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@20: The code base of mmh originates from 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@20: The other task \(en dropping ancient functionality to remove old code \(en
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@20: likes it. Without the need to justify my decisions, I was able to quickly
meillo@20: remove functionality I considered ancient.
meillo@20: The need to discuss my decisions with
meillo@20: peers likely would have slowed this process down. Of course, I researched
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@18: instead of the string ``\fLFrom\ \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@18: of
meillo@18: .Fu m_getfld() .
meillo@18: 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@18: program (\c
meillo@18: .Pn mhl )
meillo@18: and the terminal. This could have been ensured with
meillo@18: the
meillo@18: .Sw \-nomoreproc
meillo@18: 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@20: .U2 "Prompter's Control Keys
meillo@20: .P
meillo@20: The program
meillo@20: .Pn prompter
meillo@20: queries the user to fill in a message form. When used by
meillo@20: .Pn comp
meillo@20: as:
meillo@20: .DS
meillo@20: comp \-editor prompter
meillo@20: .DE
meillo@20: the resulting behavior is similar to
meillo@20: .Pn mailx .
meillo@20: Appearently,
meillo@20: .Pn prompter
meillo@20: hadn't been touched lately. Otherwise it's hardly explainable why it
meillo@20: still offered the switches
meillo@20: .Sn \-erase \fUchr\fP
meillo@20: and
meillo@20: .Sn \-kill \fUchr\fP
meillo@20: to name the characters for command line editing.
meillo@20: The times when this had been neccessary are long time gone.
meillo@20: Today these things work out-of-the-box, and if not, are configured
meillo@20: with the standard tool
meillo@20: .Pn stty .
meillo@20: 
meillo@12: 
meillo@14: .H1 "Draft and Trash Folders
meillo@16: .U2 "Draft Folder
meillo@14: .P
meillo@18: Historically, MH provided exactly one draft message, named
meillo@18: .Fn draft
meillo@18: and
meillo@14: being located in the MH directory. When starting to compose another message
meillo@14: before the former one was sent, the user had been questioned wether to use,
meillo@14: refile or replace the old draft. Working on multiple drafts at the same time
meillo@14: was impossible. One could only work on them in alteration by refiling the
meillo@14: previous one to some directory and fetching some other one for reediting. 
meillo@14: This manual draft management needed to be done each time the user wanted
meillo@14: to switch between editing one draft to editing another.
meillo@14: .P
meillo@14: To allow true parallel editing of drafts, in a straight forward way, the
meillo@14: draft folder facility exists. It had been introduced already in July 1984
meillo@14: by Marshall T. Rose. The facility was deactivated by default.
meillo@14: Even in nmh, the draft folder facility remained deactivated by default.
meillo@18: At least, Richard Coleman added the man page
meillo@18: .Mp mh-draft(5)
meillo@18: to document
meillo@14: the feature well.
meillo@14: .P
meillo@14: The only advantage of not using the draft folder facility is the static
meillo@14: name of the draft file. This could be an issue for MH frontends like mh-e.
meillo@14: But as they likely want to provide working on multiple drafts in parallel,
meillo@14: the issue is only concerning compatibility. The aim of nmh to stay compatible
meillo@14: prevented the default activation of the draft folder facility.
meillo@14: .P
meillo@14: On the other hand, a draft folder is the much more natural concept than
meillo@14: a draft message. MH's mail storage consists of folders and messages,
meillo@14: the messages named with ascending numbers. A draft message breaks with this
meillo@18: concept by introducing a message in a file named
meillo@18: .Fn draft .
meillo@18: This draft
meillo@14: message is special. It can not be simply listed with the available tools,
meillo@17: but instead requires special switches. I.e. corner-cases were
meillo@14: introduced. A draft folder, in contrast, does not introduce such
meillo@14: corner-cases. The available tools can operate on the messages within that
meillo@14: folder like on any messages within any mail folders. The only difference
meillo@18: is the fact that the default folder for
meillo@18: .Pn send
meillo@18: is the draft folder,
meillo@14: instead of the current folder, like for all other tools.
meillo@14: .P
meillo@14: The trivial part of the change was activating the draft folder facility
meillo@14: by default and setting a default name for this folder. Obviously, I chose
meillo@18: the name
meillo@18: .Fn +drafts .
meillo@18: This made the
meillo@18: .Sw \-draftfolder
meillo@18: and
meillo@18: .Sw \-draftmessage
meillo@18: switches useless, and I could remove them.
meillo@14: The more difficult but also the part that showed the real improvement,
meillo@18: was updating the tools to the new concept.
meillo@18: .Sw \-draft
meillo@18: switches could
meillo@14: be dropped, as operating on a draft message became indistinguishable to
meillo@18: operating on any other message for the tools.
meillo@18: .Pn comp
meillo@18: still has its
meillo@18: .Sw \-use
meillo@18: switch for switching between its two modes: (1) Compose a new
meillo@14: draft, possibly by taking some existing message as a form. (2) Modify
meillo@18: an existing draft. In either case, the behavior of
meillo@18: .Pn comp is
meillo@14: deterministic. There is no more need to query the user. I consider this
meillo@18: a major improvement. By making
meillo@18: .Pn send
meillo@18: simply operate on the current
meillo@17: message in the draft folder by default, with message and folder both
meillo@14: overridable by specifying them on the command line, it is now possible
meillo@17: to send a draft anywhere within the storage by simply specifying its folder
meillo@17: and name.
meillo@14: .P
meillo@14: All theses changes converted special cases to regular cases, thus
meillo@14: simplifying the tools and increasing the flexibility.
meillo@14: 
meillo@16: .U2 "Trash Folder
meillo@16: .P
meillo@16: Similar to the situation for drafts is the situation for removed messages.
meillo@16: Historically, a message was deleted by renaming. A specific
meillo@18: \fIbackup prefix\fP, often comma (\c
meillo@18: .Fn , )
meillo@18: or hash (\c
meillo@18: .Fn # ),
meillo@16: being prepended to the file name. Thus, MH wouldn't recognize the file
meillo@16: as a message anymore, as only files whose name consists of digits only
meillo@16: are treated as messages. The removed messages remained as files in the
meillo@16: same directory and needed some maintenance job to truly delete them after
meillo@16: some grace time. Usually, by running a command similar to
meillo@16: .DS
meillo@16: find /home/user/Mail \-ctime +7 \-name ',*' | xargs rm
meillo@16: .DE
meillo@16: in a cron job. Within the grace time interval
meillo@16: the original message could be restored by stripping the
meillo@16: the backup prefix from the file name. If however, the last message of
meillo@18: a folder is been removed \(en say message
meillo@18: .Fn 6
meillo@18: becomes file
meillo@18: .Fn ,6
meillo@18: \(en and a new message enters the same folder, thus the same
meillo@18: numbered being given again \(en in our case
meillo@18: .Fn 6
meillo@18: \(en, if that one
meillo@17: is removed too, then the backup of the former message gets overwritten.
meillo@16: Thus, the ability to restore removed messages does not only depend on
meillo@16: the ``sweeping cron job'' but also on the removing of further messages.
meillo@16: This is undesireable, because the real mechanism is hidden from the user
meillo@16: and the concequences of further removals are not always obvious.
meillo@16: Further more, the backup files are scattered within the whole mail
meillo@16: storage, instead of being collected at one place.
meillo@16: .P
meillo@18: To improve the situation, the profile entry
meillo@18: .Pe rmmproc
meillo@18: (previously named
meillo@18: .Pe Delete-Prog )
meillo@18: was introduced, very early.
meillo@16: It could be set to any command, which would care for the mail removal
meillo@16: instead of taking the default action, described above.
meillo@16: Refiling the to-be-removed files to some wastebin folder was a common
meillo@18: example. Nmh's man page
meillo@18: .Mp rmm(1)
meillo@18: proposes
meillo@18: .Cl "refile +d
meillo@18: to move messages to the wastebin and
meillo@18: .Cl "rm `mhpath +d all`
meillo@16: the empty the wastebin.
meillo@16: Managing the message removal this way is a sane approach. It keeps
meillo@16: the removed messages in one place, makes it easy to remove the backup
meillo@16: files, and, most important, enables the user to use the tools of MH
meillo@18: itself to operate on the removed messages. One can
meillo@18: .Pn scan
meillo@18: them,
meillo@18: .Pn show
meillo@18: them, and restore them with
meillo@18: .Pn refile .
meillo@18: There's no more
meillo@18: need to use
meillo@18: .Pn mhpath
meillo@18: to switch over from MH tools to Unix tools \(en MH can do it all itself.
meillo@16: .P
meillo@18: This apporach matches perfect with the concepts of MH, thus making
meillo@16: it powerful. Hence, I made it the default. And even more, I also
meillo@16: removed the old backup prefix approach, as it is clearly less powerful.
meillo@16: Keeping unused alternative in the code is a bad choice as they likely
meillo@16: gather bugs, by not being constantly tested. Also, the increased code
meillo@16: size and more conditions crease the maintenance costs. By strictly
meillo@16: converting to the trash folder approach, I simplified the code base.
meillo@18: .Pn rmm
meillo@18: calls
meillo@18: .Pn refile
meillo@18: internally to move the to-be-removed
meillo@18: message to the trash folder (\c
meillo@18: .Fn +trash
meillo@18: by default). Messages
meillo@16: there can be operated on like on any other message in the storage.
meillo@18: The sweep clean, one can use
meillo@18: .Cl "rmm \-unlink +trash a" ,
meillo@18: where the
meillo@18: .Sw \-unlink
meillo@18: switch causes the files to be truly unliked instead
meillo@16: of moved to the trash folder.
meillo@16: 
meillo@0: 
meillo@17: .H1 "MH Directory Split
meillo@0: .P
meillo@19: In MH and nmh, a personal setup had consisted of two parts:
meillo@19: The MH profile, named
meillo@19: .Fn \&.mh_profile
meillo@19: and being located directly in the user's home directory.
meillo@19: And the MH directory, where all his mail messages and also his personal
meillo@19: forms, scan formats, other configuration files are stored. The location
meillo@19: of this directory could be user-chosen. The default was to name it
meillo@19: .Fn Mail
meillo@19: and have it directly in the home directory.
meillo@19: .P
meillo@19: I've never liked the data storage and the configuration to be intermixed.
meillo@19: They are different kinds of data. One part, are the messages,
meillo@19: which are the data to operate on. The other part, are the personal
meillo@19: configuration files, which are able to change the behavior of the operations.
meillo@19: The actual operations are defined in the profile, however.
meillo@19: .P
meillo@19: When storing data, one should try to group data by its type.
meillo@19: There's sense in the Unix file system hierarchy, where configuration
meillo@19: file are stored separate (\c
meillo@19: .Fn /etc )
meillo@19: to the programs (\c
meillo@19: .Fn /bin
meillo@19: and
meillo@19: .Fn /usr/bin )
meillo@19: to their sources (\c
meillo@19: .Fn /usr/src ).
meillo@19: Such separation eases the backup management, for instance.
meillo@19: .P
meillo@19: In mmh, I've reorganized the file locations.
meillo@19: Still there are two places:
meillo@19: There's the mail storage directory, which, like in MH, contains all the
meillo@19: messages, but, unlike in MH, nothing else.
meillo@19: Its location still is user-chosen, with the default name
meillo@19: .Fn Mail ,
meillo@19: in the user's home directory. This is much similar to the case in nmh.
meillo@19: The configuration files, however, are grouped together in the new directory
meillo@19: .Fn \&.mmh
meillo@19: in the user's home directory.
meillo@19: The user's profile now is a file, named
meillo@19: .Fn profile ,
meillo@19: in this mmh directory.
meillo@19: Consistently, the context file and all the personal forms, scan formats,
meillo@19: and the like, are also there.
meillo@19: .P
meillo@19: The naming changed with the relocation.
meillo@19: The directory where everything, except the profile, had been stored (\c
meillo@19: .Fn $HOME/Mail ),
meillo@19: used to be called \fIMH directory\fP. Now, this directory is called the
meillo@19: user's \fImail storage\fP. The name \fImmh directory\fP is now given to
meillo@19: the new directory
meillo@19: (\c
meillo@19: .Fn $HOME/.mmh ),
meillo@19: containing all the personal configuration files.
meillo@19: .P
meillo@19: The separation of the files by type of content is logical and convenient.
meillo@19: There are no functional differences as any possible setup known to me
meillo@19: can be implemented with both approaches, although likely a bit easier
meillo@19: with the new approach. The main goal of the change had been to provide
meillo@19: sensible storage locations for any type of personal mmh file.
meillo@19: .P
meillo@19: In order for one user to have multiple MH setups, he can use the
meillo@19: environment variable
meillo@19: .Ev MH
meillo@19: the point to a different profile file.
meillo@19: The MH directory (mail storage plus personal configuration files) is
meillo@19: defined by the
meillo@19: .Pe Path
meillo@19: profile entry.
meillo@19: The context file could be defined by the
meillo@19: .Pe context
meillo@19: profile entry or by the
meillo@19: .Ev MHCONTEXT
meillo@19: environment variable.
meillo@19: The latter is useful to have a distinct context (e.g. current folders)
meillo@19: in each terminal window, for instance.
meillo@19: In mmh, there are three environment variables now.
meillo@19: .Ev MMH
meillo@19: may be used to change the location of the mmh directory.
meillo@19: .Ev MMHP
meillo@19: and
meillo@19: .Ev MMHC
meillo@19: change the profile and context files, respectively.
meillo@19: Besides providing a more consistent feel (which simply is the result
meillo@19: of being designed anew), the set of personal configuration files can
meillo@19: be chosen independently from the profile (including mail storage location)
meillo@19: and context, now. Being it relevant for practical use or not, it
meillo@19: de-facto is an improvement. However, the main achievement is the
meillo@19: split between mail storage and personal configuration files.
meillo@17: 
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@20: .H1 "mhshow to show Transition
meillo@20: .P
meillo@20: Since the very beginning, already in the first concept paper,
meillo@20: .Pn show
meillo@20: had been MH's mail display program.
meillo@20: .Pn show
meillo@20: found out which pathnames the relevant messages had and invoked
meillo@20: .Pn mhl
meillo@20: then to let it render the content.
meillo@20: With the advent of MIME, this approach wasn't sufficient anymore.
meillo@20: MIME messages can consist of multiple parts, some of which aren't
meillo@20: directly displayable, and text content can be encoded in
meillo@20: foreign charsets.
meillo@20: .Pn show 's
meillo@20: simple approach and
meillo@20: .Pn mhl 's
meillo@20: limited display facilities couldn't cope with the task any longer.
meillo@20: Instead of extending these tools, new ones were written from scratch
meillo@20: and then added to the MH toolchest. Doing so is encouraged by the
meillo@20: toolchest approach. The new tools could be added without interfearing
meillo@20: with the existing ones. This is great. It allowed MH to be the
meillo@20: first MUA to implement MIME.
meillo@20: .P
meillo@20: The new MIME features were added in form of the single program
meillo@20: .Pn mhn .
meillo@20: The command
meillo@20: .DS
meillo@20: mhn \-show 42
meillo@20: .DE
meillo@20: would show the MIME message numbered 42.
meillo@20: With the 1.0 release of nmh in February 1999, Richard Coleman finished
meillo@20: the split of
meillo@20: .Pn mhn
meillo@20: into a set of specialized programs, which together covered the
meillo@20: aspects of MIME. One of these resulting tools was
meillo@20: .Pn mhshow .
meillo@20: 
meillo@20: 
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