Consolidate test temp helpers and move file I/O + lock platform code into src/platform (#793 follow-up)

[bmehta001]

Follow-up to #793 addressing two review nits from @skottmckay that were deferred to a separate PR.

1. Consolidate TempDir / TempPath into a shared test helper

nit: Multiple tests have a TempDir class and we also have a TempPath. can we consolidate the temp dir/path logic into a shared helper in test/utils?

Four unit tests (download_test, cross_process_file_lock_test, blob_download_state_test, file_writer_test) each defined a near-identical local TempDir/TempPath RAII class, and test_helpers.h carried the CurrentPid/MakeUniqueTempPath helpers. These now live in a single test/utils/temp_dir.h (fl::test namespace); the tests use it via the existing test_helpers.h umbrella include.

2. Move platform #ifdef code into src/platform

file_writer.cc: consider moving platform code in src/platform like ORT

Both file_writer.cc and cross_process_file_lock.cc carried Win32/POSIX branches behind in-file #ifdef _WIN32. Following the existing src/platform/{windows,posix}/path.cc pattern:

• New src/platform/file_io.h declares fl::platform OpenWritableFile / WriteFileAt / CloseFile primitives over an integer handle, implemented per-OS in src/platform/{windows,posix}/file_io.cc. FileWriter stores an intptr_t handle and delegates — no more #ifdef member or branches.
• CrossProcessFileLock is split: the platform-specific State, its releasing destructor, FormatProcessInfo, the ctor/dtor, and TryAcquireForDirectory move verbatim into src/platform/{windows,posix}/cross_process_file_lock.cc; the neutral src/download/cross_process_file_lock.cc keeps only the cross-platform WaitForDirectoryLock orchestration.
• The four new sources are wired into FOUNDRY_LOCAL_PLATFORM_SOURCES.

Validation

• No behavior change — pure refactor.
• Windows RelWithDebInfo build green; 83 download / lock / file-writer / state unit tests pass (incl. all 9 CrossProcessFileLockTest).
• POSIX sources syntax-clean under g++ -std=c++20 -Wall -Wextra; full POSIX link validated by CI.

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Project	Deployment	Actions	Updated (UTC)
foundry-local	Ready	Preview, Comment	Jun 30, 2026 10:28am

[Copilot]

Pull request overview

This PR is a structural cleanup following review nits from #793. It (1) eliminates four near-identical per-test TempDir/TempPath RAII classes by consolidating them into a single shared test/utils/temp_dir.h helper in the fl::test namespace, and (2) relocates the in-file #ifdef _WIN32 / POSIX branches for blob file I/O and the cross-process download lock into per-OS sources under src/platform/{windows,posix}/, matching the existing src/platform/.../path.cc pattern. It's purely internal to sdk_v2/cpp with no public C ABI change.

I verified: the moved file_io.cc/cross_process_file_lock.cc logic and error strings match the originals (the recombined "FileWriter " + error messages reproduce the prior text exactly); namespaces follow convention (fl::platform for file_io, fl for the CrossProcessFileLock member impls); removing #include "logger.h" from the neutral cross_process_file_lock.cc is safe because WaitForDirectoryLock only forwards ILogger&; the FileWriter handle sentinel change (nullptr/fd_→std::intptr_t handle_ = -1 = kInvalidFileHandle) is internally consistent; and all TempDir/TempPath references resolve via the test_helpers.h umbrella include, with the only behavioral deltas being cosmetic test-temp naming (prefixes unified to fl_test_, dropped .bin suffix).

Changes:

• Consolidated duplicated test temp-dir/path RAII helpers into test/utils/temp_dir.h and removed the local copies plus the old test_helpers.h definitions.
• Extracted Win32/POSIX file I/O behind fl::platform::{OpenWritableFile,WriteFileAt,CloseFile} (src/platform/file_io.h + per-OS .cc); FileWriter now stores an intptr_t and delegates.
• Split CrossProcessFileLock so platform pieces (State, ctor/dtor, FormatProcessInfo, TryAcquireForDirectory) move per-OS while WaitForDirectoryLock orchestration stays neutral; wired the four new sources into FOUNDRY_LOCAL_PLATFORM_SOURCES.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
sdk_v2/cpp/test/utils/temp_dir.h	New shared fl::test TempDir/TempPath/MakeUniqueTempPath/CurrentPid helpers.
sdk_v2/cpp/test/internal_api/test_helpers.h	Removes inline temp helpers; includes the new umbrella header.
sdk_v2/cpp/test/internal_api/{download,cross_process_file_lock,blob_download_state,file_writer}_test.cc	Replace local temp classes with using fl::test::TempDir/TempPath.
sdk_v2/cpp/src/platform/file_io.h	New cross-platform file-handle I/O interface.
sdk_v2/cpp/src/platform/{windows,posix}/file_io.cc	Per-OS implementations of the file I/O primitives.
sdk_v2/cpp/src/platform/{windows,posix}/cross_process_file_lock.cc	Per-OS lock acquisition + State moved verbatim.
sdk_v2/cpp/src/download/file_writer.{h,cc}	Stores intptr_t handle and delegates to fl::platform.
sdk_v2/cpp/src/download/cross_process_file_lock.cc	Keeps only neutral WaitForDirectoryLock; drops platform branches.
sdk_v2/cpp/CMakeLists.txt	Wires the four new platform sources into the platform source list.