From 53ac5b18f6f124fe33bf6736aac0b8c85a0d0d1b Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Tue, 15 Jan 2019 08:22:41 +0000 Subject: solver: initial Perl implementation This will lookup git blobs from associated git source code repositories. If the blobs can't be found, an attempt to "solve" them via patch application will be performed. Eventually, this may become the basis of a type-agnostic frontend similar to "git show" --- lib/PublicInbox/Git.pm | 16 ++ lib/PublicInbox/SolverGit.pm | 400 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 416 insertions(+) create mode 100644 lib/PublicInbox/SolverGit.pm (limited to 'lib/PublicInbox') diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm index 90b9214a..9676086f 100644 --- a/lib/PublicInbox/Git.pm +++ b/lib/PublicInbox/Git.pm @@ -40,6 +40,7 @@ sub new { my ($class, $git_dir) = @_; my @st; $st[7] = $st[10] = 0; + # may contain {-wt} field (working-tree (File::Temp::Dir)) bless { git_dir => $git_dir, st => \@st }, $class } @@ -201,6 +202,21 @@ sub packed_bytes { sub DESTROY { cleanup(@_) } +# show the blob URL for cgit/gitweb/whatever +sub src_blob_url { + my ($self, $oid) = @_; + # blob_fmt = "https://example.com/foo.git/blob/%s" + if (my $bfu = $self->{blob_fmt_url}) { + return sprintf($bfu, $oid); + } + + # don't show full FS path, basename should be OK: + if ($self->{git_dir} =~ m!/([^/]+)\z!) { + return "/path/to/$1"; + } + '???'; +} + 1; __END__ =pod diff --git a/lib/PublicInbox/SolverGit.pm b/lib/PublicInbox/SolverGit.pm new file mode 100644 index 00000000..f28768a9 --- /dev/null +++ b/lib/PublicInbox/SolverGit.pm @@ -0,0 +1,400 @@ +# 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 File::Path qw(make_path); +use PublicInbox::Git qw(git_unquote); +use PublicInbox::Spawn qw(spawn popen_rd); +use PublicInbox::MsgIter qw(msg_iter msg_part_text); +use URI::Escape qw(uri_escape_utf8); + +# 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 { $_ => 1 } ('', '.', '..'); + +sub new { + my ($class, $gits, $inboxes) = @_; + bless { + gits => $gits, + inboxes => $inboxes, + }, $class; +} + +# look for existing blobs already in git repos +sub solve_existing ($$) { + my ($self, $want) = @_; + foreach my $git (@{$self->{gits}}) { + my ($oid_full, $type, $size) = $git->check($want->{oid_b}); + if (defined($type) && $type eq 'blob') { + return [ $git, $oid_full, $type, int($size) ]; + } + } + undef; +} + +# returns a hashref with information about a diff: +# { +# oid_a => abbreviated pre-image oid, +# oid_b => abbreviated post-image oid, +# tmp => anonymous file handle with the diff, +# hdr_lines => arrayref of various header lines for mode information +# mode_a => original mode of oid_a (string, not integer), +# ibx => PublicInbox::Inbox object containing the diff +# smsg => PublicInbox::SearchMsg object containing diff +# path_a => pre-image path +# path_b => post-image path +# } +sub extract_diff ($$$$) { + my ($p, $re, $ibx, $smsg) = @_; + my ($part) = @$p; # ignore $depth and @idx; + my $hdr_lines; # diff --git a/... b/... + my $tmp; + my $ct = $part->content_type || 'text/plain'; + my ($s, undef) = msg_part_text($part, $ct); + defined $s or return; + my $di = {}; + foreach my $l (split(/^/m, $s)) { + if ($l =~ /$re/) { + $di->{oid_a} = $1; + $di->{oid_b} = $2; + my $mode_a = $3; + if ($mode_a =~ /\A(?:100644|120000|100755)\z/) { + $di->{mode_a} = $mode_a; + } + + # start writing the diff out to a tempfile + open($tmp, '+>', undef) or die "open(tmp): $!"; + $di->{tmp} = $tmp; + $di->{hdr_lines} = $hdr_lines; + + print $tmp @$hdr_lines, $l or die "print(tmp): $!"; + + # for debugging/diagnostics: + $di->{ibx} = $ibx; + $di->{smsg} = $smsg; + } elsif ($l =~ m!\Adiff --git ("?a/.+) ("?b/.+)$!) { + return $di if $tmp; # got our blob, done! + + my ($path_a, $path_b) = ($1, $2); + + # don't care for leading 'a/' and 'b/' + my (undef, @a) = split(m{/}, git_unquote($path_a)); + my (undef, @b) = split(m{/}, git_unquote($path_b)); + + # get rid of path-traversal attempts and junk patches: + foreach (@a, @b) { + return if $bad_component{$_}; + } + + $di->{path_a} = join('/', @a); + $di->{path_b} = join('/', @b); + $hdr_lines = [ $l ]; + } elsif ($tmp) { + print $tmp $l or die "print(tmp): $!"; + } elsif ($hdr_lines) { + push @$hdr_lines, $l; + } + } + $tmp ? $di : undef; +} + +sub path_searchable ($) { defined($_[0]) && $_[0] =~ m!\A[\w/\. \-]+\z! } + +sub find_extract_diff ($$$) { + 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)) { + $q .= qq{ dfn:"$path_b"}; + + my $path_a = $want->{path_a}; + if (path_searchable($path_a) && $path_a ne $path_b) { + $q .= qq{ dfn:"$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 { + $di ||= extract_diff($_[0], $re, $ibx, $smsg); + }); + return $di if $di; + } +} + +# pure Perl "git init" +sub do_git_init_wt ($) { + my ($self) = @_; + my $wt = File::Temp->newdir('solver.wt-XXXXXXXX', TMPDIR => 1); + my $dir = $wt->dirname; + + foreach (qw(objects/info refs/heads)) { + make_path("$dir/.git/$_") or die "make_path $_: $!"; + } + open my $fh, '>', "$dir/.git/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 $fh, '>', "$dir/.git/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 = '.git/objects/info/alternates'; + open $fh, '>', "$dir/$f" or die "open: $f: $!"; + foreach my $git (@{$self->{gits}}) { + print $fh "$git->{git_dir}/objects\n" or die "print $f: $!"; + } + close $fh or die "close: $f: $!"; + $wt; +} + +sub extract_old_mode ($) { + my ($di) = @_; + if (grep(/\Aold mode (100644|100755|120000)$/, @{$di->{hdr_lines}})) { + return $1; + } + '100644'; +} + +sub reap ($$) { + my ($pid, $msg) = @_; + waitpid($pid, 0) == $pid or die "waitpid($msg): $!"; + $? == 0 or die "$msg failed: $?"; +} + +sub prepare_wt ($$$) { + my ($wt_dir, $existing, $di) = @_; + my $oid_full = $existing->[1]; + my ($r, $w); + 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); + my @git = (qw(git -C), $wt_dir); + + pipe($r, $w) or die "pipe: $!"; + my $rdr = { 0 => fileno($r) }; + my $pid = spawn([@git, qw(update-index -z --index-info)], {}, $rdr); + close $r or die "close pipe(r): $!"; + print $w "$mode_a $oid_full\t$path_a\0" or die "print update-index: $!"; + close $w or die "close update-index: $!"; + reap($pid, 'update-index -z --index-info'); + + $pid = spawn([@git, qw(checkout-index -a -f -u)]); + reap($pid, 'checkout-index -a -f -u'); +} + +sub do_apply ($$$$) { + my ($out, $wt_git, $wt_dir, $di) = @_; + + my $tmp = delete $di->{tmp} or die "BUG: no tmp ", di_info($di); + $tmp->flush or die "tmp->flush failed: $!"; + $out->flush or die "err->flush failed: $!"; + sysseek($tmp, 0, SEEK_SET) or die "sysseek(tmp) failed: $!"; + + defined(my $err_fd = fileno($out)) or die "fileno(out): $!"; + my $rdr = { 0 => fileno($tmp), 1 => $err_fd, 2 => $err_fd }; + my $cmd = [ qw(git -C), $wt_dir, + qw(apply --whitespace=warn -3 --verbose) ]; + reap(spawn($cmd, undef, $rdr), 'apply'); + + local $/ = "\0"; + my $rd = popen_rd([qw(git -C), $wt_dir, qw(ls-files -s -z)]); + + defined(my $line = <$rd>) or die "failed to read ls-files: $!"; + chomp $line or die "no trailing \\0 in [$line] from ls-files"; + + my ($info, $file) = split(/\t/, $line, 2); + my ($mode_b, $oid_b_full, $stage) = split(/ /, $info); + + defined($line = <$rd>) and die "extra files in index: $line"; + close $rd or die "close ls-files: $?"; + + $file eq $di->{path_b} or + die "index mismatch: file=$file != path_b=$di->{path_b}"; + my $abs_path = "$wt_dir/$file"; + -r $abs_path or die "WT_DIR/$file not readable"; + my $size = -s _; + + print $out "OK $mode_b $oid_b_full $stage\t$file\n"; + [ $wt_git, $oid_b_full, 'blob', $size, $di ]; +} + +sub di_url ($) { + my ($di) = @_; + # note: we don't pass the PSGI env here, different inboxes + # can have different HTTP_HOST on the same instance. + my $url = $di->{ibx}->base_url; + my $mid = $di->{smsg}->{mid}; + defined($url) ? "<$url/$mid/>" : "<$mid>"; +} + +sub apply_patches ($$$$$) { + my ($self, $out, $wt, $found, $patches) = @_; + my $wt_dir = $wt->dirname; + my $wt_git = PublicInbox::Git->new("$wt_dir/.git"); + $wt_git->{-wt} = $wt; + + my $cur = 0; + my $tot = scalar @$patches; + + foreach my $di (@$patches) { + my $i = ++$cur; + my $oid_a = $di->{oid_a}; + my $existing = $found->{$oid_a}; + my $empty_oid = $oid_a =~ /\A0+\z/; + + if ($empty_oid && $i != 0) { + die "empty oid at [$i/$tot] ", di_url($di); + } + if (!$existing && !$empty_oid) { + die "missing $oid_a at [$i/$tot] ", di_url($di); + } + + # prepare the worktree for patch application: + if ($i == 1 && $existing) { + prepare_wt($wt_dir, $existing, $di); + } + unless (-f "$wt_dir/$di->{path_a}") { + die "missing $di->{path_a} at [$i/$tot] ", di_url($di); + } + + print $out "applying [$i/$tot] ", di_url($di), "\n", + join('', @{$di->{hdr_lines}}), "\n" + or die "print \$out failed: $!"; + + # apply the patch! + $found->{$di->{oid_b}} = do_apply($out, $wt_git, $wt_dir, $di); + } +} + +sub dump_found ($$) { + my ($out, $found) = @_; + foreach my $oid (sort keys %$found) { + my ($git, $oid, $di) = @{$found->{$oid}}; + my $loc = $di ? di_info($di) : $git->src_blob_url($oid); + print $out "$oid from $loc\n"; + } +} + +sub dump_patches ($$) { + my ($out, $patches) = @_; + my $tot = scalar(@$patches); + my $i = 0; + foreach my $di (@$patches) { + ++$i; + print $out "[$i/$tot] ", di_url($di), "\n"; + } +} + +# recreate $oid_b +# Returns a 2-element array ref: [ PublicInbox::Git object, oid_full ] +# or undef if nothing was found. +sub solve ($$$$) { + my ($self, $out, $oid_b, $hints) = @_; + + # should we even get here? Probably not, but somebody + # could be manually typing URLs: + return if $oid_b =~ /\A0+\z/; + + my $req = { %$hints, oid_b => $oid_b }; + my @todo = ($req); + my $found = {}; # { oid_abbrev => [ PublicInbox::Git, oid_full, $di ] } + my $patches = []; # [ array of $di hashes ] + + my $max = $self->{max_steps} || 200; + my $steps = 0; + + while (defined(my $want = pop @todo)) { + # see if we can find the blob in an existing git repo: + if (my $existing = solve_existing($self, $want)) { + my $want_oid = $want->{oid_b}; + return $existing if $want_oid eq $oid_b; # DONE! + + $found->{$want_oid} = $existing; + next; # ok, one blob resolved, more to go? + } + + # scan through inboxes to look for emails which results in + # the oid we want: + foreach my $ibx (@{$self->{inboxes}}) { + my $di = find_extract_diff($self, $ibx, $want) or next; + + unshift @$patches, $di; + + # good, we can find a path to the oid we $want, now + # lets see if we need to apply more patches: + my $src = $di->{oid_a}; + if ($src !~ /\A0+\z/) { + if (++$steps > $max) { + print $out +"Aborting, too many steps to $oid_b\n"; + + return; + } + + # we have to solve it using another oid, fine: + my $job = { + oid_b => $src, + path_b => $di->{path_a}, + }; + push @todo, $job; + } + last; # onto the next @todo item + } + } + + unless (scalar(@$patches)) { + print $out "no patch(es) for $oid_b\n"; + dump_found($out, $found); + return; + } + + # reconstruct the oid_b blob using patches we found: + eval { + my $wt = do_git_init_wt($self); + apply_patches($self, $out, $wt, $found, $patches); + }; + if ($@) { + print $out "E: $@\nfound: "; + dump_found($out, $found); + print $out "patches: "; + dump_patches($out, $patches); + return; + } + + $found->{$oid_b}; +} + +1; -- cgit v1.2.3-24-ge0c7