[public-inbox.git] / lib / PublicInbox / LEI.pm

# Copyright (C) all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>

# Backend for `lei' (local email interface).  Unlike the C10K-oriented
# PublicInbox::Daemon, this is designed exclusively to handle trusted
# local clients with read/write access to the FS and use as many
# system resources as the local user has access to.
package PublicInbox::LEI;
use v5.12;
use parent qw(PublicInbox::DS PublicInbox::LeiExternal
        PublicInbox::LeiQuery);
use Getopt::Long ();
use Socket qw(AF_UNIX SOCK_SEQPACKET MSG_EOR pack_sockaddr_un);
use Errno qw(EPIPE EAGAIN ECONNREFUSED ENOENT ECONNRESET);
use Cwd qw(getcwd);
use POSIX qw(strftime);
use IO::Handle ();
use Fcntl qw(SEEK_SET);
use PublicInbox::Config;
use PublicInbox::Syscall qw(EPOLLIN);
use PublicInbox::DS qw(dwaitpid);
use PublicInbox::Spawn qw(spawn popen_rd);
use PublicInbox::Lock;
use PublicInbox::Eml;
use PublicInbox::Import;
use PublicInbox::ContentHash qw(git_sha);
use Time::HiRes qw(stat); # ctime comparisons for config cache
use File::Path qw(mkpath);
use File::Spec;
use Sys::Syslog qw(openlog syslog closelog);
our $quit = \&CORE::exit;
our ($current_lei, $errors_log, $listener, $oldset, $dir_idle,
        $recv_cmd, $send_cmd);
my $GLP = Getopt::Long::Parser->new;
$GLP->configure(qw(gnu_getopt no_ignore_case auto_abbrev));
my $GLP_PASS = Getopt::Long::Parser->new;
$GLP_PASS->configure(qw(gnu_getopt no_ignore_case auto_abbrev pass_through));

our %PATH2CFG; # persistent for socket daemon
our $MDIR2CFGPATH; # /path/to/maildir => { /path/to/config => [ ino watches ] }

# TBD: this is a documentation mechanism to show a subcommand
# (may) pass options through to another command:
sub pass_through { $GLP_PASS }

my $OPT;
sub opt_dash ($$) {
        my ($spec, $re_str) = @_; # 'limit|n=i', '([0-9]+)'
        my ($key) = ($spec =~ m/\A([a-z]+)/g);
        my $cb = sub { # Getopt::Long "<>" catch-all handler
                my ($arg) = @_;
                if ($arg =~ /\A-($re_str)\z/) {
                        $OPT->{$key} = $1;
                } elsif ($arg eq '--') { # "--" arg separator, ignore first
                        push @{$OPT->{-argv}}, $arg if $OPT->{'--'}++;
                # lone (single) dash is handled elsewhere
                } elsif (substr($arg, 0, 1) eq '-') {
                        if ($OPT->{'--'}) {
                                push @{$OPT->{-argv}}, $arg;
                        } else {
                                die "bad argument: $arg\n";
                        }
                } else {
                        push @{$OPT->{-argv}}, $arg;
                }
        };
        ($spec, '<>' => $cb, $GLP_PASS) # for Getopt::Long
}

# rel2abs preserves symlinks in parent, unlike abs_path
sub rel2abs {
        my ($self, $p) = @_;
        if (index($p, '/') == 0) { # already absolute
                $p =~ tr!/!/!s; # squeeze redundant slashes
                chop($p) if substr($p, -1, 1) eq '/';
                return $p;
        }
        my $pwd = $self->{env}->{PWD};
        if (defined $pwd) {
                if (my @st_pwd = stat($pwd)) {
                        my @st_cwd = stat($self->{3}) or die "stat({3}): $!";
                        "@st_pwd[1,0]" eq "@st_cwd[1,0]" or
                                $self->{env}->{PWD} = $pwd = undef;
                } else { # PWD was invalid
                        $self->{env}->{PWD} = $pwd = undef;
                }
        }
        $pwd //= $self->{env}->{PWD} = getcwd() // die "getcwd: $!";
        File::Spec->rel2abs($p, $pwd);
}

# abs_path resolves symlinks in parent iff all parents exist
sub abs_path { Cwd::abs_path($_[1]) // rel2abs(@_) }

sub canonpath_harder {
        my $p = $_[-1]; # $_[0] may be self
        $p = File::Spec->canonpath($p);
        $p =~ m!(?:/*|\A)\.\.(?:/*|\z)! && -e $p ? Cwd::abs_path($p) : $p;
}

sub share_path ($) { # $HOME/.local/share/lei/$FOO
        my ($self) = @_;
        rel2abs($self, ($self->{env}->{XDG_DATA_HOME} //
                ($self->{env}->{HOME} // '/nonexistent').'/.local/share')
                .'/lei');
}

sub store_path ($) { share_path($_[0]) . '/store' }

sub _config_path ($) {
        my ($self) = @_;
        rel2abs($self, ($self->{env}->{XDG_CONFIG_HOME} //
                ($self->{env}->{HOME} // '/nonexistent').'/.config')
                .'/lei/config');
}

sub cache_dir ($) {
        my ($self) = @_;
        rel2abs($self, ($self->{env}->{XDG_CACHE_HOME} //
                ($self->{env}->{HOME} // '/nonexistent').'/.cache')
                .'/lei');
}

sub url_folder_cache {
        my ($self) = @_;
        require PublicInbox::SharedKV; # URI => updated_at_sec_
        PublicInbox::SharedKV->new(cache_dir($self).'/uri_folder');
}

sub ale {
        my ($self) = @_;
        $self->{ale} // do {
                require PublicInbox::LeiALE;
                my $cfg = $self->_lei_cfg(1);
                $self->{ale} = $cfg->{ale} //= PublicInbox::LeiALE->new($self);
        };
}

sub index_opt {
        # TODO: drop underscore variants everywhere, they're undocumented
        qw(fsync|sync! jobs|j=i indexlevel|L=s compact
        max_size|max-size=s sequential-shard
        batch_size|batch-size=s skip-docdata)
}

my @c_opt = qw(c=s@ C=s@ quiet|q);
my @net_opt = (qw(no-torsocks torsocks=s), PublicInbox::LeiQuery::curl_opt());
my @lxs_opt = qw(remote! local! external! include|I=s@ exclude=s@ only|O=s@
        import-remote!);

# we don't support -C as an alias for --find-copies since it's already
# used for chdir
our @diff_opt = qw(unified|U=i output-indicator-new=s output-indicator-old=s
        output-indicator-context=s indent-heuristic!
        minimal patience histogram anchored=s@ diff-algorithm=s
        color-moved:s color-moved-ws=s no-color-moved no-color-moved-ws
        word-diff:s word-diff-regex=s color-words:s no-renames
        rename-empty! check ws-error-highlight=s full-index binary
        abbrev:i break-rewrites|B:s find-renames|M:s find-copies:s
        find-copies-harder irreversible-delete|D l=i diff-filter=s
        S=s G=s find-object=s pickaxe-all pickaxe-regex O=s R
        relative:s text|a ignore-cr-at-eol ignore-space-at-eol
        ignore-space-change|b ignore-all-space|w ignore-blank-lines
        inter-hunk-context=i function-context|W exit-code ext-diff
        no-ext-diff textconv! src-prefix=s dst-prefix=s no-prefix
        line-prefix=s);

# we generate shell completion + help using %CMD and %OPTDESC,
# see lei__complete() and PublicInbox::LeiHelp
# command => [ positional_args, 1-line description, Getopt::Long option spec ]
our %CMD = ( # sorted in order of importance/use:
'q' => [ '--stdin|SEARCH_TERMS...', 'search for messages matching terms',
        'stdin|', # /|\z/ must be first for lone dash
        @lxs_opt, @net_opt,
        qw(save! output|mfolder|o=s format|f=s dedupe|d=s threads|t+
        sort|s=s reverse|r offset=i pretty jobs|j=s globoff|g augment|a
        import-before! lock=s@ rsyncable alert=s@ mua=s verbose|v+
        shared color! mail-sync!), @c_opt, opt_dash('limit|n=i', '[0-9]+') ],

'up' => [ 'OUTPUT...|--all', 'update saved search',
        qw(jobs|j=s lock=s@ alert=s@ mua=s verbose|v+ exclude=s@
        remote-fudge-time=s all:s remote! local! external!), @net_opt, @c_opt ],

'lcat' => [ '--stdin|MSGID_OR_URL...', 'display local copy of message(s)',
        'stdin|', # /|\z/ must be first for lone dash
        # some of these options are ridiculous for lcat
        @lxs_opt, @net_opt,
        qw(output|mfolder|o=s format|f=s dedupe|d=s threads|t+
        sort|s=s reverse|r offset=i jobs|j=s globoff|g augment|a
        import-before! lock=s@ rsyncable alert=s@ mua=s verbose|v+
        color!), @c_opt, opt_dash('limit|n=i', '[0-9]+') ],

'blob' => [ 'OID', 'show a git blob, reconstructing from mail if necessary',
        qw(git-dir=s@ cwd! verbose|v+ mail! oid-a|A=s path-a|a=s path-b|b=s),
        @lxs_opt, @net_opt, @c_opt ],

'rediff' => [ '--stdin|LOCATION...',
                'regenerate a diff with different options',
        'stdin|', # /|\z/ must be first for lone dash
        qw(git-dir=s@ cwd! verbose|v+ color:s no-color drq:1 dequote-only:1),
        @diff_opt, @lxs_opt, @net_opt, @c_opt ],

'mail-diff' => [ '--stdin|LOCATION...', 'diff the contents of emails',
        'stdin|', # /|\z/ must be first for lone dash
        qw(verbose|v+ in-format|F=s color:s no-color raw-header),
        @diff_opt, @net_opt, @c_opt ],

'add-external' => [ 'LOCATION',
        'add/set priority of a publicinbox|extindex for extra matches',
        qw(boost=i mirror=s inbox-version=i epoch=s verbose|v+),
        @c_opt, index_opt(), @net_opt ],
'ls-external' => [ '[FILTER]', 'list publicinbox|extindex locations',
        qw(format|f=s z|0 globoff|g invert-match|v local remote), @c_opt ],
'ls-label' => [ '', 'list labels', qw(z|0 stats:s), @c_opt ],
'ls-mail-sync' => [ '[FILTER]', 'list mail sync folders',
                qw(z|0 globoff|g invert-match|v local remote), @c_opt ],
'ls-mail-source' => [ 'URL', 'list IMAP or NNTP mail source folders',
                qw(z|0 ascii l pretty url), @net_opt, @c_opt ],
'forget-external' => [ 'LOCATION...|--prune',
        'exclude further results from a publicinbox|extindex',
        qw(prune), @c_opt ],

'ls-search' => [ '[PREFIX]', 'list saved search queries',
                qw(format|f=s pretty l ascii z|0), @c_opt ],
'forget-search' => [ 'OUTPUT...|--prune', 'forget a saved search',
                qw(verbose|v+ prune:s), @c_opt ],
'edit-search' => [ 'OUTPUT', "edit saved search via `git config --edit'",
                        @c_opt ],
'rm' => [ '--stdin|LOCATION...',
        'remove a message from the index and prevent reindexing',
        'stdin|', # /|\z/ must be first for lone dash
        qw(in-format|F=s lock=s@), @net_opt, @c_opt ],
'plonk' => [ '--threads|--from=IDENT',
        'exclude mail matching From: or threads from non-Message-ID searches',
        qw(stdin| threads|t from|f=s mid=s oid=s), @c_opt ],
'tag' => [ 'KEYWORDS...',
        'set/unset keywords and/or labels on message(s)',
        qw(stdin| in-format|F=s input|i=s@ oid=s@ mid=s@),
        @net_opt, @c_opt, pass_through('-kw:foo for delete') ],

'purge-mailsource' => [ 'LOCATION|--all',
        'remove imported messages from IMAP, Maildirs, and MH',
        qw(exact! all jobs:i indexed), @c_opt ],

'add-watch' => [ 'LOCATION...', 'watch for new messages and flag changes',
        qw(poll-interval=s state=s recursive|r), @c_opt ],
'rm-watch' => [ 'LOCATION...', 'remove specified watch(es)',
        qw(recursive|r), @c_opt ],
'ls-watch' => [ '[FILTER...]', 'list active watches with numbers and status',
                qw(l z|0), @c_opt ],
'pause-watch' => [ '[WATCH_NUMBER_OR_FILTER]', qw(all local remote), @c_opt ],
'resume-watch' => [ '[WATCH_NUMBER_OR_FILTER]', qw(all local remote), @c_opt ],
'forget-watch' => [ '{WATCH_NUMBER|--prune}', 'stop and forget a watch',
        qw(prune), @c_opt ],

'reindex' => [ '', 'reindex all locally-indexed messages', @c_opt ],

'index' => [ 'LOCATION...', 'one-time index from URL or filesystem',
        qw(in-format|F=s kw! offset=i recursive|r exclude=s include|I=s
        verbose|v+ incremental!), @net_opt, # mainly for --proxy=
         @c_opt ],
'import' => [ 'LOCATION...|--stdin',
        'one-time import/update from URL or filesystem',
        qw(stdin| offset=i recursive|r exclude=s include|I=s new-only
        lock=s@ in-format|F=s kw! verbose|v+ incremental! mail-sync!),
        @net_opt, @c_opt ],
'forget-mail-sync' => [ 'LOCATION...',
        'forget sync information for a mail folder', @c_opt ],
'refresh-mail-sync' => [ 'LOCATION...|--all',
        'prune dangling sync data for a mail folder', 'all:s',
                @net_opt, @c_opt ],
'export-kw' => [ 'LOCATION...|--all',
        'one-time export of keywords of sync sources',
        qw(all:s mode=s), @net_opt, @c_opt ],
'convert' => [ 'LOCATION...|--stdin',
        'one-time conversion from URL or filesystem to another format',
        qw(stdin| in-format|F=s out-format|f=s output|mfolder|o=s lock=s@ kw!),
        @net_opt, @c_opt ],
'p2q' => [ 'LOCATION_OR_COMMIT...|--stdin',
        "use a patch to generate a query for `lei q --stdin'",
        qw(stdin| in-format|F=s want|w=s@ uri debug), @net_opt, @c_opt ],
'config' => [ '[...]', sub {
                'git-config(1) wrapper for '._config_path($_[0]);
        }, qw(config-file|system|global|file|f=s), # for conflict detection
         qw(edit|e c=s@ C=s@), pass_through('git config') ],
'inspect' => [ 'ITEMS...|--stdin', 'inspect lei/store and/or local external',
        qw(stdin| pretty ascii dir|d=s), @c_opt ],

'init' => [ '[DIRNAME]', sub {
        "initialize storage, default: ".store_path($_[0]);
        }, @c_opt ],
'daemon-kill' => [ '[-SIGNAL]', 'signal the lei-daemon',
        # "-C DIR" conflicts with -CHLD, here, and chdir makes no sense, here
        opt_dash('signal|s=s', '[0-9]+|(?:[A-Z][A-Z0-9]+)') ],
'daemon-pid' => [ '', 'show the PID of the lei-daemon' ],
'help' => [ '[SUBCOMMAND]', 'show help' ],

# TODO
#'reorder-local-store-and-break-history' => [ '[REFNAME]',
#       'rewrite git history in an attempt to improve compression',
#       qw(gc!), @c_opt ],
#'fuse-mount' => [ 'PATHNAME', 'expose lei/store as Maildir(s)', @c_opt ],
#
# internal commands are prefixed with '_'
'_complete' => [ '[...]', 'internal shell completion helper',
                pass_through('everything') ],
); # @CMD

# switch descriptions, try to keep consistent across commands
# $spec: Getopt::Long option specification
# $spec => [@ALLOWED_VALUES (default is first), $description],
# $spec => $description
# "$SUB_COMMAND TAB $spec" => as above
my $stdin_formats = [ 'MAIL_FORMAT|eml|mboxrd|mboxcl2|mboxcl|mboxo',
                        'specify message input format' ];
my $ls_format = [ 'OUT|plain|json|null', 'listing output format' ];

# we use \x{a0} (non-breaking SP) to avoid wrapping in PublicInbox::LeiHelp
my %OPTDESC = (
'help|h' => 'show this built-in help',
'c=s@' => [ 'NAME=VALUE', 'set config option' ],
'C=s@' => [ 'DIR', 'chdir to specify to directory' ],
'quiet|q' => 'be quiet',
'lock=s@' => [ 'METHOD|dotlock|fcntl|flock|none',
        'mbox(5) locking method(s) to use (default: fcntl,dotlock)' ],

'incremental!   import' => 'import already seen IMAP and NNTP articles',
'globoff|g' => "do not match locations using '*?' wildcards ".
                "and\xa0'[]'\x{a0}ranges",
'invert-match|v' => 'select non-matching lines',
'color!' => 'disable color (for --format=text)',
'verbose|v+' => 'be more verbose',
'external!' => 'do not use externals',
'mail!' => 'do not look in mail storage for OID',
'cwd!' => 'do not look in git repo of current working directory',
'oid-a|A=s' => 'pre-image OID',
'path-a|a=s' => 'pre-image pathname associated with OID',
'path-b|b=s' => 'post-image pathname associated with OID',
'git-dir=s@' => 'additional git repository to scan',
'dir|d=s        inspect' =>
        'specify a inboxdir, extindex topdir or Xapian shard',
'proxy=s' => [ 'PROTO://HOST[:PORT]', # shared with curl(1)
        "proxy for (e.g. `socks5h://0:9050')" ],
'torsocks=s' => ['VAL|auto|no|yes',
                'whether or not to wrap git and curl commands with torsocks'],
'no-torsocks' => 'alias for --torsocks=no',
'save!' =>  "do not save a search for `lei up'",
'import-remote!' => 'do not memoize remote messages into local store',

'type=s' => [ 'any|mid|git', 'disambiguate type' ],

'dedupe|d=s' => ['STRATEGY|content|oid|mid|none',
                'deduplication strategy'],
'threads|t+' =>
        'return all messages in the same threads as the actual match(es)',

'want|w=s@' => [ 'PREFIX|dfpost|dfn', # common ones in help...
                'search prefixes to extract (default: dfpost7)' ],
'uri    p2q' => [ 'URI escape output' ],

'alert=s@' => ['CMD,:WINCH,:bell,<any command>',
        'run command(s) or perform ops when done writing to output ' .
        '(default: ":WINCH,:bell" with --mua and Maildir/IMAP output, ' .
        'nothing otherwise)' ],

'augment|a' => 'augment --output destination instead of clobbering',

'output|mfolder|o=s' => [ 'MFOLDER',
        "destination (e.g.\xa0`/path/to/Maildir', ".
        "or\xa0`-'\x{a0}for\x{a0}stdout)" ],
'mua=s' => [ 'CMD',
        "MUA to run on --output Maildir or mbox (e.g.\xa0`mutt\xa0-f\xa0%f')" ],
'new-only       import' => 'only import new messages from IMAP source',

'inbox-version=i' => [ 'NUM|1|2',
                'force a public-inbox version with --mirror'],
'mirror=s' => [ 'URL', 'mirror a public-inbox'],

# public-inbox-index options
'fsync!' => 'speed up indexing after --mirror, risk index corruption',
'compact' => 'run compact index after mirroring',
'indexlevel|L=s' => [ 'LEVEL|full|medium|basic',
        "indexlevel with --mirror (default: full)" ],
'max_size|max-size=s' => [ 'SIZE',
        'do not index messages larger than SIZE (default: infinity)' ],
'batch_size|batch-size=s' => [ 'SIZE',
        'flush changes to OS after given number of bytes (default: 1m)' ],
'sequential-shard' =>
        'index Xapian shards sequentially for slow storage',
'skip-docdata' =>
        'drop compatibility w/ public-inbox <1.6 to save ~1.5% space',

'format|f=s     q' => [
        'OUT|maildir|mboxrd|mboxcl2|mboxcl|mboxo|html|json|jsonl|concatjson',
                'specify output format, default depends on --output'],
'exclude=s@     q' => [ 'LOCATION',
                'exclude specified external(s) from search' ],
'include|I=s@   q' => [ 'LOCATION',
                'include specified external(s) in search' ],
'only|O=s@      q' => [ 'LOCATION',
                'only use specified external(s) for search' ],
'jobs|j=s' => [ 'JOBSPEC',
                'control number of query and writer jobs' .
                "integers delimited by `,', either of which may be omitted"
                ],
'jobs|j=i       add-external' => 'set parallelism when indexing after --mirror',

'in-format|F=s' => $stdin_formats,
'format|f=s     ls-search' => ['OUT|json|jsonl|concatjson',
                        'listing output format' ],
'l      ls-search' => 'long listing format',
'l      ls-watch' => 'long listing format',
'l      ls-mail-source' => 'long listing format',
'url    ls-mail-source' => 'show full URL of newsgroup or IMAP folder',
'format|f=s     ls-external' => $ls_format,

'prune:s        forget-search' =>
        ['TYPE|local|remote', 'prune all, remote or local folders' ],

'limit|n=i@' => ['NUM', 'limit on number of matches (default: 10000)' ],
'offset=i' => ['OFF', 'search result offset (default: 0)'],

'sort|s=s' => [ 'VAL|received|relevance|docid',
                "order of results is `--output'-dependent"],
'reverse|r' => 'reverse search results', # like sort(1)

'boost=i' => 'increase/decrease priority of results (default: 0)',

'local' => 'limit operations to the local filesystem',
'local!' => 'exclude results from the local filesystem',
'remote' => 'limit operations to those requiring network access',
'remote!' => 'prevent operations requiring network access',

# up, refresh-mail-sync, export-kw
'all:s' => ['TYPE|local|remote', 'all remote or local folders' ],

'remote-fudge-time=s' => [ 'INTERVAL',
        'look for mail INTERVAL older than the last successful query' ],

'mid=s' => 'specify the Message-ID of a message',
'oid=s' => 'specify the git object ID of a message',

'recursive|r' => 'scan directories/mailboxes/newsgroups recursively',
'exclude=s' => 'exclude mailboxes/newsgroups based on pattern',
'include=s' => 'include mailboxes/newsgroups based on pattern',

'exact' => 'operate on exact header matches only',
'exact!' => 'rely on content match instead of exact header matches',

'by-mid|mid:s' => [ 'MID', 'match only by Message-ID, ignoring contents' ],

'kw!' => 'disable/enable importing keywords (aka "flags")',

# xargs, env, use "-0", git(1) uses "-z".  We support z|0 everywhere
'z|0' => 'use NUL \\0 instead of newline (CR) to delimit lines',

'signal|s=s' => [ 'SIG', 'signal to send lei-daemon (default: TERM)' ],
); # %OPTDESC

my %CONFIG_KEYS = (
        'leistore.dir' => 'top-level storage location',
);

my @WQ_KEYS = qw(lxs l2m ikw pmd wq1 lne v2w); # internal workers

sub _drop_wq {
        my ($self) = @_;
        for my $wq (grep(defined, delete(@$self{@WQ_KEYS}))) {
                $wq->wq_kill('-TERM');
                $wq->DESTROY;
        }
}

# pronounced "exit": x_it(1 << 8) => exit(1); x_it(13) => SIGPIPE
sub x_it ($$) {
        my ($self, $code) = @_;
        local $current_lei = $self;
        # make sure client sees stdout before exit
        $self->{1}->autoflush(1) if $self->{1};
        stop_pager($self);
        if ($self->{pkt_op_p}) { # worker => lei-daemon
                $self->{pkt_op_p}->pkt_do('x_it', $code);
        } elsif ($self->{sock}) { # lei->daemon => lei(1) client
                send($self->{sock}, "x_it $code", MSG_EOR);
        } elsif ($quit == \&CORE::exit) { # an admin (one-shot) command
                exit($code >> 8);
        } # else ignore if client disconnected
}

sub err ($;@) {
        my $self = shift;
        my $err = $self->{2} // ($self->{pgr} // [])->[2] // *STDERR{GLOB};
        my @eor = (substr($_[-1]//'', -1, 1) eq "\n" ? () : ("\n"));
        print $err @_, @eor and return;
        my $old_err = delete $self->{2};
        close($old_err) if $! == EPIPE && $old_err;
        $err = $self->{2} = ($self->{pgr} // [])->[2] // *STDERR{GLOB};
        print $err @_, @eor or print STDERR @_, @eor;
}

sub qerr ($;@) { $_[0]->{opt}->{quiet} or err(shift, @_) }

sub qfin { # show message on finalization (LeiFinmsg)
        my ($lei, $msg) = @_;
        return if $lei->{opt}->{quiet};
        $lei->{fmsg} ? push(@{$lei->{fmsg}}, "$msg\n") : qerr($lei, $msg);
}

sub fail_handler ($;$$) {
        my ($lei, $code, $io) = @_;
        local $current_lei = $lei;
        close($io) if $io; # needed to avoid warnings on SIGPIPE
        _drop_wq($lei);
        x_it($lei, $code // (1 << 8));
}

sub sigpipe_handler { # handles SIGPIPE from @WQ_KEYS workers
        fail_handler($_[0], 13, delete $_[0]->{1});
}

sub fail ($$;$) {
        my ($self, $msg, $exit_code) = @_;
        local $current_lei = $self;
        $self->{failed}++;
        warn(substr($msg, -1, 1) eq "\n" ? $msg : "$msg\n") if defined $msg;
        $self->{pkt_op_p}->pkt_do('fail_handler') if $self->{pkt_op_p};
        x_it($self, ($exit_code // 1) << 8);
        undef;
}

sub out ($;@) {
        my $self = shift;
        return if print { $self->{1} // return } @_; # likely
        return note_sigpipe($self, 1) if $! == EPIPE;
        my $err = "error writing to output: $!";
        delete $self->{1};
        fail($self, $err);
}

sub puts ($;@) { out(shift, map { "$_\n" } @_) }

sub child_error { # passes non-fatal curl exit codes to user
        my ($self, $child_error, $msg) = @_; # child_error is $?
        local $current_lei = $self;
        $child_error ||= 1 << 8;
        warn(substr($msg, -1, 1) eq "\n" ? $msg : "$msg\n") if defined $msg;
        if ($self->{pkt_op_p}) { # to top lei-daemon
                $self->{pkt_op_p}->pkt_do('child_error', $child_error);
        } elsif ($self->{sock}) { # to lei(1) client
                send($self->{sock}, "child_error $child_error", MSG_EOR);
        } else { # non-lei admin command
                $self->{child_error} ||= $child_error;
        } # else noop if client disconnected
}

sub note_sigpipe { # triggers sigpipe_handler
        my ($self, $fd) = @_;
        close(delete($self->{$fd})); # explicit close silences Perl warning
        $self->{pkt_op_p}->pkt_do('sigpipe_handler') if $self->{pkt_op_p};
        x_it($self, 13);
}

sub _lei_atfork_child {
        my ($self, $persist) = @_;
        # we need to explicitly close things which are on stack
        if ($persist) {
                open $self->{3}, '<', '/' or die "open(/) $!";
                fchdir($self);
                close($_) for (grep(defined, delete @$self{qw(0 1 2 sock)}));
                if (my $cfg = $self->{cfg}) {
                        delete @$cfg{qw(-lei_store -watches -lei_note_event)};
                }
        } else { # worker, Net::NNTP (Net::Cmd) uses STDERR directly
                open STDERR, '+>&='.fileno($self->{2}) or warn "open $!";
                STDERR->autoflush(1);
                POSIX::setpgid(0, $$) // die "setpgid(0, $$): $!";
        }
        close($_) for (grep(defined, delete @$self{qw(old_1 au_done)}));
        delete $self->{-socks};
        if (my $op_c = delete $self->{pkt_op_c}) {
                close(delete $op_c->{sock});
        }
        if (my $pgr = delete $self->{pgr}) {
                close($_) for (@$pgr[1,2]);
        }
        close $listener if $listener;
        undef $listener;
        $dir_idle->force_close if $dir_idle;
        undef $dir_idle;
        %PATH2CFG = ();
        $MDIR2CFGPATH = {};
        eval 'no warnings; undef $PublicInbox::LeiNoteEvent::to_flush';
        undef $errors_log;
        $quit = \&CORE::exit;
        if (!$self->{-eml_noisy}) { # only "lei import" sets this atm
                my $cb = $SIG{__WARN__} // \&CORE::warn;
                $SIG{__WARN__} = sub {
                        $cb->(@_) unless PublicInbox::Eml::warn_ignore(@_)
                };
        }
        $SIG{TERM} = sub { exit(128 + 15) };
        $current_lei = $persist ? undef : $self; # for SIG{__WARN__}
}

sub _delete_pkt_op { # OnDestroy callback to prevent leaks on die
        my ($self) = @_;
        if (my $op = delete $self->{pkt_op_c}) { # in case of die
                $op->close; # PublicInbox::PktOp::close
        }
        my $pkt_op_p = delete($self->{pkt_op_p}) or return;
        close $pkt_op_p->{op_p};
}

sub pkt_op_pair {
        my ($self) = @_;
        require PublicInbox::OnDestroy;
        require PublicInbox::PktOp;
        my $end = PublicInbox::OnDestroy->new($$, \&_delete_pkt_op, $self);
        @$self{qw(pkt_op_c pkt_op_p)} = PublicInbox::PktOp->pair;
        $end;
}

sub incr {
        my ($self, $field, $nr) = @_;
        $self->{counters}->{$field} += $nr;
}

sub pkt_ops {
        my ($lei, $ops) = @_;
        $ops->{fail_handler} = [ $lei ];
        $ops->{sigpipe_handler} = [ $lei ];
        $ops->{x_it} = [ $lei ];
        $ops->{child_error} = [ $lei ];
        $ops->{incr} = [ $lei ];
        $ops;
}

sub workers_start {
        my ($lei, $wq, $jobs, $ops, $flds) = @_;
        $ops //= {};
        ($wq->can('net_merge_all_done') && $lei->{auth}) and
                $lei->{auth}->op_merge($ops, $wq, $lei);
        pkt_ops($lei, $ops);
        $ops->{''} //= [ $wq->can('_lei_wq_eof') || \&wq_eof, $lei ];
        my $end = $lei->pkt_op_pair;
        my $ident = $wq->{-wq_ident} // "lei-$lei->{cmd} worker";
        $flds->{lei} = $lei;
        $wq->wq_workers_start($ident, $jobs, $lei->oldset, $flds);
        delete $lei->{pkt_op_p};
        my $op_c = delete $lei->{pkt_op_c};
        @$end = ();
        $lei->event_step_init;
        $wq->wq_wait_async($wq->can('_wq_done_wait') // \&wq_done_wait, $lei);
        ($op_c, $ops);
}

# call this when we're ready to wait on events and yield to other clients
sub wait_wq_events {
        my ($lei, $op_c, $ops) = @_;
        my $wq1 = $lei->{wq1};
        ($wq1 && $wq1->can('net_merge_all_done') && !$lei->{auth}) and
                $wq1->net_merge_all_done;
        for my $wq (grep(defined, @$lei{qw(ikw pmd)})) { # auxiliary WQs
                $wq->wq_close;
        }
        $wq1->{lei_sock} = $lei->{sock} if $wq1;
        $op_c->{ops} = $ops;
}

sub wq1_start {
        my ($lei, $wq, $jobs) = @_;
        my ($op_c, $ops) = workers_start($lei, $wq, $jobs // 1);
        $lei->{wq1} = $wq;
        wait_wq_events($lei, $op_c, $ops); # net_merge_all_done if !{auth}
}

sub _help {
        require PublicInbox::LeiHelp;
        PublicInbox::LeiHelp::call($_[0], $_[1], \%CMD, \%OPTDESC);
}

sub optparse ($$$) {
        my ($self, $cmd, $argv) = @_;
        # allow _complete --help to complete, not show help
        return 1 if substr($cmd, 0, 1) eq '_';
        $self->{cmd} = $cmd;
        $OPT = $self->{opt} //= {};
        my $info = $CMD{$cmd} // [ '[...]' ];
        my ($proto, undef, @spec) = @$info;
        my $glp = ref($spec[-1]) eq ref($GLP) ? pop(@spec) : $GLP;
        push @spec, qw(help|h);
        my $lone_dash;
        if ($spec[0] =~ s/\|\z//s) { # "stdin|" or "clear|" allows "-" alias
                $lone_dash = $spec[0];
                $OPT->{$spec[0]} = \(my $var);
                push @spec, '' => \$var;
        }
        $glp->getoptionsfromarray($argv, $OPT, @spec) or
                return _help($self, "bad arguments or options for $cmd");
        return _help($self) if $OPT->{help};

        push @$argv, @{$OPT->{-argv}} if defined($OPT->{-argv});

        # "-" aliases "stdin" or "clear"
        $OPT->{$lone_dash} = ${$OPT->{$lone_dash}} if defined $lone_dash;

        my $i = 0;
        my $POS_ARG = '[A-Z][A-Z0-9_]+';
        my ($err, $inf);
        my @args = split(/ /, $proto);
        for my $var (@args) {
                if ($var =~ /\A$POS_ARG\.\.\.\z/o) { # >= 1 args;
                        $inf = defined($argv->[$i]) and last;
                        $var =~ s/\.\.\.\z//;
                        $err = "$var not supplied";
                } elsif ($var =~ /\A$POS_ARG\z/o) { # required arg at $i
                        $argv->[$i++] // ($err = "$var not supplied");
                } elsif ($var =~ /\.\.\.\]\z/) { # optional args start
                        $inf = 1;
                        last;
                } elsif ($var =~ /\A\[-?$POS_ARG\]\z/) { # one optional arg
                        $i++;
                } elsif ($var =~ /\A.+?\|/) { # required FOO|--stdin
                        $inf = 1 if index($var, '...') > 0;
                        my @or = split(/\|/, $var);
                        my $ok;
                        for my $o (@or) {
                                if ($o =~ /\A--([a-z0-9\-]+)/) {
                                        my $sw = $1;
                                        # assume pipe/regular file on stdin
                                        # w/o args means stdin
                                        if ($sw eq 'stdin' && !@$argv &&
                                                        (-p $self->{0} ||
                                                         -f _) && -r _) {
                                                $OPT->{stdin} //= 1;
                                        }
                                        $ok = defined($OPT->{$sw});
                                        last if $ok;
                                } elsif (defined($argv->[$i])) {
                                        $ok = 1;
                                        $i++;
                                        last;
                                } # else continue looping
                        }
                        last if $ok;
                        my $last = pop @or;
                        $err = join(', ', @or) . " or $last must be set";
                } else {
                        warn "BUG: can't parse `$var' in $proto";
                }
                last if $err;
        }
        if (!$inf && scalar(@$argv) > scalar(@args)) {
                $err //= 'too many arguments';
        }
        $err ? fail($self, "usage: lei $cmd $proto\nE: $err") : 1;
}

sub _tmp_cfg { # for lei -c <name>=<value> ...
        my ($self) = @_;
        my $cfg = _lei_cfg($self, 1);
        require File::Temp;
        my $ft = File::Temp->new(TEMPLATE => 'lei_cfg-XXXX', TMPDIR => 1);
        my $tmp = { '-f' => $ft->filename, -tmp => $ft };
        $ft->autoflush(1);
        print $ft <<EOM or return fail($self, "$tmp->{-f}: $!");
[include]
        path = $cfg->{-f}
EOM
        $tmp = $self->{cfg} = bless { %$cfg, %$tmp }, ref($cfg);
        for (@{$self->{opt}->{c}}) {
                /\A([^=\.]+\.[^=]+)(?:=(.*))?\z/ or return fail($self, <<EOM);
`-c $_' is not of the form -c <name>=<value>'
EOM
                my $name = $1;
                my $value = $2 // 1;
                _config($self, '--add', $name, $value);
                if (defined(my $v = $tmp->{$name})) {
                        if (ref($v) eq 'ARRAY') {
                                push @$v, $value;
                        } else {
                                $tmp->{$name} = [ $v, $value ];
                        }
                } else {
                        $tmp->{$name} = $value;
                }
        }
}

sub lazy_cb ($$$) { # $pfx is _complete_ or lei_
        my ($self, $cmd, $pfx) = @_;
        my $ucmd = $cmd;
        $ucmd =~ tr/-/_/;
        my $cb;
        $cb = $self->can($pfx.$ucmd) and return $cb;
        my $base = $ucmd;
        $base =~ s/_([a-z])/\u$1/g;
        my $pkg = "PublicInbox::Lei\u$base";
        ($INC{"PublicInbox/Lei\u$base.pm"} // eval("require $pkg")) ?
                $pkg->can($pfx.$ucmd) : undef;
}

sub dispatch {
        my ($self, $cmd, @argv) = @_;
        fchdir($self);
        local %ENV = %{$self->{env}};
        local $current_lei = $self; # for __WARN__
        $self->{2}->autoflush(1); # keep stdout buffered until x_it|DESTROY
        return _help($self, 'no command given') unless defined($cmd);
        # do not support Getopt bundling for this
        while ($cmd eq '-C' || $cmd eq '-c') {
                my $v = shift(@argv) // return fail($self, $cmd eq '-C' ?
                                        '-C DIRECTORY' : '-c <name>=<value>');
                push @{$self->{opt}->{substr($cmd, 1, 1)}}, $v;
                $cmd = shift(@argv) // return _help($self, 'no command given');
        }
        if (my $cb = lazy_cb(__PACKAGE__, $cmd, 'lei_')) {
                optparse($self, $cmd, \@argv) or return;
                $self->{opt}->{c} and (_tmp_cfg($self) // return);
                if (my $chdir = $self->{opt}->{C}) {
                        for my $d (@$chdir) {
                                next if $d eq ''; # same as git(1)
                                chdir $d or return fail($self, "cd $d: $!");
                        }
                        open $self->{3}, '<', '.' or
                                return fail($self, "open . $!");
                }
                $cb->($self, @argv);
        } elsif (grep(/\A-/, $cmd, @argv)) { # --help or -h only
                $GLP->getoptionsfromarray([$cmd, @argv], {}, qw(help|h C=s@))
                        or return _help($self, 'bad arguments or options');
                _help($self);
        } else {
                fail($self, "`$cmd' is not an lei command");
        }
}

sub _lei_cfg ($;$) {
        my ($self, $creat) = @_;
        return $self->{cfg} if $self->{cfg};
        my $f = _config_path($self);
        my @st = stat($f);
        my $cur_st = @st ? pack('dd', $st[10], $st[7]) : ''; # 10:ctime, 7:size
        my ($sto, $sto_dir, $watches, $lne);
        if (my $cfg = $PATH2CFG{$f}) { # reuse existing object in common case
                return ($self->{cfg} = $cfg) if $cur_st eq $cfg->{-st};
                ($sto, $sto_dir, $watches, $lne) =
                                @$cfg{qw(-lei_store leistore.dir -watches
                                        -lei_note_event)};
        }
        if (!@st) {
                unless ($creat) {
                        delete $self->{cfg};
                        return bless {}, 'PublicInbox::Config';
                }
                my ($cfg_dir) = ($f =~ m!(.*?/)[^/]+\z!);
                -d $cfg_dir or mkpath($cfg_dir) or die "mkpath($cfg_dir): $!\n";
                open my $fh, '>>', $f or die "open($f): $!\n";
                @st = stat($fh) or die "fstat($f): $!\n";
                $cur_st = pack('dd', $st[10], $st[7]);
                qerr($self, "# $f created") if $self->{cmd} ne 'config';
        }
        my $cfg = PublicInbox::Config->git_config_dump($f, $self->{2});
        $cfg->{-st} = $cur_st;
        $cfg->{'-f'} = $f;
        if ($sto && canonpath_harder($sto_dir // store_path($self))
                        eq canonpath_harder($cfg->{'leistore.dir'} //
                                                store_path($self))) {
                $cfg->{-lei_store} = $sto;
                $cfg->{-lei_note_event} = $lne;
                $cfg->{-watches} = $watches if $watches;
        }
        if (scalar(keys %PATH2CFG) > 5) {
                # FIXME: use inotify/EVFILT_VNODE to detect unlinked configs
                delete(@PATH2CFG{grep(!-f, keys %PATH2CFG)});
        }
        $self->{cfg} = $PATH2CFG{$f} = $cfg;
        refresh_watches($self);
        $cfg;
}

sub _lei_store ($;$) {
        my ($self, $creat) = @_;
        my $cfg = _lei_cfg($self, $creat) // return;
        $cfg->{-lei_store} //= do {
                require PublicInbox::LeiStore;
                my $dir = $cfg->{'leistore.dir'} // store_path($self);
                return unless $creat || -d $dir;
                PublicInbox::LeiStore->new($dir, { creat => $creat });
        };
}

sub _config {
        my ($self, @argv) = @_;
        my %env = (%{$self->{env}}, GIT_CONFIG => undef);
        my $cfg = _lei_cfg($self, 1);
        my $cmd = [ qw(git config -f), $cfg->{'-f'}, @argv ];
        my %rdr = map { $_ => $self->{$_} } (0..2);
        waitpid(spawn($cmd, \%env, \%rdr), 0);
}

sub lei_daemon_pid { puts shift, $$ }

sub lei_daemon_kill {
        my ($self) = @_;
        my $sig = $self->{opt}->{signal} // 'TERM';
        kill($sig, $$) or fail($self, "kill($sig, $$): $!");
}

# Shell completion helper.  Used by lei-completion.bash and hopefully
# other shells.  Try to do as much here as possible to avoid redundancy
# and improve maintainability.
sub lei__complete {
        my ($self, @argv) = @_; # argv = qw(lei and any other args...)
        shift @argv; # ignore "lei", the entire command is sent
        @argv or return puts $self, grep(!/^_/, keys %CMD), qw(--help -h -C);
        my $cmd = shift @argv;
        my $info = $CMD{$cmd} // do { # filter matching commands
                @argv or puts $self, grep(/\A\Q$cmd\E/, keys %CMD);
                return;
        };
        my ($proto, undef, @spec) = @$info;
        my $cur = pop @argv;
        my $re = defined($cur) ? qr/\A\Q$cur\E/ : qr/./;
        if (substr(my $_cur = $cur // '-', 0, 1) eq '-') { # --switches
                # gross special case since the only git-config options
                # Consider moving to a table if we need more special cases
                # we use Getopt::Long for are the ones we reject, so these
                # are the ones we don't reject:
                if ($cmd eq 'config') {
                        puts $self, grep(/$re/, keys %CONFIG_KEYS);
                        @spec = qw(add z|null get get-all unset unset-all
                                replace-all get-urlmatch
                                remove-section rename-section
                                name-only list|l edit|e
                                get-color-name get-colorbool);
                        # fall-through
                }
                # generate short/long names from Getopt::Long specs
                puts $self, grep(/$re/, qw(--help -h -C), map {
                        if (s/[:=].+\z//) { # req/optional args, e.g output|o=i
                        } elsif (s/\+\z//) { # verbose|v+
                        } elsif (s/!\z//) {
                                # negation: mail! => no-mail|mail
                                s/([\w\-]+)/$1|no-$1/g
                        }
                        map {
                                my $x = length > 1 ? "--$_" : "-$_";
                                $x eq $_cur ? () : $x;
                        } grep(!/_/, split(/\|/, $_, -1)) # help|h
                } grep { $OPTDESC{"$_\t$cmd"} || $OPTDESC{$_} } @spec);
        } elsif ($cmd eq 'config' && !@argv && !$CONFIG_KEYS{$cur}) {
                puts $self, grep(/$re/, keys %CONFIG_KEYS);
        }

        # switch args (e.g. lei q -f mbox<TAB>)
        if (($argv[-1] // $cur // '') =~ /\A--?([\w\-]+)\z/) {
                my $opt = quotemeta $1;
                puts $self, map {
                        my $v = $OPTDESC{$_};
                        my @v = ref($v) ? split(/\|/, $v->[0]) : ();
                        # get rid of ALL CAPS placeholder (e.g "OUT")
                        # (TODO: completion for external paths)
                        shift(@v) if scalar(@v) && uc($v[0]) eq $v[0];
                        @v;
                } grep(/\A(?:[\w-]+\|)*$opt\b.*?(?:\t$cmd)?\z/, keys %OPTDESC);
        }
        if (my $cb = lazy_cb($self, $cmd, '_complete_')) {
                puts $self, $cb->($self, @argv, $cur ? ($cur) : ());
        }
        # TODO: URLs, pathnames, OIDs, MIDs, etc...  See optparse() for
        # proto parsing.
}

sub exec_buf ($$) {
        my ($argv, $env) = @_;
        my $argc = scalar @$argv;
        my $buf = 'exec '.join("\0", scalar(@$argv), @$argv);
        while (my ($k, $v) = each %$env) { $buf .= "\0$k=$v" };
        $buf;
}

sub start_mua {
        my ($self) = @_;
        if ($self->{ovv}->{fmt} =~ /\A(?:maildir)\z/) { # TODO: IMAP
                refresh_watches($self);
        }
        my $mua = $self->{opt}->{mua} // return;
        my $mfolder = $self->{ovv}->{dst};
        my (@cmd, $replaced);
        if ($mua =~ /\A(?:mutt|mailx|mail|neomutt)\z/) {
                @cmd = ($mua, '-f');
        # TODO: help wanted: other common FOSS MUAs
        } else {
                require Text::ParseWords;
                @cmd = Text::ParseWords::shellwords($mua);
                # mutt uses '%f' for open-hook with compressed mbox, we follow
                @cmd = map { $_ eq '%f' ? ($replaced = $mfolder) : $_ } @cmd;
        }
        push @cmd, $mfolder unless defined($replaced);
        if ($self->{sock}) { # lei(1) client process runs it
                # restore terminal: echo $query | lei q --stdin --mua=...
                my $io = [];
                $io->[0] = $self->{1} if $self->{opt}->{stdin} && -t $self->{1};
                send_exec_cmd($self, $io, \@cmd, {});
        }
        if ($self->{lxs} && $self->{au_done}) { # kick wait_startq
                syswrite($self->{au_done}, 'q' x ($self->{lxs}->{jobs} // 0));
        }
        return unless -t $self->{2}; # XXX how to determine non-TUI MUAs?
        $self->{opt}->{quiet} = 1;
        delete $self->{-progress};
        delete $self->{opt}->{verbose};
}

sub send_exec_cmd { # tell script/lei to execute a command
        my ($self, $io, $cmd, $env) = @_;
        my $sock = $self->{sock} // die 'lei client gone';
        my $fds = [ map { fileno($_) } @$io ];
        $send_cmd->($sock, $fds, exec_buf($cmd, $env), MSG_EOR);
}

sub poke_mua { # forces terminal MUAs to wake up and hopefully notice new mail
        my ($self) = @_;
        my $alerts = $self->{opt}->{alert} // return;
        my $sock = $self->{sock};
        while (my $op = shift(@$alerts)) {
                if ($op eq ':WINCH') {
                        # hit the process group that started the MUA
                        send($sock, '-WINCH', MSG_EOR) if $sock;
                } elsif ($op eq ':bell') {
                        out($self, "\a");
                } elsif ($op =~ /(?<!\\),/) { # bare ',' (not ',,')
                        push @$alerts, split(/(?<!\\),/, $op);
                } elsif ($op =~ m!\A([/a-z0-9A-Z].+)!) {
                        my $cmd = $1; # run an arbitrary command
                        require Text::ParseWords;
                        $cmd = [ Text::ParseWords::shellwords($cmd) ];
                        send($sock, exec_buf($cmd, {}), MSG_EOR) if $sock;
                } else {
                        warn("W: unsupported --alert=$op\n"); # non-fatal
                }
        }
}

my %path_to_fd = ('/dev/stdin' => 0, '/dev/stdout' => 1, '/dev/stderr' => 2);
$path_to_fd{"/dev/fd/$_"} = $_ for (0..2);

# this also normalizes the path
sub path_to_fd {
        my ($self, $path) = @_;
        $path = rel2abs($self, $path);
        $path =~ tr!/!/!s;
        $path_to_fd{$path} // (
                ($path =~ m!\A/(?:dev|proc/self)/fd/[0-9]+\z!) ?
                        fail($self, "cannot open $path from daemon") : -1
        );
}

# caller needs to "-t $self->{1}" to check if tty
sub start_pager {
        my ($self, $new_env) = @_;
        my $fh = popen_rd([qw(git var GIT_PAGER)]);
        chomp(my $pager = <$fh> // '');
        close($fh) or warn "`git var PAGER' error: \$?=$?";
        return if $pager eq 'cat' || $pager eq '';
        $new_env //= {};
        $new_env->{LESS} //= 'FRX';
        $new_env->{LV} //= '-c';
        $new_env->{MORE} = $new_env->{LESS} if $^O eq 'freebsd';
        pipe(my ($r, $wpager)) or return warn "pipe: $!";
        my $rdr = { 0 => $r, 1 => $self->{1}, 2 => $self->{2} };
        my $pgr = [ undef, @$rdr{1, 2} ];
        my $env = $self->{env};
        if ($self->{sock}) { # lei(1) process runs it
                delete @$new_env{keys %$env}; # only set iff unset
                send_exec_cmd($self, [ @$rdr{0..2} ], [$pager], $new_env);
        } else {
                die 'BUG: start_pager w/o socket';
        }
        $self->{1} = $wpager;
        $self->{2} = $wpager if -t $self->{2};
        $env->{GIT_PAGER_IN_USE} = 'true'; # we may spawn git
        $self->{pgr} = $pgr;
}

# display a message for user before spawning full-screen $VISUAL
sub pgr_err {
        my ($self, @msg) = @_;
        return warn(@msg) unless $self->{sock} && -t $self->{2};
        start_pager($self, { LESS => 'RX' }); # no 'F' so we prompt
        print { $self->{2} } @msg;
        $self->{2}->autoflush(1);
        stop_pager($self);
        send($self->{sock}, 'wait', MSG_EOR); # wait for user to quit pager
}

sub stop_pager {
        my ($self) = @_;
        my $pgr = delete($self->{pgr}) or return;
        $self->{2} = $pgr->[2];
        close(delete($self->{1})) if $self->{1};
        $self->{1} = $pgr->[1];
}

sub accept_dispatch { # Listener {post_accept} callback
        my ($sock) = @_; # ignore other
        $sock->autoflush(1);
        my $self = bless { sock => $sock }, __PACKAGE__;
        vec(my $rvec = '', fileno($sock), 1) = 1;
        select($rvec, undef, undef, 60) or
                return send($sock, 'timed out waiting to recv FDs', MSG_EOR);
        # (4096 * 33) >MAX_ARG_STRLEN
        my @fds = $recv_cmd->($sock, my $buf, 4096 * 33) or return; # EOF
        if (!defined($fds[0])) {
                warn(my $msg = "recv_cmd failed: $!");
                return send($sock, $msg, MSG_EOR);
        } else {
                my $i = 0;
                for my $fd (@fds) {
                        open($self->{$i++}, '+<&=', $fd) and next;
                        send($sock, "open(+<&=$fd) (FD=$i): $!", MSG_EOR);
                }
                $i == 4 or return send($sock, 'not enough FDs='.($i-1), MSG_EOR)
        }
        # $ENV_STR = join('', map { "\0$_=$ENV{$_}" } keys %ENV);
        # $buf = "$argc\0".join("\0", @ARGV).$ENV_STR."\0\0";
        substr($buf, -2, 2, '') eq "\0\0" or  # s/\0\0\z//
                return send($sock, 'request command truncated', MSG_EOR);
        my ($argc, @argv) = split(/\0/, $buf, -1);
        undef $buf;
        my %env = map { split(/=/, $_, 2) } splice(@argv, $argc);
        $self->{env} = \%env;
        eval { dispatch($self, @argv) };
        $self->fail($@) if $@;
}

sub dclose {
        my ($self) = @_;
        local $current_lei = $self;
        delete $self->{-progress};
        _drop_wq($self) if $self->{failed};
        $self->close if $self->{-event_init_done}; # PublicInbox::DS::close
}

# for long-running results
sub event_step {
        my ($self) = @_;
        local %ENV = %{$self->{env}};
        local $current_lei = $self;
        eval {
                my @fds = $recv_cmd->($self->{sock} // return, my $buf, 4096);
                if (scalar(@fds) == 1 && !defined($fds[0])) {
                        return if $! == EAGAIN;
                        die "recvmsg: $!" if $! != ECONNRESET;
                        $buf = '';
                        @fds = (); # for open loop below:
                }
                for (@fds) { open my $rfh, '+<&=', $_ }
                if ($buf eq '') {
                        _drop_wq($self); # EOF, client disconnected
                        dclose($self);
                        $buf = 'TERM';
                }
                if ($buf =~ /\A(?:STOP|CONT|TERM)\z/) {
                        my $sig = "-$buf";
                        for my $wq (grep(defined, @$self{@WQ_KEYS})) {
                                $wq->wq_kill($sig);
                        }
                } else {
                        die "unrecognized client signal: $buf";
                }
                my $s = $self->{-socks} // []; # lei up --all
                @$s = grep { send($_, $buf, MSG_EOR) } @$s;
        };
        if (my $err = $@) {
                eval { $self->fail($err) };
                dclose($self);
        }
}

sub event_step_init {
        my ($self) = @_;
        my $sock = $self->{sock} or return;
        $self->{-event_init_done} // do { # persist til $ops done
                $sock->blocking(0);
                $self->SUPER::new($sock, EPOLLIN);
                $self->{-event_init_done} = $sock;
        };
}

sub noop {}

sub oldset { $oldset }

sub dump_and_clear_log {
        if (defined($errors_log) && -s STDIN && seek(STDIN, 0, SEEK_SET)) {
                openlog('lei-daemon', 'pid,nowait,nofatal,ndelay', 'user');
                chomp(my @lines = <STDIN>);
                truncate(STDIN, 0) or
                        syslog('warning', "ftruncate (%s): %m", $errors_log);
                for my $l (@lines) { syslog('warning', '%s', $l) }
                closelog(); # don't share across fork
        }
}

sub cfg2lei ($) {
        my ($cfg) = @_;
        my $lei = bless { env => { %{$cfg->{-env}} } }, __PACKAGE__;
        open($lei->{0}, '<&', \*STDIN) or die "dup 0: $!";
        open($lei->{1}, '>>&', \*STDOUT) or die "dup 1: $!";
        open($lei->{2}, '>>&', \*STDERR) or die "dup 2: $!";
        open($lei->{3}, '<', '/') or die "open /: $!";
        my ($x, $y);
        socketpair($x, $y, AF_UNIX, SOCK_SEQPACKET, 0) or die "socketpair: $!";
        $lei->{sock} = $x;
        require PublicInbox::LeiSelfSocket;
        PublicInbox::LeiSelfSocket->new($y); # adds to event loop
        $lei;
}

sub dir_idle_handler ($) { # PublicInbox::DirIdle callback
        my ($ev) = @_; # Linux::Inotify2::Event or duck type
        my $fn = $ev->fullname;
        if ($fn =~ m!\A(.+)/(new|cur)/([^/]+)\z!) { # Maildir file
                my ($mdir, $nc, $bn) = ($1, $2, $3);
                $nc = '' if $ev->IN_DELETE || $ev->IN_MOVED_FROM;
                for my $f (keys %{$MDIR2CFGPATH->{$mdir} // {}}) {
                        my $cfg = $PATH2CFG{$f} // next;
                        eval {
                                my $lei = cfg2lei($cfg);
                                $lei->dispatch('note-event',
                                                "maildir:$mdir", $nc, $bn, $fn);
                        };
                        warn "E: note-event $f: $@\n" if $@;
                }
        }
        if ($ev->can('cancel') && ($ev->IN_IGNORE || $ev->IN_UNMOUNT)) {
                $ev->cancel;
        }
        if ($fn =~ m!\A(.+)/(?:new|cur)\z! && !-e $fn) {
                delete $MDIR2CFGPATH->{$1};
        }
        if (!-e $fn) { # config file or Maildir gone
                for my $cfgpaths (values %$MDIR2CFGPATH) {
                        delete $cfgpaths->{$fn};
                }
                delete $PATH2CFG{$fn};
        }
}

# lei(1) calls this when it can't connect
sub lazy_start {
        my ($path, $errno, $narg) = @_;
        local ($errors_log, $listener);
        my ($sock_dir) = ($path =~ m!\A(.+?)/[^/]+\z!);
        $errors_log = "$sock_dir/errors.log";
        my $addr = pack_sockaddr_un($path);
        my $lk = bless { lock_path => $errors_log }, 'PublicInbox::Lock';
        umask(077) // die("umask(077): $!");
        $lk->lock_acquire;
        socket($listener, AF_UNIX, SOCK_SEQPACKET, 0) or die "socket: $!";
        if ($errno == ECONNREFUSED || $errno == ENOENT) {
                return if connect($listener, $addr); # another process won
                if ($errno == ECONNREFUSED && -S $path) {
                        unlink($path) or die "unlink($path): $!";
                }
        } else {
                $! = $errno; # allow interpolation to stringify in die
                die "connect($path): $!";
        }
        bind($listener, $addr) or die "bind($path): $!";
        $lk->lock_release;
        undef $lk;
        my @st = stat($path) or die "stat($path): $!";
        my $dev_ino_expect = pack('dd', $st[0], $st[1]); # dev+ino
        local $oldset = PublicInbox::DS::block_signals();
        if ($narg == 5) {
                $send_cmd = PublicInbox::Spawn->can('send_cmd4');
                $recv_cmd = PublicInbox::Spawn->can('recv_cmd4') // do {
                        require PublicInbox::CmdIPC4;
                        $send_cmd = PublicInbox::CmdIPC4->can('send_cmd4');
                        PublicInbox::CmdIPC4->can('recv_cmd4');
                } // do {
                        $send_cmd = PublicInbox::Syscall->can('send_cmd4');
                        PublicInbox::Syscall->can('recv_cmd4');
                };
        }
        $recv_cmd or die <<"";
(Socket::MsgHdr || Inline::C) missing/unconfigured (narg=$narg);

        require PublicInbox::Listener;
        require PublicInbox::PktOp;
        (-p STDOUT) or die "E: stdout must be a pipe\n";
        open(STDIN, '+>>', $errors_log) or die "open($errors_log): $!";
        STDIN->autoflush(1);
        dump_and_clear_log();
        POSIX::setsid() > 0 or die "setsid: $!";
        my $pid = fork // die "fork: $!";
        return if $pid;
        $0 = "lei-daemon $path";
        local %PATH2CFG;
        local $MDIR2CFGPATH;
        $listener->blocking(0);
        my $exit_code;
        my $pil = PublicInbox::Listener->new($listener, \&accept_dispatch);
        local $quit = do {
                my (undef, $eof_p) = PublicInbox::PktOp->pair;
                sub {
                        $exit_code //= shift;
                        eval 'PublicInbox::LeiNoteEvent::flush_task()';
                        my $lis = $pil or exit($exit_code);
                        # closing eof_p triggers \&noop wakeup
                        $listener = $eof_p = $pil = $path = undef;
                        $lis->close; # DS::close
                        PublicInbox::DS->SetLoopTimeout(1000);
                };
        };
        my $sig = {
                CHLD => \&PublicInbox::DS::enqueue_reap,
                QUIT => $quit,
                INT => $quit,
                TERM => $quit,
                HUP => \&noop,
                USR1 => \&noop,
                USR2 => \&noop,
        };
        require PublicInbox::DirIdle;
        local $dir_idle = PublicInbox::DirIdle->new(sub {
                # just rely on wakeup to hit PostLoopCallback set below
                dir_idle_handler($_[0]) if $_[0]->fullname ne $path;
        });
        $dir_idle->add_watches([$sock_dir]);
        PublicInbox::DS->SetPostLoopCallback(sub {
                my ($dmap, undef) = @_;
                if (@st = defined($path) ? stat($path) : ()) {
                        if ($dev_ino_expect ne pack('dd', $st[0], $st[1])) {
                                warn "$path dev/ino changed, quitting\n";
                                $path = undef;
                        }
                } elsif (defined($path)) { # ENOENT is common
                        warn "stat($path): $!, quitting ...\n" if $! != ENOENT;
                        undef $path;
                        $quit->();
                }
                return 1 if defined($path);
                my $n = 0;
                for my $s (values %$dmap) {
                        $s->can('busy') or next;
                        if ($s->busy) {
                                ++$n;
                        } else {
                                $s->close;
                        }
                }
                $n; # true: continue, false: stop
        });

        # STDIN was redirected to /dev/null above, closing STDERR and
        # STDOUT will cause the calling `lei' client process to finish
        # reading the <$daemon> pipe.
        local $SIG{__WARN__} = sub {
                $current_lei ? err($current_lei, @_) : warn(
                  strftime('%Y-%m-%dT%H:%M:%SZ', gmtime(time))," $$ ", @_);
        };
        open STDERR, '>&STDIN' or die "redirect stderr failed: $!";
        open STDOUT, '>&STDIN' or die "redirect stdout failed: $!";
        # $daemon pipe to `lei' closed, main loop begins:
        eval { PublicInbox::DS::event_loop($sig, $oldset) };
        warn "event loop error: $@\n" if $@;
        # exit() may trigger waitpid via various DESTROY, ensure interruptible
        PublicInbox::DS::sig_setmask($oldset);
        dump_and_clear_log();
        exit($exit_code // 0);
}

sub busy { 1 } # prevent daemon-shutdown if client is connected

# ensures stdout hits the FS before sock disconnects so a client
# can immediately reread it
sub DESTROY {
        my ($self) = @_;
        if (my $counters = delete $self->{counters}) {
                for my $k (sort keys %$counters) {
                        my $nr = $counters->{$k};
                        $self->child_error(0, "$nr $k messages");
                }
        }
        $self->{1}->autoflush(1) if $self->{1};
        stop_pager($self);
        dump_and_clear_log();
        # preserve $? for ->fail or ->x_it code
}

sub wq_done_wait { # dwaitpid callback
        my ($arg, $pid) = @_;
        my ($wq, $lei) = @$arg;
        local $current_lei = $lei;
        my $err_type = $lei->{-err_type};
        $? and $lei->child_error($?,
                $err_type ? "$err_type errors during $lei->{cmd} \$?=$?" : ());
        $lei->dclose;
}

sub fchdir {
        my ($lei) = @_;
        my $dh = $lei->{3} // die 'BUG: lei->{3} (CWD) gone';
        chdir($dh) || die "fchdir: $!";
}

sub wq_eof { # EOF callback for main daemon
        my ($lei, $wq_fld) = @_;
        local $current_lei = $lei;
        my $wq = delete $lei->{$wq_fld // 'wq1'};
        $lei->sto_done_request($wq);
        $wq // $lei->fail; # already failed
}

sub watch_state_ok ($) {
        my ($state) = $_[-1]; # $_[0] may be $self
        $state =~ /\Apause|(?:import|index|tag)-(?:ro|rw)\z/;
}

sub cancel_maildir_watch ($$) {
        my ($d, $cfg_f) = @_;
        my $w = delete $MDIR2CFGPATH->{$d}->{$cfg_f};
        scalar(keys %{$MDIR2CFGPATH->{$d}}) or
                delete $MDIR2CFGPATH->{$d};
        for my $x (@{$w // []}) { $x->cancel }
}

sub add_maildir_watch ($$) {
        my ($d, $cfg_f) = @_;
        if (!exists($MDIR2CFGPATH->{$d}->{$cfg_f})) {
                my @w = $dir_idle->add_watches(["$d/cur", "$d/new"], 1);
                push @{$MDIR2CFGPATH->{$d}->{$cfg_f}}, @w if @w;
        }
}

sub refresh_watches {
        my ($lei) = @_;
        $dir_idle or return;
        my $cfg = _lei_cfg($lei) or return;
        my $old = $cfg->{-watches};
        my $watches = $cfg->{-watches} //= {};
        my %seen;
        my $cfg_f = $cfg->{'-f'};
        for my $w (grep(/\Awatch\..+\.state\z/, keys %$cfg)) {
                my $url = substr($w, length('watch.'), -length('.state'));
                require PublicInbox::LeiWatch;
                $watches->{$url} //= PublicInbox::LeiWatch->new($url);
                $seen{$url} = undef;
                my $state = $cfg->get_1("watch.$url.state");
                if (!watch_state_ok($state)) {
                        warn("watch.$url.state=$state not supported\n");
                        next;
                }
                if ($url =~ /\Amaildir:(.+)/i) {
                        my $d = canonpath_harder($1);
                        if ($state eq 'pause') {
                                cancel_maildir_watch($d, $cfg_f);
                        } else {
                                add_maildir_watch($d, $cfg_f);
                        }
                } else { # TODO: imap/nntp/jmap
                        $lei->child_error(0, "E: watch $url not supported, yet")
                }
        }

        # add all known Maildir folders as implicit watches
        my $lms = $lei->lms;
        if ($lms) {
                $lms->lms_write_prepare;
                for my $d ($lms->folders('maildir:')) {
                        substr($d, 0, length('maildir:')) = '';

                        # fixup old bugs while we're iterating:
                        my $cd = canonpath_harder($d);
                        my $f = "maildir:$cd";
                        $lms->rename_folder("maildir:$d", $f) if $d ne $cd;
                        next if $watches->{$f}; # may be set to pause
                        require PublicInbox::LeiWatch;
                        $watches->{$f} = PublicInbox::LeiWatch->new($f);
                        $seen{$f} = undef;
                        add_maildir_watch($cd, $cfg_f);
                }
        }
        if ($old) { # cull old non-existent entries
                for my $url (keys %$old) {
                        next if exists $seen{$url};
                        delete $old->{$url};
                        if ($url =~ /\Amaildir:(.+)/i) {
                                my $d = canonpath_harder($1);
                                cancel_maildir_watch($d, $cfg_f);
                        } else { # TODO: imap/nntp/jmap
                                $lei->child_error(0, "E: watch $url TODO");
                        }
                }
        }
        if (scalar keys %$watches) {
                $cfg->{-env} //= { %{$lei->{env}}, PWD => '/' }; # for cfg2lei
        } else {
                delete $cfg->{-watches};
        }
}

# TODO: support SHA-256
sub git_oid {
        my $eml = $_[-1];
        $eml->header_set($_) for @PublicInbox::Import::UNWANTED_HEADERS;
        git_sha(1, $eml);
}

sub lms {
        my ($lei, $creat) = @_;
        my $sto = $lei->{sto} // _lei_store($lei) // return;
        require PublicInbox::LeiMailSync;
        my $f = "$sto->{priv_eidx}->{topdir}/mail_sync.sqlite3";
        (-f $f || $creat) ? PublicInbox::LeiMailSync->new($f) : undef;
}

sub sto_done_request {
        my ($lei, $wq) = @_;
        return unless $lei->{sto};
        local $current_lei = $lei;
        my $sock = $wq ? $wq->{lei_sock} : undef;
        $sock //= $lei->{sock};
        my @io;
        push(@io, $sock) if $sock; # async wait iff possible
        eval { $lei->{sto}->wq_io_do('done', \@io) };
        warn($@) if $@;
}

sub cfg_dump ($$) {
        my ($lei, $f) = @_;
        my $ret = eval { PublicInbox::Config->git_config_dump($f, $lei->{2}) };
        return $ret if !$@;
        warn($@);
        undef;
}

sub request_umask {
        my ($lei) = @_;
        my $s = $lei->{sock} // return;
        send($s, 'umask', MSG_EOR) // die "send: $!";
        vec(my $rvec = '', fileno($s), 1) = 1;
        select($rvec, undef, undef, 2) or die 'timeout waiting for umask';
        recv($s, my $v, 5, 0) // die "recv: $!";
        (my $u, $lei->{client_umask}) = unpack('AV', $v);
        $u eq 'u' or warn "E: recv $v has no umask";
}

1;