Merge pull request #14679 from NixOS/backport-14676-to-2.31-maintenance

[Backport 2.31-maintenance] libstore: Use makeTempPath in optimizePath_, assorted fs fixes

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);
@@ -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

src/libutil/file-system.cc

@@ -730,11 +730,10 @@ Path makeTempPath(const Path & root, const Path & suffix)
 
 void createSymlink(const Path & target, const Path & link)
 {
-    try {
+    std::error_code ec;
-        std::filesystem::create_symlink(target, link);
+    std::filesystem::create_symlink(target, link, ec);
-    } catch (std::filesystem::filesystem_error & e) {
+    if (ec)
-        throw SysError("creating symlink '%1%' -> '%2%'", link, target);
+        throw SysError(ec.value(), "creating symlink '%1%' -> '%2%'", link, target);
-    }
 }
 
 void replaceSymlink(const std::filesystem::path & target, const std::filesystem::path & link)

src/libutil/include/nix/util/file-system.hh

@@ -287,6 +287,10 @@ 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();