# Copyright (C) 2020-2021 all contributors
# License: AGPL-3.0+
# backend for a git-cat-file-workalike based on libgit2,
# other libgit2 stuff may go here, too.
package PublicInbox::Gcf2;
use strict;
use v5.10.1;
use PublicInbox::Spawn qw(which popen_rd); # may set PERL_INLINE_DIRECTORY
use Fcntl qw(LOCK_EX SEEK_SET);
use Time::HiRes qw(clock_gettime CLOCK_MONOTONIC);
use IO::Handle; # autoflush
BEGIN {
my (%CFG, $c_src);
# PublicInbox::Spawn will set PERL_INLINE_DIRECTORY
# to ~/.cache/public-inbox/inline-c if it exists
my $inline_dir = $ENV{PERL_INLINE_DIRECTORY} //
die 'PERL_INLINE_DIRECTORY not defined';
my $f = "$inline_dir/.public-inbox.lock";
open my $fh, '+>', $f or die "open($f): $!";
# CentOS 7.x ships Inline 0.53, 0.64+ has built-in locking
flock($fh, LOCK_EX) or die "LOCK_EX($f): $!\n";
my $pc = which($ENV{PKG_CONFIG} // 'pkg-config') //
die "pkg-config missing for libgit2";
my ($dir) = (__FILE__ =~ m!\A(.+?)/[^/]+\z!);
my $ef = "$inline_dir/.public-inbox.pkg-config.err";
open my $err, '+>', $ef or die "open($ef): $!";
for my $x (qw(libgit2)) {
my $rdr = { 2 => $err };
my ($l, $pid) = popen_rd([$pc, '--libs', $x], undef, $rdr);
$l = do { local $/; <$l> };
waitpid($pid, 0);
next if $?;
(my $c, $pid) = popen_rd([$pc, '--cflags', $x], undef, $rdr);
$c = do { local $/; <$c> };
waitpid($pid, 0);
next if $?;
# note: we name C source files .h to prevent
# ExtUtils::MakeMaker from automatically trying to
# build them.
my $f = "$dir/gcf2_$x.h";
open(my $src, '<', $f) or die "E: open($f): $!";
chomp($l, $c);
local $/;
defined($c_src = <$src>) or die "read $f: $!";
$CFG{LIBS} = $l;
$CFG{CCFLAGSEX} = $c;
last;
}
unless ($c_src) {
seek($err, 0, SEEK_SET);
$err = do { local $/; <$err> };
die "E: libgit2 not installed: $err\n";
}
open my $oldout, '>&', \*STDOUT or die "dup(1): $!";
open my $olderr, '>&', \*STDERR or die "dup(2): $!";
open STDOUT, '>&', $fh or die "1>$f: $!";
open STDERR, '>&', $fh or die "2>$f: $!";
STDERR->autoflush(1);
STDOUT->autoflush(1);
# we use Capitalized and ALLCAPS for compatibility with old Inline::C
eval <<'EOM';
use Inline C => Config => %CFG, BOOT => q[git_libgit2_init();];
use Inline C => $c_src, BUILD_NOISY => 1;
EOM
$err = $@;
open(STDERR, '>&', $olderr) or warn "restore stderr: $!";
open(STDOUT, '>&', $oldout) or warn "restore stdout: $!";
if ($err) {
seek($fh, 0, SEEK_SET);
my @msg = <$fh>;
die "Inline::C Gcf2 build failed:\n", $err, "\n", @msg;
}
}
sub add_alt ($$) {
my ($gcf2, $objdir) = @_;
# libgit2 (tested 0.27.7+dfsg.1-0.2 and 0.28.3+dfsg.1-1~bpo10+1
# in Debian) doesn't handle relative epochs properly when nested
# multiple levels. Add all the absolute paths to workaround it,
# since $EXTINDEX_DIR/ALL.git/objects/info/alternates uses absolute
# paths to reference $V2INBOX_DIR/all.git/objects and
# $V2INBOX_DIR/all.git/objects/info/alternates uses relative paths
# to refer to $V2INBOX_DIR/git/$EPOCH.git/objects
#
# See https://bugs.debian.org/975607
if (open(my $fh, '<', "$objdir/info/alternates")) {
chomp(my @abs_alt = grep(m!^/!, <$fh>));
$gcf2->add_alternate($_) for @abs_alt;
}
$gcf2->add_alternate($objdir);
1;
}
sub have_unlinked_files () {
# FIXME: port gcf2-like over to git.git so we won't need to
# deal with libgit2
return 1 if $^O ne 'linux';
open my $fh, '<', "/proc/$$/maps" or return;
while (<$fh>) { return 1 if /\.(?:idx|pack) \(deleted\)$/ }
undef;
}
# Usage: $^X -MPublicInbox::Gcf2 -e PublicInbox::Gcf2::loop [EXPIRE-TIMEOUT]
# (see lib/PublicInbox/Gcf2Client.pm)
sub loop (;$) {
my $exp = $_[0] || $ARGV[0] || 60; # seconds
my $gcf2 = new();
my (%seen, $check_at);
STDERR->autoflush(1);
STDOUT->autoflush(1);
while () {
chomp;
my ($oid, $git_dir) = split(/ /, $_, 2);
$seen{$git_dir} //= add_alt($gcf2, "$git_dir/objects");
if (!$gcf2->cat_oid(1, $oid)) {
# retry once if missing. We only get unabbreviated OIDs
# from SQLite or Xapian DBs, here, so malicious clients
# can't trigger excessive retries:
warn "I: $$ $oid missing, retrying in $git_dir\n";
$gcf2 = new();
%seen = ($git_dir => add_alt($gcf2,"$git_dir/objects"));
$check_at = clock_gettime(CLOCK_MONOTONIC) + $exp;
if ($gcf2->cat_oid(1, $oid)) {
warn "I: $$ $oid found after retry\n";
} else {
warn "W: $$ $oid missing after retry\n";
print "$oid missing\n"; # mimic git-cat-file
}
} else { # check expiry to deal with deleted pack files
my $now = clock_gettime(CLOCK_MONOTONIC);
$check_at //= $now + $exp;
if ($now > $check_at && have_unlinked_files()) {
undef $check_at;
$gcf2 = new();
%seen = ();
}
}
}
}
1;