UI/updater: Fix race condition

Fixes a race condition where a hash value could be overwritten from
different threads, causing corruption

UI/win-update/updater/hash.cpp

@@ -45,11 +45,13 @@ void StringToHash(const wchar_t *in, BYTE *out)
 
 bool CalculateFileHash(const wchar_t *path, BYTE *hash)
 {
-	static BYTE hashBuffer[1048576];
+	static __declspec(thread) vector<BYTE> hashBuffer;
 	blake2b_state blake2;
 	if (blake2b_init(&blake2, BLAKE2_HASH_LENGTH) != 0)
 		return false;
 
+	hashBuffer.resize(1048576);
+
 	WinHandle handle = CreateFileW(path, GENERIC_READ, FILE_SHARE_READ,
 				       nullptr, OPEN_EXISTING, 0, nullptr);
 	if (handle == INVALID_HANDLE_VALUE)
@@ -57,14 +59,14 @@ bool CalculateFileHash(const wchar_t *path, BYTE *hash)
 
 	for (;;) {
 		DWORD read = 0;
-		if (!ReadFile(handle, hashBuffer, sizeof(hashBuffer), &read,
+		if (!ReadFile(handle, &hashBuffer[0], hashBuffer.size(), &read,
 			      nullptr))
 			return false;
 
 		if (!read)
 			break;
 
-		if (blake2b_update(&blake2, hashBuffer, read) != 0)
+		if (blake2b_update(&blake2, &hashBuffer[0], read) != 0)
 			return false;
 	}