1 files changed, 35 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/pathlocks.hh b/third_party/nix/src/libstore/pathlocks.hh
new file mode 100644
index 0000000000..d515963e76
--- /dev/null
+++ b/third_party/nix/src/libstore/pathlocks.hh
@@ -0,0 +1,35 @@
+#pragma once
+
+#include "libutil/util.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. */
+AutoCloseFD 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;
+  std::list<FDPair> fds;
+  bool deletePaths;
+
+ public:
+  PathLocks();
+  PathLocks(const PathSet& paths, const std::string& waitMsg = "");
+  bool lockPaths(const PathSet& _paths, const std::string& waitMsg = "",
+                 bool wait = true);
+  ~PathLocks();
+  void unlock();
+  void setDeletion(bool deletePaths);
+};
+
+}  // namespace nix