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1 .H0 "Discussion
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2 .P
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3 This main chapter discusses the practical work done in the mmh project.
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4 It is structured along the goals to achieve. The concrete work done
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5 is described in the examples of how the general goals were achieved.
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6
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7
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8
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9
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10 .H1 "Stream-lining
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11
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12 .P
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13 MH had been considered an all-in-one system for mail handling.
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14 The community around nmh has a similar understanding.
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15 In fundamental difference, I believe that mmh should be a MUA but
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16 nothing more. I believe that all-in-one mail systems are not the way
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17 to go. There are excellent specialized MTAs, like Postfix;
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18 there are specialized MDAs, like Procmail; there are specialized
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19 MRAs, like Fetchmail. I believe it's best to use them instead of
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20 providing the same function ourselves. Doing something well requires to
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21 focus on this particular aspect or a small set of aspects. The more
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22 it is possible to focus, the better the result in this particular
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23 area will be. The limiting resource in Free Software community development
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24 usually is human power. If the low development power is even parted
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25 into multiple development areas, it will hardly be possible to
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26 compete with the specialists in the various fields. This is even
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27 increased, given the small community \(en developers and users \(en
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28 that MH-based mail systems have. In consequence, I believe that the
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29 available resources should be concentrated at the point where MH is
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30 most unique. This is clearly the MUA part.
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31 .P
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32 The goal for mmh was to remove peripheral parts and stream-line
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33 it for the MUA task.
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34
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35
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36 .H2 "Removal of Mail Transfer Facilities
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37 .P
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38 In contrast to nmh, which also provides mail submission and mail retrieval
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39 facilities, mmh is a MUA only.
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40 This general difference in the view on the character of nmh
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41 strongly supported the development of mmh.
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42 Removing the mail transfer facilities had been the first work task
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43 for the mmh project.
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44 .P
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45 The MSA is called \fIMessage Transfer Service\fP (MTS) in nmh.
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46 The facility establishes TCP/IP connections and speaks SMTP to submit
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47 messages for relay to the outside world.
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48 This part is implemented in the
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49 .Pn post
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50 command.
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51 Demanded by the changes in
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52 emailing, this part of nmh required changes in the last years.
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53 Encrypted connections needed to be supported, hence SASL was introduced
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54 into nmh. This added complexity to the nmh without improving it in
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55 its core functions. Also, keeping up with recent developments in
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56 this field needs requires development power and specialists.
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57 Mmh cuts this whole facility off and depends on an external MTA instead.
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58 The only outgoing interface available to mmh is the
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59 .Pn sendmail
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60 command.
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61 Almost any MTA provides a
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62 .Pn sendmail
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63 command.
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64 It not, any program can be substituted if it reads the
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65 message from the standard input, extracts the recipient addresses
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66 from the message header and does not conflict
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67 with sendmail-specific command line arguments.
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68 .P
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69 To retrieve mail, the
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70 .Pn inc
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71 command in nmh has the ability to establish TCP/IP connections
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72 and speaks POP3 to retrieve mail from remote servers.
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73 As with mail submission, here encrypted connections are required
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74 today, thus SASL support was added.
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75 As POP3 is superseded by IMAP more and more, support for message
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76 retrieval through IMAP will become necessary to be added soon.
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77 Mmh has no support for retrieving mail from remote locations.
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78 It depends on an external tool to cover this task.
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79 There are two ways for messages to enter mmh's mail storage:
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80 Incorporate them with
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81 .Pn inc
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82 from the system maildrop, or with
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83 .Pn rcvstore
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84 from the standard input.
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85 In consequence, mmh has not any longer networking code
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86 and thus does no more need to do transfer encryption and authentication.
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87 Two large functional units are removed.
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88 .P
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89 With the removal of the MSA and MRA, mmh converted from an all-in-one
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90 mail system to being only a MUA.
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91 Following the Unix philosophy, it focuses on one job and to do that well.
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92 Now, of course, mmh depends on third-party software.
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93 An external MTA/MSA is required to transfer mail to the outside world;
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94 an external MRA is required to retrieve mail from remote machines.
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95 There exist excellent implementations of such software,
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96 which do this specific task likely much better than the internal
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97 versions of nmh do it. Also, this provides the choice for the best
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98 suiting one of the available implementation.
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99 .P
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100 As it had already been possible to use an external MSA or MRA,
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101 why not keep the internal version for convenience?
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102 If this would question the sense in having a fall-back pager in all
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103 the command line tools, in case
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104 .Pn more
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105 or
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106 .Pn less
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107 wouldn't be available, the answer is intuitively seen.
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108 Now, an MSA or MRA is clearly more complex than a text pager, but
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109 still the concept holds: If programs become complex, split them;
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110 if projects become complex, split them.
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111 Complexity is demanded by the problem to solve. Decades ago,
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112 emailing had been small and simple.
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113 (Remember,
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114 .Pn /bin/mail
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115 had once covered anything there was to email and still had been small.)
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116 As the complexity in emailing increased, MH remainded mostly unchanged.
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117 Nontheless, in nmh the POP server, which the original MH had included,
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118 was removed. Now is the time to take one step further and remove
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119 the MSA and MRA.
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120 Not only does it decrease the code amount of the project,
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121 but more important, it removes the whole field of message transfer
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122 with all its implications from the project.
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123 .P
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124 If a project needs some kind of function, there's always the choice
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125 between implementing the the function in the project directly or
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126 depending on a library that provides the function or depending on
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127 a program that provides the function.
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128 Whereas adding the function directly to the project increases the
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129 code size most, it makes the project most independent.
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130 On the other end, interfacing external programs keeps the interface
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131 smallest, but the depencency highest.
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132 Using a library is in the middle.
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133 Adding the function directly to the project is a bad choice for
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134 any function of higher complexity, unless it's not available in other ways.
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135 Hence, the dependencies only change in kind, not in their existence.
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136 In mmh, library dependencies on
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137 .Pn libsasl2
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138 and
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139 .Pn libcrypto /\c
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140 .Pn libssl
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141 were treated against program dependencies on an MSA and an MRA.
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142 Besides program dependencies providing the stronger separation
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143 and being more flexible, they also allowed
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144 over 6\|000 lines of code to be removed from mmh.
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145 This made mmh's code base about 12\|% smaller.
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146 Reducing the projects code size by such an amount without actually
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147 losing function is a convincing argument.
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148 .P
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149 Users of MH should have not problem to set up an external MSA and MRA.
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150 Also, the popular MSAs and MRAs have large communities and a lot
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151 of documentation available.
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152 .P
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153 Choices for MSAs range from the full-featured
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154 .I Postfix
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155 over mid-size solutions like
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156 .I masqmail
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157 and
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158 .I dma
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159 to small forwarders like
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160 .I ssmtp
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161 and
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162 .I nullmailer .
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163 Choices for MRAs include
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164 .I fetchmail ,
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165 .I getmail ,
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166 .I mpop
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167 and
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168 .I fdm .
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169
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170
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171 .H2 "Removal of non-MUA Tools
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172 .P
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173 Some of nmh's tools were removed from mmh because they didn't
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174 match the main focus of adding to the MUA's task.
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175 .BU
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176 .Pn conflict
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177 was removed because it is a mail system maintenance tool.
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178 Besides, it even checks
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179 .Fn /etc/passwd
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180 and
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181 .Fn /etc/group
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182 for consistency, which has nothing at all to do with emailing.
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183 The tool might be useful, but it should not be shipped with mmh.
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184 .BU
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185 .Pn rcvtty
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186 was removed because its usecase of writing to the user's terminal
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187 on receiving of mail is hardly wanted today. If users like to be
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188 informed of new mail, then using the shell's
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189 .Ev MAILPATH
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190 variable or graphical notifications are likely more
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191 appealing.
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192 Writing directly to a terminals is hardly ever wanted today.
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193 If though one wants to have it this way, the standard tool
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194 .Pn write
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195 can be used in a way similar to:
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196 .DS
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197 scan -file - | write `id -un`
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198 .DE
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199 .BU
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200 .Pn viamail
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201 was removed when the new attachment system was introduced, because
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202 .Pn forw
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203 could can now the task itself.
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204 The program
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205 .Pn sendfiles
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206 was rewritten as a shell script wrapper around
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207 .Pn forw .
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208 .BU
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209 .Pn msgchk
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210 was removed, because it lost its usefulness when POP support was removed.
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211 .Pn msgchk
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212 provides hardly more information than:
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213 .DS
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214 ls -l /var/mail/meillo
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215 .DE
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216 It does separate between old and new mail, but that's merely a detail
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217 and can be done with
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218 .Pn stat (1)
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219 too.
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220 A very small shell script could be written to output the information
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221 in a convenient way, if truly necessary.
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222 As mmh's inc only incorporates mail from the user's local maildrop
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223 and thus no data transfers over slow networks are involved,
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224 there's hardly need to check for new mail before incorporating it.
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225 .BU
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226 .Pn msh
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227 was removed because the tool was in conflict with the
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228 philosophy of MH. It provided an interactive shell to access the
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229 features of MH. One major feature of MH is being a tool chest.
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230 .Pn msh
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231 wouldn't be just another shell, tailored to the needs of mail
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232 handling, but one large program to have the MH tools built in.
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233 It's main use was for accessing Bulletin Boards, which have seized to
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234 be popular.
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235 .P
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236 Removing
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237 .Pn msh ,
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238 together with the truly obsolete code relicts
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239 .Pn vmh
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240 and
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241 .Pn wmh ,
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242 saved more than 7\|000 lines of C code \(en
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243 about 15\|% of the project's original source code amount.
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244 Having the same functionality in less code (with equal readability,
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245 of course) is an advantage.
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246 Less code means less bugs and less maintenance work.
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247 If
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248 .Pn rcvtty
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249 and
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250 .Pn msgchk
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251 are rarely used and can be implemented in different ways,
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252 then why should one keep them?
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253 .Pn viamail 's
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254 use case is now partly obsolete and partly covered by
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255 .Pn forw ,
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256 hence there's no reason to still have
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257 .Pn viamail
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258 around.
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259 .Pn conflict
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260 is not related with the mail client, and
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261 .Pn msh
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262 conflicts with the basic concept of MH.
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263 Both tools could still be useful, but not as part of mmh.
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264 .P
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265 It is a design goal of mmh to remove those parts that are rarely used.
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266 The project shall become more stream-lined.
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267 Rarely used and loosely related tools distract from the lean appearance.
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268 They require maintenance cost without adding to the core task.
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269 Therefore they were removed.
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270
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271
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272 .H2 "Merge of \f(CWshow\fP and \f(CWmhshow\fP
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273 .P
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274 Since the very beginning \(en already in the first concept paper \(en
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275 .Pn show
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276 had been MH's message display program.
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277 .Pn show
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278 found out which pathnames the relevant messages had and invoked
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279 .Pn mhl
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280 then to have the content formated.
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281 With the advent of MIME, this approach wasn't sufficient anymore.
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282 MIME messages can consist of multiple parts, some of which aren't
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283 directly displayable, and text content might be encoded in
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284 foreign charsets.
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285 .Pn show 's
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286 simple approach and
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287 .Pn mhl 's
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288 limited display facilities couldn't cope with the task any longer.
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289 .P
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290 Instead of extending these tools, additional ones were written from scratch
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291 and then added to the MH tool chest. Doing so is encouraged by the
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292 tool chest approach. The new tools could be added without interfering
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293 with the existing ones. This is great. The ease of adding new tools
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294 even made MH the first MUA to implement MIME.
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295 .P
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296 First, the new MIME features were added in form of the single program
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297 .Pn mhn .
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298 The command
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299 .Cl "mhn \-show 42
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300 would show the MIME message numbered 42.
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301 With the 1.0 release of nmh in February 1999, Richard Coleman finished
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302 the split of
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303 .Pn mhn
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304 into a set of specialized programs, which together covered the
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305 multiple aspects of MIME. One of these resulting tools was
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306 .Pn mhshow ,
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307 which replaced the
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308 .Cl "mhn \-show
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309 call.
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310 .P
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|
meillo@69
|
311 From then on, two message display tools were part of nmh.
|
|
meillo@69
|
312 Because it should not require user actions to invoke the right tool
|
|
meillo@69
|
313 whether the message uses MIME or not,
|
|
meillo@69
|
314 .Pn show
|
|
meillo@69
|
315 was extended to automatically hand the job over to
|
|
meillo@69
|
316 .Pn mhshow
|
|
meillo@69
|
317 if displaying the message would be beyond
|
|
meillo@69
|
318 .Pn show 's
|
|
meillo@69
|
319 abilities.
|
|
meillo@69
|
320 For convenience,
|
|
meillo@69
|
321 .Pn show
|
|
meillo@69
|
322 would still display MIME messages if they contained only a single text
|
|
meillo@69
|
323 part.
|
|
meillo@69
|
324 In consequence, the user would invoke
|
|
meillo@69
|
325 .Pn show
|
|
meillo@69
|
326 (possibly through
|
|
meillo@69
|
327 .Pn next
|
|
meillo@69
|
328 or
|
|
meillo@69
|
329 .Pn prev )
|
|
meillo@69
|
330 and get the message printed with either
|
|
meillo@69
|
331 .Pn show
|
|
meillo@69
|
332 or
|
|
meillo@69
|
333 .Pn mhshow ,
|
|
meillo@69
|
334 whatever was more appropriate.
|
|
meillo@69
|
335 (There was also a switch for
|
|
meillo@69
|
336 .Pn show
|
|
meillo@69
|
337 to never invoke
|
|
meillo@69
|
338 .Pn mhshow .)
|
|
meillo@69
|
339 .P
|
|
meillo@69
|
340 Having two similar tools for essentially the same task is redundant.
|
|
meillo@69
|
341 Both programs needed to be developed syncronously as they were
|
|
meillo@69
|
342 used as a single tool by the user. Thus they needed to act in a
|
|
meillo@69
|
343 similar way to not distract the user.
|
|
meillo@69
|
344 .P
|
|
meillo@69
|
345 Today, non-MIME messages are rather seen to be a special case of
|
|
meillo@69
|
346 MIME messages, than MIME messages are seen to be an extension to
|
|
meillo@69
|
347 original mail.
|
|
meillo@69
|
348 As
|
|
meillo@69
|
349 .Pn mhshow
|
|
meillo@69
|
350 had already be able to display non-MIME messages, it was natural
|
|
meillo@69
|
351 to drop
|
|
meillo@69
|
352 .Pn show
|
|
meillo@69
|
353 in favor of using
|
|
meillo@69
|
354 .Pn mhshow
|
|
meillo@69
|
355 exclusively.
|
|
meillo@72
|
356 .Ci 4c1efddfd499300c7e74263e57d8aa137e84c853
|
|
meillo@69
|
357 This decision follows the idea of orthogonal design.
|
|
meillo@69
|
358 .P
|
|
meillo@69
|
359 To allow this replacement,
|
|
meillo@69
|
360 .Pn mhshow
|
|
meillo@69
|
361 was reworked to behave more like
|
|
meillo@69
|
362 .Pn show
|
|
meillo@69
|
363 first.
|
|
meillo@69
|
364 Section XXX describes this rework from a different perspective.
|
|
meillo@69
|
365 Once the tools behaved similar, the replacing became a natural decision.
|
|
meillo@69
|
366 In mmh,
|
|
meillo@69
|
367 .Pn show
|
|
meillo@69
|
368 is the one single message display program again, but it handles
|
|
meillo@69
|
369 MIME messages as well as non-MIME messages.
|
|
meillo@69
|
370 There's only one program to maintain and users don't need to deal
|
|
meillo@69
|
371 with the existance of two display programs.
|
|
meillo@69
|
372 .P
|
|
meillo@69
|
373 Though, there's one reason why removing the old
|
|
meillo@69
|
374 .Pn show
|
|
meillo@69
|
375 hurts: It had been such a simple program.
|
|
meillo@69
|
376 Its lean elegance is missing to
|
|
meillo@69
|
377 .Pn mhshow ,
|
|
meillo@69
|
378 i.e. the new
|
|
meillo@69
|
379 .Pn show .
|
|
meillo@69
|
380 But there is no chance, because supporting MIME causes essentially
|
|
meillo@69
|
381 higher complexity.
|
|
meillo@58
|
382
|
|
meillo@58
|
383
|
|
meillo@58
|
384 .H2 "Removal of Configure Options
|
|
meillo@58
|
385 .P
|
|
meillo@72
|
386 Choice is a double-edged sword.
|
|
meillo@72
|
387 It allows customization and thus better suiting solutions,
|
|
meillo@72
|
388 but that comes with costs.
|
|
meillo@72
|
389 First, there is the cost of code complexity to have choice.
|
|
meillo@72
|
390 Second, there is the cost of less tested setups, because there are
|
|
meillo@72
|
391 more possible setups and especially corner-cases.
|
|
meillo@72
|
392 Third, there is the cost of choice itself.
|
|
meillo@72
|
393 The code complexity affects the developers.
|
|
meillo@72
|
394 Less tested code affects both, users and developers.
|
|
meillo@72
|
395 The problem of choice affects the users, for once simply by having to
|
|
meillo@72
|
396 choose but also by complexer interfaces that require more documentation.
|
|
meillo@72
|
397 Whenever options add little advantages, they should be considered for
|
|
meillo@72
|
398 removal.
|
|
meillo@72
|
399 .P
|
|
meillo@72
|
400 I have reduced the number of project-specific configure options from
|
|
meillo@72
|
401 fifteen to three.
|
|
meillo@74
|
402
|
|
meillo@74
|
403 .U3 "Mail Transfer Facility Options
|
|
meillo@74
|
404 .P
|
|
meillo@72
|
405 With the removal of the mail transfer facilities five option vanished:
|
|
meillo@72
|
406 .IP \f(CW--with-mts=[smtp|sendmail]\fP
|
|
meillo@72
|
407 Specified the default mail transport service, which now is sendmail always.
|
|
meillo@72
|
408 .IP \f(CW--with-smtpservers=[server1...]\fP
|
|
meillo@72
|
409 Specified the default SMTP servers for the smtp mail transfer service.
|
|
meillo@72
|
410 .Ci 128545e06224233b7e91fc4c83f8830252fe16c9
|
|
meillo@72
|
411 .IP \f(CW--with-cyrus-sasl\fP
|
|
meillo@72
|
412 Enabled SASL support for mail transfer.
|
|
meillo@72
|
413 .IP \f(CW--with-tls\fP
|
|
meillo@72
|
414 Enabled TLS support for mail transfer.
|
|
meillo@72
|
415 .IP \f(CW--enable-pop\fP
|
|
meillo@72
|
416 Enabled the message retrieval facility.
|
|
meillo@72
|
417
|
|
meillo@74
|
418 .U3 "Backup Prefix
|
|
meillo@74
|
419 .P
|
|
meillo@72
|
420 The default backup prefix, i.e. the string that was prepended to message
|
|
meillo@72
|
421 filenames to tag them as deleted, had been the comma `\f(CW,\fP'.
|
|
meillo@72
|
422 There was a configure option to change the default to the hash symbol
|
|
meillo@72
|
423 `\f(CW#\fP':
|
|
meillo@72
|
424 .CW --with-hash-backup .
|
|
meillo@72
|
425 The implication of the hash symbol is that it introduces a comment
|
|
meillo@72
|
426 in the Unix shell.
|
|
meillo@72
|
427 Thus, the command line
|
|
meillo@72
|
428 .Cl "rm #13 #15
|
|
meillo@72
|
429 calls
|
|
meillo@72
|
430 .Pn rm
|
|
meillo@72
|
431 without arguments because the first hash symbol starts the comment
|
|
meillo@72
|
432 that reaches until the end of the line.
|
|
meillo@72
|
433 To delete the backup files,
|
|
meillo@72
|
434 .Cl "rm ./#13 ./#15"
|
|
meillo@72
|
435 needs to be used.
|
|
meillo@72
|
436 .\" XXX check historical background
|
|
meillo@72
|
437 Besides this effect, the choice was personal preference.
|
|
meillo@72
|
438 I removed the configure option but added the profile entry
|
|
meillo@72
|
439 .Pe backup-prefix ,
|
|
meillo@72
|
440 which allows to specify an arbitrary string as backup prefix.
|
|
meillo@72
|
441 .Ci 6c40d481d661d532dd527eaf34cebb6d3f8ed086
|
|
meillo@72
|
442 This did not remove the choice but moved it to a location where
|
|
meillo@72
|
443 it suited better.
|
|
meillo@72
|
444 Profile entries are the common method to change mmh's behavior.
|
|
meillo@72
|
445 The name of the
|
|
meillo@72
|
446 .Fn .mh-sequences ,
|
|
meillo@72
|
447 for instance, is specified there, too.
|
|
meillo@72
|
448 Moving the specification of the backup prefix there, appears to be right.
|
|
meillo@72
|
449 Eventually, the new trash folder obsoleted the concept of the
|
|
meillo@72
|
450 backup prefix completely.
|
|
meillo@72
|
451 (Well, there still are corner-cases to remove until the backup
|
|
meillo@72
|
452 prefix can be layed to rest, eventually.)
|
|
meillo@72
|
453 .\" FIXME: Do this work in the code!
|
|
meillo@74
|
454 .P
|
|
meillo@74
|
455 The two configure options
|
|
meillo@74
|
456 .CW --with-editor=EDITOR
|
|
meillo@74
|
457 .CW --with-pager=PAGER
|
|
meillo@74
|
458 were used to specify the default editor and pager at configure time.
|
|
meillo@74
|
459 Doing so at configure time made sense in the Eighties,
|
|
meillo@74
|
460 when the available editors and pagers varied more across different systems.
|
|
meillo@74
|
461 Today, the situation is much more homegenic.
|
|
meillo@74
|
462 The programs
|
|
meillo@74
|
463 .Pn vi
|
|
meillo@74
|
464 and
|
|
meillo@74
|
465 .Pn more
|
|
meillo@74
|
466 can be expected to be available anywhere on every Unix system,
|
|
meillo@74
|
467 as they are specified by POSIX since two decades.
|
|
meillo@74
|
468 (The specifications for
|
|
meillo@74
|
469 .Pn vi
|
|
meillo@74
|
470 and
|
|
meillo@74
|
471 .Pn more
|
|
meillo@74
|
472 appeared in
|
|
meillo@74
|
473 .[
|
|
meillo@74
|
474 posix 1987
|
|
meillo@74
|
475 .]
|
|
meillo@74
|
476 and,
|
|
meillo@74
|
477 .[
|
|
meillo@74
|
478 posix 1992
|
|
meillo@74
|
479 .]
|
|
meillo@74
|
480 respectively.)
|
|
meillo@74
|
481 As a first step, these two tools were hard-coded as defaults.
|
|
meillo@74
|
482 .Ci 5d43a99db70c12a673028c7758c20cbe3e13ef5f
|
|
meillo@74
|
483 Not changed were the
|
|
meillo@74
|
484 .Pe editor
|
|
meillo@74
|
485 and
|
|
meillo@74
|
486 .Pe moreproc
|
|
meillo@74
|
487 profile entries, which allowed the user to change the default
|
|
meillo@74
|
488 by personal preference.
|
|
meillo@74
|
489 Later, the concept was reworked to respect the standard environment
|
|
meillo@74
|
490 variables
|
|
meillo@74
|
491 .Ev VISUAL
|
|
meillo@74
|
492 and
|
|
meillo@74
|
493 .Ev PAGER
|
|
meillo@74
|
494 if they were set.
|
|
meillo@74
|
495 Today, mmh determines the editor to use in the following order,
|
|
meillo@74
|
496 taking the first available and non-empty item:
|
|
meillo@74
|
497 .IP (1)
|
|
meillo@74
|
498 Environment variable
|
|
meillo@74
|
499 .Ev MMHEDITOR
|
|
meillo@74
|
500 .IP (2)
|
|
meillo@74
|
501 Profile entry
|
|
meillo@74
|
502 .Pe Editor
|
|
meillo@74
|
503 .IP (3)
|
|
meillo@74
|
504 Environment variable
|
|
meillo@74
|
505 .Ev VISUAL
|
|
meillo@74
|
506 .IP (4)
|
|
meillo@74
|
507 Environment variable
|
|
meillo@74
|
508 .Ev EDITOR
|
|
meillo@74
|
509 .IP (5)
|
|
meillo@74
|
510 Command
|
|
meillo@74
|
511 .Pn vi .
|
|
meillo@74
|
512 .P
|
|
meillo@74
|
513 The pager to use is deteminded in the following order,
|
|
meillo@74
|
514 also taking the first available and non-empty item:
|
|
meillo@74
|
515 .IP (1)
|
|
meillo@74
|
516 Environment variable
|
|
meillo@74
|
517 .Ev MMHPAGER
|
|
meillo@74
|
518 .IP (2)
|
|
meillo@74
|
519 Profile entry
|
|
meillo@74
|
520 .Pe Pager
|
|
meillo@74
|
521 (replaces
|
|
meillo@74
|
522 .Pe moreproc )
|
|
meillo@74
|
523 .IP (3)
|
|
meillo@74
|
524 Environment variable
|
|
meillo@74
|
525 .Ev PAGER
|
|
meillo@74
|
526 .IP (4)
|
|
meillo@74
|
527 Command
|
|
meillo@74
|
528 .Pn more .
|
|
meillo@74
|
529 .P
|
|
meillo@74
|
530 .Ci f85f4b7ae62e3d05a945dcd46ead51f0a2a89a9b
|
|
meillo@74
|
531 .Ci 0c4214ea2aec6497d0d67b436bbee9bc1d225f1e
|
|
meillo@74
|
532 .P
|
|
meillo@74
|
533 The new behavior confirms better to the common behavior on Unix
|
|
meillo@74
|
534 systems, as
|
|
meillo@74
|
535 .Ev VISUAL /\c
|
|
meillo@74
|
536 .Ev EDITOR
|
|
meillo@74
|
537 and
|
|
meillo@74
|
538 .Ev PAGER
|
|
meillo@74
|
539 are respected.
|
|
meillo@74
|
540 Additionally, the new approach is more uniform and
|
|
meillo@74
|
541 without surprise for users.
|
|
meillo@72
|
542
|
|
meillo@74
|
543 .U3 "Locale
|
|
meillo@74
|
544 .P
|
|
meillo@74
|
545 The configure option
|
|
meillo@74
|
546 .Sw --disable-locale
|
|
meillo@74
|
547 was removed because today there's hardly any need to disable locale
|
|
meillo@74
|
548 support.
|
|
meillo@74
|
549 .Ci ccf4f175ef4c4e7522f9510a4a1149c15d810dd9
|
|
meillo@72
|
550
|
|
meillo@74
|
551 .U3 "\fLslocal\fP Supress Duplicates
|
|
meillo@72
|
552 .P
|
|
meillo@74
|
553 .Pn slocal
|
|
meillo@74
|
554 is an MDA included in mmh.
|
|
meillo@74
|
555 This is a violation of the idea that mmh is a MUA only.
|
|
meillo@74
|
556 .Pn slocal
|
|
meillo@74
|
557 should become a separate project.
|
|
meillo@74
|
558 Nonetheless, ouf of convenience and due to lack of convincement,
|
|
meillo@74
|
559 yet it remains being part of mmh.
|
|
meillo@74
|
560 This is likely to change in the future.
|
|
meillo@74
|
561 Already,
|
|
meillo@74
|
562 .Pn slocal was stripped down.
|
|
meillo@74
|
563 It used to depend on
|
|
meillo@74
|
564 .I ndbm ,
|
|
meillo@74
|
565 a database library.
|
|
meillo@74
|
566 The database is used to store the message ids of all messages delivered.
|
|
meillo@74
|
567 This enables
|
|
meillo@74
|
568 .Pn slocal
|
|
meillo@74
|
569 to suppress delivering the same message to the same user twice.
|
|
meillo@74
|
570 (This features was enabled by the
|
|
meillo@74
|
571 .Sw -suppressdup
|
|
meillo@74
|
572 switch.)
|
|
meillo@74
|
573 .P
|
|
meillo@74
|
574 A variety of version of the database library exist.
|
|
meillo@74
|
575 Complicated autoconf code was needed to detect them correctly.
|
|
meillo@74
|
576 Further more, the configure switches
|
|
meillo@74
|
577 .Sw --with-ndbm=ARG
|
|
meillo@74
|
578 and
|
|
meillo@74
|
579 .Sw --with-ndbmheader=ARG
|
|
meillo@74
|
580 were added to help with difficult setups that would
|
|
meillo@74
|
581 not be detected automatically.
|
|
meillo@74
|
582 .P
|
|
meillo@74
|
583 By removing the suppress duplicates feature of
|
|
meillo@74
|
584 .Pn slocal ,
|
|
meillo@74
|
585 the dependency on
|
|
meillo@74
|
586 .I ndbm
|
|
meillo@74
|
587 was removed and 120 lines of complex autoconf could be saved.
|
|
meillo@74
|
588 .Ci ecd6d6a20cb7a1507e3a20d6c4cb3a1cf14c6bbf
|
|
meillo@74
|
589 The change removed funtionality too, but the value it would have added
|
|
meillo@74
|
590 is minor to the weight loss by dropping the dependency and
|
|
meillo@74
|
591 the complex autoconf code.
|
|
meillo@72
|
592
|
|
meillo@74
|
593 .U3 "mh-e Support
|
|
meillo@72
|
594 .P
|
|
meillo@74
|
595 The configure option
|
|
meillo@74
|
596 .Sw --disable-mhe
|
|
meillo@74
|
597 was removed when the mh-e support was reworked.
|
|
meillo@74
|
598 Mh-e is the Emacs front-end to MH.
|
|
meillo@74
|
599 It requires MH to act different in some minor ways.
|
|
meillo@74
|
600 The configure option could switch the extension off.
|
|
meillo@74
|
601 After removing support for old versions of mh-e,
|
|
meillo@74
|
602 only the
|
|
meillo@74
|
603 .Sw -build
|
|
meillo@74
|
604 switches for
|
|
meillo@74
|
605 .Pn forw
|
|
meillo@74
|
606 and
|
|
meillo@74
|
607 .Pn repl
|
|
meillo@74
|
608 are left to be mh-e-specific.
|
|
meillo@74
|
609 They are now always available because they add little code and complexity.
|
|
meillo@74
|
610 This change was first done in nmh and thereafter merged into mmh.
|
|
meillo@74
|
611 The interface changes in mmh require mh-e to be adjusted to use mmh
|
|
meillo@74
|
612 as the back-end. This requires minor changes to mh-e, though removing
|
|
meillo@74
|
613 the
|
|
meillo@74
|
614 .Sw -build
|
|
meillo@74
|
615 switches would require larger adjustments.
|
|
meillo@74
|
616 The
|
|
meillo@74
|
617 .Sw --disable-mhe
|
|
meillo@74
|
618 configure option was removed and the remaining support for mh-e is always
|
|
meillo@74
|
619 built in.
|
|
meillo@72
|
620 .Ci a7ce7b4a580d77b6c2c4d980812beb589aa4c643
|
|
meillo@74
|
621 Removing the option removed a second code setup that would have
|
|
meillo@74
|
622 needed to be tested.
|
|
meillo@72
|
623
|
|
meillo@74
|
624 .U3 "Masquerading
|
|
meillo@72
|
625 .P
|
|
meillo@74
|
626 The configure option
|
|
meillo@74
|
627 .Sw --enable-masquerade
|
|
meillo@74
|
628 could take up to three items: draft_from, mmailid, username_extension.
|
|
meillo@74
|
629 They activated different types of address masquerading.
|
|
meillo@74
|
630 All of them were implemented in the SMTP-speaking
|
|
meillo@74
|
631 .Pn post
|
|
meillo@74
|
632 command.
|
|
meillo@74
|
633 Mmh no longer speaks SMTP and the replacing
|
|
meillo@74
|
634 .Pn spost
|
|
meillo@74
|
635 command no longer does MTA jobs like this one.
|
|
meillo@74
|
636 Because address masquerading is an MTA's task and mmh does not cover
|
|
meillo@74
|
637 this field anymore, the funtion needs to be implemented in the
|
|
meillo@74
|
638 external MTA used.
|
|
meillo@74
|
639 .P
|
|
meillo@74
|
640 The
|
|
meillo@74
|
641 .I mmailid
|
|
meillo@74
|
642 masquerading type is the oldest one of the three and the only one
|
|
meillo@74
|
643 available in the original MH.
|
|
meillo@74
|
644 It provided a
|
|
meillo@74
|
645 .I username
|
|
meillo@74
|
646 to
|
|
meillo@74
|
647 .I fakeusername
|
|
meillo@74
|
648 mapping, based on the value of the password file's GECOS field.
|
|
meillo@74
|
649 The man page
|
|
meillo@74
|
650 .Mp mh-tailor(5)
|
|
meillo@74
|
651 described the use case as being the following:
|
|
meillo@74
|
652 .QP
|
|
meillo@74
|
653 This is useful if you want the messages you send to always
|
|
meillo@74
|
654 appear to come from the name of an MTA alias rather than your
|
|
meillo@74
|
655 actual account name. For instance, many organizations set up
|
|
meillo@74
|
656 `First.Last' sendmail aliases for all users. If this is
|
|
meillo@74
|
657 the case, the GECOS field for each user should look like:
|
|
meillo@74
|
658 ``First [Middle] Last <First.Last>''
|
|
meillo@74
|
659 .P
|
|
meillo@74
|
660 As mmh sends outgoing mail via the local MTA only,
|
|
meillo@74
|
661 it is the best location to do such global rewrites.
|
|
meillo@74
|
662 Besides, the MTA is conceptionally the right location because it
|
|
meillo@74
|
663 does the reverse mapping for incoming mail (aliasing), too.
|
|
meillo@74
|
664 The masquerading set up there is set up once for all
|
|
meillo@74
|
665 mail software on the system.
|
|
meillo@74
|
666 .Ci 0836c8000ccb34b59410ef1c15b1b7feac70ce5f
|
|
meillo@74
|
667 .P
|
|
meillo@74
|
668 The
|
|
meillo@74
|
669 .I username_extension
|
|
meillo@74
|
670 masquerading type did not replace the username but could append a suffix
|
|
meillo@74
|
671 to it.
|
|
meillo@74
|
672 The suffix needed to be specified by the
|
|
meillo@74
|
673 .Ev USERNAME_EXTENSION
|
|
meillo@74
|
674 environment variable.
|
|
meillo@74
|
675 It provided support for the
|
|
meillo@74
|
676 .I user-extension
|
|
meillo@74
|
677 feature of qmail and the similar
|
|
meillo@74
|
678 .I "plussed user
|
|
meillo@74
|
679 processing of sendmail.
|
|
meillo@74
|
680 The decision to remove this username_extension masquerading was
|
|
meillo@74
|
681 motivated by the fact that
|
|
meillo@74
|
682 .Pn spost
|
|
meillo@74
|
683 hadn't supported it.
|
|
meillo@74
|
684 .Ci 2abae0bfd0ad5bf898461e50aa4b466d641f23d9_username_extension
|
|
meillo@74
|
685 Mmh now provides a more general, though in this case less convenient,
|
|
meillo@74
|
686 kind of masquerading.
|
|
meillo@74
|
687 .P
|
|
meillo@74
|
688 The
|
|
meillo@74
|
689 .I draft_from
|
|
meillo@74
|
690 masquerading type instructed
|
|
meillo@74
|
691 .Pn post
|
|
meillo@74
|
692 to use the value of the `From:' header as SMTP envelope sender.
|
|
meillo@74
|
693 This allowes to replace the sender address completely.
|
|
meillo@74
|
694 .Ci b14ea6073f77b4359aaf3fddd0e105989db9
|
|
meillo@74
|
695 Mmh now offers a kind of masquerading similar in effect, but
|
|
meillo@74
|
696 with technical differences.
|
|
meillo@74
|
697 As mmh does not transfer messages itself, the local MTA has full control
|
|
meillo@74
|
698 over the sending address. Any masquerading mmh introduces may be reverted
|
|
meillo@74
|
699 by the MTA. In times of pedantic spam checking, an MTA will likely do so
|
|
meillo@74
|
700 to keep its own reputation up.
|
|
meillo@74
|
701 Nonetheless, the MUA can set the `From:' header and thus propose
|
|
meillo@74
|
702 a sender address to be used to the MTA.
|
|
meillo@74
|
703 The MTA may then decide to take that one or generate the canonical sender
|
|
meillo@74
|
704 address for use as envelope sender address.
|
|
meillo@74
|
705 .P
|
|
meillo@74
|
706 In mmh, the MTA will always extract the recipient and sender from the
|
|
meillo@74
|
707 headers (\c
|
|
meillo@74
|
708 .Pn sendmail 's
|
|
meillo@74
|
709 .Sw -t
|
|
meillo@74
|
710 switch).
|
|
meillo@74
|
711 The `From:' header of the draft may be set arbitrary by the user.
|
|
meillo@74
|
712 If it is missing, the canonical sender address will be generated by the MTA.
|
|
meillo@74
|
713
|
|
meillo@74
|
714 .U3 "Remaining Options
|
|
meillo@74
|
715 .P
|
|
meillo@74
|
716 Two configure options remain in mmh.
|
|
meillo@74
|
717 One is the locking method to use:
|
|
meillo@74
|
718 .Sw --with-locking=[dot|fcntl|flock|lockf] .
|
|
meillo@74
|
719 Removing all other methods except the portable dot locking and having
|
|
meillo@74
|
720 that as default is appealing, but requires deeper investigation into the
|
|
meillo@74
|
721 topic.
|
|
meillo@74
|
722 The other,
|
|
meillo@74
|
723 .Sw --enable-debug ,
|
|
meillo@74
|
724 compiles the programs with debugging symbols and does not strip them.
|
|
meillo@74
|
725 This option is likely to stay.
|
|
meillo@72
|
726
|
|
meillo@72
|
727
|
|
meillo@58
|
728
|
|
meillo@63
|
729
|
|
meillo@58
|
730 .H2 "Removal of switches
|
|
meillo@58
|
731 .P
|
|
meillo@58
|
732
|
|
meillo@58
|
733
|
|
meillo@58
|
734
|
|
meillo@58
|
735
|
|
meillo@74
|
736 .H1 "Modernizing
|
|
meillo@58
|
737
|
|
meillo@58
|
738
|
|
meillo@58
|
739 .H2 "Removal of Code Relicts
|
|
meillo@0
|
740 .P
|
|
meillo@51
|
741 The code base of mmh originates from the late Seventies,
|
|
meillo@51
|
742 had been extensively
|
|
meillo@51
|
743 worked on in the mid Eighties, and had been partly reorganized and extended
|
|
meillo@51
|
744 in the Nineties. Relicts of all those times had gathered in the code base.
|
|
meillo@12
|
745 My goal was to remove any ancient code parts. One part of the task was
|
|
meillo@12
|
746 converting obsolete code constructs to standard constructs, the other part
|
|
meillo@12
|
747 was dropping obsolete functions.
|
|
meillo@12
|
748 .P
|
|
meillo@12
|
749 As I'm not even thirty years old and have no more than seven years of
|
|
meillo@51
|
750 Unix experience, I needed to learn about the history in retrospective.
|
|
meillo@51
|
751 Older people likely have used those ancient constructs themselves
|
|
meillo@51
|
752 and have suffered from their incompatibilities and have longed for
|
|
meillo@12
|
753 standardization. Unfortunately, I have only read that others had done so.
|
|
meillo@12
|
754 This put me in a much more difficult positions when working on the old
|
|
meillo@12
|
755 code. I needed to recherche what other would have known by heart from
|
|
meillo@12
|
756 experience. All my programming experience comes from a time past ANSI C
|
|
meillo@12
|
757 and past POSIX. Although I knew about the times before, I took the
|
|
meillo@51
|
758 current state implicitly for granted most of the time.
|
|
meillo@12
|
759 .P
|
|
meillo@12
|
760 Being aware of
|
|
meillo@12
|
761 these facts, I rather let people with more historic experience solve the
|
|
meillo@12
|
762 task of converting the ancient code constructs to standardized ones.
|
|
meillo@12
|
763 Luckily, Lyndon Nerenberg focused on this task at the nmh project.
|
|
meillo@12
|
764 He converted large parts of the code to POSIX constructs, removing
|
|
meillo@12
|
765 the conditionals compilation for now standardized features.
|
|
meillo@12
|
766 I'm thankful for this task being solved. I only pulled the changes into
|
|
meillo@12
|
767 mmh.
|
|
meillo@12
|
768 .P
|
|
meillo@20
|
769 The other task \(en dropping ancient functionality to remove old code \(en
|
|
meillo@12
|
770 I did myself, though. My position to strip mmh to the bare minimum of
|
|
meillo@12
|
771 frequently used features is much more revolutional than the nmh community
|
|
meillo@20
|
772 likes it. Without the need to justify my decisions, I was able to quickly
|
|
meillo@20
|
773 remove functionality I considered ancient.
|
|
meillo@20
|
774 The need to discuss my decisions with
|
|
meillo@20
|
775 peers likely would have slowed this process down. Of course, I researched
|
|
meillo@12
|
776 if a particular feature really should be dropped. Having not had any
|
|
meillo@12
|
777 contact to this feature within my computer life was a first indicator to
|
|
meillo@12
|
778 drop it, but I also asked others and searched the literature for modern
|
|
meillo@12
|
779 usage of the feature. If it appeared to be truly ancient, I dropped it.
|
|
meillo@12
|
780 The reason for dropping is always part of the commit message in the
|
|
meillo@12
|
781 version control system. Thus, it is easy for others to check their
|
|
meillo@12
|
782 view on the topic with mine and possibly to argue for reinclusion.
|
|
meillo@12
|
783
|
|
meillo@12
|
784 .U2 "MMDF maildrop support
|
|
meillo@12
|
785 .P
|
|
meillo@12
|
786 I did drop any support for the MMDF maildrop format. This type of format
|
|
meillo@12
|
787 is conceptionally similar to the mbox format, but uses four bytes with
|
|
meillo@12
|
788 value 1 (\fL^A^A^A^A\fP) as message delimiter,
|
|
meillo@18
|
789 instead of the string ``\fLFrom\ \fP''.
|
|
meillo@12
|
790 Due to the similarity and mbox being the de-facto standard maildrop
|
|
meillo@12
|
791 format on Unix, but also due to the larger influence of Sendmail than MMDF,
|
|
meillo@12
|
792 the MMDF maildrop format had vanished.
|
|
meillo@12
|
793 .P
|
|
meillo@12
|
794 The simplifications within the code were only moderate. Switches could
|
|
meillo@12
|
795 be removed from tools like
|
|
meillo@12
|
796 .L packf ,
|
|
meillo@12
|
797 which generate packed mailboxes. Only one packed mailbox format remained:
|
|
meillo@12
|
798 mbox.
|
|
meillo@12
|
799 The most important changes affect the equally named mail parsing routine in
|
|
meillo@12
|
800 .L sbr/m_getfld.c .
|
|
meillo@12
|
801 The direct MMDF code had been removed, but as now only one packed mailbox
|
|
meillo@12
|
802 format is left, code structure simplifications are likely possible.
|
|
meillo@12
|
803 The reason why they are still outstanding is the heavily optimized code
|
|
meillo@18
|
804 of
|
|
meillo@18
|
805 .Fu m_getfld() .
|
|
meillo@18
|
806 Changes beyond a small local scope \(en
|
|
meillo@12
|
807 which restructuring in its core is \(en cause a high risk of damaging
|
|
meillo@12
|
808 the intricate workings of the optimized code. This problem is know
|
|
meillo@12
|
809 to the developers of nmh, too. They also avoid touching this minefield
|
|
meillo@12
|
810 if possible.
|
|
meillo@12
|
811
|
|
meillo@12
|
812 .U2 "UUCP Bang Paths
|
|
meillo@12
|
813 .P
|
|
meillo@12
|
814 More questionably than the former topic is the removal of support for the
|
|
meillo@12
|
815 UUCP bang path address style. However, the user may translate the bang
|
|
meillo@12
|
816 paths on retrieval to Internet addresses and the other way on posting
|
|
meillo@12
|
817 messages. The former can be done my an MDA like procmail; the latter
|
|
meillo@12
|
818 by a sendmail wrapper. This would ensure that any address handling would
|
|
meillo@12
|
819 work as expected. However, it might just work well without any
|
|
meillo@12
|
820 such modifications, as mmh does not touch addresses much, in general.
|
|
meillo@12
|
821 But I can't ensure as I have never used an environment with bang paths.
|
|
meillo@12
|
822 Also, the behavior might break at any point in further development.
|
|
meillo@12
|
823
|
|
meillo@12
|
824 .U2 "Hardcopy terminal support
|
|
meillo@12
|
825 .P
|
|
meillo@12
|
826 More of a funny anecdote is the remaining of a check for printing to a
|
|
meillo@12
|
827 hardcopy terminal until Spring 2012, when I finally removed it.
|
|
meillo@12
|
828 I surely would be very happy to see such a terminal in action, maybe
|
|
meillo@12
|
829 actually being able to work on it, but I fear my chances are null.
|
|
meillo@12
|
830 .P
|
|
meillo@12
|
831 The check only prevented a pager to be placed between the outputting
|
|
meillo@18
|
832 program (\c
|
|
meillo@18
|
833 .Pn mhl )
|
|
meillo@18
|
834 and the terminal. This could have been ensured with
|
|
meillo@18
|
835 the
|
|
meillo@18
|
836 .Sw \-nomoreproc
|
|
meillo@18
|
837 at the command line statically, too.
|
|
meillo@12
|
838
|
|
meillo@12
|
839 .U2 "Removed support for header fields
|
|
meillo@12
|
840 .P
|
|
meillo@12
|
841 The `Encrypted' header had been introduced by RFC\^822, but already
|
|
meillo@12
|
842 marked legacy in RFC 2822. It was superseded by FIXME.
|
|
meillo@12
|
843 Mmh does no more support this header.
|
|
meillo@12
|
844 .P
|
|
meillo@21
|
845 Native support for `Face' headers
|
|
meillo@21
|
846 had been removed, as well.
|
|
meillo@21
|
847 The feature is similar to the `X-Face' header in its intent,
|
|
meillo@21
|
848 but takes a different approach to store the image.
|
|
meillo@21
|
849 Instead of encoding the image data directly into the header,
|
|
meillo@21
|
850 the the header contains the hostname and UDP port where the image
|
|
meillo@21
|
851 date could be retrieved.
|
|
meillo@21
|
852 Neither `X-Face' nor the here described `Face' system
|
|
meillo@21
|
853 \**
|
|
meillo@21
|
854 .FS
|
|
meillo@21
|
855 There is also a newer but different system, invented 2005,
|
|
meillo@21
|
856 using `Face' headers.
|
|
meillo@21
|
857 It is the successor of `X-Face' providing colored PNG images.
|
|
meillo@21
|
858 .FE
|
|
meillo@21
|
859 became well used in the large scale.
|
|
meillo@21
|
860 It's still possible to use a Face systems,
|
|
meillo@21
|
861 although mmh does not provide support for any of the different systems
|
|
meillo@21
|
862 anymore. It's fairly easy to write a small shell script to
|
|
meillo@21
|
863 extract the embedded or fetch the external Face data and display the image.
|
|
meillo@21
|
864 Own Face headers can be added into the draft template files.
|
|
meillo@21
|
865 .P
|
|
meillo@12
|
866 `Content-MD5' headers were introduced by RFC\^1864. They provide only
|
|
meillo@12
|
867 a verification of data corruption during the transfer. By no means can
|
|
meillo@12
|
868 they ensure verbatim end-to-end delivery of the contents. This is clearly
|
|
meillo@12
|
869 stated in the RFC. The proper approach to provide verificationability
|
|
meillo@12
|
870 of content in an end-to-end relationship is the use of digital cryptography
|
|
meillo@12
|
871 (RFCs FIXME). On the other hand, transfer protocols should ensure the
|
|
meillo@12
|
872 integrity of the transmission. In combinations these two approaches
|
|
meillo@12
|
873 make the `Content-MD5' header field useless. In consequence, I removed
|
|
meillo@12
|
874 the support for it. By this removal, MD5 computation is not needed
|
|
meillo@12
|
875 anywhere in mmh. Hence, over 500 lines of code were removed by this one
|
|
meillo@12
|
876 change. Even if the `Content-MD5' header field is useful sometimes,
|
|
meillo@12
|
877 I value its usefulnes less than the improvement in maintainability, caused
|
|
meillo@12
|
878 by the removal.
|
|
meillo@12
|
879
|
|
meillo@20
|
880 .U2 "Prompter's Control Keys
|
|
meillo@20
|
881 .P
|
|
meillo@20
|
882 The program
|
|
meillo@20
|
883 .Pn prompter
|
|
meillo@20
|
884 queries the user to fill in a message form. When used by
|
|
meillo@20
|
885 .Pn comp
|
|
meillo@20
|
886 as:
|
|
meillo@20
|
887 .DS
|
|
meillo@20
|
888 comp \-editor prompter
|
|
meillo@20
|
889 .DE
|
|
meillo@20
|
890 the resulting behavior is similar to
|
|
meillo@20
|
891 .Pn mailx .
|
|
meillo@51
|
892 Apparently,
|
|
meillo@20
|
893 .Pn prompter
|
|
meillo@20
|
894 hadn't been touched lately. Otherwise it's hardly explainable why it
|
|
meillo@20
|
895 still offered the switches
|
|
meillo@20
|
896 .Sn \-erase \fUchr\fP
|
|
meillo@20
|
897 and
|
|
meillo@20
|
898 .Sn \-kill \fUchr\fP
|
|
meillo@20
|
899 to name the characters for command line editing.
|
|
meillo@21
|
900 The times when this had been necessary are long time gone.
|
|
meillo@20
|
901 Today these things work out-of-the-box, and if not, are configured
|
|
meillo@20
|
902 with the standard tool
|
|
meillo@20
|
903 .Pn stty .
|
|
meillo@20
|
904
|
|
meillo@21
|
905 .U2 "Vfork and Retry Loops
|
|
meillo@21
|
906 .P
|
|
meillo@51
|
907 MH creates many processes, which is a consequence of the tool chest approach.
|
|
meillo@21
|
908 In earlier times
|
|
meillo@21
|
909 .Fu fork()
|
|
meillo@21
|
910 had been an expensive system call, as the process's whole image needed
|
|
meillo@21
|
911 to be duplicated. One common case is replacing the image with
|
|
meillo@21
|
912 .Fu exec()
|
|
meillo@21
|
913 right after having forked the child process.
|
|
meillo@21
|
914 To speed up this case, the
|
|
meillo@21
|
915 .Fu vfork()
|
|
meillo@21
|
916 system call was invented at Berkeley. It completely omits copying the
|
|
meillo@21
|
917 image. If the image gets replaced right afterwards then unnecessary
|
|
meillo@21
|
918 work is omited. On old systems this results in large speed ups.
|
|
meillo@21
|
919 MH uses
|
|
meillo@21
|
920 .Fu vfork()
|
|
meillo@21
|
921 whenever possible.
|
|
meillo@21
|
922 .P
|
|
meillo@21
|
923 Memory management units that support copy-on-write semantics make
|
|
meillo@21
|
924 .Fu fork()
|
|
meillo@21
|
925 almost as fast as
|
|
meillo@21
|
926 .Fu vfork()
|
|
meillo@21
|
927 in the cases when they can be exchanged.
|
|
meillo@21
|
928 With
|
|
meillo@21
|
929 .Fu vfork()
|
|
meillo@51
|
930 being more error-prone and hardly faster, it's preferable to simply
|
|
meillo@21
|
931 use
|
|
meillo@21
|
932 .Fu fork()
|
|
meillo@21
|
933 instead.
|
|
meillo@21
|
934 .P
|
|
meillo@21
|
935 Related to the costs of
|
|
meillo@21
|
936 .Fu fork()
|
|
meillo@21
|
937 is the probability of its success.
|
|
meillo@21
|
938 Today on modern systems, the system call will succeed almost always.
|
|
meillo@51
|
939 In the Eighties on heavy loaded systems, as they were common at
|
|
meillo@21
|
940 universities, this had been different. Thus, many of the
|
|
meillo@21
|
941 .Fu fork()
|
|
meillo@21
|
942 calls were wrapped into loops to retry to fork several times in
|
|
meillo@21
|
943 short intervals, in case of previous failure.
|
|
meillo@21
|
944 In mmh, the program aborts at once if the fork failed.
|
|
meillo@21
|
945 The user can reexecute the command then. This is expected to be a
|
|
meillo@21
|
946 very rare case on modern systems, especially personal ones, which are
|
|
meillo@21
|
947 common today.
|
|
meillo@21
|
948
|
|
meillo@12
|
949
|
|
meillo@58
|
950 .H2 "Attachments
|
|
meillo@22
|
951 .P
|
|
meillo@58
|
952 MIME
|
|
meillo@58
|
953
|
|
meillo@58
|
954
|
|
meillo@58
|
955 .H2 "Digital Cryptography
|
|
meillo@22
|
956 .P
|
|
meillo@58
|
957 Signing and encryption.
|
|
meillo@58
|
958
|
|
meillo@58
|
959
|
|
meillo@58
|
960 .H2 "Good Defaults
|
|
meillo@22
|
961 .P
|
|
meillo@58
|
962 foo
|
|
meillo@58
|
963
|
|
meillo@58
|
964
|
|
meillo@58
|
965
|
|
meillo@58
|
966
|
|
meillo@58
|
967 .H1 "Code style
|
|
meillo@22
|
968 .P
|
|
meillo@58
|
969 foo
|
|
meillo@58
|
970
|
|
meillo@58
|
971
|
|
meillo@58
|
972 .H2 "Standard Code
|
|
meillo@22
|
973 .P
|
|
meillo@58
|
974 POSIX
|
|
meillo@22
|
975
|
|
meillo@22
|
976
|
|
meillo@58
|
977 .H2 "Separation
|
|
meillo@14
|
978
|
|
meillo@58
|
979 .U2 "MH Directory Split
|
|
meillo@0
|
980 .P
|
|
meillo@19
|
981 In MH and nmh, a personal setup had consisted of two parts:
|
|
meillo@19
|
982 The MH profile, named
|
|
meillo@19
|
983 .Fn \&.mh_profile
|
|
meillo@19
|
984 and being located directly in the user's home directory.
|
|
meillo@19
|
985 And the MH directory, where all his mail messages and also his personal
|
|
meillo@19
|
986 forms, scan formats, other configuration files are stored. The location
|
|
meillo@19
|
987 of this directory could be user-chosen. The default was to name it
|
|
meillo@19
|
988 .Fn Mail
|
|
meillo@19
|
989 and have it directly in the home directory.
|
|
meillo@19
|
990 .P
|
|
meillo@19
|
991 I've never liked the data storage and the configuration to be intermixed.
|
|
meillo@19
|
992 They are different kinds of data. One part, are the messages,
|
|
meillo@19
|
993 which are the data to operate on. The other part, are the personal
|
|
meillo@19
|
994 configuration files, which are able to change the behavior of the operations.
|
|
meillo@19
|
995 The actual operations are defined in the profile, however.
|
|
meillo@19
|
996 .P
|
|
meillo@19
|
997 When storing data, one should try to group data by its type.
|
|
meillo@19
|
998 There's sense in the Unix file system hierarchy, where configuration
|
|
meillo@19
|
999 file are stored separate (\c
|
|
meillo@19
|
1000 .Fn /etc )
|
|
meillo@19
|
1001 to the programs (\c
|
|
meillo@19
|
1002 .Fn /bin
|
|
meillo@19
|
1003 and
|
|
meillo@19
|
1004 .Fn /usr/bin )
|
|
meillo@19
|
1005 to their sources (\c
|
|
meillo@19
|
1006 .Fn /usr/src ).
|
|
meillo@19
|
1007 Such separation eases the backup management, for instance.
|
|
meillo@19
|
1008 .P
|
|
meillo@19
|
1009 In mmh, I've reorganized the file locations.
|
|
meillo@19
|
1010 Still there are two places:
|
|
meillo@19
|
1011 There's the mail storage directory, which, like in MH, contains all the
|
|
meillo@19
|
1012 messages, but, unlike in MH, nothing else.
|
|
meillo@19
|
1013 Its location still is user-chosen, with the default name
|
|
meillo@19
|
1014 .Fn Mail ,
|
|
meillo@19
|
1015 in the user's home directory. This is much similar to the case in nmh.
|
|
meillo@19
|
1016 The configuration files, however, are grouped together in the new directory
|
|
meillo@19
|
1017 .Fn \&.mmh
|
|
meillo@19
|
1018 in the user's home directory.
|
|
meillo@19
|
1019 The user's profile now is a file, named
|
|
meillo@19
|
1020 .Fn profile ,
|
|
meillo@19
|
1021 in this mmh directory.
|
|
meillo@19
|
1022 Consistently, the context file and all the personal forms, scan formats,
|
|
meillo@19
|
1023 and the like, are also there.
|
|
meillo@19
|
1024 .P
|
|
meillo@19
|
1025 The naming changed with the relocation.
|
|
meillo@19
|
1026 The directory where everything, except the profile, had been stored (\c
|
|
meillo@19
|
1027 .Fn $HOME/Mail ),
|
|
meillo@19
|
1028 used to be called \fIMH directory\fP. Now, this directory is called the
|
|
meillo@19
|
1029 user's \fImail storage\fP. The name \fImmh directory\fP is now given to
|
|
meillo@19
|
1030 the new directory
|
|
meillo@19
|
1031 (\c
|
|
meillo@19
|
1032 .Fn $HOME/.mmh ),
|
|
meillo@19
|
1033 containing all the personal configuration files.
|
|
meillo@19
|
1034 .P
|
|
meillo@19
|
1035 The separation of the files by type of content is logical and convenient.
|
|
meillo@19
|
1036 There are no functional differences as any possible setup known to me
|
|
meillo@19
|
1037 can be implemented with both approaches, although likely a bit easier
|
|
meillo@19
|
1038 with the new approach. The main goal of the change had been to provide
|
|
meillo@19
|
1039 sensible storage locations for any type of personal mmh file.
|
|
meillo@19
|
1040 .P
|
|
meillo@19
|
1041 In order for one user to have multiple MH setups, he can use the
|
|
meillo@19
|
1042 environment variable
|
|
meillo@19
|
1043 .Ev MH
|
|
meillo@19
|
1044 the point to a different profile file.
|
|
meillo@19
|
1045 The MH directory (mail storage plus personal configuration files) is
|
|
meillo@19
|
1046 defined by the
|
|
meillo@19
|
1047 .Pe Path
|
|
meillo@19
|
1048 profile entry.
|
|
meillo@19
|
1049 The context file could be defined by the
|
|
meillo@19
|
1050 .Pe context
|
|
meillo@19
|
1051 profile entry or by the
|
|
meillo@19
|
1052 .Ev MHCONTEXT
|
|
meillo@19
|
1053 environment variable.
|
|
meillo@19
|
1054 The latter is useful to have a distinct context (e.g. current folders)
|
|
meillo@19
|
1055 in each terminal window, for instance.
|
|
meillo@19
|
1056 In mmh, there are three environment variables now.
|
|
meillo@19
|
1057 .Ev MMH
|
|
meillo@19
|
1058 may be used to change the location of the mmh directory.
|
|
meillo@19
|
1059 .Ev MMHP
|
|
meillo@19
|
1060 and
|
|
meillo@19
|
1061 .Ev MMHC
|
|
meillo@19
|
1062 change the profile and context files, respectively.
|
|
meillo@19
|
1063 Besides providing a more consistent feel (which simply is the result
|
|
meillo@19
|
1064 of being designed anew), the set of personal configuration files can
|
|
meillo@19
|
1065 be chosen independently from the profile (including mail storage location)
|
|
meillo@19
|
1066 and context, now. Being it relevant for practical use or not, it
|
|
meillo@19
|
1067 de-facto is an improvement. However, the main achievement is the
|
|
meillo@19
|
1068 split between mail storage and personal configuration files.
|
|
meillo@17
|
1069
|
|
meillo@0
|
1070
|
|
meillo@58
|
1071 .H2 "Modularization
|
|
meillo@0
|
1072 .P
|
|
meillo@58
|
1073 whatnowproc
|
|
meillo@0
|
1074 .P
|
|
meillo@49
|
1075 The \fIMH library\fP
|
|
meillo@49
|
1076 .Fn libmh.a
|
|
meillo@49
|
1077 collects a bunch of standard functions that many of the MH tools need,
|
|
meillo@49
|
1078 like reading the profile or context files.
|
|
meillo@49
|
1079 This doesn't hurt the separation.
|
|
meillo@49
|
1080
|
|
meillo@58
|
1081
|
|
meillo@58
|
1082 .H2 "Style
|
|
meillo@58
|
1083 .P
|
|
meillo@58
|
1084 Code layout, goto, ...
|
|
meillo@58
|
1085
|
|
meillo@58
|
1086
|
|
meillo@58
|
1087
|
|
meillo@58
|
1088
|
|
meillo@58
|
1089 .H1 "Concept Exploitation/Homogeniety
|
|
meillo@58
|
1090
|
|
meillo@58
|
1091
|
|
meillo@58
|
1092 .H2 "Draft Folder
|
|
meillo@58
|
1093 .P
|
|
meillo@58
|
1094 Historically, MH provided exactly one draft message, named
|
|
meillo@58
|
1095 .Fn draft
|
|
meillo@58
|
1096 and
|
|
meillo@58
|
1097 being located in the MH directory. When starting to compose another message
|
|
meillo@58
|
1098 before the former one was sent, the user had been questioned whether to use,
|
|
meillo@58
|
1099 refile or replace the old draft. Working on multiple drafts at the same time
|
|
meillo@58
|
1100 was impossible. One could only work on them in alteration by refiling the
|
|
meillo@58
|
1101 previous one to some directory and fetching some other one for reediting.
|
|
meillo@58
|
1102 This manual draft management needed to be done each time the user wanted
|
|
meillo@58
|
1103 to switch between editing one draft to editing another.
|
|
meillo@58
|
1104 .P
|
|
meillo@58
|
1105 To allow true parallel editing of drafts, in a straight forward way, the
|
|
meillo@58
|
1106 draft folder facility exists. It had been introduced already in July 1984
|
|
meillo@58
|
1107 by Marshall T. Rose. The facility was deactivated by default.
|
|
meillo@58
|
1108 Even in nmh, the draft folder facility remained deactivated by default.
|
|
meillo@58
|
1109 At least, Richard Coleman added the man page
|
|
meillo@58
|
1110 .Mp mh-draft(5)
|
|
meillo@58
|
1111 to document
|
|
meillo@58
|
1112 the feature well.
|
|
meillo@58
|
1113 .P
|
|
meillo@58
|
1114 The only advantage of not using the draft folder facility is the static
|
|
meillo@58
|
1115 name of the draft file. This could be an issue for MH frontends like mh-e.
|
|
meillo@58
|
1116 But as they likely want to provide working on multiple drafts in parallel,
|
|
meillo@58
|
1117 the issue is only concerning compatibility. The aim of nmh to stay compatible
|
|
meillo@58
|
1118 prevented the default activation of the draft folder facility.
|
|
meillo@58
|
1119 .P
|
|
meillo@58
|
1120 On the other hand, a draft folder is the much more natural concept than
|
|
meillo@58
|
1121 a draft message. MH's mail storage consists of folders and messages,
|
|
meillo@58
|
1122 the messages named with ascending numbers. A draft message breaks with this
|
|
meillo@58
|
1123 concept by introducing a message in a file named
|
|
meillo@58
|
1124 .Fn draft .
|
|
meillo@58
|
1125 This draft
|
|
meillo@58
|
1126 message is special. It can not be simply listed with the available tools,
|
|
meillo@58
|
1127 but instead requires special switches. I.e. corner-cases were
|
|
meillo@58
|
1128 introduced. A draft folder, in contrast, does not introduce such
|
|
meillo@58
|
1129 corner-cases. The available tools can operate on the messages within that
|
|
meillo@58
|
1130 folder like on any messages within any mail folders. The only difference
|
|
meillo@58
|
1131 is the fact that the default folder for
|
|
meillo@58
|
1132 .Pn send
|
|
meillo@58
|
1133 is the draft folder,
|
|
meillo@58
|
1134 instead of the current folder, like for all other tools.
|
|
meillo@58
|
1135 .P
|
|
meillo@58
|
1136 The trivial part of the change was activating the draft folder facility
|
|
meillo@58
|
1137 by default and setting a default name for this folder. Obviously, I chose
|
|
meillo@58
|
1138 the name
|
|
meillo@58
|
1139 .Fn +drafts .
|
|
meillo@58
|
1140 This made the
|
|
meillo@58
|
1141 .Sw \-draftfolder
|
|
meillo@58
|
1142 and
|
|
meillo@58
|
1143 .Sw \-draftmessage
|
|
meillo@58
|
1144 switches useless, and I could remove them.
|
|
meillo@58
|
1145 The more difficult but also the part that showed the real improvement,
|
|
meillo@58
|
1146 was updating the tools to the new concept.
|
|
meillo@58
|
1147 .Sw \-draft
|
|
meillo@58
|
1148 switches could
|
|
meillo@58
|
1149 be dropped, as operating on a draft message became indistinguishable to
|
|
meillo@58
|
1150 operating on any other message for the tools.
|
|
meillo@58
|
1151 .Pn comp
|
|
meillo@58
|
1152 still has its
|
|
meillo@58
|
1153 .Sw \-use
|
|
meillo@58
|
1154 switch for switching between its two modes: (1) Compose a new
|
|
meillo@58
|
1155 draft, possibly by taking some existing message as a form. (2) Modify
|
|
meillo@58
|
1156 an existing draft. In either case, the behavior of
|
|
meillo@58
|
1157 .Pn comp is
|
|
meillo@58
|
1158 deterministic. There is no more need to query the user. I consider this
|
|
meillo@58
|
1159 a major improvement. By making
|
|
meillo@58
|
1160 .Pn send
|
|
meillo@58
|
1161 simply operate on the current
|
|
meillo@58
|
1162 message in the draft folder by default, with message and folder both
|
|
meillo@58
|
1163 overridable by specifying them on the command line, it is now possible
|
|
meillo@58
|
1164 to send a draft anywhere within the storage by simply specifying its folder
|
|
meillo@58
|
1165 and name.
|
|
meillo@58
|
1166 .P
|
|
meillo@58
|
1167 All theses changes converted special cases to regular cases, thus
|
|
meillo@58
|
1168 simplifying the tools and increasing the flexibility.
|
|
meillo@58
|
1169
|
|
meillo@58
|
1170
|
|
meillo@58
|
1171 .H2 "Trash Folder
|
|
meillo@58
|
1172 .P
|
|
meillo@58
|
1173 Similar to the situation for drafts is the situation for removed messages.
|
|
meillo@58
|
1174 Historically, a message was deleted by renaming. A specific
|
|
meillo@58
|
1175 \fIbackup prefix\fP, often comma (\c
|
|
meillo@58
|
1176 .Fn , )
|
|
meillo@58
|
1177 or hash (\c
|
|
meillo@58
|
1178 .Fn # ),
|
|
meillo@58
|
1179 being prepended to the file name. Thus, MH wouldn't recognize the file
|
|
meillo@58
|
1180 as a message anymore, as only files whose name consists of digits only
|
|
meillo@58
|
1181 are treated as messages. The removed messages remained as files in the
|
|
meillo@58
|
1182 same directory and needed some maintenance job to truly delete them after
|
|
meillo@58
|
1183 some grace time. Usually, by running a command similar to
|
|
meillo@58
|
1184 .DS
|
|
meillo@58
|
1185 find /home/user/Mail \-ctime +7 \-name ',*' | xargs rm
|
|
meillo@58
|
1186 .DE
|
|
meillo@58
|
1187 in a cron job. Within the grace time interval
|
|
meillo@58
|
1188 the original message could be restored by stripping the
|
|
meillo@58
|
1189 the backup prefix from the file name. If however, the last message of
|
|
meillo@58
|
1190 a folder is been removed \(en say message
|
|
meillo@58
|
1191 .Fn 6
|
|
meillo@58
|
1192 becomes file
|
|
meillo@58
|
1193 .Fn ,6
|
|
meillo@58
|
1194 \(en and a new message enters the same folder, thus the same
|
|
meillo@58
|
1195 numbered being given again \(en in our case
|
|
meillo@58
|
1196 .Fn 6
|
|
meillo@58
|
1197 \(en, if that one
|
|
meillo@58
|
1198 is removed too, then the backup of the former message gets overwritten.
|
|
meillo@58
|
1199 Thus, the ability to restore removed messages does not only depend on
|
|
meillo@58
|
1200 the ``sweeping cron job'' but also on the removing of further messages.
|
|
meillo@58
|
1201 This is undesirable, because the real mechanism is hidden from the user
|
|
meillo@58
|
1202 and the consequences of further removals are not always obvious.
|
|
meillo@58
|
1203 Further more, the backup files are scattered within the whole mail
|
|
meillo@58
|
1204 storage, instead of being collected at one place.
|
|
meillo@58
|
1205 .P
|
|
meillo@58
|
1206 To improve the situation, the profile entry
|
|
meillo@58
|
1207 .Pe rmmproc
|
|
meillo@58
|
1208 (previously named
|
|
meillo@58
|
1209 .Pe Delete-Prog )
|
|
meillo@58
|
1210 was introduced, very early.
|
|
meillo@58
|
1211 It could be set to any command, which would care for the mail removal
|
|
meillo@58
|
1212 instead of taking the default action, described above.
|
|
meillo@58
|
1213 Refiling the to-be-removed files to some garbage folder was a common
|
|
meillo@58
|
1214 example. Nmh's man page
|
|
meillo@58
|
1215 .Mp rmm(1)
|
|
meillo@58
|
1216 proposes
|
|
meillo@58
|
1217 .Cl "refile +d
|
|
meillo@58
|
1218 to move messages to the garbage folder and
|
|
meillo@58
|
1219 .Cl "rm `mhpath +d all`
|
|
meillo@58
|
1220 the empty the garbage folder.
|
|
meillo@58
|
1221 Managing the message removal this way is a sane approach. It keeps
|
|
meillo@58
|
1222 the removed messages in one place, makes it easy to remove the backup
|
|
meillo@58
|
1223 files, and, most important, enables the user to use the tools of MH
|
|
meillo@58
|
1224 itself to operate on the removed messages. One can
|
|
meillo@58
|
1225 .Pn scan
|
|
meillo@58
|
1226 them,
|
|
meillo@58
|
1227 .Pn show
|
|
meillo@58
|
1228 them, and restore them with
|
|
meillo@58
|
1229 .Pn refile .
|
|
meillo@58
|
1230 There's no more
|
|
meillo@58
|
1231 need to use
|
|
meillo@58
|
1232 .Pn mhpath
|
|
meillo@58
|
1233 to switch over from MH tools to Unix tools \(en MH can do it all itself.
|
|
meillo@58
|
1234 .P
|
|
meillo@58
|
1235 This approach matches perfect with the concepts of MH, thus making
|
|
meillo@58
|
1236 it powerful. Hence, I made it the default. And even more, I also
|
|
meillo@58
|
1237 removed the old backup prefix approach, as it is clearly less powerful.
|
|
meillo@58
|
1238 Keeping unused alternative in the code is a bad choice as they likely
|
|
meillo@58
|
1239 gather bugs, by not being constantly tested. Also, the increased code
|
|
meillo@58
|
1240 size and more conditions crease the maintenance costs. By strictly
|
|
meillo@58
|
1241 converting to the trash folder approach, I simplified the code base.
|
|
meillo@58
|
1242 .Pn rmm
|
|
meillo@58
|
1243 calls
|
|
meillo@58
|
1244 .Pn refile
|
|
meillo@58
|
1245 internally to move the to-be-removed
|
|
meillo@58
|
1246 message to the trash folder (\c
|
|
meillo@58
|
1247 .Fn +trash
|
|
meillo@58
|
1248 by default). Messages
|
|
meillo@58
|
1249 there can be operated on like on any other message in the storage.
|
|
meillo@58
|
1250 The sweep clean, one can use
|
|
meillo@58
|
1251 .Cl "rmm \-unlink +trash a" ,
|
|
meillo@58
|
1252 where the
|
|
meillo@58
|
1253 .Sw \-unlink
|
|
meillo@58
|
1254 switch causes the files to be truly unliked instead
|
|
meillo@58
|
1255 of moved to the trash folder.
|
|
meillo@58
|
1256
|
|
meillo@58
|
1257
|
|
meillo@58
|
1258 .H2 "Path Notations
|
|
meillo@58
|
1259 .P
|
|
meillo@58
|
1260 foo
|
|
meillo@58
|
1261
|
|
meillo@58
|
1262
|
|
meillo@58
|
1263 .H2 "MIME Integration
|
|
meillo@58
|
1264 .P
|
|
meillo@58
|
1265 user-visible access to whole messages and MIME parts are inherently
|
|
meillo@58
|
1266 different
|
|
meillo@58
|
1267
|
|
meillo@58
|
1268
|
|
meillo@58
|
1269 .H2 "Of One Cast
|
|
meillo@58
|
1270 .P
|
