fusefrontend_reverse: use OpenNofollow in findLongnameParent

Protects findLongnameParent against symlink races.

Also add comments to several functions along the way.

Reported at https://github.com/rfjakob/gocryptfs/issues/165

1 files changed, 6 insertions, 1 deletions

diff --git a/internal/fusefrontend_reverse/rpath_cache.go b/internal/fusefrontend_reverse/rpath_cache.go
index f90b357..221f578 100644
--- a/internal/fusefrontend_reverse/rpath_cache.go
+++ b/internal/fusefrontend_reverse/rpath_cache.go
@@ -17,6 +17,8 @@ type rPathCacheContainer struct {
 	dirIV []byte
 }
 
+// lookup relative ciphertext path "cPath". Returns dirIV, relative
+// plaintext path.
 func (c *rPathCacheContainer) lookup(cPath string) ([]byte, string) {
 	c.Lock()
 	defer c.Unlock()
@@ -28,7 +30,9 @@ func (c *rPathCacheContainer) lookup(cPath string) ([]byte, string) {
 	return nil, ""
 }
 
-// store - write entry for "cPath" into the cache
+// store - write entry for the directory at relative ciphertext path "cPath"
+// into the cache.
+// "dirIV" = directory IV of the directory, "pPath" = relative plaintext path
 func (c *rPathCacheContainer) store(cPath string, dirIV []byte, pPath string) {
 	c.Lock()
 	defer c.Unlock()
@@ -37,4 +41,5 @@ func (c *rPathCacheContainer) store(cPath string, dirIV []byte, pPath string) {
 	c.pPath = pPath
 }
 
+// rPathCache: see rPathCacheContainer above for a detailed description
 var rPathCache rPathCacheContainer