Various bug fixes (#778)

zencore fixes:
- filesystem.cpp: ReadFile error reporting logic
- compactbinaryvalue.h: CbValue::As*String error reporting logic

zenhttp fixes:
- httpasio BindAcceptor would `return 0;` in a function returning `std::string` (UB)
- httpsys async workpool initialization race

zenstore fixes:
- cas.cpp: GetFileCasResults Results param passed by value instead of reference (large chunk results were silently lost)
- structuredcachestore.cpp: MissCount unconditionally incremented (counted hits as misses)
- cacherpc.cpp: Wrong boolean in Incomplete response array (all entries marked incomplete)
- cachedisklayer.cpp: sizeof(sizeof(...)) in two validation checks computed sizeof(size_t) instead of struct size
- buildstore.cpp: Wrong hash tracked in GC key list (BlobHash pushed twice instead of MetadataHash)
- buildstore.cpp: Removed duplicate m_LastAccessTimeUpdateCount increment in PutBlob

zenserver fixes:
- httpbuildstore.cpp: Reversed subtraction in HTTP range calculation (unsigned underflow)
- hubservice.cpp: Deadlock in Provision() calling Wake() while holding m_Lock (extracted WakeLocked helper)
- zipfs.cpp: Data race in GetFile() lazy initialization (added RwLock with shared/exclusive paths)

1 files changed, 10 insertions, 7 deletions

diff --git a/src/zenhttp/servers/httpsys.cpp b/src/zenhttp/servers/httpsys.cpp
index c640ba90b..6995ffca9 100644
--- a/src/zenhttp/servers/httpsys.cpp
+++ b/src/zenhttp/servers/httpsys.cpp
@@ -25,6 +25,7 @@
 #	include <zencore/workthreadpool.h>
 #	include "iothreadpool.h"
 
+#	include <atomic>
 #	include <http.h>
 
 namespace zen {
@@ -129,8 +130,8 @@ private:
 
 	std::unique_ptr<WinIoThreadPool> m_IoThreadPool;
 
-	RwLock			  m_AsyncWorkPoolInitLock;
-	WorkerThreadPool* m_AsyncWorkPool = nullptr;
+	RwLock						   m_AsyncWorkPoolInitLock;
+	std::atomic<WorkerThreadPool*> m_AsyncWorkPool = nullptr;
 
 	std::vector<std::wstring> m_BaseUris;  // eg: http://*:nnnn/
 	HTTP_SERVER_SESSION_ID	  m_HttpSessionId	   = 0;
@@ -1032,8 +1033,10 @@ HttpSysServer::~HttpSysServer()
 		ZEN_ERROR("~HttpSysServer() called without calling Close() first");
 	}
 
-	delete m_AsyncWorkPool;
+	auto WorkPool	= m_AsyncWorkPool.load(std::memory_order_relaxed);
 	m_AsyncWorkPool = nullptr;
+
+	delete WorkPool;
 }
 
 void
@@ -1323,17 +1326,17 @@ HttpSysServer::WorkPool()
 {
 	ZEN_MEMSCOPE(GetHttpsysTag());
 
-	if (!m_AsyncWorkPool)
+	if (!m_AsyncWorkPool.load(std::memory_order_acquire))
 	{
 		RwLock::ExclusiveLockScope _(m_AsyncWorkPoolInitLock);
 
-		if (!m_AsyncWorkPool)
+		if (!m_AsyncWorkPool.load(std::memory_order_relaxed))
 		{
-			m_AsyncWorkPool = new WorkerThreadPool(m_InitialConfig.AsyncWorkThreadCount, "http_async");
+			m_AsyncWorkPool.store(new WorkerThreadPool(m_InitialConfig.AsyncWorkThreadCount, "http_async"), std::memory_order_release);
 		}
 	}
 
-	return *m_AsyncWorkPool;
+	return *m_AsyncWorkPool.load(std::memory_order_relaxed);
 }
 
 void