diff --git a/internal/imgcache/eviction_internal_test.go b/internal/imgcache/eviction_internal_test.go index ed7b4eb..fe64af1 100644 --- a/internal/imgcache/eviction_internal_test.go +++ b/internal/imgcache/eviction_internal_test.go @@ -9,8 +9,10 @@ import ( "log/slog" "os" "path/filepath" + "slices" "strings" "sync" + "syscall" "testing" "time" @@ -785,6 +787,205 @@ func TestReconcileVariantRowsDropsOnlyRowsOfMissingFiles(t *testing.T) { } } +// openDirectoryNearPathLimit makes a chain of directories inside dir, each +// named with 255 zeros, the longest name Linux allows. Linux refuses a path +// of 4096 bytes or more, and the chain goes as deep as it can below that. +// It returns the chain's deepest directory as an os.Root, closed when the +// test ends. An entry made through it with a 255-byte name has a path even +// the root user cannot read. The os.Root can make that entry because it +// names the entry only by its name, not by the whole path. +func openDirectoryNearPathLimit(t *testing.T, dir string) *os.Root { + t.Helper() + + name := strings.Repeat("0", 255) + deepest := dir + + for len(filepath.Join(deepest, name)) < 4096 { + deepest = filepath.Join(deepest, name) + } + + err := os.MkdirAll(deepest, StorageDirPerm) + if err != nil { + t.Fatalf("failed to make a chain of directories: %v", err) + } + + root, err := os.OpenRoot(deepest) + if err != nil { + t.Fatalf("os.OpenRoot(%s) error = %v", deepest, err) + } + + t.Cleanup(func() { _ = root.Close() }) + + return root +} + +// makeEntriesTooLongToRead makes a new directory and a new file in the +// deepest directory of the chain that openDirectoryNearPathLimit makes +// inside dir. Even the root user can then neither list the new directory +// nor read the new file's info. It returns the paths of the new directory +// and the new file. +func makeEntriesTooLongToRead(t *testing.T, dir string) []string { + t.Helper() + + deepest := openDirectoryNearPathLimit(t, dir) + dirName := strings.Repeat("0", 255) + + err := deepest.Mkdir(dirName, StorageDirPerm) + if err != nil { + t.Fatalf("failed to make a directory too deep to list: %v", err) + } + + fileName := strings.Repeat("1", 255) + + err = deepest.WriteFile(fileName, []byte("unreadable"), StorageFilePerm) + if err != nil { + t.Fatalf("failed to make a file too deep to read: %v", err) + } + + return []string{ + filepath.Join(deepest.Name(), dirName), + filepath.Join(deepest.Name(), fileName), + } +} + +// makeTempFileTooLongToRead makes a temp file in the deepest directory of +// the chain that openDirectoryNearPathLimit makes inside dir. Even the +// root user then cannot read the temp file's info. It returns the temp +// file's path. +func makeTempFileTooLongToRead(t *testing.T, dir string) string { + t.Helper() + + deepest := openDirectoryNearPathLimit(t, dir) + name := tempFilePrefix + strings.Repeat("1", 255-len(tempFilePrefix)) + + err := deepest.WriteFile(name, []byte("partial"), StorageFilePerm) + if err != nil { + t.Fatalf("failed to make a temp file too deep to read: %v", err) + } + + return filepath.Join(deepest.Name(), name) +} + +// assertSkippedEntryWarning checks that logs hold the warning "skipped +// unreadable entry in cache directory" naming path, with the error +// ENAMETOOLONG for that path. +func assertSkippedEntryWarning(t *testing.T, logs, path string) { + t.Helper() + + for line := range strings.Lines(logs) { + if strings.Contains(line, `"level":"WARN"`) && + strings.Contains(line, `"msg":"skipped unreadable entry in cache directory"`) && + strings.Contains(line, `"path":"`+path+`"`) && + strings.Contains(line, path+": "+syscall.ENAMETOOLONG.Error()) { + return + } + } + + t.Errorf("no warning %q names %s with the error %q", + "skipped unreadable entry in cache directory", path, syscall.ENAMETOOLONG) +} + +// TestReconciliationGoesOnPastEntriesItCannotRead puts, in each storage +// directory, a directory the pass cannot list and a file whose info it +// cannot read. The pass walks each directory in name order, so it reaches +// them before the cache's files, whose keys start with a letter. It must +// log a warning naming each one's path and the error, and still do the +// rest of its work: +// - adopt a variant file that has no row +// - drop the row of a variant whose file is missing +// - remove a source file that has no row +// - correct a wrong total cache usage +func TestReconciliationGoesOnPastEntriesItCannotRead(t *testing.T) { + t.Parallel() + + cache, _ := newEvictionTestCache(t, 1<<30) + ctx := t.Context() + + untrackedVariant := []byte("variant with no row") + + err := cache.variants.Write(string(testVariantKeyOne), untrackedVariant) + if err != nil { + t.Fatalf("failed to write a variant file with no row: %v", err) + } + + storeEvictionTestVariant(t, cache, testVariantKeyTwo, []byte("variant two")) + + err = os.Remove(cache.variants.keyToPath(string(testVariantKeyTwo))) + if err != nil { + t.Fatalf("failed to remove the second variant's file: %v", err) + } + + untrackedSourceKey := "ffeeddcc0001" + + err = cache.srcContent.Write(untrackedSourceKey, []byte("source with no row")) + if err != nil { + t.Fatalf("failed to write a source file with no row: %v", err) + } + + _, err = cache.db.ExecContext(ctx, + `UPDATE cache_usage SET total_size_bytes = 1 WHERE id = 1`) + if err != nil { + t.Fatalf("failed to set a wrong total: %v", err) + } + + unreadable := slices.Concat( + makeEntriesTooLongToRead(t, cache.variants.baseDir), + makeEntriesTooLongToRead(t, cache.srcContent.baseDir), + ) + + logs := reconcileAsAtStartup(t, cache) + + for _, path := range unreadable { + assertSkippedEntryWarning(t, logs, path) + } + + rowQuery := `SELECT COUNT(*) FROM variant_content WHERE cache_key = ?` + + if n := countRows(t, cache, rowQuery, string(testVariantKeyOne)); n != 1 { + t.Errorf("the variant file with no row got %d rows, want 1", n) + } + + if n := countRows(t, cache, rowQuery, string(testVariantKeyTwo)); n != 0 { + t.Errorf("the variant with no file kept %d rows, want 0", n) + } + + _, err = os.Stat(cache.srcContent.keyToPath(untrackedSourceKey)) + if err == nil { + t.Error("the source file with no row is still on disk") + } + + usage, err := cache.UsageBytes(ctx) + if err != nil { + t.Fatalf("UsageBytes() error = %v", err) + } + + if usage != int64(len(untrackedVariant)) { + t.Errorf("UsageBytes() = %d, want %d, the size of the adopted variant", + usage, len(untrackedVariant)) + } +} + +// TestReconciliationWarnsOfTempFilesWhoseInfoItCannotRead puts, in each +// storage directory, a temp file whose info the pass cannot read. The +// pass must log a warning naming each one's path and the error, as it +// does for any other file whose info it cannot read. +func TestReconciliationWarnsOfTempFilesWhoseInfoItCannotRead(t *testing.T) { + t.Parallel() + + cache, _ := newEvictionTestCache(t, 1<<30) + + unreadable := []string{ + makeTempFileTooLongToRead(t, cache.variants.baseDir), + makeTempFileTooLongToRead(t, cache.srcContent.baseDir), + } + + logs := reconcileAsAtStartup(t, cache) + + for _, path := range unreadable { + assertSkippedEntryWarning(t, logs, path) + } +} + // TestPeriodicReconciliationAdoptsFileThatAppearsAfterStartup proves // reconciliation is not a one-shot startup-only pass: it must also run // on the periodic ticker, so a variant file that lands on disk with no