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-rw-r--r--internal/syscallcompat/quirks_linux.go36
1 files changed, 36 insertions, 0 deletions
diff --git a/internal/syscallcompat/quirks_linux.go b/internal/syscallcompat/quirks_linux.go
new file mode 100644
index 0000000..ffdbfab
--- /dev/null
+++ b/internal/syscallcompat/quirks_linux.go
@@ -0,0 +1,36 @@
+package syscallcompat
+
+import (
+ "golang.org/x/sys/unix"
+
+ "github.com/rfjakob/gocryptfs/internal/tlog"
+)
+
+// DetectQuirks decides if there are known quirks on the backing filesystem
+// that need to be workarounded.
+//
+// Tested by tests/root_test.TestBtrfsQuirks
+func DetectQuirks(cipherdir string) (q uint64) {
+ const (
+ // From Linux' man statfs
+ BTRFS_SUPER_MAGIC = 0x9123683e
+ )
+
+ var st unix.Statfs_t
+ err := unix.Statfs(cipherdir, &st)
+ if err != nil {
+ tlog.Warn.Printf("DetectQuirks: Statfs on %q failed: %v", cipherdir, err)
+ return 0
+ }
+
+ // Preallocation on Btrfs is broken ( https://github.com/rfjakob/gocryptfs/issues/395 )
+ // and slow ( https://github.com/rfjakob/gocryptfs/issues/63 ).
+ //
+ // Cast to uint32 avoids compile error on arm: "constant 2435016766 overflows int32"
+ if uint32(st.Type) == BTRFS_SUPER_MAGIC {
+ logQuirk("Btrfs detected, forcing -noprealloc. See https://github.com/rfjakob/gocryptfs/issues/395 for why.")
+ q |= QuirkBrokenFalloc
+ }
+
+ return q
+}