contrib/nmbug: new script for sharing tags with a given prefix.

The main idea is consider the notmuch database as analogous to the
work-tree. A bare git repo is maintained in the users home directory,
with a tree of the form tags/$message-id/$tag

Like notmuch and git, we have a set of subcommnds, mainly modelled on
git.

Implementation wise, the heavy lifting is in the following functions.

   commit	xapian -> git
   checkout	git -> xapian
   merge	fetched git + git -> xapian
   status	find differences between xapian, git, and remote git.

The central implementation trick, from an idea I think due to
tomprince on IRC is manipulate the git index directly from the xapian
tag information.  The merge routine is still done using a temporary
checkout as I wasn't able to get it working with the index only.

There are also some convenience wrappers around git commands, like "fetch"
that essential just set GIT_DIR in the environment.

In order to encode tags (viewed as octet sequences) into filenames,
we whitelist a smallish set of characters and %hex escape anything outside.

The prefix is omitted in git, which lets one save and restore to
different prefixes (although this is only lightly tested).

Thanks to Tomi Ollila for a huge amount of feedback and patches while
putting this together.
This commit is contained in:
David Bremner 2011-11-12 21:24:25 -04:00
parent 9207f90f52
commit ebd1adc55b

621
contrib/nmbug Executable file
View file

@ -0,0 +1,621 @@
#!/usr/bin/env perl
# Copyright (c) 2011 David Bremner
# License: same as notmuch
use strict;
use warnings;
use File::Temp qw(tempdir);
use Pod::Usage;
no encoding;
my $NMBGIT = $ENV{NMBGIT} || $ENV{HOME}.'/.nmbug';
$NMBGIT .= '/.git' if (-d $NMBGIT.'/.git');
my $TAGPREFIX = $ENV{NMBPREFIX} || 'notmuch::';
# magic hash for git
my $EMPTYBLOB = 'e69de29bb2d1d6434b8b29ae775ad8c2e48c5391';
# for encoding
my $ESCAPE_CHAR = '%';
my $NO_ESCAPE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.
'0123456789+-_@=.:,';
my $MUST_ENCODE = qr{[^\Q$NO_ESCAPE\E]};
my $ESCAPED_RX = qr{$ESCAPE_CHAR([A-Fa-f0-9]{2})};
my %command = (
archive => \&do_archive,
checkout => \&do_checkout,
commit => \&do_commit,
fetch => \&do_fetch,
help => \&do_help,
log => \&do_log,
merge => \&do_merge,
pull => \&do_pull,
push => \&do_push,
status => \&do_status,
);
my $subcommand = shift || usage ();
if (!exists $command{$subcommand}) {
usage ();
}
&{$command{$subcommand}}(@ARGV);
sub git_pipe {
my $envref = (ref $_[0] eq 'HASH') ? shift : {};
my $ioref = (ref $_[0] eq 'ARRAY') ? shift : undef;
my $dir = ($_[0] eq '-|' or $_[0] eq '|-') ? shift : undef;
unshift @_, 'git';
$envref->{GIT_DIR} ||= $NMBGIT;
spawn ($envref, defined $ioref ? $ioref : (), defined $dir ? $dir : (), @_);
}
sub git {
my $fh = git_pipe (@_);
my $str = join ('', <$fh>);
chomp($str);
return $str;
}
sub spawn {
my $envref = (ref $_[0] eq 'HASH') ? shift : {};
my $ioref = (ref $_[0] eq 'ARRAY') ? shift : undef;
my $dir = ($_[0] eq '-|' or $_[0] eq '|-') ? shift : '-|';
die unless @_;
if (open my $child, $dir) {
return $child;
}
# child
while (my ($key, $value) = each %{$envref}) {
$ENV{$key} = $value;
}
if (defined $ioref && $dir eq '-|') {
open my $fh, '|-', @_ or die "open |- @_: $!";
foreach my $line (@{$ioref}) {
print $fh $line, "\n";
}
exit 0;
} else {
if ($dir ne '|-') {
open STDIN, '<', '/dev/null' or die "reopening stdin: $!"
}
exec @_;
die "exec @_: $!";
}
}
sub get_tags {
my $prefix = shift;
my @tags;
my $fh = spawn ('-|', qw/notmuch search --output=tags/, "*")
or die 'error dumping tags';
while (<$fh>) {
chomp ();
push @tags, $_ if (m/^$prefix/);
}
return @tags;
}
sub do_archive {
system ('git', "--git-dir=$NMBGIT", 'archive', 'HEAD');
}
sub is_committed {
my $status = shift;
return scalar (@{$status->{added}} ) + scalar (@{$status->{deleted}} ) == 0;
}
sub do_commit {
my @args = @_;
my $status = compute_status ();
if ( is_committed ($status) ) {
print "Nothing to commit\n";
return;
}
my $index = read_tree ('HEAD');
update_index ($index, $status);
my $tree = git ( { GIT_INDEX_FILE => $index }, 'write-tree')
or die 'no output from write-tree';
my $parent = git ( 'rev-parse', 'HEAD' )
or die 'no output from rev-parse';
my $commit = git ([ @args ], 'commit-tree', $tree, '-p', $parent)
or die 'commit-tree';
git ('update-ref', 'HEAD', $commit);
unlink $index || die "unlink: $!";
}
sub read_tree {
my $treeish = shift;
my $index = $NMBGIT.'/nmbug.index';
git ({ GIT_INDEX_FILE => $index }, 'read-tree', '--empty');
git ({ GIT_INDEX_FILE => $index }, 'read-tree', $treeish);
return $index;
}
sub update_index {
my $index = shift;
my $status = shift;
my $git = spawn ({ GIT_DIR => $NMBGIT, GIT_INDEX_FILE => $index },
'|-', qw/git update-index --index-info/)
or die 'git update-index';
foreach my $pair (@{$status->{deleted}}) {
index_tags_for_msg ($git, $pair->{id}, 'D', $pair->{tag});
}
foreach my $pair (@{$status->{added}}) {
index_tags_for_msg ($git, $pair->{id}, 'A', $pair->{tag});
}
}
sub do_fetch {
my $remote = shift || 'origin';
git ('fetch', $remote);
}
sub notmuch {
my @args = @_;
system ('notmuch', @args) == 0 or die "notmuch @args failed: $?";
}
sub index_tags {
my $index = $NMBGIT.'/nmbug.index';
my $query = join ' ', map ("tag:$_", get_tags ($TAGPREFIX));
my $fh = spawn ('-|', qw/notmuch dump --/, $query)
or die "notmuch dump: $!";
git ('read-tree', '--empty');
my $git = spawn ({ GIT_DIR => $NMBGIT, GIT_INDEX_FILE => $index },
'|-', qw/git update-index --index-info/)
or die 'git update-index';
while (<$fh>) {
m/ ( [^ ]* ) \s+ \( ([^\)]* ) \) /x || die 'syntax error in dump';
my ($id,$rest) = ($1,$2);
#strip prefixes before writing
my @tags = grep { s/^$TAGPREFIX//; } split (' ', $rest);
index_tags_for_msg ($git,$id, 'A', @tags);
}
close $git;
return $index;
}
sub index_tags_for_msg {
my $fh = shift;
my $msgid = shift;
my $mode = shift;
my $hash = $EMPTYBLOB;
my $blobmode = '100644';
if ($mode eq 'D') {
$blobmode = '0';
$hash = '0000000000000000000000000000000000000000';
}
foreach my $tag (@_) {
my $tagpath = 'tags/' . encode_for_fs ($msgid) . '/' . encode_for_fs ($tag);
print $fh "$blobmode $hash\t$tagpath\n";
}
}
sub do_checkout {
do_sync (action => 'checkout');
}
sub do_sync {
my %args = @_;
my $status = compute_status ();
my ($A_action, $D_action);
if ($args{action} eq 'checkout') {
$A_action = '-';
$D_action = '+';
} else {
$A_action = '+';
$D_action = '-';
}
foreach my $pair (@{$status->{added}}) {
notmuch ('tag', $A_action.$TAGPREFIX.$pair->{tag},
'id:'.$pair->{id});
}
foreach my $pair (@{$status->{deleted}}) {
notmuch ('tag', $D_action.$TAGPREFIX.$pair->{tag},
'id:'.$pair->{id});
}
}
sub insist_committed {
my $status=compute_status();
if ( !is_committed ($status) ) {
print "Uncommitted changes to $TAGPREFIX* tags in notmuch
For a summary of changes, run 'nmbug status'
To save your changes, run 'nmbug commit' before merging/pull
To discard your changes, run 'nmbug checkout'
";
exit (1);
}
}
sub do_pull {
my $remote = shift || 'origin';
git ( 'fetch', $remote);
do_merge ();
}
sub do_merge {
insist_committed ();
my $tempwork = tempdir ('/tmp/nmbug-merge.XXXXXX', CLEANUP => 1);
git ( { GIT_WORK_TREE => $tempwork }, 'checkout', '-f', 'HEAD');
git ( { GIT_WORK_TREE => $tempwork }, 'merge', 'FETCH_HEAD');
do_checkout ();
}
sub do_log {
# we don't want output trapping here, because we want the pager.
system ( 'git', "--git-dir=$NMBGIT", 'log', '--name-status', @_);
}
sub do_push {
my $remote = shift || 'origin';
git ('push', $remote);
}
sub do_status {
my $status = compute_status ();
my %output = ();
foreach my $pair (@{$status->{added}}) {
$output{$pair->{id}} ||= {};
$output{$pair->{id}}{$pair->{tag}} = 'A'
}
foreach my $pair (@{$status->{deleted}}) {
$output{$pair->{id}} ||= {};
$output{$pair->{id}}{$pair->{tag}} = 'D'
}
foreach my $pair (@{$status->{missing}}) {
$output{$pair->{id}} ||= {};
$output{$pair->{id}}{$pair->{tag}} = 'U'
}
if (is_unmerged ()) {
foreach my $pair (diff_refs ('A')) {
$output{$pair->{id}} ||= {};
$output{$pair->{id}}{$pair->{tag}} ||= ' ';
$output{$pair->{id}}{$pair->{tag}} .= 'a';
}
foreach my $pair (diff_refs ('D')) {
$output{$pair->{id}} ||= {};
$output{$pair->{id}}{$pair->{tag}} ||= ' ';
$output{$pair->{id}}{$pair->{tag}} .= 'd';
}
}
foreach my $id (sort keys %output) {
foreach my $tag (sort keys %{$output{$id}}) {
printf "%s\t%s\t%s\n", $output{$id}{$tag}, $id, $tag;
}
}
}
sub is_unmerged {
return 0 if (! -f $NMBGIT.'/FETCH_HEAD');
my $fetch_head = git ('rev-parse', 'FETCH_HEAD');
my $base = git ( 'merge-base', 'HEAD', 'FETCH_HEAD');
return ($base ne $fetch_head);
}
sub compute_status {
my %args = @_;
my @added;
my @deleted;
my @missing;
my $index = index_tags ();
my @maybe_deleted = diff_index ($index, 'D');
foreach my $pair (@maybe_deleted) {
my $id = $pair->{id};
my $fh = spawn ('-|', qw/notmuch search --output=files/,"id:$id")
or die "searching for $id";
if (!<$fh>) {
push @missing, $pair;
} else {
push @deleted, $pair;
}
}
@added = diff_index ($index, 'A');
unlink $index || die "unlink $index: $!";
return { added => [@added], deleted => [@deleted], missing => [@missing] };
}
sub diff_index {
my $index = shift;
my $filter = shift;
my $fh = git_pipe ({ GIT_INDEX_FILE => $index },
qw/diff-index --cached/,
"--diff-filter=$filter", qw/--name-only HEAD/ );
return unpack_diff_lines ($fh);
}
sub diff_refs {
my $filter = shift;
my $ref1 = shift || 'HEAD';
my $ref2 = shift || 'FETCH_HEAD';
my $fh= git_pipe ( 'diff', "--diff-filter=$filter", '--name-only',
$ref1, $ref2);
return unpack_diff_lines ($fh);
}
sub unpack_diff_lines {
my $fh = shift;
my @found;
while(<$fh>) {
chomp ();
my ($id,$tag) = m|tags/ ([^/]+) / ([^/]+) |x;
$id = decode_from_fs ($id);
$tag = decode_from_fs ($tag);
push @found, { id => $id, tag => $tag };
}
return @found;
}
sub encode_for_fs {
my $str = shift;
$str =~ s/($MUST_ENCODE)/"$ESCAPE_CHAR".sprintf ("%02x",ord ($1))/ge;
return $str;
}
sub decode_from_fs {
my $str = shift;
$str =~ s/$ESCAPED_RX/ chr (hex ($1))/eg;
return $str;
}
sub usage {
pod2usage ();
exit (1);
}
sub do_help {
pod2usage ( -verbose => 2 );
exit (0);
}
__END__
=head1 NAME
nmbug - manage notmuch tags about notmuch
=head1 SYNOPSIS
nmbug subcommand [options]
B<nmbug help> for more help
=head1 OPTIONS
=head2 Most common commands
=over 8
=item B<commit> [message]
Commit appropriately prefixed tags from the notmuch database to
git. Any extra arguments are used (one per line) as a commit message.
=item B<push> [remote]
push local nmbug git state to remote repo
=item B<pull> [remote]
pull (merge) remote repo changes to notmuch. B<pull> is equivalent to
B<fetch> followed by B<merge>.
=back
=head2 Other Useful Commands
=over 8
=item B<checkout>
Update the notmuch database from git. This is mainly useful to discard
your changes in notmuch relative to git.
=item B<fetch> [remote]
Fetch changes from the remote repo (see merge to bring those changes
into notmuch).
=item B<help> [subcommand]
print help [for subcommand]
=item B<log> [parameters]
A simple wrapper for git log. After running C<nmbug fetch>, you can
inspect the changes with C<nmbug log HEAD..FETCH_HEAD>
=item B<merge>
Merge changes from FETCH_HEAD into HEAD, and load the result into
notmuch.
=item B<status>
Show pending updates in notmuch or git repo. See below for more
information about the output format.
=back
=head2 Less common commands
=over 8
=item B<archive>
Dump a tar archive (using git archive) of the current nmbug tag set.
=back
=head1 STATUS FORMAT
B<nmbug status> prints lines of the form
ng Message-Id tag
where n is a single character representing notmuch database status
=over 8
=item B<A>
Tag is present in notmuch database, but not committed to nmbug
(equivalently, tag has been deleted in nmbug repo, e.g. by a pull, but
not restored to notmuch database).
=item B<D>
Tag is present in nmbug repo, but not restored to notmuch database
(equivalently, tag has been deleted in notmuch)
=item B<U>
Message is unknown (missing from local notmuch database)
=back
The second character (if present) represents a difference between remote
git and local. Typically C<nmbug fetch> needs to be run to update this.
=over 8
=item B<a>
Tag is present in remote, but not in local git.
=item B<d>
Tag is present in local git, but not in remote git.
=back
=head1 DUMP FORMAT
Each tag $tag for message with Message-Id $id is written to
an empty file
tags/encode($id)/encode($tag)
The encoding preserves alphanumerics, and the characters "+-_@=.:,"
(not the quotes). All other octets are replaced with '%' followed by
a two digit hex number.
=head1 ENVIRONMENT
B<NMBGIT> specifies the location of the git repository used by nmbug.
If not specified $HOME/.nmbug is used.
B<NMBPREFIX> specifies the prefix in the notmuch database for tags of
interest to nmbug. If not specified 'notmuch::' is used.