1 files changed, 158 insertions, 0 deletions
diff --git a/tests/matrix/fallocate_test.go b/tests/matrix/fallocate_test.go
new file mode 100644
index 0000000..6928b4a
--- /dev/null
+++ b/tests/matrix/fallocate_test.go
@@ -0,0 +1,158 @@
+package matrix
+
+import (
+	"os"
+	"runtime"
+	"syscall"
+	"testing"
+
+	"github.com/rfjakob/gocryptfs/internal/syscallcompat"
+	"github.com/rfjakob/gocryptfs/tests/test_helpers"
+)
+
+const (
+	// From man statfs
+	TMPFS_MAGIC      = 0x01021994
+	EXT4_SUPER_MAGIC = 0xef53
+)
+
+// isWellKnownFS decides if the backing filesystem is well-known.
+// The expected allocated sizes are only valid on tmpfs and ext4. btrfs
+// gives different results, but that's not an error.
+func isWellKnownFS(fn string) bool {
+	var fs syscall.Statfs_t
+	err := syscall.Statfs(fn, &fs)
+	if err != nil {
+		panic(err)
+	}
+	if fs.Type == EXT4_SUPER_MAGIC || fs.Type == TMPFS_MAGIC {
+		return true
+	}
+	return false
+}
+
+const FALLOC_DEFAULT = 0x00
+const FALLOC_FL_KEEP_SIZE = 0x01
+
+func TestFallocate(t *testing.T) {
+	if runtime.GOOS == "darwin" {
+		t.Skipf("OSX does not support fallocate")
+	}
+	fn := test_helpers.DefaultPlainDir + "/fallocate"
+	file, err := os.Create(fn)
+	if err != nil {
+		t.FailNow()
+	}
+	defer file.Close()
+	wellKnown := isWellKnownFS(test_helpers.DefaultCipherDir)
+	fd := int(file.Fd())
+	nBytes := test_helpers.Du(t, fd)
+	if nBytes != 0 {
+		t.Fatalf("Empty file has %d bytes", nBytes)
+	}
+	// Allocate 30 bytes, keep size
+	// gocryptfs ||        (0 blocks)
+	//      ext4 |  d   |  (1 block)
+	//              ^ d = data block
+	err = syscallcompat.Fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, 30)
+	if err != nil {
+		t.Error(err)
+	}
+	var want int64
+	nBytes = test_helpers.Du(t, fd)
+	want = 4096
+	if nBytes != want {
+		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
+	}
+	test_helpers.VerifySize(t, fn, 0)
+	// Three ciphertext blocks. The middle one should be a file hole.
+	// gocryptfs |  h   |   h  | d|   (1 block)
+	//      ext4 |  d  |  h  |  d  |  (2 blocks)
+	//                    ^ h = file hole
+	// (Note that gocryptfs blocks are slightly bigger than the ext4 blocks,
+	// but the last one is partial)
+	err = file.Truncate(9000)
+	if err != nil {
+		t.Fatal(err)
+	}
+	nBytes = test_helpers.Du(t, fd)
+	want = 2 * 4096
+	if wellKnown && nBytes != want {
+		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
+	}
+	if md5 := test_helpers.Md5fn(fn); md5 != "5420afa22f6423a9f59e669540656bb4" {
+		t.Errorf("Wrong md5 %s", md5)
+	}
+	// Allocate the whole file space
+	// gocryptfs |  h   |   h  | d|   (1 block)
+	//      ext4 |  d  |  d  |  d  |  (3 blocks
+	err = syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 0, 9000)
+	if err != nil {
+		t.Fatal(err)
+	}
+	nBytes = test_helpers.Du(t, fd)
+	want = 3 * 4096
+	if nBytes != want {
+		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
+	}
+	// Neither apparent size nor content should have changed
+	test_helpers.VerifySize(t, fn, 9000)
+	if md5 := test_helpers.Md5fn(fn); md5 != "5420afa22f6423a9f59e669540656bb4" {
+		t.Errorf("Wrong md5 %s", md5)
+	}
+
+	// Partial block on the end. The first ext4 block is dirtied by the header.
+	// gocryptfs |  h   |   h  | d|   (1 block)
+	//      ext4 |  d  |  h  |  d  |  (2 blocks)
+	file.Truncate(0)
+	file.Truncate(9000)
+	nBytes = test_helpers.Du(t, fd)
+	want = 2 * 4096
+	if wellKnown && nBytes != want {
+		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
+	}
+	// Allocate 10 bytes in the second block
+	// gocryptfs |  h   |   h  | d|   (1 block)
+	//      ext4 |  d  |  d  |  d  |  (3 blocks)
+	syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 5000, 10)
+	nBytes = test_helpers.Du(t, fd)
+	want = 3 * 4096
+	if wellKnown && nBytes != want {
+		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
+	}
+	// Neither apparent size nor content should have changed
+	test_helpers.VerifySize(t, fn, 9000)
+	if md5 := test_helpers.Md5fn(fn); md5 != "5420afa22f6423a9f59e669540656bb4" {
+		t.Errorf("Wrong md5 %s", md5)
+	}
+	// Grow the file to 4 blocks
+	// gocryptfs |  h   |  h   |  d   |d|  (2 blocks)
+	//      ext4 |  d  |  d  |  d  |  d  | (4 blocks)
+	syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 15000, 10)
+	nBytes = test_helpers.Du(t, fd)
+	want = 4 * 4096
+	if wellKnown && nBytes != want {
+		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
+	}
+	test_helpers.VerifySize(t, fn, 15010)
+	if md5 := test_helpers.Md5fn(fn); md5 != "c4c44c7a41ab7798a79d093eb44f99fc" {
+		t.Errorf("Wrong md5 %s", md5)
+	}
+	// Shrinking a file using fallocate should have no effect
+	for _, off := range []int64{0, 10, 2000, 5000} {
+		for _, sz := range []int64{0, 1, 42, 6000} {
+			syscallcompat.Fallocate(fd, FALLOC_DEFAULT, off, sz)
+			test_helpers.VerifySize(t, fn, 15010)
+			if md5 := test_helpers.Md5fn(fn); md5 != "c4c44c7a41ab7798a79d093eb44f99fc" {
+				t.Errorf("Wrong md5 %s", md5)
+			}
+		}
+	}
+	// Cleanup
+	syscall.Unlink(fn)
+	if !wellKnown {
+		// Even though most tests have been executed still, inform the user
+		// that some were disabled
+		t.Skipf("backing fs is not ext4 or tmpfs, skipped some disk-usage checks\n")
+	}
+}