118 lines
2.9 KiB
Go
118 lines
2.9 KiB
Go
package fusefrontend
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import (
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"fmt"
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"log"
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"sync"
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"syscall"
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"time"
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"github.com/rfjakob/gocryptfs/internal/nametransform"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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type dirCacheStruct struct {
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sync.Mutex
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// relative plaintext path to the directory
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dirRelPath string
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// fd to the directory (opened with O_PATH!)
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fd int
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// content of gocryptfs.diriv in this directory
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iv []byte
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// on the first Lookup(), the expire thread is stared, and this is set
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// to true.
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expireThreadRunning bool
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}
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// Clear clears the cache contents.
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func (d *dirCacheStruct) Clear() {
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d.Lock()
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defer d.Unlock()
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d.doClear()
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}
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// doClear closes the fd and clears the cache contents.
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// Caller must hold d.Lock()!
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func (d *dirCacheStruct) doClear() {
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// An earlier clear may have already closed the fd, or the cache
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// has never been filled (fd is 0 in that case).
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if d.fd > 0 {
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err := syscall.Close(d.fd)
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if err != nil {
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tlog.Warn.Printf("dirCache.Clear: Close failed: %v", err)
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}
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}
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d.fd = -1
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d.dirRelPath = ""
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d.iv = nil
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}
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// Store the entry in the cache. The passed "fd" will be Dup()ed, and the caller
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// can close their copy at will.
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func (d *dirCacheStruct) Store(dirRelPath string, fd int, iv []byte) {
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if fd <= 0 || len(iv) != nametransform.DirIVLen {
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log.Panicf("Store sanity check failed: fd=%d len=%d", fd, len(iv))
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}
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d.Lock()
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defer d.Unlock()
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// Close the old fd
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d.doClear()
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fd2, err := syscall.Dup(fd)
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if err != nil {
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tlog.Warn.Printf("dirCache.Store: Dup failed: %v", err)
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return
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}
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d.fd = fd2
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d.dbg("Store: %q %d %x\n", dirRelPath, fd2, iv)
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d.dirRelPath = dirRelPath
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d.iv = iv
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// expireThread is started on the first Lookup()
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if !d.expireThreadRunning {
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d.expireThreadRunning = true
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go d.expireThread()
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}
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}
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// Lookup checks if relPath is in the cache, and returns and (fd, iv) pair.
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// It returns (-1, nil) if not found. The fd is internally Dup()ed and the
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// caller must close it when done.
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func (d *dirCacheStruct) Lookup(dirRelPath string) (fd int, iv []byte) {
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d.Lock()
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defer d.Unlock()
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if d.fd <= 0 {
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// Cache is empty
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d.dbg("Lookup %q: empty\n", dirRelPath)
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return -1, nil
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}
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if dirRelPath != d.dirRelPath {
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d.dbg("Lookup %q: miss\n", dirRelPath)
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return -1, nil
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}
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fd, err := syscall.Dup(d.fd)
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if err != nil {
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tlog.Warn.Printf("dirCache.Lookup: Dup failed: %v", err)
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return -1, nil
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}
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if fd <= 0 || len(d.iv) != nametransform.DirIVLen {
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log.Panicf("Lookup sanity check failed: fd=%d len=%d", fd, len(d.iv))
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}
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d.dbg("Lookup %q: hit %d %x\n", dirRelPath, fd, d.iv)
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return fd, d.iv
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}
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// expireThread is started on the first Lookup()
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func (d *dirCacheStruct) expireThread() {
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for {
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time.Sleep(1 * time.Second)
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d.Clear()
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}
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}
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// dbg prints a debug message. Usually disabled.
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func (d *dirCacheStruct) dbg(format string, a ...interface{}) {
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const EnableDebugMessages = false
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if EnableDebugMessages {
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fmt.Printf(format, a...)
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}
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}
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