From 220000dc1aaa1157862ea287542092eeab14111a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 13 Mar 2025 15:48:52 +0100
Subject: [PATCH] makeJSONLogger(): Support logging to a Unix domain socket

---
 src/libstore/uds-remote-store.cc  | 4 +---
 src/libutil/logging.cc            | 6 +++++-
 src/libutil/unix-domain-socket.cc | 7 +++++++
 src/libutil/unix-domain-socket.hh | 5 +++++
 4 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/libstore/uds-remote-store.cc b/src/libstore/uds-remote-store.cc
index 3c445eb13..93c48c0e6 100644
--- a/src/libstore/uds-remote-store.cc
+++ b/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();
-
-    nix::connect(toSocket(conn->fd.get()), path);
+    conn->fd = nix::connect(path);
 
     conn->from.fd = conn->fd.get();
     conn->to.fd = conn->fd.get();
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index 8ef7a3612..94683cca5 100644
--- a/src/libutil/logging.cc
+++ b/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);
 
diff --git a/src/libutil/unix-domain-socket.cc b/src/libutil/unix-domain-socket.cc
index 1707fdb75..0a7af1308 100644
--- a/src/libutil/unix-domain-socket.cc
+++ b/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;
+}
+
 }
diff --git a/src/libutil/unix-domain-socket.hh b/src/libutil/unix-domain-socket.hh
index ba2baeb13..e0d934011 100644
--- a/src/libutil/unix-domain-socket.hh
+++ b/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);
+
 }