makeJSONLogger(): Support logging to a Unix domain socket

src/libstore/uds-remote-store.cc

@@ -84,9 +84,7 @@ ref<RemoteStore::Connection> UDSRemoteStore::openConnection()
     auto conn = make_ref<Connection>();
 
     /* Connect to a daemon that does the privileged work for us. */
-    conn->fd = createUnixDomainSocket();
+    conn->fd = nix::connect(path);
-
-    nix::connect(toSocket(conn->fd.get()), path);
 
     conn->from.fd = conn->fd.get();
     conn->to.fd = conn->fd.get();

src/libutil/logging.cc

@@ -7,6 +7,7 @@
 #include "source-path.hh"
 #include "position.hh"
 #include "sync.hh"
+#include "unix-domain-socket.hh"
 
 #include <atomic>
 #include <sstream>
@@ -296,7 +297,10 @@ Logger * makeJSONLogger(const std::filesystem::path & path, bool includeNixPrefi
         { }
     };
 
-    AutoCloseFD fd{toDescriptor(open(path.c_str(), O_CREAT | O_APPEND | O_WRONLY, 0644))};
+    AutoCloseFD fd =
+        std::filesystem::is_socket(path)
+        ? connect(path)
+        : toDescriptor(open(path.c_str(), O_CREAT | O_APPEND | O_WRONLY, 0644));
     if (!fd)
         throw SysError("opening log file '%1%'", path);
 

src/libutil/unix-domain-socket.cc

@@ -114,4 +114,11 @@ void connect(Socket fd, const std::string & path)
     bindConnectProcHelper("connect", ::connect, fd, path);
 }
 
+AutoCloseFD connect(const std::filesystem::path & path)
+{
+    auto fd = createUnixDomainSocket();
+    nix::connect(toSocket(fd.get()), path);
+    return fd;
+}
+
 }

src/libutil/unix-domain-socket.hh

@@ -80,4 +80,9 @@ void bind(Socket fd, const std::string & path);
  */
 void connect(Socket fd, const std::string & path);
 
+/**
+ * Connect to a Unix domain socket.
+ */
+AutoCloseFD connect(const std::filesystem::path & path);
+
 }