1 files changed, 45 insertions, 0 deletions
diff --git a/nix/libstore/pathlocks.hh b/nix/libstore/pathlocks.hh
new file mode 100644
index 0000000000..8a6b1450da
--- /dev/null
+++ b/nix/libstore/pathlocks.hh
@@ -0,0 +1,45 @@
+#pragma once
+
+#include "types.hh"
+
+
+namespace nix {
+
+
+/* Open (possibly create) a lock file and return the file descriptor.
+   -1 is returned if create is false and the lock could not be opened
+   because it doesn't exist.  Any other error throws an exception. */
+int openLockFile(const Path & path, bool create);
+
+/* Delete an open lock file. */
+void deleteLockFile(const Path & path, int fd);
+
+enum LockType { ltRead, ltWrite, ltNone };
+
+bool lockFile(int fd, LockType lockType, bool wait);
+
+
+class PathLocks 
+{
+private:
+    typedef std::pair<int, Path> FDPair;
+    list<FDPair> fds;
+    bool deletePaths;
+
+public:
+    PathLocks();
+    PathLocks(const PathSet & paths,
+        const string & waitMsg = "");
+    bool lockPaths(const PathSet & _paths,
+        const string & waitMsg = "",
+        bool wait = true);
+    ~PathLocks();
+    void unlock();
+    void setDeletion(bool deletePaths);
+};
+
+
+bool pathIsLockedByMe(const Path & path);
+
+
+}