TmpDir: Create nested directories

... and keep parent directories alive while nested directories exist.

2 files changed, 22 insertions, 5 deletions

diff --git a/src/utils/cpp/tmp_dir.cpp b/src/utils/cpp/tmp_dir.cpp
index c46586ef..88cc0f98 100644
--- a/src/utils/cpp/tmp_dir.cpp
+++ b/src/utils/cpp/tmp_dir.cpp
@@ -30,10 +30,19 @@
 #include "src/buildtool/logging/logger.hpp"
 
 auto TmpDir::Create(std::filesystem::path const& prefix) noexcept -> Ptr {
-    return CreateImpl(prefix);
+    return CreateImpl(/*parent=*/nullptr, prefix);
 }
 
-auto TmpDir::CreateImpl(std::filesystem::path const& path) noexcept -> Ptr {
+auto TmpDir::CreateNestedDirectory(TmpDir::Ptr const& parent) noexcept
+    -> TmpDir::Ptr {
+    if (parent == nullptr) {
+        return nullptr;
+    }
+    return CreateImpl(parent, parent->GetPath());
+}
+
+auto TmpDir::CreateImpl(TmpDir::Ptr parent,
+                        std::filesystem::path const& path) noexcept -> Ptr {
     static constexpr std::string_view kDirTemplate = "tmp.XXXXXX";
     // make sure prefix folder exists
     if (not FileSystemManager::CreateDirectory(path)) {
@@ -51,7 +60,8 @@ auto TmpDir::CreateImpl(std::filesystem::path const& path) noexcept -> Ptr {
         if (mkdtemp(file_path.data()) == nullptr) {
             return nullptr;
         }
-        return std::shared_ptr<TmpDir const>(new TmpDir(file_path));
+        return std::shared_ptr<TmpDir const>(
+            new TmpDir(std::move(parent), file_path));
     } catch (...) {
         if (not file_path.empty()) {
             rmdir(file_path.c_str());
diff --git a/src/utils/cpp/tmp_dir.hpp b/src/utils/cpp/tmp_dir.hpp
index e2e1e7a7..28805e3d 100644
--- a/src/utils/cpp/tmp_dir.hpp
+++ b/src/utils/cpp/tmp_dir.hpp
@@ -38,13 +38,20 @@ class TmpDir final {
     [[nodiscard]] static auto Create(
         std::filesystem::path const& prefix) noexcept -> Ptr;
 
+    /// \brief Create a new nested temporary directory. This nested directory
+    /// remains valid even if the parent directory goes out of scope.
+    [[nodiscard]] static auto CreateNestedDirectory(
+        TmpDir::Ptr const& parent) noexcept -> Ptr;
+
   private:
-    explicit TmpDir(std::filesystem::path path) noexcept
-        : tmp_dir_{std::move(path)} {}
+    explicit TmpDir(TmpDir::Ptr parent, std::filesystem::path path) noexcept
+        : parent_{std::move(parent)}, tmp_dir_{std::move(path)} {}
 
     [[nodiscard]] static auto CreateImpl(
+        TmpDir::Ptr parent,
         std::filesystem::path const& path) noexcept -> Ptr;
 
+    TmpDir::Ptr parent_;
     std::filesystem::path tmp_dir_;
 };