Merge commit 'd334fd4882' into auto-uid-allocation

src/libstore/lock.hh

@@ -0,0 +1,41 @@
+#pragma once
+
+#include "types.hh"
+
+namespace nix {
+
+struct UserLock
+{
+    virtual ~UserLock() { }
+
+    /* Get the first and last UID. */
+    virtual std::pair<uid_t, uid_t> getUIDRange() = 0;
+
+    /* Get the first UID. */
+    uid_t getUID()
+    {
+        return getUIDRange().first;
+    }
+
+    uid_t getUIDCount()
+    {
+        return getUIDRange().second - getUIDRange().first + 1;
+    }
+
+    virtual gid_t getGID() = 0;
+
+    virtual std::vector<gid_t> getSupplementaryGIDs() = 0;
+
+    /* Kill any processes currently executing as this user. */
+    virtual void kill() = 0;
+
+    virtual std::optional<Path> getCgroup() { return {}; };
+};
+
+/* Acquire a user lock. Note that this may return nullptr if no user
+   is available. */
+std::unique_ptr<UserLock> acquireUserLock();
+
+bool useBuildUsers();
+
+}