From d888846b68dd5fad998b84c5cb6246b1b63398cd Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Mon, 1 Dec 2025 02:51:37 +0300
Subject: [PATCH 1/4] libstore: Use makeTempPath in optimizePath_

This was intended to be cherry-picked in 6aed9d877cfbe1e649b69d2f15b6aeccbfbb0f3a,
but was left hanging. This is actually important for fixing [^]. emilazy let me know
of this bad cherry-pick and its significance.

[^]: https://github.com/NixOS/nix/issues/7273

Originally fixed by Lily Ballard <lily@ballards.net> in https://gerrit.lix.systems/c/lix/+/2100.
---
 src/libstore/optimise-store.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index dca093e04..3d8adedbf 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -234,7 +234,7 @@ void LocalStore::optimisePath_(
        its timestamp back to 0. */
     MakeReadOnly makeReadOnly(mustToggle ? dirOfPath : "");
 
-    std::filesystem::path tempLink = fmt("%1%/.tmp-link-%2%-%3%", config->realStoreDir, getpid(), rand());
+    std::filesystem::path tempLink = makeTempPath(config->realStoreDir.get(), ".tmp-link");
 
     try {
         std::filesystem::create_hard_link(linkPath, tempLink);

From 1cc337bb5f7363a711d7bd7f4e28e2ecc54aa975 Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Mon, 1 Dec 2025 02:56:44 +0300
Subject: [PATCH 2/4] libstore: Actually correctly call remove in case rename
 fails

---
 src/libstore/optimise-store.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index 3d8adedbf..d1e858300 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -255,8 +255,12 @@ void LocalStore::optimisePath_(
     try {
         std::filesystem::rename(tempLink, path);
     } catch (std::filesystem::filesystem_error & e) {
-        std::filesystem::remove(tempLink);
-        printError("unable to unlink %1%", tempLink);
+        {
+            std::error_code ec;
+            remove(tempLink, ec); /* Clean up after ourselves. */
+            if (ec)
+                printError("unable to unlink %1%: %2%", tempLink, ec.message());
+        }
         if (e.code() == std::errc::too_many_links) {
             /* Some filesystems generate too many links on the rename,
                rather than on the original link.  (Probably it

From bf7c53f2d3e665720c371167b8934d50e818656b Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Mon, 1 Dec 2025 03:00:45 +0300
Subject: [PATCH 3/4] libutil: Propagate error code in createSymlink

---
 src/libutil/file-system.cc | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/libutil/file-system.cc b/src/libutil/file-system.cc
index 6b145b343..9e27940c5 100644
--- a/src/libutil/file-system.cc
+++ b/src/libutil/file-system.cc
@@ -737,11 +737,10 @@ std::filesystem::path makeTempPath(const std::filesystem::path & root, const std
 
 void createSymlink(const Path & target, const Path & link)
 {
-    try {
-        std::filesystem::create_symlink(target, link);
-    } catch (std::filesystem::filesystem_error & e) {
-        throw SysError("creating symlink '%1%' -> '%2%'", link, target);
-    }
+    std::error_code ec;
+    std::filesystem::create_symlink(target, link, ec);
+    if (ec)
+        throw SysError(ec.value(), "creating symlink '%1%' -> '%2%'", link, target);
 }
 
 void replaceSymlink(const std::filesystem::path & target, const std::filesystem::path & link)

From 40e3f5c0a471075d02e258e950c0f2c931b36177 Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Mon, 1 Dec 2025 03:09:20 +0300
Subject: [PATCH 4/4] libutil: Make AutoDelete non-copyable and non-movable

This is a good precaution, since we don't want to delete
directories twice accidentally.
---
 src/libutil/include/nix/util/file-system.hh | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/libutil/include/nix/util/file-system.hh b/src/libutil/include/nix/util/file-system.hh
index 7673c24fd..d8b266e02 100644
--- a/src/libutil/include/nix/util/file-system.hh
+++ b/src/libutil/include/nix/util/file-system.hh
@@ -294,6 +294,10 @@ class AutoDelete
 public:
     AutoDelete();
     AutoDelete(const std::filesystem::path & p, bool recursive = true);
+    AutoDelete(AutoDelete &&) = delete;
+    AutoDelete(const AutoDelete &) = delete;
+    AutoDelete & operator=(AutoDelete &&) = delete;
+    AutoDelete & operator=(const AutoDelete &) = delete;
     ~AutoDelete();
 
     void cancel();