Subject: Re: Bug in .mailmap handling?

From: Stefan Beller <[email-masked]>
Date: Fri, 12 Jul 2013 22:35:36 +0200

On 07/12/2013 10:28 PM, Junio C Hamano wrote:
> Stefan Beller <[email-masked]> writes:
> 
>> 	# Adding the line to the mailmap should make life easy, so we know
>> 	# it's the same person
>> 	echo "A <[email-masked]> <[email-masked]>" > .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 <[email-masked]>...", 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
> 
> 	<[email-masked]> <[email-masked]>
> 
> without the name.  I do not think this bug affected anything you
> observed, though.
> 
>> 	git shortlog -sne
>> 		 1  A <[email-masked]>
>> 		 1  A <[email-masked]>
> 
> This is coming from mailmap.c::add_mapping() that downcases the
> e-mail address.
> 
> [email-masked] is mapped to [email-masked] because of this
> downcasing, while "A <[email-masked]>" does not have any entry for it
> in the .mailmap file, so it is given back as-is.  Hence we see two
> distinct entries.
> 

So do I understand it right, we're having 2 bugs in here?

One being triggered by the short name, only one character.
So if you want to debug the other bug with a longer name,
you can either use a made up name, or run
    git shortlog -sne |grep Knut
in the git repository having the mailmap file already updated.
The way the mailmap file is written, I'd assume only one line
to be found, as of now 2 lines come up
     2	Knut Franke <[email-masked]>
     1	Knut Franke <[email-masked]>

which seems to downcase the whole first email.