# Copyright (C) 2019 all contributors # License: AGPL-3.0+ # "Solve" blobs which don't exist in git code repositories by # searching inboxes for post-image blobs. # this emits a lot of debugging/tracing information which may be # publically viewed over HTTP(S). Be careful not to expose # local filesystem layouts in the process. package PublicInbox::SolverGit; use strict; use warnings; use File::Temp qw(); use Fcntl qw(SEEK_SET); use PublicInbox::Git qw(git_unquote git_quote); use PublicInbox::Spawn qw(spawn popen_rd); use PublicInbox::MsgIter qw(msg_iter msg_part_text); use PublicInbox::Qspawn; use URI::Escape qw(uri_escape_utf8); # POSIX requires _POSIX_ARG_MAX >= 4096, and xargs is required to # subtract 2048 bytes. We also don't factor in environment variable # headroom into this. use POSIX qw(sysconf _SC_ARG_MAX); my $ARG_SIZE_MAX = (sysconf(_SC_ARG_MAX) || 4096) - 2048; my $OID_MIN = 7; # By default, "git format-patch" generates filenames with a four-digit # prefix, so that means 9999 patch series are OK, right? :> # Maybe we can make this configurable, main concern is disk space overhead # for uncompressed patch fragments. Aside from space, public-inbox-httpd # is otherwise unaffected by having many patches, here, as it can share # work fairly. Other PSGI servers may have trouble, though. my $MAX_PATCH = 9999; # di = diff info / a hashref with information about a diff ($di): # { # oid_a => abbreviated pre-image oid, # oid_b => abbreviated post-image oid, # tmp => anonymous file handle with the diff, # hdr_lines => arrayref of various header lines for mode information # mode_a => original mode of oid_a (string, not integer), # ibx => PublicInbox::Inbox object containing the diff # smsg => PublicInbox::SearchMsg object containing diff # path_a => pre-image path # path_b => post-image path # } # don't bother if somebody sends us a patch with these path components, # it's junk at best, an attack attempt at worse: my %bad_component = map { $_ => 1 } ('', '.', '..'); sub dbg ($$) { print { $_[0]->{out} } $_[1], "\n" or ERR($_[0], "print(dbg): $!"); } sub ERR ($$) { my ($self, $err) = @_; print { $self->{out} } $err, "\n"; my $ucb = delete($self->{user_cb}); eval { $ucb->($err) } if $ucb; die $err; } # look for existing blobs already in git repos sub solve_existing ($$) { my ($self, $want) = @_; my $oid_b = $want->{oid_b}; my @ambiguous; # Array of [ git, $oids] foreach my $git (@{$self->{gits}}) { my ($oid_full, $type, $size) = $git->check($oid_b); if (defined($type) && $type eq 'blob') { return [ $git, $oid_full, $type, int($size) ]; } next if length($oid_b) == 40; # parse stderr of "git cat-file --batch-check" my $err = $git->last_check_err; my (@oids) = ($err =~ /\b([a-f0-9]{40})\s+blob\b/g); next unless scalar(@oids); # TODO: do something with the ambiguous array? # push @ambiguous, [ $git, @oids ]; dbg($self, "`$oid_b' ambiguous in " . join("\n\t", $git->pub_urls) . "\n" . join('', map { "$_ blob\n" } @oids)); } scalar(@ambiguous) ? \@ambiguous : undef; } sub extract_diff ($$$$$) { my ($self, $p, $re, $ibx, $smsg) = @_; my ($part) = @$p; # ignore $depth and @idx; my $hdr_lines; # diff --git a/... b/... my $tmp; my $ct = $part->content_type || 'text/plain'; my ($s, undef) = msg_part_text($part, $ct); defined $s or return; my $di = {}; # Email::MIME::Encodings forces QP to be CRLF upon decoding, # change it back to LF: my $cte = $part->header('Content-Transfer-Encoding') || ''; if ($cte =~ /\bquoted-printable\b/i && $part->crlf eq "\n") { $s =~ s/\r\n/\n/sg; } foreach my $l (split(/^/m, $s)) { if ($l =~ $re) { $di->{oid_a} = $1; $di->{oid_b} = $2; if (defined($3)) { my $mode_a = $3; if ($mode_a =~ /\A(?:100644|120000|100755)\z/) { $di->{mode_a} = $mode_a; } } # start writing the diff out to a tempfile my $pn = ++$self->{tot}; open($tmp, '>', $self->{tmp}->dirname . "/$pn") or die "open(tmp): $!"; push @$hdr_lines, $l; $di->{hdr_lines} = $hdr_lines; utf8::encode($_) for @$hdr_lines; print $tmp @$hdr_lines or die "print(tmp): $!"; # for debugging/diagnostics: $di->{ibx} = $ibx; $di->{smsg} = $smsg; } elsif ($l =~ m!\Adiff --git ("?[^/]+/.+) ("?[^/]+/.+)$!) { last if $tmp; # got our blob, done! my ($path_a, $path_b) = ($1, $2); # diff header lines won't have \r because git # will quote them, but Email::MIME gives CRLF # for quoted-printable: $path_b =~ tr/\r//d; # don't care for leading 'a/' and 'b/' my (undef, @a) = split(m{/}, git_unquote($path_a)); my (undef, @b) = split(m{/}, git_unquote($path_b)); # get rid of path-traversal attempts and junk patches: foreach (@a, @b) { return if $bad_component{$_}; } $di->{path_a} = join('/', @a); $di->{path_b} = join('/', @b); $hdr_lines = [ $l ]; } elsif ($tmp) { utf8::encode($l); print $tmp $l or die "print(tmp): $!"; } elsif ($hdr_lines) { push @$hdr_lines, $l; if ($l =~ /\Anew file mode (100644|120000|100755)$/) { $di->{mode_a} = $1; } } } return undef unless $tmp; close $tmp or die "close(tmp): $!"; $di; } sub path_searchable ($) { defined($_[0]) && $_[0] =~ m!\A[\w/\. \-]+\z! } # ".." appears in path names, which confuses Xapian into treating # it as a range query. So we split on ".." since Xapian breaks # on punctuation anyways: sub filename_query ($) { join('', map { qq( dfn:"$_") } split(/\.\./, $_[0])); } sub find_extract_diff ($$$) { my ($self, $ibx, $want) = @_; my $srch = $ibx->search or return; my $post = $want->{oid_b} or die 'BUG: no {oid_b}'; $post =~ /\A[a-f0-9]+\z/ or die "BUG: oid_b not hex: $post"; my $q = "dfpost:$post"; my $pre = $want->{oid_a}; if (defined $pre && $pre =~ /\A[a-f0-9]+\z/) { $q .= " dfpre:$pre"; } else { $pre = '[a-f0-9]{7}'; # for $re below } my $path_b = $want->{path_b}; if (path_searchable($path_b)) { $q .= filename_query($path_b); my $path_a = $want->{path_a}; if (path_searchable($path_a) && $path_a ne $path_b) { $q .= filename_query($path_a); } } my $msgs = $srch->query($q, { relevance => 1 }); my $re = qr/\Aindex ($pre[a-f0-9]*)\.\.($post[a-f0-9]*)(?: (\d+))?/; my $di; foreach my $smsg (@$msgs) { $ibx->smsg_mime($smsg) or next; msg_iter(delete($smsg->{mime}), sub { $di ||= extract_diff($self, $_[0], $re, $ibx, $smsg); }); return $di if $di; } } sub prepare_index ($) { my ($self) = @_; my $patches = $self->{patches}; $self->{nr} = 0; my $di = $patches->[0] or die 'no patches'; my $oid_a = $di->{oid_a} or die '{oid_a} unset'; my $existing = $self->{found}->{$oid_a}; # no index creation for added files $oid_a =~ /\A0+\z/ and return next_step($self); die "BUG: $oid_a not not found" unless $existing; my $oid_full = $existing->[1]; my $path_a = $di->{path_a} or die "BUG: path_a missing for $oid_full"; my $mode_a = $di->{mode_a} || extract_old_mode($di); open my $in, '+>', undef or die "open: $!"; print $in "$mode_a $oid_full\t$path_a\0" or die "print: $!"; $in->flush or die "flush: $!"; sysseek($in, 0, 0) or die "seek: $!"; dbg($self, 'preparing index'); my $rdr = { 0 => fileno($in) }; my $cmd = [ qw(git update-index -z --index-info) ]; my $qsp = PublicInbox::Qspawn->new($cmd, $self->{git_env}, $rdr); $qsp->psgi_qx($self->{psgi_env}, undef, sub { my ($bref) = @_; if (my $err = $qsp->{err}) { ERR($self, "git update-index error: $err"); } dbg($self, "index prepared:\n" . "$mode_a $oid_full\t" . git_quote($path_a)); next_step($self); # onto do_git_apply }); } # pure Perl "git init" sub do_git_init ($) { my ($self) = @_; my $dir = $self->{tmp}->dirname; my $git_dir = "$dir/git"; foreach ('', qw(objects refs objects/info refs/heads)) { mkdir("$git_dir/$_") or die "mkdir $_: $!"; } open my $fh, '>', "$git_dir/config" or die "open git/config: $!"; print $fh <<'EOF' or die "print git/config $!"; [core] repositoryFormatVersion = 0 filemode = true bare = false fsyncObjectfiles = false logAllRefUpdates = false EOF close $fh or die "close git/config: $!"; open $fh, '>', "$git_dir/HEAD" or die "open git/HEAD: $!"; print $fh "ref: refs/heads/master\n" or die "print git/HEAD: $!"; close $fh or die "close git/HEAD: $!"; my $f = 'objects/info/alternates'; open $fh, '>', "$git_dir/$f" or die "open: $f: $!"; foreach my $git (@{$self->{gits}}) { print $fh $git->git_path('objects'),"\n" or die "print $f: $!"; } close $fh or die "close: $f: $!"; my $tmp_git = $self->{tmp_git} = PublicInbox::Git->new($git_dir); $tmp_git->{-tmp} = $self->{tmp}; $self->{git_env} = { GIT_DIR => $git_dir, GIT_INDEX_FILE => "$git_dir/index", }; prepare_index($self); } sub extract_old_mode ($) { my ($di) = @_; if (join('', @{$di->{hdr_lines}}) =~ /^old mode (100644|100755|120000)\b/) { return $1; } '100644'; } sub do_finish ($$) { my ($self, $user_cb) = @_; my $found = $self->{found}; my $oid_want = $self->{oid_want}; if (my $exists = $found->{$oid_want}) { return $user_cb->($exists); } # let git disambiguate if oid_want was too short, # but long enough to be unambiguous: my $tmp_git = $self->{tmp_git}; if (my @res = $tmp_git->check($oid_want)) { return $user_cb->($found->{$res[0]}); } if (my $err = $tmp_git->last_check_err) { dbg($self, $err); } $user_cb->(undef); } sub do_step ($) { my ($self) = @_; eval { # step 1: resolve blobs to patches in the todo queue if (my $want = pop @{$self->{todo}}) { # this populates {patches} and {todo} resolve_patch($self, $want); # step 2: then we instantiate a working tree once # the todo queue is finally empty: } elsif (!defined($self->{tmp_git})) { do_git_init($self); # step 3: apply each patch in the stack } elsif (scalar @{$self->{patches}}) { do_git_apply($self); # step 4: execute the user-supplied callback with # our result: (which may be undef) # Other steps may call user_cb to terminate prematurely # on error } elsif (my $user_cb = delete($self->{user_cb})) { do_finish($self, $user_cb); } else { die 'about to call user_cb twice'; # Oops :x } }; # eval my $err = $@; if ($err) { $err =~ s/^\s*Exception:\s*//; # bad word to show users :P dbg($self, "E: $err"); my $ucb = delete($self->{user_cb}); eval { $ucb->($err) } if $ucb; } } sub step_cb ($) { my ($self) = @_; sub { do_step($self) }; } sub next_step ($) { my ($self) = @_; # if outside of public-inbox-httpd, caller is expected to be # looping step_cb, anyways my $async = $self->{psgi_env}->{'pi-httpd.async'} or return; # PublicInbox::HTTPD::Async->new $async->(undef, step_cb($self)); } sub mark_found ($$$) { my ($self, $oid, $found_info) = @_; my $found = $self->{found}; $found->{$oid} = $found_info; my $oid_cur = $found_info->[1]; while ($oid_cur ne $oid && length($oid_cur) > $OID_MIN) { $found->{$oid_cur} = $found_info; chop($oid_cur); } } sub parse_ls_files ($$$$) { my ($self, $qsp, $bref, $di) = @_; if (my $err = $qsp->{err}) { die "git ls-files error: $err"; } my ($line, @extra) = split(/\0/, $$bref); scalar(@extra) and die "BUG: extra files in index: <", join('> <', @extra), ">"; my ($info, $file) = split(/\t/, $line, 2); my ($mode_b, $oid_b_full, $stage) = split(/ /, $info); if ($file ne $di->{path_b}) { die "BUG: index mismatch: file=$file != path_b=$di->{path_b}"; } my $tmp_git = $self->{tmp_git} or die 'no git working tree'; my (undef, undef, $size) = $tmp_git->check($oid_b_full); defined($size) or die "check $oid_b_full failed"; dbg($self, "index at:\n$mode_b $oid_b_full\t$file"); my $created = [ $tmp_git, $oid_b_full, 'blob', $size, $di ]; mark_found($self, $di->{oid_b}, $created); next_step($self); # onto the next patch } sub start_ls_files ($$) { my ($self, $di) = @_; my $cmd = [qw(git ls-files -s -z)]; my $qsp = PublicInbox::Qspawn->new($cmd, $self->{git_env}); $qsp->psgi_qx($self->{psgi_env}, undef, sub { my ($bref) = @_; eval { parse_ls_files($self, $qsp, $bref, $di) }; ERR($self, $@) if $@; }); } sub do_git_apply ($) { my ($self) = @_; my $dn = $self->{tmp}->dirname; my $patches = $self->{patches}; # we need --ignore-whitespace because some patches are CRLF my @cmd = (qw(git -C), $dn, qw(apply --cached --ignore-whitespace --whitespace=warn --verbose)); my $len = length(join(' ', @cmd)); my $total = $self->{tot}; my $di; # keep track of the last one for "git ls-files" do { my $i = ++$self->{nr}; $di = shift @$patches; dbg($self, "\napplying [$i/$total] " . di_url($self, $di) . "\n" . join('', @{$di->{hdr_lines}})); my $path = $total + 1 - $i; $len += length($path) + 1; push @cmd, $path; } while (@$patches && $len < $ARG_SIZE_MAX); my $rdr = { 2 => 1 }; my $qsp = PublicInbox::Qspawn->new(\@cmd, $self->{git_env}, $rdr); $qsp->psgi_qx($self->{psgi_env}, undef, sub { my ($bref) = @_; dbg($self, $$bref); if (my $err = $qsp->{err}) { ERR($self, "git apply error: $err"); } eval { start_ls_files($self, $di) }; ERR($self, $@) if $@; }); } sub di_url ($$) { my ($self, $di) = @_; # note: we don't pass the PSGI env unconditionally, here, # different inboxes can have different HTTP_HOST on the same instance. my $ibx = $di->{ibx}; my $env = $self->{psgi_env} if $ibx eq $self->{inboxes}->[0]; my $url = $ibx->base_url($env); my $mid = $di->{smsg}->{mid}; defined($url) ? "$url$mid/" : "<$mid>"; } sub resolve_patch ($$) { my ($self, $want) = @_; if (scalar(@{$self->{patches}}) > $MAX_PATCH) { die "Aborting, too many steps to $self->{oid_want}"; } # see if we can find the blob in an existing git repo: my $cur_want = $want->{oid_b}; if ($self->{seen_oid}->{$cur_want}++) { die "Loop detected solving $cur_want\n"; } if (my $existing = solve_existing($self, $want)) { dbg($self, "found $cur_want in " . join("\n", $existing->[0]->pub_urls)); if ($cur_want eq $self->{oid_want}) { # all done! eval { delete($self->{user_cb})->($existing) }; die "E: $@" if $@; return; } mark_found($self, $cur_want, $existing); return next_step($self); # onto patch application } # scan through inboxes to look for emails which results in # the oid we want: my $di; foreach my $ibx (@{$self->{inboxes}}) { $di = find_extract_diff($self, $ibx, $want) or next; unshift @{$self->{patches}}, $di; dbg($self, "found $cur_want in ".di_url($self, $di)); # good, we can find a path to the oid we $want, now # lets see if we need to apply more patches: my $src = $di->{oid_a}; unless ($src =~ /\A0+\z/) { # we have to solve it using another oid, fine: my $job = { oid_b => $src, path_b => $di->{path_a} }; push @{$self->{todo}}, $job; } return next_step($self); # onto the next todo item } if (length($cur_want) > $OID_MIN) { chop($cur_want); dbg($self, "retrying $want->{oid_b} as $cur_want"); $want->{oid_b} = $cur_want; push @{$self->{todo}}, $want; return next_step($self); # retry with shorter abbrev } dbg($self, "could not find $cur_want"); eval { delete($self->{user_cb})->(undef) }; # not found! :< die "E: $@" if $@; } # this API is designed to avoid creating self-referential structures; # so user_cb never references the SolverGit object sub new { my ($class, $ibx, $user_cb) = @_; bless { gits => $ibx->{-repo_objs}, user_cb => $user_cb, # TODO: config option for searching related inboxes inboxes => [ $ibx ], }, $class; } # recreate $oid_want using $hints # Calls {user_cb} with: [ ::Git object, oid_full, type, size, di (diff_info) ] # with found object, or undef if nothing was found # Calls {user_cb} with a string error on fatal errors sub solve ($$$$$) { my ($self, $env, $out, $oid_want, $hints) = @_; # should we even get here? Probably not, but somebody # could be manually typing URLs: return (delete $self->{user_cb})->(undef) if $oid_want =~ /\A0+\z/; $self->{oid_want} = $oid_want; $self->{out} = $out; $self->{seen_oid} = {}; $self->{tot} = 0; $self->{psgi_env} = $env; $self->{todo} = [ { %$hints, oid_b => $oid_want } ]; $self->{patches} = []; # [ $di, $di, ... ] $self->{found} = {}; # { abbr => [ ::Git, oid, type, size, $di ] } $self->{tmp} = File::Temp->newdir('solver.tmp-XXXXXXXX', TMPDIR => 1); dbg($self, "solving $oid_want ..."); my $step_cb = step_cb($self); if (my $async = $env->{'pi-httpd.async'}) { # PublicInbox::HTTPD::Async->new $async->(undef, $step_cb); } else { $step_cb->() while $self->{user_cb}; } } 1;