The Annoyance Filter.pdf - Fourmilab

212 DEVELOPMENT LOG ANNOYANCE-FILTER §256
Added logic to configure.in to test for the presence of the system function and the gnuplot and
ppmtogif utilities required by the −−plot option. If any of them is missing, the option will be disabled
when the program is compiled.
Added a test to configure.in for the presence of readlink and disabled the code that chases symbolic
links in file name arguments if it’s absent. I also added a “probable loop” warning if this code exceeds
the maximum link depth limit.
Added a configurator test for the presence of popen and code to disable the ability to read compressed
files if it’s not present. This allowed me to remove the special case for WIN32 I added last night to build
on DJGPP—it’s now subsumed into the test for popen.
Designed this version as “Release Candidate 1” and indicated this by setting VERSION to "0.1−RC1".
Proofed the program documentation and the formatting of the code listing and fixed numerous typos
and infelicitous layout.
Defined −t as a shortcut single-letter option for −−test and −r as a shortcut for −−read.
Release 0.1-RC1.
2002 September 24
Hugh Daniel took a look at the program and had many comments and suggestions. Until otherwise
noted, the following items result from them.
Corrected “vertical interlace” terminology in the document to “vertical retrace”. I’m forever screwing
that one up.
Renamed −−purge to −−prune, which is a more precise (and less intimidating) description of what it
does. For the moment, −−purge is still accepted to ease the transition. Fixed the check target in
Makefile.in to use −−prune.
Added the hideous logic to Makefile.in to report overall pass/fail status for the check target.
Clarified the infectuous nature of the GPL in COPYING. While I was at it, I added information about
the public domain status of DCDFlib.
Okay, back to self-generated items. . . . Changed the −−plot option to use pnmtopng to generate the
plot in PNG format instead of GIF.
Release 0.1-RC2.
2002 September 26
Added the ability to treat a directory as a mail folder consisting of messages in individual files in the
directory. The contents of the directory are simply logically concatenated and are not restricted to one
message per file–they may be UNIX mail folders in their own right.
After a huge amount of wasted effort trying to do this in an ultra-clean C++ fashion by defining an
idirstream flavour of istream which returns the concatenated contents of files in a directory (I got that
close, but couldn’t make it work with the getline function for string without stooping to ugliness and
making assumptions about the guts of the iostream package I believed unwarranted. This dead end is
why you see no log entries for yesterday.
So, I ripped all that out and simply added logic to mailFolder to detect when it’s passed a directory
and wrap a loop traversing the directory around the main input loop; when end of file is encountered and
we’re traversing a directory, we look for the next file and commence processing it, declaring a genuine
end of file only at the end of the directory.
This interacts in an interesting way with the MIME decoders. Recall that they are passed the actual
istream from which the mailFolder normally reads and take charge of it until the end of the encoded