From 0aa05d37ebcc6ac4919c9b2cdf96a09053dc4473 Mon Sep 17 00:00:00 2001
From: Joel Rosdahl <joel@rosdahl.net>
Date: Sun, 5 Oct 2025 19:29:36 +0200
Subject: [PATCH] chore: Improve util::FileLock

- Release current lock on move.
- Check for invalid file descriptor in acquire/release.
- Use UnlockFileEx on Windows for symmetry with LockFileEx.
- Added noexcept where applicable.
---
 src/ccache/util/filelock.cpp | 14 ++++++++++----
 src/ccache/util/filelock.hpp |  4 ++--
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/ccache/util/filelock.cpp b/src/ccache/util/filelock.cpp
index 6c35b115..479195e0 100644
--- a/src/ccache/util/filelock.cpp
+++ b/src/ccache/util/filelock.cpp
@@ -49,6 +49,7 @@ FileLock&
 FileLock::operator=(FileLock&& other) noexcept
 {
   if (&other != this) {
+    release();
     m_fd = other.m_fd;
     m_acquired = other.m_acquired;
     other.m_fd = -1;
@@ -58,8 +59,12 @@ FileLock::operator=(FileLock&& other) noexcept
 }
 
 bool
-FileLock::acquire()
+FileLock::acquire() noexcept
 {
+  if (m_fd == -1) {
+    return false;
+  }
+
 #ifdef _WIN32
   HANDLE handle = reinterpret_cast<HANDLE>(_get_osfhandle(m_fd));
   if (handle == INVALID_HANDLE_VALUE) {
@@ -85,16 +90,17 @@ FileLock::acquire()
 }
 
 void
-FileLock::release()
+FileLock::release() noexcept
 {
-  if (!acquired()) {
+  if (!acquired() || m_fd == -1) {
     return;
   }
 
 #ifdef _WIN32
   HANDLE handle = reinterpret_cast<HANDLE>(_get_osfhandle(m_fd));
   if (handle != INVALID_HANDLE_VALUE) {
-    UnlockFile(handle, 0, 0, MAXDWORD, MAXDWORD);
+    OVERLAPPED overlapped{};
+    UnlockFileEx(handle, 0, MAXDWORD, MAXDWORD, &overlapped);
   }
 #else
   struct flock lock;
diff --git a/src/ccache/util/filelock.hpp b/src/ccache/util/filelock.hpp
index 6c1b9a2e..9be1e699 100644
--- a/src/ccache/util/filelock.hpp
+++ b/src/ccache/util/filelock.hpp
@@ -34,10 +34,10 @@ public:
   ~FileLock();
 
   // Acquire lock, blocking. Returns true if acquired, otherwise false.
-  [[nodiscard]] bool acquire();
+  [[nodiscard]] bool acquire() noexcept;
 
   // Release lock early. If not previously acquired, nothing happens.
-  void release();
+  void release() noexcept;
 
   // Return whether the lock is acquired successfully.
   bool acquired() const;
-- 
2.47.3