in the mid 80s, and had been partly reorganized and extended
meillo@12: in the 90s. Relicts of all those times had gathered in the code base.
meillo@12: My goal was to remove any ancient code parts. One part of the task was
meillo@12: converting obsolete code constructs to standard constructs, the other part
meillo@12: was dropping obsolete functions.
meillo@12: .P
meillo@12: As I'm not even thirty years old and have no more than seven years of
meillo@12: Unix experience, I needed to learn about the history in retroperspective.
meillo@12: Older people likely have used those ancient constructs themself
meillo@12: and have suffered from their incompatiblities and have longed for
meillo@12: standardization. Unfortunately, I have only read that others had done so.
meillo@12: This put me in a much more difficult positions when working on the old
meillo@12: code. I needed to recherche what other would have known by heart from
meillo@12: experience. All my programming experience comes from a time past ANSI C
meillo@12: and past POSIX. Although I knew about the times before, I took the
meillo@12: current state implicitely for granted most of the time.
meillo@12: .P
meillo@12: Being aware of
meillo@12: these facts, I rather let people with more historic experience solve the 
meillo@12: task of converting the ancient code constructs to standardized ones.
meillo@12: Luckily, Lyndon Nerenberg focused on this task at the nmh project.
meillo@12: He converted large parts of the code to POSIX constructs, removing
meillo@12: the conditionals compilation for now standardized features.
meillo@12: I'm thankful for this task being solved. I only pulled the changes into
meillo@12: mmh.
meillo@12: .P
meillo@12: The other task of dropping ancient functionality to remove old code,
meillo@12: I did myself, though. My position to strip mmh to the bare minimum of
meillo@12: frequently used features is much more revolutional than the nmh community
meillo@12: sees it. Without the need to justify my decisions, I was able to quickly
meillo@12: remove code I considered ancient. The need to discuss my decisions with
meillo@12: peers likely would have slowed this process down. Of course, I did research
meillo@12: if a particular feature really should be dropped. Having not had any
meillo@12: contact to this feature within my computer life was a first indicator to
meillo@12: drop it, but I also asked others and searched the literature for modern
meillo@12: usage of the feature. If it appeared to be truly ancient, I dropped it.
meillo@12: The reason for dropping is always part of the commit message in the
meillo@12: version control system. Thus, it is easy for others to check their
meillo@12: view on the topic with mine and possibly to argue for reinclusion.
meillo@12: 
meillo@12: .U2 "MMDF maildrop support
meillo@12: .P
meillo@12: I did drop any support for the MMDF maildrop format. This type of format
meillo@12: is conceptionally similar to the mbox format, but uses four bytes with
meillo@12: value 1 (\fL^A^A^A^A\fP) as message delimiter,
meillo@12: instead of the string ``\fLFrom\0\fP''.
meillo@12: Due to the similarity and mbox being the de-facto standard maildrop
meillo@12: format on Unix, but also due to the larger influence of Sendmail than MMDF,
meillo@12: the MMDF maildrop format had vanished.
meillo@12: .P
meillo@12: The simplifications within the code were only moderate. Switches could
meillo@12: be removed from tools like
meillo@12: .L packf ,
meillo@12: which generate packed mailboxes. Only one packed mailbox format remained:
meillo@12: mbox.
meillo@12: The most important changes affect the equally named mail parsing routine in
meillo@12: .L sbr/m_getfld.c .
meillo@12: The direct MMDF code had been removed, but as now only one packed mailbox
meillo@12: format is left, code structure simplifications are likely possible.
meillo@12: The reason why they are still outstanding is the heavily optimized code
meillo@12: of \fLm_getfld()\fP. Changes beyond a small local scope \(en
meillo@12: which restructuring in its core is \(en cause a high risk of damaging
meillo@12: the intricate workings of the optimized code. This problem is know
meillo@12: to the developers of nmh, too. They also avoid touching this minefield
meillo@12: if possible.
meillo@12: 
meillo@12: .U2 "UUCP Bang Paths
meillo@12: .P
meillo@12: More questionably than the former topic is the removal of support for the
meillo@12: UUCP bang path address style. However, the user may translate the bang
meillo@12: paths on retrieval to Internet addresses and the other way on posting
meillo@12: messages. The former can be done my an MDA like procmail; the latter
meillo@12: by a sendmail wrapper. This would ensure that any address handling would
meillo@12: work as expected. However, it might just work well without any
meillo@12: such modifications, as mmh does not touch addresses much, in general.
meillo@12: But I can't ensure as I have never used an environment with bang paths.
meillo@12: Also, the behavior might break at any point in further development.
meillo@12: 
meillo@12: .U2 "Hardcopy terminal support
meillo@12: .P
meillo@12: More of a funny anecdote is the remaining of a check for printing to a
meillo@12: hardcopy terminal until Spring 2012, when I finally removed it.
meillo@12: I surely would be very happy to see such a terminal in action, maybe
meillo@12: actually being able to work on it, but I fear my chances are null.
meillo@12: .P
meillo@12: The check only prevented a pager to be placed between the outputting
meillo@12: program (\fLmhl\fP) and the terminal. This could have been ensured with
meillo@12: the \fL-nomoreproc\fP at the command line statically, too.
meillo@12: 
meillo@12: .U2 "Removed support for header fields
meillo@12: .P
meillo@12: The `Encrypted' header had been introduced by RFC\^822, but already
meillo@12: marked legacy in RFC 2822. It was superseded by FIXME.
meillo@12: Mmh does no more support this header.
meillo@12: .P
meillo@12: `Content-MD5' headers were introduced by RFC\^1864. They provide only
meillo@12: a verification of data corruption during the transfer. By no means can
meillo@12: they ensure verbatim end-to-end delivery of the contents. This is clearly
meillo@12: stated in the RFC. The proper approach to provide verificationability
meillo@12: of content in an end-to-end relationship is the use of digital cryptography
meillo@12: (RFCs FIXME). On the other hand, transfer protocols should ensure the
meillo@12: integrity of the transmission. In combinations these two approaches
meillo@12: make the `Content-MD5' header field useless. In consequence, I removed
meillo@12: the support for it. By this removal, MD5 computation is not needed
meillo@12: anywhere in mmh. Hence, over 500 lines of code were removed by this one
meillo@12: change. Even if the `Content-MD5' header field is useful sometimes,
meillo@12: I value its usefulnes less than the improvement in maintainability, caused
meillo@12: by the removal.
meillo@12: 
meillo@12: 
meillo@0: 
meillo@0: .H1 "Paths to ...
meillo@0: .P
meillo@0: foo
meillo@0: 
meillo@0: .H1 "Path Notations
meillo@0: .P
meillo@0: foo
meillo@0: 
meillo@0: .H1 "Attachments
meillo@0: .P
meillo@0: foo
meillo@0: 
meillo@0: .H1 "Blind Carbon Copies
meillo@0: .P
meillo@0: foo
meillo@0: 
meillo@0: .H1 "Good Defaults
meillo@0: .P
meillo@0: foo
meillo@0: 
meillo@0: .H1 "Modularization
meillo@0: .P
meillo@0: foo
meillo@0: 
meillo@0: .H1 "Code style
meillo@0: .P
meillo@0: foo