# Copyright (C) 2019-2021 all contributors
# License: AGPL-3.0+
#
# used by PublicInbox::View
# This adds CSS spans for diff highlighting.
# It also generates links for ViewVCS + SolverGit to show
# (or reconstruct) blobs.
package PublicInbox::ViewDiff;
use strict;
use v5.10.1;
use parent qw(Exporter);
our @EXPORT_OK = qw(flush_diff);
use URI::Escape qw(uri_escape_utf8);
use PublicInbox::Hval qw(ascii_html to_attr);
use PublicInbox::Git qw(git_unquote);
my $UNSAFE = "^A-Za-z0-9\-\._~/"; # '/' + $URI::Escape::Unsafe{RFC3986}
my $OID_NULL = '0{7,}';
my $OID_BLOB = '[a-f0-9]{7,}';
my $LF = qr!\n!;
my $ANY = qr![^\n]!;
my $FN = qr!(?:"?[^/\n]+/[^\n]+|/dev/null)!;
# cf. git diff.c :: get_compact_summary
my $DIFFSTAT_COMMENT =
qr/(?: *\((?:new|gone|(?:(?:new|mode) [\+\-][lx]))\))? *\z/s;
my $NULL_TO_BLOB = qr/^(index $OID_NULL\.\.)($OID_BLOB)\b/ms;
my $BLOB_TO_NULL = qr/^index ($OID_BLOB)(\.\.$OID_NULL)\b/ms;
my $BLOB_TO_BLOB = qr/^index ($OID_BLOB)\.\.($OID_BLOB)/ms;
our $EXTRACT_DIFFS = qr/(
(?: # begin header stuff, don't capture filenames, here,
# but instead wait for the --- and +++ lines.
(?:^diff\x20--git\x20$FN\x20$FN$LF)
# old mode || new mode || copy|rename|deleted|...
(?:^[a-z]$ANY+$LF)*
)? # end of optional stuff, everything below is required
^index\x20($OID_BLOB)\.\.($OID_BLOB)$ANY*$LF
^---\x20($FN)$LF
^\+{3}\x20($FN)$LF)/msx;
our $IS_OID = qr/\A$OID_BLOB\z/s;
# link to line numbers in blobs
sub diff_hunk ($$$$) {
my ($dst, $dctx, $ca, $cb) = @_;
my ($oid_a, $oid_b, $spfx) = @$dctx{qw(oid_a oid_b spfx)};
if (defined($spfx) && defined($oid_a) && defined($oid_b)) {
my ($n) = ($ca =~ /^-([0-9]+)/);
$n = defined($n) ? "#n$n" : '';
$$dst .= qq(@@ {Q}$n">$ca);
($n) = ($cb =~ /^\+([0-9]+)/);
$n = defined($n) ? "#n$n" : '';
$$dst .= qq( {Q}$n">$cb @@);
} else {
$$dst .= "@@ $ca $cb @@";
}
}
sub oid ($$$) {
my ($dctx, $spfx, $oid) = @_;
defined($spfx) ? qq({Q}">$oid) : $oid;
}
# returns true if diffstat anchor written, false otherwise
sub anchor0 ($$$$) {
my ($dst, $ctx, $fn, $rest) = @_;
my $orig = $fn;
# normal git diffstat output is impossible to parse reliably
# without --numstat, and that isn't the default for format-patch.
# So only do best-effort handling of renames for common cases;
# which works well in practice. If projects put "=>", or trailing
# spaces in filenames, oh well :P
$fn =~ s/$DIFFSTAT_COMMENT//;
$fn =~ s/\{(?:.+) => (.+)\}/$1/ or $fn =~ s/.* => (.+)/$1/;
$fn = git_unquote($fn);
# long filenames will require us to check in anchor1()
push(@{$ctx->{-long_path}}, $fn) if $fn =~ s!\A\.\.\./?!!;
if (my $attr = to_attr($ctx->{-apfx}.$fn)) {
$ctx->{-anchors}->{$attr} = 1;
my $spaces = ($orig =~ s/( +)\z//) ? $1 : '';
$$dst .= " " .
ascii_html($orig) . '' . $spaces .
$ctx->{-linkify}->to_html($rest);
return 1;
}
undef;
}
# returns "diff --git" anchor destination, undef otherwise
sub anchor1 ($$) {
my ($ctx, $pb) = @_;
my $attr = to_attr($ctx->{-apfx}.$pb) or return;
my $ok = delete $ctx->{-anchors}->{$attr};
# unlikely, check the end of long path names we captured,
# assume diffstat and diff output follow the same order,
# and ignore different ordering (could be malicious input)
unless ($ok) {
my $fn = shift(@{$ctx->{-long_path}}) or return;
$pb =~ /\Q$fn\E\z/s or return;
$attr = to_attr($ctx->{-apfx}.$fn) or return;
$ok = delete $ctx->{-anchors}->{$attr} or return;
}
$ok ? "diff --git" : undef
}
sub diff_header ($$$) {
my ($x, $ctx, $top) = @_;
my (undef, undef, $pa, $pb) = splice(@$top, 0, 4); # ignore oid_{a,b}
my $spfx = $ctx->{-spfx};
my $dctx = { spfx => $spfx };
# get rid of leading "a/" or "b/" (or whatever --{src,dst}-prefix are)
$pa = (split(m'/', git_unquote($pa), 2))[1] if $pa ne '/dev/null';
$pb = (split(m'/', git_unquote($pb), 2))[1] if $pb ne '/dev/null';
if ($pa eq $pb && $pb ne '/dev/null') {
$dctx->{Q} = "?b=".uri_escape_utf8($pb, $UNSAFE);
} else {
my @q;
if ($pb ne '/dev/null') {
push @q, 'b='.uri_escape_utf8($pb, $UNSAFE);
}
if ($pa ne '/dev/null') {
push @q, 'a='.uri_escape_utf8($pa, $UNSAFE);
}
$dctx->{Q} = '?'.join('&', @q);
}
# linkify early and all at once, since we know the following
# subst ops on $$x won't need further escaping:
$$x = $ctx->{-linkify}->to_html($$x);
# no need to capture oid_a and oid_b on add/delete,
# we just linkify OIDs directly via s///e in conditional
if (($$x =~ s/$NULL_TO_BLOB/$1 . oid($dctx, $spfx, $2)/e) ||
($$x =~ s/$BLOB_TO_NULL/
'index ' . oid($dctx, $spfx, $1) . $2/e)) {
} elsif ($$x =~ $BLOB_TO_BLOB) {
# modification-only, not add/delete:
# linkify hunk headers later using oid_a and oid_b
@$dctx{qw(oid_a oid_b)} = ($1, $2);
} else {
warn "BUG? <$$x> had no ^index line";
}
$$x =~ s!^diff --git!anchor1($ctx, $pb) // 'diff --git'!ems;
my $dst = $ctx->{obuf};
$$dst .= qq();
$$dst .= $$x;
$$dst .= '';
$dctx;
}
sub diff_before_or_after ($$) {
my ($ctx, $x) = @_;
my $linkify = $ctx->{-linkify};
my $dst = $ctx->{obuf};
my $anchors = exists($ctx->{-anchors}) ? 1 : 0;
for my $y (split(/(^---\n)/sm, $$x)) {
if ($y =~ /\A---\n\z/s) {
$$dst .= "---\n"; # all HTML is "\r\n" => "\n"
$anchors |= 2;
} elsif ($anchors == 3 && $y =~ /^ [0-9]+ files? changed, /sm) {
# ok, looks like a diffstat, go line-by-line:
for my $l (split(/^/m, $y)) {
if ($l =~ /^ (.+)( +\| .*\z)/s) {
anchor0($dst, $ctx, $1, $2) and next;
}
$$dst .= $linkify->to_html($l);
}
} else { # commit message, notes, etc
$$dst .= $linkify->to_html($y);
}
}
}
# callers must do CRLF => LF conversion before calling this
sub flush_diff ($$) {
my ($ctx, $cur) = @_;
my @top = split($EXTRACT_DIFFS, $$cur);
undef $$cur; # free memory
my $linkify = $ctx->{-linkify};
my $dst = $ctx->{obuf};
my $dctx; # {}, keys: Q, oid_a, oid_b
while (defined(my $x = shift @top)) {
if (scalar(@top) >= 4 &&
$top[1] =~ $IS_OID &&
$top[0] =~ $IS_OID) {
$dctx = diff_header(\$x, $ctx, \@top);
} elsif ($dctx) {
my $after = '';
# Quiet "Complex regular subexpression recursion limit"
# warning. Perl will truncate matches upon hitting
# that limit, giving us more (and shorter) scalars than
# would be ideal, but otherwise it's harmless.
#
# We could replace the `+' metacharacter with `{1,100}'
# to limit the matches ourselves to 100, but we can
# let Perl do it for us, quietly.
no warnings 'regexp';
for my $s (split(/((?:(?:^\+[^\n]*\n)+)|
(?:(?:^-[^\n]*\n)+)|
(?:^@@ [^\n]+\n))/xsm, $x)) {
if (!defined($dctx)) {
$after .= $s;
} elsif ($s =~ s/\A@@ (\S+) (\S+) @@//) {
$$dst .= qq();
diff_hunk($dst, $dctx, $1, $2);
$$dst .= $linkify->to_html($s);
$$dst .= '';
} elsif ($s =~ /\A\+/) {
$$dst .= qq();
$$dst .= $linkify->to_html($s);
$$dst .= '';
} elsif ($s =~ /\A-- $/sm) { # email sig starts
$dctx = undef;
$after .= $s;
} elsif ($s =~ /\A-/) {
$$dst .= qq();
$$dst .= $linkify->to_html($s);
$$dst .= '';
} else {
$$dst .= $linkify->to_html($s);
}
}
diff_before_or_after($ctx, \$after) unless $dctx;
} else {
diff_before_or_after($ctx, \$x);
}
}
}
1;