# Copyright (C) 2014-2020 all contributors # License: GPLv2 or later # # Used to read files from a git repository without excessive forking. # Used in our web interfaces as well as our -nntpd server. # This is based on code in Git.pm which is GPLv2+, but modified to avoid # dependence on environment variables for compatibility with mod_perl. # There are also API changes to simplify our usage and data set. package PublicInbox::Git; use strict; use v5.10.1; use parent qw(Exporter); use POSIX (); use IO::Handle; # ->autoflush use Errno qw(EINTR); use File::Glob qw(bsd_glob GLOB_NOSORT); use Time::HiRes qw(stat); use PublicInbox::Spawn qw(popen_rd); use PublicInbox::Tmpfile; use Carp qw(croak); our @EXPORT_OK = qw(git_unquote git_quote); our $PIPE_BUFSIZ = 65536; # Linux default our $in_cleanup; use constant MAX_INFLIGHT => (($^O eq 'linux' ? 4096 : POSIX::_POSIX_PIPE_BUF()) * 3) / 65; # SHA-256 hex size + "\n" in preparation for git using non-SHA1 my %GIT_ESC = ( a => "\a", b => "\b", f => "\f", n => "\n", r => "\r", t => "\t", v => "\013", '"' => '"', '\\' => '\\', ); my %ESC_GIT = map { $GIT_ESC{$_} => $_ } keys %GIT_ESC; # unquote pathnames used by git, see quote.c::unquote_c_style.c in git.git sub git_unquote ($) { return $_[0] unless ($_[0] =~ /\A"(.*)"\z/); $_[0] = $1; $_[0] =~ s/\\([\\"abfnrtv])/$GIT_ESC{$1}/g; $_[0] =~ s/\\([0-7]{1,3})/chr(oct($1))/ge; $_[0]; } sub git_quote ($) { if ($_[0] =~ s/([\\"\a\b\f\n\r\t\013]|[^[:print:]])/ '\\'.($ESC_GIT{$1}||sprintf("%0o",ord($1)))/egs) { return qq{"$_[0]"}; } $_[0]; } sub new { my ($class, $git_dir) = @_; # may contain {-tmp} field for File::Temp::Dir bless { git_dir => $git_dir, alt_st => '', -git_path => {} }, $class } sub git_path ($$) { my ($self, $path) = @_; $self->{-git_path}->{$path} ||= do { local $/ = "\n"; chomp(my $str = $self->qx(qw(rev-parse --git-path), $path)); # git prior to 2.5.0 did not understand --git-path if ($str eq "--git-path\n$path") { $str = "$self->{git_dir}/$path"; } $str; }; } sub alternates_changed { my ($self) = @_; my $alt = git_path($self, 'objects/info/alternates'); my @st = stat($alt) or return 0; # can't rely on 'q' on some 32-bit builds, but `d' works my $st = pack('dd', $st[10], $st[7]); # 10: ctime, 7: size return 0 if $self->{alt_st} eq $st; $self->{alt_st} = $st; # always a true value } sub last_check_err { my ($self) = @_; my $fh = $self->{err_c} or return; sysseek($fh, 0, 0) or fail($self, "sysseek failed: $!"); defined(sysread($fh, my $buf, -s $fh)) or fail($self, "sysread failed: $!"); $buf; } sub _bidi_pipe { my ($self, $batch, $in, $out, $pid, $err) = @_; if ($self->{$pid}) { if (defined $err) { # "err_c" my $fh = $self->{$err}; sysseek($fh, 0, 0) or fail($self, "sysseek failed: $!"); truncate($fh, 0) or fail($self, "truncate failed: $!"); } return; } my ($out_r, $out_w); pipe($out_r, $out_w) or fail($self, "pipe failed: $!"); my @cmd = (qw(git), "--git-dir=$self->{git_dir}", qw(-c core.abbrev=40 cat-file), $batch); my $redir = { 0 => $out_r }; if ($err) { my $id = "git.$self->{git_dir}$batch.err"; my $fh = tmpfile($id) or fail($self, "tmpfile($id): $!"); $self->{$err} = $fh; $redir->{2} = $fh; } my ($in_r, $p) = popen_rd(\@cmd, undef, $redir); $self->{$pid} = $p; $out_w->autoflush(1); if ($^O eq 'linux') { # 1031: F_SETPIPE_SZ fcntl($out_w, 1031, 4096); fcntl($in_r, 1031, 4096) if $batch eq '--batch-check'; } $self->{$out} = $out_w; $self->{$in} = $in_r; } sub my_read ($$$) { my ($fh, $rbuf, $len) = @_; my $left = $len - length($$rbuf); my $r; while ($left > 0) { $r = sysread($fh, $$rbuf, $PIPE_BUFSIZ, length($$rbuf)); if ($r) { $left -= $r; } else { next if (!defined($r) && $! == EINTR); return $r; } } \substr($$rbuf, 0, $len, ''); } sub my_readline ($$) { my ($fh, $rbuf) = @_; while (1) { if ((my $n = index($$rbuf, "\n")) >= 0) { return substr($$rbuf, 0, $n + 1, ''); } my $r = sysread($fh, $$rbuf, $PIPE_BUFSIZ, length($$rbuf)); next if $r || (!defined($r) && $! == EINTR); return defined($r) ? '' : undef; # EOF or error } } sub cat_async_retry ($$$$$) { my ($self, $inflight, $req, $cb, $arg) = @_; # {inflight} may be non-existent, but if it isn't we delete it # here to prevent cleanup() from waiting: delete $self->{inflight}; cleanup($self); $self->{inflight} = $inflight; batch_prepare($self); my $buf = "$req\n"; for (my $i = 0; $i < @$inflight; $i += 3) { $buf .= "$inflight->[$i]\n"; } print { $self->{out} } $buf or fail($self, "write error: $!"); unshift(@$inflight, \$req, $cb, $arg); # \$ref to indicate retried cat_async_step($self, $inflight); # take one step } sub cat_async_step ($$) { my ($self, $inflight) = @_; die 'BUG: inflight empty or odd' if scalar(@$inflight) < 3; my ($req, $cb, $arg) = splice(@$inflight, 0, 3); my $rbuf = delete($self->{cat_rbuf}) // \(my $new = ''); my ($bref, $oid, $type, $size); my $head = my_readline($self->{in}, $rbuf); # ->fail may be called via Gcf2Client.pm if ($head =~ /^([0-9a-f]{40,}) (\S+) ([0-9]+)$/) { ($oid, $type, $size) = ($1, $2, $3 + 0); $bref = my_read($self->{in}, $rbuf, $size + 1) or $self->fail(defined($bref) ? 'read EOF' : "read: $!"); chop($$bref) eq "\n" or $self->fail('LF missing after blob'); } elsif ($head =~ s/ missing\n//s) { $oid = $head; # ref($req) indicates it's already been retried # -gcf2 retries internally, so it never hits this path: if (!ref($req) && !$in_cleanup && $self->alternates_changed) { return cat_async_retry($self, $inflight, $req, $cb, $arg); } $type = 'missing'; $oid = ref($req) ? $$req : $req if $oid eq ''; } else { $self->fail("Unexpected result from async git cat-file: $head"); } eval { $cb->($bref, $oid, $type, $size, $arg) }; $self->{cat_rbuf} = $rbuf if $$rbuf ne ''; warn "E: $oid: $@\n" if $@; } sub cat_async_wait ($) { my ($self) = @_; my $inflight = delete $self->{inflight} or return; while (scalar(@$inflight)) { cat_async_step($self, $inflight); } } sub batch_prepare ($) { _bidi_pipe($_[0], qw(--batch in out pid)); } sub _cat_file_cb { my ($bref, undef, undef, $size, $result) = @_; @$result = ($bref, $size); } sub cat_file { my ($self, $oid, $sizeref) = @_; my $result = []; cat_async($self, $oid, \&_cat_file_cb, $result); cat_async_wait($self); $$sizeref = $result->[1] if $sizeref; $result->[0]; } sub check_async_step ($$) { my ($self, $inflight_c) = @_; die 'BUG: inflight empty or odd' if scalar(@$inflight_c) < 3; my ($req, $cb, $arg) = splice(@$inflight_c, 0, 3); my $rbuf = delete($self->{rbuf_c}) // \(my $new = ''); chomp(my $line = my_readline($self->{in_c}, $rbuf)); my ($hex, $type, $size) = split(/ /, $line); # Future versions of git.git may have type=ambiguous, but for now, # we must handle 'dangling' below (and maybe some other oddball # stuff): # https://public-inbox.org/git/20190118033845.s2vlrb3wd3m2jfzu@dcvr/T/ if ($hex eq 'dangling' || $hex eq 'notdir' || $hex eq 'loop') { my $ret = my_read($self->{in_c}, $rbuf, $type + 1); fail($self, defined($ret) ? 'read EOF' : "read: $!") if !$ret; } eval { $cb->($hex, $type, $size, $arg, $self) }; warn "E: check($req) $@\n" if $@; $self->{rbuf_c} = $rbuf if $$rbuf ne ''; } sub check_async_wait ($) { my ($self) = @_; my $inflight_c = delete $self->{inflight_c} or return; while (scalar(@$inflight_c)) { check_async_step($self, $inflight_c); } } sub check_async_begin ($) { my ($self) = @_; cleanup($self) if alternates_changed($self); _bidi_pipe($self, qw(--batch-check in_c out_c pid_c err_c)); die 'BUG: already in async check' if $self->{inflight_c}; $self->{inflight_c} = []; } sub check_async ($$$$) { my ($self, $oid, $cb, $arg) = @_; my $inflight_c = $self->{inflight_c} // check_async_begin($self); if (scalar(@$inflight_c) >= MAX_INFLIGHT) { check_async_step($self, $inflight_c); } print { $self->{out_c} } $oid, "\n" or fail($self, "write error: $!"); push(@$inflight_c, $oid, $cb, $arg); } sub _check_cb { # check_async callback my ($hex, $type, $size, $result) = @_; @$result = ($hex, $type, $size); } sub check { my ($self, $oid) = @_; my $result = []; check_async($self, $oid, \&_check_cb, $result); check_async_wait($self); my ($hex, $type, $size) = @$result; # Future versions of git.git may show 'ambiguous', but for now, # we must handle 'dangling' below (and maybe some other oddball # stuff): # https://public-inbox.org/git/20190118033845.s2vlrb3wd3m2jfzu@dcvr/T/ return if $type eq 'missing' || $type eq 'ambiguous'; return if $hex eq 'dangling' || $hex eq 'notdir' || $hex eq 'loop'; ($hex, $type, $size); } sub _destroy { my ($self, $rbuf, $in, $out, $pid, $err) = @_; delete @$self{($rbuf, $in, $out)}; delete $self->{$err} if $err; # `err_c' # GitAsyncCat::event_step may delete {pid} my $p = delete $self->{$pid} or return; # PublicInbox::DS may not be loaded eval { PublicInbox::DS::dwaitpid($p, undef, undef) }; waitpid($p, 0) if $@; # wait synchronously if not in event loop } sub cat_async_abort ($) { my ($self) = @_; if (my $inflight = delete $self->{inflight}) { while (@$inflight) { my ($req, $cb, $arg) = splice(@$inflight, 0, 3); $req =~ s/ .*//; # drop git_dir for Gcf2Client eval { $cb->(undef, $req, undef, undef, $arg) }; warn "E: $req: $@ (in abort)\n" if $@; } } cleanup($self); } sub fail { my ($self, $msg) = @_; cat_async_abort($self); croak(ref($self) . ' ' . ($self->{git_dir} // '') . ": $msg"); } sub popen { my ($self, @cmd) = @_; @cmd = ('git', "--git-dir=$self->{git_dir}", @cmd); popen_rd(\@cmd); } sub qx { my ($self, @cmd) = @_; my $fh = $self->popen(@cmd); local $/ = "\n"; return <$fh> if wantarray; local $/; <$fh> } # returns true if there are pending "git cat-file" processes sub cleanup { my ($self) = @_; local $in_cleanup = 1; delete $self->{async_cat}; check_async_wait($self); cat_async_wait($self); _destroy($self, qw(cat_rbuf in out pid)); _destroy($self, qw(chk_rbuf in_c out_c pid_c err_c)); !!($self->{pid} || $self->{pid_c}); } # assuming a well-maintained repo, this should be a somewhat # accurate estimation of its size # TODO: show this in the WWW UI as a hint to potential cloners sub packed_bytes { my ($self) = @_; my $n = 0; my $pack_dir = git_path($self, 'objects/pack'); foreach my $p (bsd_glob("$pack_dir/*.pack", GLOB_NOSORT)) { $n += -s $p; } $n } sub DESTROY { cleanup(@_) } sub local_nick ($) { my ($self) = @_; my $ret = '???'; # don't show full FS path, basename should be OK: if ($self->{git_dir} =~ m!/([^/]+)(?:/\.git)?\z!) { $ret = "/path/to/$1"; } wantarray ? ($ret) : $ret; } sub host_prefix_url ($$) { my ($env, $url) = @_; return $url if index($url, '//') >= 0; my $scheme = $env->{'psgi.url_scheme'}; my $host_port = $env->{HTTP_HOST} // "$env->{SERVER_NAME}:$env->{SERVER_PORT}"; "$scheme://$host_port". ($env->{SCRIPT_NAME} || '/') . $url; } sub pub_urls { my ($self, $env) = @_; if (my $urls = $self->{cgit_url}) { return map { host_prefix_url($env, $_) } @$urls; } local_nick($self); } sub cat_async_begin { my ($self) = @_; cleanup($self) if $self->alternates_changed; $self->batch_prepare; die 'BUG: already in async' if $self->{inflight}; $self->{inflight} = []; } sub cat_async ($$$;$) { my ($self, $oid, $cb, $arg) = @_; my $inflight = $self->{inflight} // cat_async_begin($self); if (scalar(@$inflight) >= MAX_INFLIGHT) { cat_async_step($self, $inflight); } print { $self->{out} } $oid, "\n" or fail($self, "write error: $!"); push(@$inflight, $oid, $cb, $arg); } sub async_prefetch { my ($self, $oid, $cb, $arg) = @_; if (my $inflight = $self->{inflight}) { # we could use MAX_INFLIGHT here w/o the halving, # but lets not allow one client to monopolize a git process if (scalar(@$inflight) < int(MAX_INFLIGHT/2)) { print { $self->{out} } $oid, "\n" or fail($self, "write error: $!"); return push(@$inflight, $oid, $cb, $arg); } } undef; } sub extract_cmt_time { my ($bref, undef, undef, undef, $modified) = @_; if ($$bref =~ /^committer .*?> ([0-9]+) [\+\-]?[0-9]+/sm) { my $cmt_time = $1 + 0; $$modified = $cmt_time if $cmt_time > $$modified; } } # returns the modified time of a git repo, same as the "modified" field # of a grokmirror manifest sub modified ($) { my ($self) = @_; my $modified = 0; my $fh = popen($self, qw(rev-parse --branches)); local $/ = "\n"; while (my $oid = <$fh>) { chomp $oid; cat_async($self, $oid, \&extract_cmt_time, \$modified); } cat_async_wait($self); $modified || time; } 1; __END__ =pod =head1 NAME PublicInbox::Git - git wrapper =head1 VERSION version 1.0 =head1 SYNOPSIS use PublicInbox::Git; chomp(my $git_dir = `git rev-parse --git-dir`); $git_dir or die "GIT_DIR= must be specified\n"; my $git = PublicInbox::Git->new($git_dir); =head1 DESCRIPTION Unstable API outside of the L method. It requires L to be installed. =head1 METHODS =cut =head2 new my $git = PublicInbox::Git->new($git_dir); Initialize a new PublicInbox::Git object for use with L This is the only public API method we support. Everything else in this module is subject to change. =head1 SEE ALSO L, L =head1 CONTACT All feedback welcome via plain-text mail to L The mail archives are hosted at L =head1 COPYRIGHT Copyright (C) 2016 all contributors L License: AGPL-3.0+ L =cut