* The determination of the root set should be made by the privileged

process, so forward the operation.
* Spam the user about GC misconfigurations (NIX-71).
* findRoots: skip all roots that are unreadable - the warnings with
  which we spam the user should be enough.

src/libstore/worker-protocol.hh

@@ -2,6 +2,9 @@
 #define __WORKER_PROTOCOL_H
 
 
+namespace nix {
+
+
 #define WORKER_MAGIC_1 0x6e697864
 #define WORKER_MAGIC_2 0x6478696e
 
@@ -21,6 +24,7 @@ typedef enum {
     wopAddTempRoot,
     wopAddIndirectRoot,
     wopSyncWithGC,
+    wopFindRoots,
 } WorkerOp;
 
 
@@ -34,4 +38,11 @@ typedef enum {
 #define DEFAULT_SOCKET_PATH "/daemon.socket"
 
 
+Path readStorePath(Source & from);
+PathSet readStorePaths(Source & from);
+
+    
+}
+
+
 #endif /* !__WORKER_PROTOCOL_H */