From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 12 Jul 2013 20:28:57 GMT
Subject: Re: Bug in .mailmap handling?
Message-ID: <7vfvvjjzee.fsf@alter.siamese.dyndns.org>
In-Reply-To: <51E029B9.20108@googlemail.com>

Stefan Beller <stefanbeller@googlemail.com> writes:

> 	# Adding the line to the mailmap should make life easy, so we know
> 	# it's the same person
> 	echo "A <A@example.org> <changed_email@example.org>" > .mailmap

While I was looking at this, I noticed this piece of code:

diff --git a/mailmap.c b/mailmap.c
index 2a7b366..418081e 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -122,7 +122,7 @@ static char *parse_name_and_email(char *buffer, char **name,
 	while (nend > nstart && isspace(*nend))
 		--nend;
 
-	*name = (nstart < nend ? nstart : NULL);
+	*name = (nstart <= nend ? nstart : NULL);
 	*email = left+1;
 	*(nend+1) = '\0';
 	*right++ = '\0';

The function is given a buffer "A <A@example.org>...", nstart scans
from the beginning of the buffer, skipping whitespaces (there isn't
any, so nstart points at the buffer), while nend starts from one
byte before the first '<' and skips whitespaces backwards and ends
at the first non-whitespace (i.e. it hits "A" at the beginning of
the buffer).  nstart == nend in this case for a single-letter name,
and an off-by-one error makes it fail to pick up the name, which
makes the entry equivalent to

	<A@example.org> <changed_email@example.org>

without the name.  I do not think this bug affected anything you
observed, though.

> 	git shortlog -sne
> 		 1  A <A@example.org>
> 		 1  A <a@example.org>

This is coming from mailmap.c::add_mapping() that downcases the
e-mail address.

changed_email@example.org is mapped to a@example.org because of this
downcasing, while "A <A@example.org>" does not have any entry for it
in the .mailmap file, so it is given back as-is.  Hence we see two
distinct entries.