From e2d85579d891cea7ea25f34f56ba1b5d3da77a9a Mon Sep 17 00:00:00 2001
From: Emily <hello@emily.moe>
Date: Mon, 4 Aug 2025 15:10:28 +0100
Subject: [PATCH] libutil: add `makeTempSiblingPath` helper

The prospective callers of this should probably be doing something
smarter or more abstracted to begin with, but this is useful as an
incremental improvement for call sites with existing `makeTempPath`
logic in the face of filename length limits.

Change-Id: I6a6a6964374f47abbf0ec10aa8d945c4e50a43af
---
 lix/libutil/file-system.cc | 5 +++++
 lix/libutil/file-system.hh | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/lix/libutil/file-system.cc b/lix/libutil/file-system.cc
index 60f2e91ff..4464fccf5 100644
--- a/lix/libutil/file-system.cc
+++ b/lix/libutil/file-system.cc
@@ -693,6 +693,11 @@ Path makeTempPath(const Path & root, const Path & suffix)
     return fmt("%1%%2%-%3%-%4%", root, suffix, getpid(), counter.fetch_add(1, std::memory_order_relaxed));
 }
 
+Path makeTempSiblingPath(const Path & path)
+{
+    return makeTempPath(fs::path(path).remove_filename());
+}
+
 void createSymlink(const Path & target, const Path & link)
 {
     if (symlink(target.c_str(), link.c_str()))
diff --git a/lix/libutil/file-system.hh b/lix/libutil/file-system.hh
index 8b9100bdc..cdcb61a65 100644
--- a/lix/libutil/file-system.hh
+++ b/lix/libutil/file-system.hh
@@ -318,6 +318,11 @@ Path createTempSubdir(const Path & parent, const Path & prefix = "nix",
  */
 Path makeTempPath(const Path & root, const Path & suffix = ".tmp");
 
+/**
+ * Return temporary path in the same directory as a given path.
+ */
+Path makeTempSiblingPath(const Path & root);
+
 /**
  * Used in various places.
  */