Reload a project changed on disk, fingerprinted by its manifest and image sizes (12.13a)

tests/ProjectDigestRaceTests.cpp

@@ -0,0 +1,72 @@
+#include "IO/ProjectDigest.h"
+#include <QDir>
+#include <QFile>
+#include <QTemporaryDir>
+#include <QtTest>
+#include <dirent.h>
+#include <dlfcn.h>
+#include <unistd.h>
+
+// An image gone between listing and looking: no digest.
+namespace {
+// The file to remove once its folder's listing ends.
+QByteArray vanishing;
+bool vanished = false;
+
+bool listsImages(DIR *directory)
+{
+    char path[4096];
+    const QByteArray link = "/proc/self/fd/" + QByteArray::number(dirfd(directory));
+    const ssize_t size = readlink(link.constData(), path, sizeof path - 1);
+    return size > 0 && QByteArray(path, int(size)).endsWith("/images");
+}
+
+// At the listing's end the image goes, before any lookup.
+template <typename Entry> Entry *listed(DIR *directory, Entry *entry)
+{
+    if (!entry && !vanishing.isEmpty() && !vanished && listsImages(directory))
+        vanished = ::unlink(vanishing.constData()) == 0;
+    return entry;
+}
+}
+
+// These take libc's place in the test executable.
+extern "C" struct dirent *readdir(DIR *directory)
+{
+    static const auto real = reinterpret_cast<struct dirent *(*)(DIR *)>(dlsym(RTLD_NEXT, "readdir"));
+    return listed(directory, real(directory));
+}
+
+extern "C" struct dirent64 *readdir64(DIR *directory)
+{
+    static const auto real = reinterpret_cast<struct dirent64 *(*)(DIR *)>(dlsym(RTLD_NEXT, "readdir64"));
+    return listed(directory, real(directory));
+}
+
+class ProjectDigestRaceTests : public QObject {
+    Q_OBJECT
+private slots:
+    void anImageGoneMidListingGivesNoDigest();
+};
+
+void ProjectDigestRaceTests::anImageGoneMidListingGivesNoDigest()
+{
+    QTemporaryDir root;
+    const QString path = root.filePath(QStringLiteral("Race.comp"));
+    QVERIFY(QDir().mkpath(path + QStringLiteral("/images")));
+    for (const QString &name : {QStringLiteral("manifest.json"), QStringLiteral("images/A.png"), QStringLiteral("images/B.png")}) {
+        QFile file(path + QLatin1Char('/') + name);
+        QVERIFY(file.open(QIODevice::WriteOnly) && file.write("bytes") == 5);
+    }
+    // Listed whole, one image looked up after it is gone.
+    const QByteArray whole = ProjectDigest::compute(path);
+    vanishing = QFile::encodeName(path + QStringLiteral("/images/A.png"));
+    QVERIFY_THROWS_EXCEPTION(std::runtime_error, ProjectDigest::compute(path));
+    QVERIFY(vanished);
+    // Settled, the package fingerprints again, without it.
+    vanishing.clear();
+    QVERIFY(ProjectDigest::compute(path) != whole);
+}
+
+QTEST_GUILESS_MAIN(ProjectDigestRaceTests)
+#include "ProjectDigestRaceTests.moc"