Storing Maintainers info around the kernel tree

From: Kyle Moffett
Date: Thu Aug 16 2007 - 09:05:35 EST


Merging a couple related threads here:

On Aug 16, 2007, at 07:57:23, Rene Herman wrote:
On 08/16/2007 01:26 PM, Salikh Zakirov wrote:
Rene Herman wrote:
Perhaps that immediately suggests an implementation to someone already familiar with git internals?
perhaps http://www.kernel.org/pub/software/scm/git/docs/ gitattributes.html and http://www.kernel.org/pub/software/scm/git/ docs/git-check-attr.html can help you?

No, thanks, saw them, but .gitattributes is in fact in the same category as .gitignore, which would _be_ a property.

If you do this stuff in files scattered around the tree, updating and moving stuff becomes a pain -- the tool would need to go edit files.

From a practical standpoint we don't want to duplicate someone's maintainer information in the attributes of every file they maintain. It would be much easier to put in the "kernel/somesubsys" directory a Maintainers file which has:

[SOME RANDOM SUBSYSTEM]
P: J. Random Hacker
M: j.random.hacker@localhost
L: random-subsys-devel@xxxxxxxxxxxxxxx
F: *

Anywhere else you had files that you wanted to associate with J. Random Hacker's maintainership, you would just use:

[SOME RANDOM SUBSYSTEM]
F: somesubsys.h


I posted a comment describing a mechanism like this a couple days ago:
http://lkml.org/lkml/2007/8/14/488

Executive overview:
On Aug 15, 2007, at 07:21:04, Rafael J. Wysocki wrote:
On Wednesday, 15 August 2007 04:51, Kyle Moffett wrote:
(a) "Maintainers" files sprinkled around the source tree with relative pathnames and other data

(b) Tool to generate a combined "MAINTAINERS" file from the ones sprinkled around the source tree

(c) Tool to search through the generated "MAINTAINERS" file with all sorts of useful command-line options

(d) Tool to check the generated "MAINTAINERS" file against recent git history and make suggestions

I like this idea. :-)

Well, to back up this idea with some code, I'm attaching a little perl script which does part (b). Basically you call it as:
./maint-combine $(find . -name Maintainers)

It will print any syntax errors on stderr during parsing. Once it's done it will dump to stdout its combined "MAINTAINERS" text. A couple notes:

* It uses a little "priority" system to figure out what order to print the data from each origin in. For example, the "F:" tag is given a score of 0, to force data consisting of just files towards the end. The "P:", "M:", and "L:" tags are given scores of 5, since people are generally interesting to know about. Everything else is given a score of "1". The scores are added up per ($file, $subsystem) pair and then during printing each subsystem's data is ordered by score (highest comes first).

* It generally allows any field at all; eventually we might want to limit it to a fixed list to help avoid typos.

* It has a little bit of magic logic for the "F:" field so that it figures out the relative directory for each field when generating the output. For example, an entry of "asm-*/suspend.h" in a file "include/Maintainers" will produce the output file entry: "F: include/ asm-*/suspend.h"

* The format isn't quite the same as the current MAINTAINERS file, to make parsing easier and more dummy-proof I changed the syntax for a subsystem-name to use square brackets (IE: "[SUSPEND TO RAM]"). The samples I gave in my previous email are what I used to test it with, plus a little dummy file with some syntax errors to check out the error messages:

Maintainers:
[EVERYTHING ELSE]
P: Various Linux Kernel Developers
L: linux-kernel@xxxxxxxxxxxxxxx
F: *

kernel/power/Maintainers:
[SUSPEND TO RAM]
P: Pavel Machek
M: pavel@xxxxxxx
P: Rafael J. Wysocki
M: rjw@xxxxxxx
L: linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx
S: Maintained
F: *

include/Maintainers:
[SUSPEND TO RAM]
F: linux/suspend.h
F: linux/freezer.h
F: linux/pm.h
F: asm-*/suspend.h



If you have any other questions, the perl script is pretty self- explanatory and I'll be completely back online this weekend. With any luck I'll have some time in a hotel tomorrow (mmm, slow-as-dirt hotel wireless, what fun) to work on parts (c) and (d).

Cheers,
Kyle Moffett

#! /usr/bin/perl

use strict;
use warnings;

## This table is for determining what order to show entries from different
## source "Maintainers" files. They are prioritized based on the number and
## significance of each field, as listed in this table. Any field not found
## here will be assumed to have a significance of "1".
my %fieldprio = (
p => 5, ## Person
m => 5, ## Email
l => 5, ## Mailing List
f => 0, ## File
);


my %mprio;
my %maint;
my $section;
my $origin;
my $pathprefix;
my $printorigin;

while (<>) {
unless (defined $origin and $origin eq $ARGV) {
undef $section;

## Get rid of extra slashes, unnecessary "./" entries
$ARGV =~ s{//+}{/}g;
$ARGV =~ s{(^|/)\./}{$1};

$origin = $ARGV;
}

chomp; s/\s+/ /g; s/^ //; s/ $//;
/\S+/ or next;

if (/^\[ ?([^]]+) ?\]$/) {
$section = uc $1;

$printorigin = 1 if $origin ne '-';

$maint{$section}{$origin} ||= [];
$mprio{$section}{$origin} ||= 0;

## Figure out a useful path prefix if there is one
$pathprefix = ($origin =~ m{(^.*/)(?!\.\.?$)[^/]+$})?$1:"";

next;
}

unless (/^([^:]+?) ?: ?(.*)$/) {
print STDERR "$ARGV:$.: Invalid line: $_\n";
next;
}

my($field,$value) = (lc($1), $2);

unless (defined $section) {
print STDERR "$ARGV:$.: Found field '\u$field' before ",
"any subsystem declaration: $_\n";
next;
}

## Preprocess paths to make them absolute
$value = $pathprefix.$value if $field eq 'f';

## Update the sorting order
if (exists $fieldprio{$field}) {
$mprio{$section}{$origin} += $fieldprio{$field};
} else {
$mprio{$section}{$origin}++;
}

push @{$maint{$section}{$origin}}, [$field, $value];
}

sub priosort ( $@ )
{
my $section = shift;
return sort {$mprio{$section}{$b} <=> $mprio{$section}{$a}} @_;
}

for $section (sort {$a cmp $b} keys %maint) {
print "[$section]\n";
for my $origin (priosort $section, keys %{$maint{$section}}) {
print "\nOrigin: $origin\n" if $printorigin;
print "\u$_->[0]: $_->[1]\n" for @{$maint{$section}{$origin}};
}
print "\n\n";
}

# vim:set ft=perl: