Restore

Restore file to captured state

Every captured change carries its SHA-256-addressed content in BLOB_STORE. Restoring writes that content back to the original path — current file gets backed up to <path>.drift_restore_backup_<epoch> before overwrite.

What will change

Preview -- nothing has been written yet.

Target file	/var/www/vhosts/3dshawn.com/site1/diff.cgi
Site	DriftSense self-monitor on local
Kind	local
Captured at	2026-07-12 00:02:03
Captured SHA	7d22f9eb85f48701360de2b04eccc692fbfb0f917565390088f5c04962a496b9

Current state on disk

Live check just now. If SHAs match, the restore is a no-op.

File present	yes
Size	9204 bytes
Current SHA	902f256a1a7c
Same as captured?	no -- restore will change it

See exactly what's different →

What restore will change — live diff

Left column shows current on-disk content; right shows what restore will write. +1 additions, -27 deletions, 200 unchanged context lines.

1	1	#!/usr/bin/perl
2	2	#======================================================================
3	3	# DriftSense -- /diff.cgi
4	4	#
5	5	# Renders a two-pane diff for a single change captured in FILE_CHANGES
6	6	# or SCHEMA_CHANGE. Pulls both blobs from BLOB_STORE, decompresses,
7	7	# runs a naive LCS-style line diff, marks added / removed / context,
8	8	# renders as syntax-highlight-ish HTML with monospace typography.
9	9	#
10	10	# URL:
11	11	# /diff.cgi?kind=file&id=N -- FILE_CHANGES row
12	12	# /diff.cgi?kind=schema&id=N -- SCHEMA_CHANGE row
13	13	#======================================================================
14	14	use strict;
15	15	use warnings;
16	16	use CGI ();
17	17	use Compress::Zlib qw(uncompress);
18	18	use MODS::Config; use MODS::DBConnect; use MODS::Template; use MODS::PageWrapper;
19	19	use MODS::Diff;
20		use MODS::CompileCheck;
21		use JSON::PP ();
22	20
23	21	my $cgi = CGI->new;
24	22	my $db = MODS::DBConnect->new;
25	23	my $tpl = MODS::Template->new;
26		$\|=1;
	24	$\|=1; print "Content-Type: text/html; charset=utf-8\nCache-Control: no-cache\n\n";
27	25
28	26	my $kind = $cgi->param('kind') \|\| '';
29	27	my $id = int($cgi->param('id') \|\| 0);
30		my $op = $cgi->param('op') \|\| '';
31
32		# ---- AJAX: compile check ------------------------------------------
33		if ($op eq 'compile' && $id) {
34		my $dbh2 = $db->db_connect;
35		my $r = $db->db_readwrite($dbh2, qq~
36		SELECT fc.file_name, fc.blob_sha, bs.content_gz
37		FROM FILE_CHANGES fc
38		LEFT JOIN BLOB_STORE bs ON bs.blob_sha = fc.blob_sha
39		WHERE fc.file_changes_id = $id LIMIT 1
40		~, __FILE__, __LINE__);
41		$db->db_disconnect($dbh2);
42		print "Content-Type: application/json\nCache-Control: no-cache\n\n";
43		unless ($r && $r->{content_gz}) {
44		print JSON::PP::encode_json({ status => 'unchecked', message => 'no blob' });
45		exit;
46		}
47		my $content = eval { Compress::Zlib::uncompress($r->{content_gz}) };
48		my $result = MODS::CompileCheck::check($content, $r->{file_name});
49		print JSON::PP::encode_json($result);
50		exit;
51		}
52	28
53		# HTML branch from here on
54		print "Content-Type: text/html; charset=utf-8\nCache-Control: no-cache\n\n";
55	29	my $dbh = $db->db_connect or die "DB connect failed\n";
56	30
57	31	my ($title, $subtitle, $blob_sha, $prev_sha, $meta) = ('', '', '', '', {});
58	32
59	33	if ($kind eq 'file' && $id) {
60	34	my $row = $db->db_readwrite($dbh, qq~
61	35	SELECT fc.file_changes_id AS id, fc.file_name, fc.status, fc.blob_sha,
62	36	fc.date_time, UNIX_TIMESTAMP(fc.date_time) AS ts_epoch,
63	37	fc.uid, fc.gid, fc.permissions, fc.is_ts_only,
64	38	fc.file_monitor_list_id, s.server_name
65	39	FROM FILE_CHANGES fc LEFT JOIN SERVERS s ON s.server_id = fc.server_id
66	40	WHERE fc.file_changes_id = $id LIMIT 1
67	41	~, __FILE__, __LINE__);
68	42	if ($row && $row->{id}) {
69	43	# Find the previous captured version of this file for the "before" pane.
70	44	# Prefer same-monitor scope, but fall back to file-name-only for legacy
71	45	# rows where file_monitor_list_id is NULL.
72	46	my $q_fname = $dbh->quote($row->{file_name});
73	47	my $scope = defined $row->{file_monitor_list_id}
74	48	? "file_monitor_list_id = $row->{file_monitor_list_id} AND "
75	49	: '';
76	50	my $prev = $db->db_readwrite($dbh, qq~
77	51	SELECT blob_sha FROM FILE_CHANGES
78	52	WHERE $scope
79	53	file_name = $q_fname
80	54	AND file_changes_id < $id
81	55	AND blob_sha IS NOT NULL
82	56	ORDER BY file_changes_id DESC LIMIT 1
83	57	~, __FILE__, __LINE__);
84	58	$title = $row->{file_name};
85	59	my $ep = int($row->{ts_epoch} \|\| 0);
86	60	$subtitle = qq~$row->{status} on $row->{server_name} at <span class="ts" data-ts="$ep" data-fmt="datetime">$row->{date_time}</span>~;
87	61	$blob_sha = $row->{blob_sha};
88	62	$prev_sha = $prev && $prev->{blob_sha} ? $prev->{blob_sha} : '';
89	63	$meta = { %$row };
90	64	}
91	65	}
92	66	elsif ($kind eq 'schema' && $id) {
93	67	my $row = $db->db_readwrite($dbh, qq~
94	68	SELECT sc.schema_change_id AS id, sc.database_name, sc.table_name, sc.changes,
95	69	sc.schema_blob_sha, sc.change_datetime,
96	70	UNIX_TIMESTAMP(sc.change_datetime) AS ts_epoch,
97	71	s.server_name, sc.server_id
98	72	FROM SCHEMA_CHANGE sc LEFT JOIN SERVERS s ON s.server_id = sc.server_id
99	73	WHERE sc.schema_change_id = $id LIMIT 1
100	74	~, __FILE__, __LINE__);
101	75	if ($row && $row->{id}) {
102	76	my $q_db = $dbh->quote($row->{database_name});
103	77	my $q_t = $dbh->quote($row->{table_name});
104	78	my $prev = $db->db_readwrite($dbh, qq~
105	79	SELECT schema_blob_sha FROM SCHEMA_CHANGE
106	80	WHERE server_id = $row->{server_id}
107	81	AND database_name = $q_db AND table_name = $q_t
108	82	AND schema_change_id < $id
109	83	AND schema_blob_sha IS NOT NULL
110	84	ORDER BY schema_change_id DESC LIMIT 1
111	85	~, __FILE__, __LINE__);
112	86	$title = "$row->{database_name}.$row->{table_name}";
113	87	my $ep = int($row->{ts_epoch} \|\| 0);
114	88	$subtitle = qq~on $row->{server_name} at <span class="ts" data-ts="$ep" data-fmt="datetime">$row->{change_datetime}</span>~;
115	89	$blob_sha = $row->{schema_blob_sha};
116	90	$prev_sha = $prev && $prev->{schema_blob_sha} ? $prev->{schema_blob_sha} : '';
117	91	$meta = { %$row };
118	92	}
119	93	}
120	94
121	95	# Fetch + decompress blobs
122	96	my $curr = $blob_sha ? _fetch_blob($db, $dbh, $blob_sha) : '';
123	97	my $prev = $prev_sha ? _fetch_blob($db, $dbh, $prev_sha) : '';
124	98
125	99	$db->db_disconnect($dbh);
126	100
127	101	# Compute a naive line-level diff
128	102	my @lines = MODS::Diff::lines($prev // '', $curr // '');
129	103	my ($ct_add, $ct_del) = (0, 0);
130	104	foreach my $L (@lines) {
131	105	$ct_add++ if $L->{op} eq 'add';
132	106	$ct_del++ if $L->{op} eq 'del';
133	107	# HTML-escape diff'd content -- files under monitor may themselves be
134	108	# HTML/JS/CSS, and dumping raw content into an on-screen table renders
135	109	# the tags live. Escape it so it displays as source.
136	110	my $t = $L->{text}; $t = '' unless defined $t;
137	111	$t =~ s/&/&/g; $t =~ s/</</g; $t =~ s/>/>/g;
138	112	$L->{text} = $t;
139	113	}
140	114
141	115	my $tvars = {
142	116	title => $title \|\| '(unknown)',
143	117	subtitle => $subtitle,
144	118	kind => $kind,
145	119	id => $id,
146	120	has_diff => scalar(@lines) ? 1 : 0,
147	121	lines => \@lines,
148	122	ct_add => $ct_add,
149	123	ct_del => $ct_del,
150	124	ct_context => scalar(@lines) - $ct_add - $ct_del,
151	125	has_prev => $prev_sha ? 1 : 0,
152	126	curr_sha => substr($blob_sha \|\| '', 0, 12),
153	127	prev_sha => substr($prev_sha \|\| '', 0, 12),
154	128	restore_url => ($kind eq 'file' && $blob_sha) ? "/restore.cgi?id=$id" : '',
155	129	};
156	130
157	131	my @body = $tpl->template('diff.html', $tvars);
158	132	MODS::PageWrapper->new->wrapper(
159	133	page_title => "Diff -- $title",
160	134	page_key => ($kind eq 'schema' ? 'schema_changes' : 'file_changes'),
161	135	body_html => join('', @body),
162	136	userinfo => { display_name => 'Operator' },
163	137	);
164	138
165	139	#---------------------------------------------------------------------
166	140	sub _fetch_blob {
167	141	my ($db, $dbh, $sha) = @_;
168	142	my $sth = $dbh->prepare("SELECT content_gz FROM BLOB_STORE WHERE blob_sha = ?");
169	143	return '' unless $sth && $sth->execute($sha);
170	144	my $row = $sth->fetchrow_arrayref;
171	145	$sth->finish;
172	146	return '' unless $row && $row->[0];
173	147	my $decompressed = eval { uncompress($row->[0]) };
174	148	return $decompressed // '';
175	149	}
176	150
177	151	#---------------------------------------------------------------------
178	152	# _line_diff -- naive line-level diff. Returns an array of hashrefs:
179	153	# { op => 'add' \| 'del' \| 'ctx', text => $line, old_n, new_n }
180	154	# Uses a simple LCS-based approach; adequate for small-to-medium files.
181	155	# For huge diffs shell out to /usr/bin/diff (future optimization).
182	156	#---------------------------------------------------------------------
183	157	sub _line_diff {
184	158	my ($old, $new) = @_;
185	159	my @old_lines = split /\r?\n/, ($old // '');
186	160	my @new_lines = split /\r?\n/, ($new // '');
187	161
188	162	# LCS length table (dynamic programming) -- capped to prevent
189	163	# runaway memory on huge inputs.
190	164	my $O = scalar @old_lines;
191	165	my $N = scalar @new_lines;
192	166	if ($O > 5000 \|\| $N > 5000) {
193	167	# Fall back: just dump both sides linearly, marked as del/add.
194	168	my @out;
195	169	my $i = 0;
196	170	push @out, { op => 'del', text => $_, old_n => ++$i, new_n => '' } for @old_lines;
197	171	my $j = 0;
198	172	push @out, { op => 'add', text => $_, old_n => '', new_n => ++$j } for @new_lines;
199	173	return @out;
200	174	}
201	175
202	176	my @lcs; for my $i (0..$O) { $lcs[$i][0] = 0; }
203	177	for my $j (0..$N) { $lcs[0][$j] = 0; }
204	178	for my $i (1..$O) {
205	179	for my $j (1..$N) {
206	180	$lcs[$i][$j] = $old_lines[$i-1] eq $new_lines[$j-1]
207	181	? $lcs[$i-1][$j-1] + 1
208	182	: ($lcs[$i-1][$j] >= $lcs[$i][$j-1] ? $lcs[$i-1][$j] : $lcs[$i][$j-1]);
209	183	}
210	184	}
211	185
212	186	my @out;
213	187	my ($i, $j) = ($O, $N);
214	188	while ($i > 0 \|\| $j > 0) {
215	189	if ($i > 0 && $j > 0 && $old_lines[$i-1] eq $new_lines[$j-1]) {
216	190	unshift @out, { op => 'ctx', text => $old_lines[$i-1], old_n => $i, new_n => $j };
217	191	$i--; $j--;
218	192	} elsif ($j > 0 && ($i == 0 \|\| $lcs[$i][$j-1] >= $lcs[$i-1][$j])) {
219	193	unshift @out, { op => 'add', text => $new_lines[$j-1], old_n => '', new_n => $j };
220	194	$j--;
221	195	} else {
222	196	unshift @out, { op => 'del', text => $old_lines[$i-1], old_n => $i, new_n => '' };
223	197	$i--;
224	198	}
225	199	}
226	200	return @out;
227	201	}

Confirm restore

Backs current content to <target>.drift_restore_backup_<epoch>, writes the captured content, verifies SHA post-write.