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1 .H0 "Work Report
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2 .P
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3 foo
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4 .P
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5 bar
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6
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meillo@12
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7 .H1 "Removal of Code Relicts
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8 .P
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meillo@12
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9 The code base of mmh originates in the late 70s, had been extensively
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10 worked on in the mid 80s, and had been partly reorganized and extended
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11 in the 90s. Relicts of all those times had gathered in the code base.
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12 My goal was to remove any ancient code parts. One part of the task was
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13 converting obsolete code constructs to standard constructs, the other part
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14 was dropping obsolete functions.
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15 .P
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16 As I'm not even thirty years old and have no more than seven years of
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17 Unix experience, I needed to learn about the history in retroperspective.
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18 Older people likely have used those ancient constructs themself
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19 and have suffered from their incompatiblities and have longed for
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20 standardization. Unfortunately, I have only read that others had done so.
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21 This put me in a much more difficult positions when working on the old
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22 code. I needed to recherche what other would have known by heart from
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23 experience. All my programming experience comes from a time past ANSI C
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24 and past POSIX. Although I knew about the times before, I took the
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25 current state implicitely for granted most of the time.
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26 .P
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27 Being aware of
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28 these facts, I rather let people with more historic experience solve the
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29 task of converting the ancient code constructs to standardized ones.
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30 Luckily, Lyndon Nerenberg focused on this task at the nmh project.
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31 He converted large parts of the code to POSIX constructs, removing
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32 the conditionals compilation for now standardized features.
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33 I'm thankful for this task being solved. I only pulled the changes into
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34 mmh.
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35 .P
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36 The other task of dropping ancient functionality to remove old code,
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37 I did myself, though. My position to strip mmh to the bare minimum of
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38 frequently used features is much more revolutional than the nmh community
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39 sees it. Without the need to justify my decisions, I was able to quickly
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40 remove code I considered ancient. The need to discuss my decisions with
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41 peers likely would have slowed this process down. Of course, I did research
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42 if a particular feature really should be dropped. Having not had any
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43 contact to this feature within my computer life was a first indicator to
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44 drop it, but I also asked others and searched the literature for modern
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45 usage of the feature. If it appeared to be truly ancient, I dropped it.
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46 The reason for dropping is always part of the commit message in the
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47 version control system. Thus, it is easy for others to check their
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48 view on the topic with mine and possibly to argue for reinclusion.
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49
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50 .U2 "MMDF maildrop support
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51 .P
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52 I did drop any support for the MMDF maildrop format. This type of format
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53 is conceptionally similar to the mbox format, but uses four bytes with
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54 value 1 (\fL^A^A^A^A\fP) as message delimiter,
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55 instead of the string ``\fLFrom\0\fP''.
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56 Due to the similarity and mbox being the de-facto standard maildrop
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57 format on Unix, but also due to the larger influence of Sendmail than MMDF,
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58 the MMDF maildrop format had vanished.
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59 .P
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60 The simplifications within the code were only moderate. Switches could
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61 be removed from tools like
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62 .L packf ,
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63 which generate packed mailboxes. Only one packed mailbox format remained:
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64 mbox.
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65 The most important changes affect the equally named mail parsing routine in
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66 .L sbr/m_getfld.c .
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67 The direct MMDF code had been removed, but as now only one packed mailbox
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68 format is left, code structure simplifications are likely possible.
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69 The reason why they are still outstanding is the heavily optimized code
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70 of \fLm_getfld()\fP. Changes beyond a small local scope \(en
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71 which restructuring in its core is \(en cause a high risk of damaging
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72 the intricate workings of the optimized code. This problem is know
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73 to the developers of nmh, too. They also avoid touching this minefield
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74 if possible.
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75
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76 .U2 "UUCP Bang Paths
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77 .P
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78 More questionably than the former topic is the removal of support for the
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79 UUCP bang path address style. However, the user may translate the bang
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80 paths on retrieval to Internet addresses and the other way on posting
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81 messages. The former can be done my an MDA like procmail; the latter
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82 by a sendmail wrapper. This would ensure that any address handling would
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83 work as expected. However, it might just work well without any
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84 such modifications, as mmh does not touch addresses much, in general.
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85 But I can't ensure as I have never used an environment with bang paths.
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86 Also, the behavior might break at any point in further development.
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87
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88 .U2 "Hardcopy terminal support
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89 .P
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90 More of a funny anecdote is the remaining of a check for printing to a
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91 hardcopy terminal until Spring 2012, when I finally removed it.
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92 I surely would be very happy to see such a terminal in action, maybe
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93 actually being able to work on it, but I fear my chances are null.
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94 .P
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95 The check only prevented a pager to be placed between the outputting
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96 program (\fLmhl\fP) and the terminal. This could have been ensured with
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97 the \fL-nomoreproc\fP at the command line statically, too.
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98
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99 .U2 "Removed support for header fields
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100 .P
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101 The `Encrypted' header had been introduced by RFC\^822, but already
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102 marked legacy in RFC 2822. It was superseded by FIXME.
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103 Mmh does no more support this header.
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104 .P
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105 `Content-MD5' headers were introduced by RFC\^1864. They provide only
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106 a verification of data corruption during the transfer. By no means can
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107 they ensure verbatim end-to-end delivery of the contents. This is clearly
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108 stated in the RFC. The proper approach to provide verificationability
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109 of content in an end-to-end relationship is the use of digital cryptography
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110 (RFCs FIXME). On the other hand, transfer protocols should ensure the
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111 integrity of the transmission. In combinations these two approaches
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112 make the `Content-MD5' header field useless. In consequence, I removed
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113 the support for it. By this removal, MD5 computation is not needed
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114 anywhere in mmh. Hence, over 500 lines of code were removed by this one
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115 change. Even if the `Content-MD5' header field is useful sometimes,
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116 I value its usefulnes less than the improvement in maintainability, caused
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117 by the removal.
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118
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119
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120
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121 .H1 "Paths to ...
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122 .P
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123 foo
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124
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125 .H1 "Path Notations
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126 .P
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127 foo
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128
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129 .H1 "Attachments
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130 .P
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131 foo
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132
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133 .H1 "Blind Carbon Copies
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134 .P
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135 foo
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136
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137 .H1 "Good Defaults
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138 .P
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139 foo
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140
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141 .H1 "Modularization
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142 .P
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143 foo
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144
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145 .H1 "Code style
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146 .P
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147 foo
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