libgocryptfs/internal/nametransform/diriv_cache.go

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package nametransform
import (
"sync"
"time"
)
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// Single-entry DirIV cache. Stores the directory IV and the encrypted
// path.
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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// The cached entry my become out-of-date if the ciphertext directory is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
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// Ecrypted version of "dir"
cDir string
// Invalidated?
cleared bool
sync.RWMutex
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}
// 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, ""
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}
if time.Since(c.expiry) > 0 {
c.cleared = true
return nil, ""
}
return c.iv, c.cDir
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}
// store - write entry for "dir" into the cache
func (c *dirIVCache) store(dir string, iv []byte, cDir string) {
c.Lock()
defer c.Unlock()
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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)
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}
// Clear ... clear the cache.
// Exported because it is called from fusefrontend when directories are
// renamed or deleted.
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func (c *dirIVCache) Clear() {
c.Lock()
defer c.Unlock()
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c.cleared = true
}