git

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#!/usr/bin/perl
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# List people who might be interested in a patch.  Useful as the argument to
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# git-send-email --cc-cmd option, and in other situations.
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#
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# Usage: git contacts <file | rev-list option> ...
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use strict;
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use warnings;
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use IPC::Open2;
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my $since = '5-years-ago';
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my $min_percent = 10;
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my $labels_rx = qr/Signed-off-by|Reviewed-by|Acked-by|Cc|Reported-by/i;
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my %seen;
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sub format_contact {
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	my ($name, $email) = @_;
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	return "$name <$email>";
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}
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sub parse_commit {
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	my ($commit, $data) = @_;
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	my $contacts = $commit->{contacts};
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	my $inbody = 0;
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	for (split(/^/m, $data)) {
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		if (not $inbody) {
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			if (/^author ([^<>]+) <(\S+)> .+$/) {
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				$contacts->{format_contact($1, $2)} = 1;
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			} elsif (/^$/) {
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				$inbody = 1;
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			}
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		} elsif (/^$labels_rx:\s+([^<>]+)\s+<(\S+?)>$/o) {
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			$contacts->{format_contact($1, $2)} = 1;
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		}
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	}
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}
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sub import_commits {
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	my ($commits) = @_;
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	return unless %$commits;
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	my $pid = open2 my $reader, my $writer, qw(git cat-file --batch);
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	for my $id (keys(%$commits)) {
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		print $writer "$id\n";
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		my $line = <$reader>;
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		if ($line =~ /^([0-9a-f]{40}) commit (\d+)/) {
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			my ($cid, $len) = ($1, $2);
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			die "expected $id but got $cid\n" unless $id eq $cid;
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			my $data;
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			# cat-file emits newline after data, so read len+1
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			read $reader, $data, $len + 1;
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			parse_commit($commits->{$id}, $data);
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		}
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	}
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	close $reader;
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	close $writer;
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	waitpid($pid, 0);
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	die "git-cat-file error: $?\n" if $?;
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}
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sub get_blame {
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	my ($commits, $source, $from, $ranges) = @_;
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	return unless @$ranges;
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	open my $f, '-|',
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		qw(git blame --porcelain -C),
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		map({"-L$_->[0],+$_->[1]"} @$ranges),
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		'--since', $since, "$from^", '--', $source or die;
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	while (<$f>) {
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		if (/^([0-9a-f]{40}) \d+ \d+ \d+$/) {
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			my $id = $1;
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			$commits->{$id} = { id => $id, contacts => {} }
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				unless $seen{$id};
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			$seen{$id} = 1;
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		}
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	}
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	close $f;
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}
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sub blame_sources {
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	my ($sources, $commits) = @_;
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	for my $s (keys %$sources) {
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		for my $id (keys %{$sources->{$s}}) {
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			get_blame($commits, $s, $id, $sources->{$s}{$id});
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		}
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	}
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}
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sub scan_patches {
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	my ($sources, $id, $f) = @_;
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	my $source;
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	while (<$f>) {
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		if (/^From ([0-9a-f]{40}) Mon Sep 17 00:00:00 2001$/) {
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			$id = $1;
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			$seen{$id} = 1;
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		}
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		next unless $id;
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		if (m{^--- (?:a/(.+)|/dev/null)$}) {
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			$source = $1;
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		} elsif (/^@@ -(\d+)(?:,(\d+))?/ && $source) {
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			my $len = defined($2) ? $2 : 1;
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			push @{$sources->{$source}{$id}}, [$1, $len] if $len;
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		}
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	}
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}
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sub scan_patch_file {
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	my ($commits, $file) = @_;
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	open my $f, '<', $file or die "read failure: $file: $!\n";
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	scan_patches($commits, undef, $f);
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	close $f;
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}
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sub parse_rev_args {
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	my @args = @_;
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	open my $f, '-|',
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		qw(git rev-parse --revs-only --default HEAD --symbolic), @args
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		or die;
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	my @revs;
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	while (<$f>) {
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		chomp;
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		push @revs, $_;
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	}
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	close $f;
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	return @revs if scalar(@revs) != 1;
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	return "^$revs[0]", 'HEAD' unless $revs[0] =~ /^-/;
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	return $revs[0], 'HEAD';
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}
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sub scan_rev_args {
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	my ($commits, $args) = @_;
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	my @revs = parse_rev_args(@$args);
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	open my $f, '-|', qw(git rev-list --reverse), @revs or die;
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	while (<$f>) {
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		chomp;
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		my $id = $_;
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		$seen{$id} = 1;
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		open my $g, '-|', qw(git show -C --oneline), $id or die;
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		scan_patches($commits, $id, $g);
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		close $g;
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	}
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	close $f;
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}
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sub mailmap_contacts {
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	my ($contacts) = @_;
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	my %mapped;
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	my $pid = open2 my $reader, my $writer, qw(git check-mailmap --stdin);
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	for my $contact (keys(%$contacts)) {
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		print $writer "$contact\n";
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		my $canonical = <$reader>;
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		chomp $canonical;
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		$mapped{$canonical} += $contacts->{$contact};
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	}
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	close $reader;
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	close $writer;
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	waitpid($pid, 0);
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	die "git-check-mailmap error: $?\n" if $?;
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	return \%mapped;
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}
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if (!@ARGV) {
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	die "No input revisions or patch files\n";
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}
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my (@files, @rev_args);
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for (@ARGV) {
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	if (-e) {
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		push @files, $_;
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	} else {
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		push @rev_args, $_;
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	}
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}
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my %sources;
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for (@files) {
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	scan_patch_file(\%sources, $_);
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}
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if (@rev_args) {
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	scan_rev_args(\%sources, \@rev_args)
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}
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my $toplevel = `git rev-parse --show-toplevel`;
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chomp $toplevel;
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chdir($toplevel) or die "chdir failure: $toplevel: $!\n";
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my %commits;
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blame_sources(\%sources, \%commits);
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import_commits(\%commits);
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my $contacts = {};
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for my $commit (values %commits) {
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	for my $contact (keys %{$commit->{contacts}}) {
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		$contacts->{$contact}++;
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	}
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}
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$contacts = mailmap_contacts($contacts);
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my $ncommits = scalar(keys %commits);
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for my $contact (keys %$contacts) {
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	my $percent = $contacts->{$contact} * 100 / $ncommits;
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	next if $percent < $min_percent;
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	print "$contact\n";
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}
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