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.qetz: read the project database the way SQLite advises for untrusted files

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A .qetz's project.sqlite comes from a file, which may be damaged, made
by another tool, edited by hand (issue #1458) or made to harm. SQLite's
advice for such files (https://www.sqlite.org/security.html) was only
partly followed: trusted_schema was off and every name had to be a plain
table. readAsUntrusted() now also turns on the defensive mode, turns off
triggers and views, checks each cell's size as its page is read, limits
a value to 256 MiB, and runs quick_check before anything is read, for
the database read on opening and for the one a save copies kept folios
from.

A damaged database is now refused as "the project database is damaged",
where it was "cannot be read: database disk image is malformed" or a
missing row. Damage on disk was already caught before SQLite: the zip
checks each entry (one flipped bit in project.sqlite: refused, "unexpected
decompressed size"). quick_check does not see a changed value inside a
row (49 of 400 random small changes read silently, quick_check "ok"):
only the zip's checksum does.

New test damagedDatabaseRefused (a page overwritten at three places):
fails without this change on the message. Opening nuri (136 folios):
3.56-3.66 s with and without. ctest: the 7 container, save and lazy
folio suites pass.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
ispyisail
2026-10-16 08:41:27 +13:00
parent c4b5cf2f11
commit e3fa4a049c
2 changed files with 65 additions and 4 deletions
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tests/qttest/tst_qetcontainer.cpp
+33
View File
@@ -3,6 +3,7 @@
#include <QDir>
#include <QFile>
#include <QtEndian>
#include <functional>
@@ -533,6 +534,38 @@ private slots:
QVERIFY(!error.isEmpty());
}
// A page of the database overwritten, as a bad disk or a broken copy
// would: refused, and said to be damaged (quick_check on opening),
// whichever table the page held
void damagedDatabaseRefused_data()
{
QTest::addColumn<double>("where");
QTest::newRow("second page") << 0.0;
QTest::newRow("middle page") << 0.5;
QTest::newRow("last page") << 1.0;
}
void damagedDatabaseRefused()
{
QFETCH(double, where);
QDomDocument original;
QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
bool damaged = false;
for (QetZip::Entry &entry : entries) {
if (entry.name != QLatin1String("project.sqlite")) continue;
const int page_size = qFromBigEndian<quint16>(entry.data.constData() + 16);
const int pages = int(entry.data.size() / page_size);
QVERIFY(pages > 3);
const int page = 1 + int(where * (pages - 2));
entry.data.replace(page * page_size, page_size, QByteArray(page_size, char(0xff)));
damaged = true;
}
QVERIFY(damaged);
QDomDocument back;
QString error;
QVERIFY(!QetContainer::join(entries, &back, &error));
QVERIFY2(error.contains(QStringLiteral("damaged")), qPrintable(error));
}
// project.sqlite changed by @p sql in @p entries
static void alterDatabase(QList<QetZip::Entry> &entries, const char *sql)
{