# 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 warnings;
use POSIX ();
use IO::Handle; # ->autoflush
use File::Glob qw(bsd_glob GLOB_NOSORT);
use PublicInbox::Spawn qw(popen_rd);
use PublicInbox::Tmpfile;
use base qw(Exporter);
our @EXPORT_OK = qw(git_unquote git_quote);
use constant MAX_INFLIGHT =>
($^O eq 'linux' ? 4096 : POSIX::_POSIX_PIPE_BUF())
/
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) = @_;
my @st;
$st[7] = $st[10] = 0;
# may contain {-tmp} field for File::Temp::Dir
bless { git_dir => $git_dir, st => \@st, -git_path => {} }, $class
}
sub git_path ($$) {
my ($self, $path) = @_;
$self->{-git_path}->{$path} ||= do {
local $/ = "\n";
chomp(my $str = $self->qx(qw(rev-parse --git-path), $path));
# git prior to 2.5.0 did not understand --git-path
if ($str eq "--git-path\n$path") {
$str = "$self->{git_dir}/$path";
}
$str;
};
}
sub alternates_changed {
my ($self) = @_;
my $alt = git_path($self, 'objects/info/alternates');
my @st = stat($alt) or return 0;
my $old_st = $self->{st};
# 10 - ctime, 7 - size
return 0 if ($st[10] == $old_st->[10] && $st[7] == $old_st->[7]);
$self->{st} = \@st;
}
sub last_check_err {
my ($self) = @_;
my $fh = $self->{err_c} or return;
sysseek($fh, 0, 0) or fail($self, "sysseek failed: $!");
defined(sysread($fh, my $buf, -s $fh)) or
fail($self, "sysread failed: $!");
$buf;
}
sub _bidi_pipe {
my ($self, $batch, $in, $out, $pid, $err) = @_;
if ($self->{$pid}) {
if (defined $err) { # "err_c"
my $fh = $self->{$err};
sysseek($fh, 0, 0) or fail($self, "sysseek failed: $!");
truncate($fh, 0) or fail($self, "truncate failed: $!");
}
return;
}
my ($out_r, $out_w);
pipe($out_r, $out_w) or fail($self, "pipe failed: $!");
my @cmd = (qw(git), "--git-dir=$self->{git_dir}",
qw(-c core.abbrev=40 cat-file), $batch);
my $redir = { 0 => $out_r };
if ($err) {
my $id = "git.$self->{git_dir}$batch.err";
my $fh = tmpfile($id) or fail($self, "tmpfile($id): $!");
$self->{$err} = $fh;
$redir->{2} = $fh;
}
my ($in_r, $p) = popen_rd(\@cmd, undef, $redir);
$self->{$pid} = $p;
$out_w->autoflush(1);
if ($^O eq 'linux') { # 1031: F_SETPIPE_SZ
fcntl($out_w, 1031, 4096);
fcntl($in_r, 1031, 4096) if $batch eq '--batch-check';
}
$self->{$out} = $out_w;
$self->{$in} = $in_r;
}
sub read_cat_in_full ($$$) {
my ($self, $in, $left) = @_;
my $offset = 0;
my $buf = '';
while ($left > 0) {
my $r = read($in, $buf, $left, $offset);
defined($r) or fail($self, "read failed: $!");
$r == 0 and fail($self, 'exited unexpectedly');
$left -= $r;
$offset += $r;
}
my $r = read($in, my $lf, 1);
defined($r) or fail($self, "read failed: $!");
fail($self, 'newline missing after blob') if ($r != 1 || $lf ne "\n");
\$buf;
}
sub _cat_async_step ($$$) {
my ($self, $inflight, $in) = @_;
my $pair = shift @$inflight or die 'BUG: inflight empty';
my ($cb, $arg) = @$pair;
local $/ = "\n";
my $head = $in->getline;
$head =~ / missing$/ and return
eval { $cb->(undef, undef, undef, undef, $arg) };
$head =~ /^([0-9a-f]{40}) (\S+) ([0-9]+)$/ or
fail($self, "Unexpected result from async git cat-file: $head");
my ($oid_hex, $type, $size) = ($1, $2, $3 + 0);
my $bref = read_cat_in_full($self, $in, $size);
eval { $cb->($bref, $oid_hex, $type, $size, $arg) };
}
sub cat_async_wait ($) {
my ($self) = @_;
my $inflight = delete $self->{inflight} or return;
my $in = $self->{in};
while (scalar(@$inflight)) {
_cat_async_step($self, $inflight, $in);
}
}
sub cat_file {
my ($self, $obj, $ref) = @_;
my ($retried, $in, $head);
cat_async_wait($self);
again:
batch_prepare($self);
$self->{out}->print($obj, "\n") or fail($self, "write error: $!");
$in = $self->{in};
local $/ = "\n";
$head = $in->getline;
if ($head =~ / missing$/) {
if (!$retried && alternates_changed($self)) {
$retried = 1;
cleanup($self);
goto again;
}
return;
}
$head =~ /^[0-9a-f]{40} \S+ ([0-9]+)$/ or
fail($self, "Unexpected result from git cat-file: $head");
my $size = $1;
$$ref = $size if $ref;
read_cat_in_full($self, $in, $size);
}
sub batch_prepare ($) { _bidi_pipe($_[0], qw(--batch in out pid)) }
sub check {
my ($self, $obj) = @_;
_bidi_pipe($self, qw(--batch-check in_c out_c pid_c err_c));
$self->{out_c}->print($obj, "\n") or fail($self, "write error: $!");
local $/ = "\n";
chomp(my $line = $self->{in_c}->getline);
my ($hex, $type, $size) = split(' ', $line);
# 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' || $type eq 'ambiguous';
if ($hex eq 'dangling' || $hex eq 'notdir' || $hex eq 'loop') {
$size = $type + length("\n");
my $r = read($self->{in_c}, my $buf, $size);
defined($r) or fail($self, "read failed: $!");
return;
}
($hex, $type, $size);
}
sub _destroy {
my ($self, $in, $out, $pid, $err) = @_;
my $p = delete $self->{$pid} or return;
delete @$self{($in, $out)};
delete $self->{$err} if $err; # `err_c'
# PublicInbox::DS may not be loaded
eval { PublicInbox::DS::dwaitpid($p, undef, undef) };
waitpid($p, 0) if $@; # wait synchronously if not in event loop
}
sub cat_async_abort ($) {
my ($self) = @_;
my $inflight = delete $self->{inflight} or die 'BUG: not in async';
cleanup($self);
}
sub fail {
my ($self, $msg) = @_;
$self->{inflight} ? cat_async_abort($self) : cleanup($self);
die $msg;
}
sub popen {
my ($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 ($self) = @_;
_destroy($self, qw(in out pid));
_destroy($self, qw(in_c out_c pid_c err_c));
!!($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 ($$) {
my ($env, $url) = @_;
return $url if index($url, '//') >= 0;
my $scheme = $env->{'psgi.url_scheme'};
my $host_port = $env->{HTTP_HOST} //
"$env->{SERVER_NAME}:$env->{SERVER_PORT}";
"$scheme://$host_port". ($env->{SCRIPT_NAME} || '/') . $url;
}
sub pub_urls {
my ($self, $env) = @_;
if (my $urls = $self->{cgit_url}) {
return map { host_prefix_url($env, $_) } @$urls;
}
local_nick($self);
}
sub cat_async_begin {
my ($self) = @_;
cleanup($self) if alternates_changed($self);
batch_prepare($self);
die 'BUG: already in async' if $self->{inflight};
$self->{inflight} = [];
}
sub cat_async ($$$;$) {
my ($self, $oid, $cb, $arg) = @_;
my $inflight = $self->{inflight} or die 'BUG: not in async';
if (scalar(@$inflight) >= MAX_INFLIGHT) {
_cat_async_step($self, $inflight, $self->{in});
}
$self->{out}->print($oid, "\n") or fail($self, "write error: $!");
push(@$inflight, [ $cb, $arg ]);
}
sub extract_cmt_time {
my ($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));
cat_async_begin($self);
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