fix: Block creating files with non-existing parent directories using O_CREATE

pkg/fs/filesystem.go

@@ -31,10 +31,10 @@ type STFS struct {
 
 	metadata config.MetadataConfig
 
-	compressionLevel string
-	getFileBuffer    func() (cache.WriteCache, func() error, error)
-	readOnly         bool
-	writeImpliesRead bool
+	compressionLevel         string
+	getFileBuffer            func() (cache.WriteCache, func() error, error)
+	readOnly                 bool
+	writePermImpliesReadPerm bool
 
 	ioLock sync.Mutex
 
@@ -51,7 +51,7 @@ func NewSTFS(
 	compressionLevel string,
 	getFileBuffer func() (cache.WriteCache, func() error, error),
 	readOnly bool,
-	writeImpliesRead bool,
+	writePermImpliesReadPerm bool,
 
 	onHeader func(hdr *config.Header),
 	log logging.StructuredLogger,
@@ -62,10 +62,10 @@ func NewSTFS(
 
 		metadata: metadata,
 
-		compressionLevel: compressionLevel,
-		getFileBuffer:    getFileBuffer,
-		readOnly:         readOnly,
-		writeImpliesRead: writeImpliesRead,
+		compressionLevel:         compressionLevel,
+		getFileBuffer:            getFileBuffer,
+		readOnly:                 readOnly,
+		writePermImpliesReadPerm: writePermImpliesReadPerm,
 
 		onHeader: onHeader,
 		log:      log,
@@ -376,7 +376,7 @@ func (f *STFS) OpenFile(name string, flag int, perm os.FileMode) (afero.File, er
 		if (flag & O_ACCMODE) == os.O_RDONLY {
 			flags.Read = true
 		} else if (flag & O_ACCMODE) == os.O_WRONLY {
-			if f.writeImpliesRead {
+			if f.writePermImpliesReadPerm {
 				flags.Read = true
 			}
 
@@ -406,6 +406,21 @@ func (f *STFS) OpenFile(name string, flag int, perm os.FileMode) (afero.File, er
 	if err != nil {
 		if err == sql.ErrNoRows {
 			if !f.readOnly && flag&os.O_CREATE != 0 && flag&os.O_EXCL == 0 {
+				if _, err := inventory.Stat(
+					f.metadata,
+
+					filepath.Dir(name),
+					false,
+
+					f.onHeader,
+				); err != nil {
+					if err == sql.ErrNoRows {
+						return nil, os.ErrNotExist
+					}
+
+					return nil, err
+				}
+
 				if err := f.mknodeWithoutLocking(false, name, perm, false, "", false); err != nil {
 					return nil, err
 				}

pkg/fs/filesystem_test.go

@@ -1114,15 +1114,14 @@ var openFileTests = []struct {
 		func(f afero.File) error { return nil },
 		false,
 	},
-	// FIXME: STFS can create file in non-existent directory, which should not be possible
-	// {
-	// 	"Can not open /mydir/test.txt if O_CREATE is set",
-	// 	openFileArgs{"/mydir/test.txt", os.O_CREATE, os.ModePerm},
-	// 	true,
-	// 	func(f afero.Fs) error { return nil },
-	// 	func(f afero.File) error { return nil },
-	//  false,
-	// },
+	{
+		"Can not open /mydir/test.txt if O_CREATE is set",
+		openFileArgs{"/mydir/test.txt", os.O_CREATE, os.ModePerm},
+		true,
+		func(f afero.Fs) error { return nil },
+		func(f afero.File) error { return nil },
+		false,
+	},
 	{
 		"Can open /mydir/test.txt after creating it",
 		openFileArgs{"/mydir/test.txt", os.O_RDONLY, 0},