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-rw-r--r--internal/nametransform/dirivcache/dirivcache.go63
1 files changed, 63 insertions, 0 deletions
diff --git a/internal/nametransform/dirivcache/dirivcache.go b/internal/nametransform/dirivcache/dirivcache.go
new file mode 100644
index 0000000..890ebac
--- /dev/null
+++ b/internal/nametransform/dirivcache/dirivcache.go
@@ -0,0 +1,63 @@
+package dirivcache
+
+import (
+ "sync"
+ "time"
+)
+
+// Single-entry DirIV cache. Stores the directory IV and the encrypted
+// path.
+type DirIVCache struct {
+ // Directory the DirIV belongs to
+ dir string
+ // Time the entry expires.
+ // The cached entry my become out-of-date if the ciphertext directory is
+ // modifed behind the back of gocryptfs. Having an expiry time limits the
+ // inconstency to one second, like attr_timeout does for the kernel
+ // getattr cache.
+ expiry time.Time
+
+ // The DirIV
+ iv []byte
+ // Ecrypted version of "dir"
+ cDir string
+
+ // Invalidated?
+ cleared bool
+ sync.RWMutex
+}
+
+// lookup - fetch entry for "dir" from the cache
+func (c *DirIVCache) Lookup(dir string) ([]byte, string) {
+ c.RLock()
+ defer c.RUnlock()
+ if c.cleared || c.dir != dir {
+ return nil, ""
+ }
+ if time.Since(c.expiry) > 0 {
+ c.cleared = true
+ return nil, ""
+ }
+ return c.iv, c.cDir
+}
+
+// store - write entry for "dir" into the cache
+func (c *DirIVCache) Store(dir string, iv []byte, cDir string) {
+ c.Lock()
+ defer c.Unlock()
+ c.cleared = false
+ c.iv = iv
+ c.dir = dir
+ c.cDir = cDir
+ // Set expiry time one second into the future
+ c.expiry = time.Now().Add(1 * time.Second)
+}
+
+// Clear ... clear the cache.
+// Exported because it is called from fusefrontend when directories are
+// renamed or deleted.
+func (c *DirIVCache) Clear() {
+ c.Lock()
+ defer c.Unlock()
+ c.cleared = true
+}