Bug#970209: mhonarc: -conlen mbox parsing breaks on messages with last line starting with "From " (despite Content-Length)

[Guilhem Moulin]

Package: mhonarc
Version: 2.6.19-2
Severity: normal
Tags: patch upstream

Dear Maintainer,

Consider the attached UUCP-style mbox, where for each message the
byte-length of its body is indicated with a Content-Length: header.
The ‘-conlen’ [0] flag is meant to make MHonArc read the correct body
length and remove the need for unescaping lines starting with “From: ”.
This works well except when it's the *last* line that starts with
“From: ”.

    $ mhonarc -conlen -outdir /tmp/out - </tmp/test.mbox
    This is MHonArc v2.6.19+, Perl 5.030003 linux
    Converting messages to /tmp/out
    Reading - ..
    Warning: Could not parse date for message
             Message-Id: 
<d41d8cd98f00b204e9800998ecf84...@no-id-found.mhonarc.org>
             Date:
    .

    Writing mail ...
    Writing /tmp/out/maillist.html ...
    Writing /tmp/out/threads.html ...
    Writing database ...
    3 new messages
    3 total messages

    $ grep X-Message-Id /tmp/out/msg*.html
    /tmp/out/msg00000.html:<!--X-Message-Id: f...@example.net -->
    /tmp/out/msg00001.html:<!--X-Message-Id: 
d41d8cd98f00b204e9800998ecf8427e@NO&#45;ID&#45;FOUND.mhonarc.org -->
    /tmp/out/msg00002.html:<!--X-Message-Id: b...@example.net -->

That's because MHonArc slurps “bogus” lines after after the message with

    # Slurp up bogus data if required (should I do this?)
    while (!/$FROM/o && !eof($handle)) {
      $_ = <$handle>;
    }

where $_ is initially set to the last body line…  (By that loop is
AFAICT required to read “\nFrom …\n”.)  The fix is use a post condition
instead:

    $ mhonarc -conlen -outdir /tmp/out - </tmp/test.mbox
    This is MHonArc v2.6.19+, Perl 5.030003 linux
    Converting messages to /tmp/out
    Reading - ..

    Writing mail ..
    Writing /tmp/out/maillist.html ...
    Writing /tmp/out/threads.html ...
    Writing database ...
    2 new messages
    2 total messages

    $ grep X-Message-Id /tmp/out/msg*.html
    /tmp/out/msg00000.html:<!--X-Message-Id: f...@example.net -->
    /tmp/out/msg00001.html:<!--X-Message-Id: b...@example.net -->

Cheers,
-- 
Guilhem.

[0] https://www.mhonarc.org/MHonArc/doc/resources/conlen.html

test.mbox
Description: application/mbox

--- mhonarc-2.6.19/lib/mhamain.pl
+++ mhonarc-2.6.19/lib/mhamain.pl
@@ -1017,9 +1017,9 @@
 		}
 	    }
 	    # Slurp up bogus data if required (should I do this?)
-	    while (!/$FROM/o && !eof($handle)) {
+	    do {
 		$_ = <$handle>;
-	    }
+	    } while (!/$FROM/o && !eof($handle));
 
 	} else {				# No content-length
 	    while (<$handle>) {

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