[code/myrepos.git] / mr

#!/usr/bin/perl

#man{{{

=head1 NAME

mr - a Multiple Repository management tool

=head1 SYNOPSIS

B<mr> [options] checkout

B<mr> [options] update

B<mr> [options] status

B<mr> [options] commit [-m "message"]

B<mr> [options] diff

B<mr> [options] log

B<mr> [options] register [repository]

B<mr> [options] config section ["parameter=[value]" ...]

B<mr> [options] action [params ...]

=head1 DESCRIPTION

B<mr> is a Multiple Repository management tool. It can checkout, update, or
perform other actions on a set of repositories as if they were one combined
respository. It supports any combination of subversion, git, cvs, mecurial,
bzr and darcs repositories, and support for other revision control systems can
easily be added.

B<mr> cds into and operates on all registered repositories at or below your
working directory. Or, if you are in a subdirectory of a repository that
contains no other registered repositories, it will stay in that directory,
and work on only that repository,

These predefined commands should be fairly familiar to users of any revision
control system:

=over 4

=item checkout (or co)

Checks out any repositories that are not already checked out.

=item update

Updates each repository from its configured remote repository.

If a repository isn't checked out yet, it will first check it out.

=item status

Displays a status report for each repository, showing what
uncommitted changes are present in the repository.

=item commit (or ci)

Commits changes to each repository. (By default, changes are pushed to the
remote repository too, when using distributed systems like git.)

The optional -m parameter allows specifying a commit message.

=item diff

Show a diff of uncommitted changes.

=item log

Show the commit log.

=back

These commands are also available:

=over 4

=item list (or ls)

List the repositories that mr will act on.

=item register

Register an existing repository in a mrconfig file. By default, the
repository in the current directory is registered, or you can specify a
directory to register.

The mrconfig file that is modified is chosen by either the -c option, or by
looking for the closest known one at or below the current directory.

=item config

Adds, modifies, removes, or prints a value from a mrconfig file. The next
parameter is the name of the section the value is in. To add or modify
values, use one or more instances of "parameter=value". Use "parameter=" to
remove a parameter. Use just "parameter" to get the value of a parameter.

For example, to add (or edit) a repository in src/foo:

  mr config src/foo checkout="svn co svn://example.com/foo/trunk foo"

To show the command that mr uses to update the repository in src/foo:

  mr config src/foo update

To see the built-in library of shell functions contained in mr:

  mr config DEFAULT lib

The ~/.mrconfig file is used by default. To use a different config file,
use the -c option.

=item help

Displays this help.

=back

Actions can be abbreviated to any unambiguous subsctring, so
"mr st" is equivilant to "mr status", and "mr up" is equivilant to "mr
update"

Additional parameters can be passed to most commands, and are passed on
unchanged to the underlying revision control system. This is mostly useful
if the repositories mr will act on all use the same revision control
system.

=head1 OPTIONS

=over 4

=item -d directory

Specifies the topmost directory that B<mr> should work in. The default is
the current working directory.

=item -c mrconfig

Use the specified mrconfig file. The default is B<~/.mrconfig>

=item -v

Be verbose.

=item -s

Expand the statistics line displayed at the end to include information
about exactly which repositories failed and were skipped, if any.

=item -n

Just operate on the repository for the current directory, do not 
recurse into deeper repositories.

=item -j number

Run the specified number of jobs in parallel. This can greatly speed up
operations such as updates. It is not recommended for interactive
operations.

=back

=head1 FILES

B<mr> is configured by .mrconfig files. It starts by reading the .mrconfig
file in your home directory, and this can in turn chain load .mrconfig files
from repositories.

Here is an example .mrconfig file:

  [src]
  checkout = svn co svn://svn.example.com/src/trunk src
  chain = true

  [src/linux-2.6]
  checkout = git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git &&
        cd linux-2.6 &&
        git checkout -b mybranch origin/master

The .mrconfig file uses a variant of the INI file format. Lines starting with
"#" are comments. Values can be continued to the following line by
indenting the line with whitespace.

The "DEFAULT" section allows setting default values for the sections that
come after it.

The "ALIAS" section allows adding aliases for actions. Each parameter
is an alias, and its value is the action to use.

All other sections add repositories. The section header specifies the
directory where the repository is located. This is relative to the directory
that contains the mrconfig file, but you can also choose to use absolute
paths.

Within a section, each parameter defines a shell command to run to handle a
given action. mr contains default handlers for "update", "status",
"commit", and other standard actions. Normally you only need to specify what
to do for "checkout".

Note that these shell commands are run in a "set -e" shell
environment, where any additional parameters you pass are available in
"$@". The "checkout" command is run in the parent of the repository
directory, since the repository isn't checked out yet. All other commands
are run inside the repository, though not necessarily at the top of it.

The "MR_REPO" environment variable is set to the path to the top of the
repository. The "MR_CONFIG" environment variable is set to the .mrconfig file
that defines the repo being acted on, or, if the repo is not yet in a config
file, the .mrconfig file that should be modified to register the repo.

A few parameters have special meanings:

=over 4

=item skip

If the "skip" parameter is set and its command returns true, then B<mr>
will skip acting on that repository. The command is passed the action
name in $1.

Here are two examples. The first skips the repo unless
mr is run by joey. The second uses the hours_since function
(included in mr's built-in library) to skip updating the repo unless it's
been at least 12 hours since the last update.

  skip = test $(whoami) != joey
  skip = [ "$1" = update ] && ! hours_since "$1" 12

=item order

The "order" parameter can be used to override the default ordering of
repositories. The default order value is 10. Use smaller values to make
repositories be processed earlier, and larger values to make repositories
be processed later.

Note that if a repository is located in a subdirectory of another
repository, ordering it to be processed earlier is not recommended.

=item chain

If the "chain" parameter is set and its command returns true, then B<mr>
will try to load a .mrconfig file from the root of the repository. (You
should avoid chaining from repositories with untrusted committers.)

=item lib

The "lib" parameter can specify some shell code that will be run before each
command, this can be a useful way to define shell functions for other commands
to use.

=back

=head1 AUTHOR

Copyright 2007 Joey Hess <joey@kitenet.net>

Licensed under the GNU GPL version 2 or higher.

http://kitenet.net/~joey/code/mr/

=cut

#}}}

use warnings;
use strict;
use Getopt::Long;
use Cwd qw(getcwd abs_path);
use POSIX "WNOHANG";
use constant {
        OK => 0,
        FAILED => 1,
        SKIPPED => 2,
        ABORT => 3,
};

$SIG{INT}=sub {
        print STDERR "mr: interrupted\n";
        exit 2;
};

$ENV{MR_CONFIG}="$ENV{HOME}/.mrconfig";
my $config_overridden=0;
my $verbose=0;
my $stats=0;
my $no_recurse=0;
my $jobs=1;
my %config;
my %configfiles;
my %knownactions;
my %alias;
my $directory=getcwd();

Getopt::Long::Configure("no_permute");
my $result=GetOptions(
        "d|directory=s" => sub { $directory=abs_path($_[1]) },
        "c|config=s" => sub { $ENV{MR_CONFIG}=$_[1]; $config_overridden=1 },
        "v|verbose" => \$verbose,
        "s|stats" => \$stats,
        "n|no-recurse" => \$no_recurse,
        "j|jobs=i" => \$jobs,
);
if (! $result || @ARGV < 1) {
        die("Usage: mr [-d directory] action [params ...]\n".
            "(Use mr help for man page.)\n");

}
if (! defined $directory) {
        die("mr: failed to determine working directory\n");
}

# Make sure MR_CONFIG is an absolute path, but don't use abs_path since
# the config file might be a symlink to elsewhere, and the directory it's
# in is significant.
if ($ENV{MR_CONFIG} !~ /^\//) {
        $ENV{MR_CONFIG}=getcwd()."/".$ENV{MR_CONFIG};
}
# Try to set MR_PATH to the path to the program.
eval {
        use FindBin qw($Bin $Script);
        $ENV{MR_PATH}=$Bin."/".$Script;
};

loadconfig(\*DATA);
loadconfig($ENV{MR_CONFIG});
#use Data::Dumper;
#print Dumper(\%config);

# alias expansion and command stemming
my $action=shift @ARGV;
if (exists $alias{$action}) {
        $action=$alias{$action};
}
if (! exists $knownactions{$action}) {
        my @matches = grep { /^\Q$action\E/ }
                keys %knownactions, keys %alias;
        if (@matches == 1) {
                $action=$matches[0];
        }
        elsif (@matches == 0) {
                die "mr: unknown action \"$action\" (known actions: ".
                        join(", ", sort keys %knownactions).")\n";
        }
        else {
                die "mr: ambiguous action \"$action\" (matches: ".
                        join(", ", @matches).")\n";
        }
}

# commands that do not operate on all repos
if ($action eq 'help') {
        exec($config{''}{DEFAULT}{$action}) || die "exec: $!";
}
elsif ($action eq 'config') {
        if (@ARGV < 2) {
                die "mr config: not enough parameters\n";
        }
        my $section=shift;
        if ($section=~/^\//) {
                # try to convert to a path relative to the config file
                my ($dir)=$ENV{MR_CONFIG}=~/^(.*\/)[^\/]+$/;
                $dir=abs_path($dir);
                $dir.="/" unless $dir=~/\/$/;
                if ($section=~/^\Q$dir\E(.*)/) {
                        $section=$1;
                }
        }
        my %changefields;
        foreach (@ARGV) {
                if (/^([^=]+)=(.*)$/) {
                        $changefields{$1}=$2;
                }
                else {
                        my $found=0;
                        foreach my $topdir (sort keys %config) {
                                if (exists $config{$topdir}{$section} &&
                                    exists $config{$topdir}{$section}{$_}) {
                                        print $config{$topdir}{$section}{$_}."\n";
                                        $found=1;
                                        last if $section eq 'DEFAULT';
                                }
                        }
                        if (! $found) {
                                die "mr $action: $section $_ not set\n";
                        }
                }
        }
        modifyconfig($ENV{MR_CONFIG}, $section, %changefields) if %changefields;
        exit 0;
}
elsif ($action eq 'register') {
        if (! $config_overridden) {
                # Find the closest known mrconfig file to the current
                # directory.
                $directory.="/" unless $directory=~/\/$/;
                foreach my $topdir (reverse sort keys %config) {
                        next unless length $topdir;
                        if ($directory=~/^\Q$topdir\E/) {
                                $ENV{MR_CONFIG}=$configfiles{$topdir};
                                last;
                        }
                }
        }
        my $command="set -e; ".$config{''}{DEFAULT}{lib}."\n".
                "my_action(){ $config{''}{DEFAULT}{$action}\n }; my_action ".
                join(" ", map { s/\//\/\//g; s/"/\"/g; '"'.$_.'"' } @ARGV);
        print STDERR "mr $action: running >>$command<<\n" if $verbose;
        exec($command) || die "exec: $!";
}

# an ordered list of repos
my @list;
foreach my $topdir (sort keys %config) {
        foreach my $subdir (sort keys %{$config{$topdir}}) {
                push @list, {
                        topdir => $topdir,
                        subdir => $subdir,
                        order => $config{$topdir}{$subdir}{order},
                };
        }
}
@list = sort {
                $a->{order}  <=> $b->{order}
                             ||
                $a->{topdir} cmp $b->{topdir}
                             ||
                $a->{subdir} cmp $b->{subdir}
        } @list;

# work out what repos to act on
my @repos;
my $nochdir=0;
foreach my $repo (@list) {
        my $topdir=$repo->{topdir};
        my $subdir=$repo->{subdir};

        next if $subdir eq 'DEFAULT';
        my $dir=($subdir =~/^\//) ? $subdir : $topdir.$subdir;
        my $d=$directory;
        $dir.="/" unless $dir=~/\/$/;
        $d.="/" unless $d=~/\/$/;
        next if $no_recurse && $d ne $dir;
        next if $dir ne $d && $dir !~ /^\Q$d\E/;
        push @repos, [$dir, $topdir, $subdir];
}
if (! @repos) {
        # fallback to find a leaf repo
        foreach my $repo (reverse @list) {
                my $topdir=$repo->{topdir};
                my $subdir=$repo->{subdir};
                
                next if $subdir eq 'DEFAULT';
                my $dir=($subdir =~/^\//) ? $subdir : $topdir.$subdir;
                my $d=$directory;
                $dir.="/" unless $dir=~/\/$/;
                $d.="/" unless $d=~/\/$/;
                if ($d=~/^\Q$dir\E/) {
                        push @repos, [$dir, $topdir, $subdir];
                        last;
                }
        }
        $nochdir=1;
}

# run the action on each repository and print stats
my (@ok, @failed, @skipped);
if ($jobs > 1) {
        mrs(@repos);
}
else {
        foreach my $repo (@repos) {
                record($repo, action($action, @$repo));
        }
}
if (! @ok && ! @failed && ! @skipped) {
        die "mr $action: no repositories found to work on\n";
}
print "mr $action: finished (".join("; ",
        showstat($#ok+1, "ok", "ok"),
        showstat($#failed+1, "failed", "failed"),
        showstat($#skipped+1, "skipped", "skipped"),
).")\n";
if ($stats) {
        if (@skipped) {
                print "mr $action: (skipped: ".join(" ", @skipped).")\n";
        }
        if (@failed) {
                print STDERR "mr $action: (failed: ".join(" ", @failed).")\n";
        }
}
if (@failed) {
        exit 1;
}
elsif (! @ok && @skipped) {
        exit 1;
}
exit 0;

sub action { #{{{
        my ($action, $dir, $topdir, $subdir) = @_;

        $ENV{MR_CONFIG}=$configfiles{$topdir};
        my $lib=exists $config{$topdir}{$subdir}{lib} ?
                       $config{$topdir}{$subdir}{lib}."\n" : "";

        if ($action eq 'checkout') {
                if (-d $dir) {
                        print "mr $action: $dir already exists, skipping checkout\n" if $verbose;
                        return SKIPPED;
                }

                $dir=~s/^(.*)\/[^\/]+\/?$/$1/;

                if (! -d $dir) {
                        print "mr $action: creating parent directory $dir\n" if $verbose;
                        system("mkdir", "-p", $dir);
                }
        }
        elsif ($action =~ /update/) {
                if (! -d $dir) {
                        return action("checkout", $dir, $topdir, $subdir);
                }
        }
        
        $ENV{MR_REPO}=$dir;

        if (exists $config{$topdir}{$subdir}{skip}) {
                my $test="set -e;".$lib.
                        "my_action(){ $config{$topdir}{$subdir}{skip}\n }; my_action '$action'";
                print "mr $action: running skip test >>$test<<\n" if $verbose;
                my $ret=system($test);
                if ($ret != 0) {
                        if (($? & 127) == 2) {
                                print STDERR "mr $action: interrupted\n";
                                return ABORT;
                        }
                        elsif ($? & 127) {
                                print STDERR "mr $action: skip test received signal ".($? & 127)."\n";
                                return ABORT;
                        }
                }
                if ($ret >> 8 == 0) {
                        print "mr $action: $dir skipped per config file\n" if $verbose;
                        return SKIPPED;
                }
        }
        
        if (! $nochdir && ! chdir($dir)) {
                print STDERR "mr $action: failed to chdir to $dir: $!\n";
                return FAILED;
        }
        elsif (! exists $config{$topdir}{$subdir}{$action}) {
                print STDERR "mr $action: no defined $action command for $topdir$subdir, skipping\n";
                return SKIPPED;
        }
        else {
                if (! $nochdir) {
                        print "mr $action: $topdir$subdir\n";
                }
                else {
                        my $s=$directory;
                        $s=~s/^\Q$topdir$subdir\E\/?//;
                        print "mr $action: $topdir$subdir (in subdir $s)\n";
                }
                my $command="set -e; ".$lib.
                        "my_action(){ $config{$topdir}{$subdir}{$action}\n }; my_action ".
                        join(" ", map { s/\//\/\//g; s/"/\"/g; '"'.$_.'"' } @ARGV);
                print STDERR "mr $action: running >>$command<<\n" if $verbose;
                my $ret=system($command);
                if ($ret != 0) {
                        if (($? & 127) == 2) {
                                print STDERR "mr $action: interrupted\n";
                                return ABORT;
                        }
                        elsif ($? & 127) {
                                print STDERR "mr $action: received signal ".($? & 127)."\n";
                                return ABORT;
                        }
                        print STDERR "mr $action: failed ($ret)\n" if $verbose;
                        if ($ret >> 8 != 0) {
                                print STDERR "mr $action: command failed\n";
                        }
                        elsif ($ret != 0) {
                                print STDERR "mr $action: command died ($ret)\n";
                        }
                        return FAILED;
                }
                else {
                        if ($action eq 'checkout' && ! -d $dir) {
                                print STDERR "mr $action: $dir missing after checkout\n";;
                                return FAILED;
                        }

                        return OK;
                }
        }
} #}}}

# run actions on multiple repos, in parallel
sub mrs { #{{{
        $| = 1;
        my @active;
        my @fhs;
        my @out;
        my $running=0;
        while (@fhs or @repos) {
                while ($running < $jobs && @repos) {
                        $running++;
                        my $repo = shift @repos;
                        pipe(my $outfh, CHILD_STDOUT);
                        pipe(my $errfh, CHILD_STDERR);
                        my $pid;
                        unless ($pid = fork) {
                                die "mr $action: cannot fork: $!" unless defined $pid;
                                open(STDOUT, ">&CHILD_STDOUT") || die "mr $action cannot reopen stdout: $!";
                                open(STDERR, ">&CHILD_STDERR") || die "mr $action cannot reopen stderr: $!";
                                close CHILD_STDOUT;
                                close CHILD_STDERR;
                                close $outfh;
                                close $errfh;
                                exit action($action, @$repo);
                        }
                        close CHILD_STDOUT;
                        close CHILD_STDERR;
                        push @active, [$pid, $repo];
                        push @fhs, [$outfh, $errfh];
                        push @out, ['',     ''];
                }
                my ($rin, $rout) = ('','');
                my $nfound;
                foreach my $fh (@fhs) {
                        next unless defined $fh;
                        vec($rin, fileno($fh->[0]), 1) = 1 if defined $fh->[0];
                        vec($rin, fileno($fh->[1]), 1) = 1 if defined $fh->[1];
                }
                $nfound = select($rout=$rin, undef, undef, 1);
                foreach my $channel (0, 1) {
                        foreach my $i (0..$#fhs) {
                                next unless defined $fhs[$i];
                                my $fh = $fhs[$i][$channel];
                                next unless defined $fh;
                                if (vec($rout, fileno($fh), 1) == 1) {
                                        my $r = '';
                                        if (sysread($fh, $r, 1024) == 0) {
                                                close($fh);
                                                $fhs[$i][$channel] = undef;
                                                if (! defined $fhs[$i][0] &&
                                                    ! defined $fhs[$i][1]) {
                                                        waitpid($active[$i][0], 0);
                                                        print STDOUT $out[$i][0];
                                                        print STDERR $out[$i][1];
                                                        record($active[$i][1], $? >> 8);
                                                        splice(@fhs, $i, 1);
                                                        splice(@active, $i, 1);
                                                        splice(@out, $i, 1);
                                                        $running--;
                                                }
                                        }
                                        $out[$i][$channel] .= $r;
                                }
                        }
                }
        }
} #}}}

sub record { #{{{
        my $dir=shift()->[0];
        my $ret=shift;

        if ($ret == OK) {
                push @ok, $dir;
                print "\n";
        }
        elsif ($ret == FAILED) {
                push @failed, $dir;
                print "\n";
        }
        elsif ($ret == SKIPPED) {
                push @skipped, $dir;
        }
        elsif ($ret == ABORT) {
                exit 1;
        }
        else {
                die "unknown exit status $ret";
        }
} #}}}

sub showstat { #{{{
        my $count=shift;
        my $singular=shift;
        my $plural=shift;
        if ($count) {
                return "$count ".($count > 1 ? $plural : $singular);
        }
        return;
} #}}}

my %loaded;
sub loadconfig { #{{{
        my $f=shift;

        my @toload;

        my $in;
        my $dir;
        if (ref $f eq 'GLOB') {
                $dir="";
                $in=$f; 
        }
        else {
                if (! -e $f) {
                        return;
                }

                my $absf=abs_path($f);
                if ($loaded{$absf}) {
                        return;
                }
                $loaded{$absf}=1;

                ($dir)=$f=~/^(.*\/)[^\/]+$/;
                if (! defined $dir) {
                        $dir=".";
                }
                $dir=abs_path($dir)."/";
                
                if (! exists $configfiles{$dir}) {
                        $configfiles{$dir}=$f;
                }

                # copy in defaults from first parent
                my $parent=$dir;
                while ($parent=~s/^(.*\/)[^\/]+\/?$/$1/) {
                        if ($parent eq '/') {
                                $parent="";
                        }
                        if (exists $config{$parent} &&
                            exists $config{$parent}{DEFAULT}) {
                                $config{$dir}{DEFAULT}={ %{$config{$parent}{DEFAULT}} };
                                last;
                        }
                }
                
                print "mr: loading config $f\n" if $verbose;
                open($in, "<", $f) || die "mr: open $f: $!\n";
        }
        my @lines=<$in>;
        close $in;

        my $section;
        my $line=0;
        while (@lines) {
                $_=shift @lines;
                $line++;
                chomp;
                next if /^\s*\#/ || /^\s*$/;
                if (/^\[([^\]]*)\]\s*$/) {
                        $section=$1;
                }
                elsif (/^(\w+)\s*=\s*(.*)/) {
                        my $parameter=$1;
                        my $value=$2;

                        # continued value
                        while (@lines && $lines[0]=~/^\s(.+)/) {
                                shift(@lines);
                                $line++;
                                $value.="\n$1";
                                chomp $value;
                        }

                        if (! defined $section) {
                                die "$f line $.: parameter ($parameter) not in section\n";
                        }
                        if ($section ne 'ALIAS' &&
                            ! exists $config{$dir}{$section} &&
                            exists $config{$dir}{DEFAULT}) {
                                # copy in defaults
                                $config{$dir}{$section}={ %{$config{$dir}{DEFAULT}} };
                        }
                        if ($section eq 'ALIAS') {
                                $alias{$parameter}=$value;
                        }
                        elsif ($parameter eq 'lib') {
                                $config{$dir}{$section}{lib}.=$value."\n";
                        }
                        else {
                                $config{$dir}{$section}{$parameter}=$value;
                                $knownactions{$parameter}=1;
                                if ($parameter eq 'chain' &&
                                    length $dir && $section ne "DEFAULT" &&
                                    -e $dir.$section."/.mrconfig") {
                                        my $ret=system($value);
                                        if ($ret != 0) {
                                                if (($? & 127) == 2) {
                                                        print STDERR "mr $action: chain test interrupted\n";
                                                        exit 2;
                                                }
                                                elsif ($? & 127) {
                                                        print STDERR "mr $action: chain test received signal ".($? & 127)."\n";
                                                }
                                        }
                                        else {
                                                push @toload, $dir.$section."/.mrconfig";
                                        }
                                }
                        }
                }
                else {
                        die "$f line $line: parse error\n";
                }
        }

        foreach (@toload) {
                loadconfig($_);
        }
} #}}}

sub modifyconfig { #{{{
        my $f=shift;
        # the section to modify or add
        my $targetsection=shift;
        # fields to change in the section
        # To remove a field, set its value to "".
        my %changefields=@_;

        my @lines;
        my @out;

        if (-e $f) {
                open(my $in, "<", $f) || die "mr: open $f: $!\n";
                @lines=<$in>;
                close $in;
        }

        my $formatfield=sub {
                my $field=shift;
                my @value=split(/\n/, shift);

                return "$field = ".shift(@value)."\n".
                        join("", map { "\t$_\n" } @value);
        };
        my $addfields=sub {
                my @blanks;
                while ($out[$#out] =~ /^\s*$/) {
                        unshift @blanks, pop @out;
                }
                foreach my $field (sort keys %changefields) {
                        if (length $changefields{$field}) {
                                push @out, "$field = $changefields{$field}\n";
                                delete $changefields{$field};
                        }
                }
                push @out, @blanks;
        };

        my $section;
        while (@lines) {
                $_=shift(@lines);

                if (/^\s*\#/ || /^\s*$/) {
                        push @out, $_;
                }
                elsif (/^\[([^\]]*)\]\s*$/) {
                        if (defined $section && 
                            $section eq $targetsection) {
                                $addfields->();
                        }

                        $section=$1;

                        push @out, $_;
                }
                elsif (/^(\w+)\s*=\s(.*)/) {
                        my $parameter=$1;
                        my $value=$2;

                        # continued value
                        while (@lines && $lines[0]=~/^\s(.+)/) {
                                shift(@lines);
                                $value.="\n$1";
                                chomp $value;
                        }

                        if ($section eq $targetsection) {
                                if (exists $changefields{$parameter}) {
                                        if (length $changefields{$parameter}) {
                                                $value=$changefields{$parameter};
                                        }
                                        delete $changefields{$parameter};
                                }
                        }

                        push @out, $formatfield->($parameter, $value);
                }
        }

        if (defined $section && 
            $section eq $targetsection) {
                $addfields->();
        }
        elsif (%changefields) {
                push @out, "\n[$targetsection]\n";
                foreach my $field (sort keys %changefields) {
                        if (length $changefields{$field}) {
                                push @out, $formatfield->($field, $changefields{$field});
                        }
                }
        }

        open(my $out, ">", $f) || die "mr: write $f: $!\n";
        print $out @out;
        close $out;     
} #}}}

# Finally, some useful actions that mr knows about by default.
# These can be overridden in ~/.mrconfig.
#DATA{{{
__DATA__
[ALIAS]
co = checkout
ci = commit
ls = list

[DEFAULT]
order = 10
lib =
        error() {
                echo "mr: $@" >&2
                exit 1
        }
        hours_since() {
                if [ -z "$1" ] || [ -z "$2" ]; then
                        error "mr: usage: hours_since action num"
                fi
                for dir in .git .svn .bzr CVS .hg _darcs; do
                        if [ -e "$MR_REPO/$dir" ]; then
                                flagfile="$MR_REPO/$dir/.mr_last$1"
                                break
                        fi
                done
                if [ -z "$flagfile" ]; then
                        error "cannot determine flag filename"
                fi
                delta=$(perl -wle 'print -f shift() ? int((-M _) * 24) : 9999' "$flagfile")
                if [ "$delta" -lt "$2" ]; then
                        exit 0
                else
                        touch "$flagfile"
                        exit 1
                fi
        }

update =
        if [ -d "$MR_REPO"/.svn ]; then
                svn update "$@"
        elif [ -d "$MR_REPO"/.git ]; then
                if [ -z "$@" ]; then
                        git pull -t origin master
                else
                        git pull "$@"
                fi
        elif [ -d "$MR_REPO"/.bzr ]; then
                bzr merge "$@"
        elif [ -d "$MR_REPO"/CVS ]; then
                cvs update "$@"
        elif [ -d "$MR_REPO"/.hg ]; then
                hg pull "$@" && hg update "$@"
        elif [ -d "$MR_REPO"/_darcs ]; then
                darcs pull -a "$@"
        else
                error "unknown repo type"
        fi
status =
        if [ -d "$MR_REPO"/.svn ]; then
                svn status "$@"
        elif [ -d "$MR_REPO"/.git ]; then
                git status "$@" || true
        elif [ -d "$MR_REPO"/.bzr ]; then
                bzr status "$@"
        elif [ -d "$MR_REPO"/CVS ]; then
                cvs status "$@"
        elif [ -d "$MR_REPO"/.hg ]; then
                hg status "$@"
        elif [ -d "$MR_REPO"/_darcs ]; then
                darcs whatsnew -ls "$@"
        else
                error "unknown repo type"
        fi
commit =
        if [ -d "$MR_REPO"/.svn ]; then
                svn commit "$@"
        elif [ -d "$MR_REPO"/.git ]; then
                git commit -a "$@" && git push --all
        elif [ -d "$MR_REPO"/.bzr ]; then
                bzr commit "$@" && bzr push
        elif [ -d "$MR_REPO"/CVS ]; then
                cvs commit "$@"
        elif [ -d "$MR_REPO"/.hg ]; then
                hg commit -m "$@" && hg push
        elif [ -d "$MR_REPO"/_darcs ]; then
                darcs commit -a -m "$@" && darcs push -a
        else
                error "unknown repo type"
        fi
diff =
        if [ -d "$MR_REPO"/.svn ]; then
                svn diff "$@"
        elif [ -d "$MR_REPO"/.git ]; then
                git diff "$@"
        elif [ -d "$MR_REPO"/.bzr ]; then
                bzr diff "$@"
        elif [ -d "$MR_REPO"/CVS ]; then
                cvs diff "$@"
        elif [ -d "$MR_REPO"/.hg ]; then
                hg diff "$@"
        elif [ -d "$MR_REPO"/_darcs ]; then
                darcs diff "$@"
        else
                error "unknown repo type"
        fi
log =
        if [ -d "$MR_REPO"/.svn ]; then
                svn log"$@"
        elif [ -d "$MR_REPO"/.git ]; then
                git log "$@"
        elif [ -d "$MR_REPO"/.bzr ]; then
                bzr log "$@"
        elif [ -d "$MR_REPO"/CVS ]; then
                cvs log "$@"
        elif [ -d "$MR_REPO"/.hg ]; then
                hg log "$@"
        elif [ -d "$MR_REPO"/_darcs ]; then
                darcs changes "$@"
        else
                error "unknown repo type"
        fi
register =
        if [ -n "$1" ]; then
                cd "$1"
        fi
        basedir="$(basename $(pwd))"
        if [ -d .svn ]; then
                url=$(LANG=C svn info . | grep -i ^URL: | cut -d ' ' -f 2)
                if [ -z "$url" ]; then
                        error "cannot determine svn url"
                fi
                echo "Registering svn url: $url in $MR_CONFIG"
                mr -c "$MR_CONFIG" config "$(pwd)" checkout="svn co $url $basedir"
        elif [ -d .git ]; then
                url=$(LANG=C git-config --get remote.origin.url)
                if [ -z "$url" ]; then
                        error "cannot determine git url"
                fi
                echo "Registering git url: $url in $MR_CONFIG"
                mr -c "$MR_CONFIG" config "$(pwd)" checkout="git clone $url $basedir"
        elif [ -d .bzr ]; then
                url=$(cat .bzr/branch/parent)
                if [ -z "$url" ]; then
                        error "cannot determine bzr url"
                fi
                echo "Registering bzr url: $url in $MR_CONFIG"
                mr -c "$MR_CONFIG" config "$(pwd)" checkout="bzr clone $url $basedir"
        elif [ -d CVS ]; then
                repo=$(cat CVS/Repository)
                root=$(cat CVS/Root)
                if [ -z "$root" ]; then
                        error "cannot determine cvs root"
                fi
                echo "Registering cvs repository $repo at root $root"
                mr -c "$MR_CONFIG" config "$(pwd)" \
                        checkout="cvs -d '$root' co -d $basedir $repo"
        elif [ -d .hg ]; then
                url=$(hg showconfig paths.default)
                echo "Registering mercurial repo url: $url in $MR_CONFIG"
                mr -c "$MR_CONFIG" config "$(pwd)" \
                        checkout="hg clone $url $basedir"
        elif [ -d _darcs ]; then
                url=$(cat _darcs/prefs/defaultrepo)
                echo "Registering darcs repository $url in $MR_CONFIG"
                mr -c "$MR_CONFIG" config "$(pwd)" \
                        checkout="darcs get $url $basedir"
        else
                error "unable to register this repo type"
        fi
help =
        if [ ! -e "$MR_PATH" ]; then
                error "cannot find program path"
        fi
        (pod2man -c mr "$MR_PATH" | man -l -) || error "pod2man or man failed"
list = true
config = 

ed = echo "A horse is a horse, of course, of course.."
T = echo "I pity the fool."
right = echo "Not found."
#}}}