# Copyright (C) 2020 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 PublicInbox::Spawn qw(which popen_rd);
use Fcntl qw(LOCK_EX);
use IO::Handle; # autoflush
my (%CFG, $c_src, $lockfh);
BEGIN {
# 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 $lockfh, '>', $f or die "failed to open $f: $!\n";
my $pc = which($ENV{PKG_CONFIG} // 'pkg-config');
my ($dir) = (__FILE__ =~ m!\A(.+?)/[^/]+\z!);
my $rdr = {};
open $rdr->{2}, '>', '/dev/null' or die "open /dev/null: $!";
for my $x (qw(libgit2)) {
my $l = popen_rd([$pc, '--libs', $x], undef, $rdr);
$l = do { local $/; <$l> };
next if $?;
my $c = popen_rd([$pc, '--cflags', $x], undef, $rdr);
$c = do { local $/; <$c> };
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";
if (open(my $fh, '<', $f)) {
chomp($l, $c);
local $/;
defined($c_src = <$fh>) or die "read $f: $!\n";
$CFG{LIBS} = $l;
$CFG{CCFLAGSEX} = $c;
last;
} else {
die "E: $f: $!\n";
}
}
die "E: libgit2 not installed\n" unless $c_src;
# CentOS 7.x ships Inline 0.53, 0.64+ has built-in locking
flock($lockfh, LOCK_EX) or die "LOCK_EX failed on $f: $!\n";
}
# we use Capitalized and ALLCAPS for compatibility with old Inline::C
use Inline C => Config => %CFG, BOOT => 'git_libgit2_init();';
use Inline C => $c_src;
undef $c_src;
undef %CFG;
undef $lockfh;
sub add_alt ($$) {
my ($gcf2, $objdir) = @_;
# libgit2 (tested 0.27.7+dfsg.1-0.2 and 0.28.3+dfsg.1-1~bpo10+1
# in Debian) doesn't handle relative epochs properly when nested
# multiple levels. Add all the absolute paths to workaround it,
# since $EXTINDEX_DIR/ALL.git/objects/info/alternates uses absolute
# paths to reference $V2INBOX_DIR/all.git/objects and
# $V2INBOX_DIR/all.git/objects/info/alternates uses relative paths
# to refer to $V2INBOX_DIR/git/$EPOCH.git/objects
#
# See https://bugs.debian.org/975607
if (open(my $fh, '<', "$objdir/info/alternates")) {
chomp(my @abs_alt = grep(m!^/!, <$fh>));
$gcf2->add_alternate($_) for @abs_alt;
}
$gcf2->add_alternate($objdir);
}
# Usage: $^X -MPublicInbox::Gcf2 -e 'PublicInbox::Gcf2::loop()'
# (see lib/PublicInbox/Gcf2Client.pm)
sub loop {
my $gcf2 = new();
my %seen;
STDERR->autoflush(1);
STDOUT->autoflush(1);
while () {
chomp;
my ($oid, $git_dir) = split(/ /, $_, 2);
$seen{$git_dir}++ or add_alt($gcf2, "$git_dir/objects");
if (!$gcf2->cat_oid(1, $oid)) {
# retry once if missing. We only get unabbreviated OIDs
# from SQLite or Xapian DBs, here, so malicious clients
# can't trigger excessive retries:
warn "I: $$ $oid missing, retrying in $git_dir\n";
$gcf2 = new();
%seen = ($git_dir => 1);
add_alt($gcf2, "$git_dir/objects");
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
}
}
}
}
1;