ceph/src/jaegertracing/opentracing-cpp/src/dynamic_load_windows.cpp

   1 #include <opentracing/dynamic_load.h>
   2 #include <opentracing/version.h>
   3
   4 #include <windows.h>
   5
   6 namespace opentracing {
   7 BEGIN_OPENTRACING_ABI_NAMESPACE
   8 // Returns the last Win32 error, in string format. Returns an empty string if
   9 // there is no error.
  10 //
  11 // Taken from https://stackoverflow.com/a/17387176/4447365
  12 static std::string GetLastErrorAsString() {
  13   // Get the error message, if any.
  14   DWORD errorMessageID = ::GetLastError();
  15   if (errorMessageID == 0)
  16     return std::string();  // No error message has been recorded
  17
  18   LPSTR messageBuffer = nullptr;
  19   size_t size = FormatMessageA(
  20       FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
  21           FORMAT_MESSAGE_IGNORE_INSERTS,
  22       NULL, errorMessageID, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
  23       (LPSTR)&messageBuffer, 0, NULL);
  24
  25   std::string message(messageBuffer, size);
  26
  27   // Free the buffer.
  28   LocalFree(messageBuffer);
  29
  30   return message;
  31 }
  32
  33 namespace {
  34 class DynamicLibraryHandleWindows : public DynamicLibraryHandle {
  35  public:
  36   explicit DynamicLibraryHandleWindows(HINSTANCE handle) : handle_{handle} {}
  37
  38   ~DynamicLibraryHandleWindows() override { FreeLibrary(handle_); }
  39
  40  private:
  41   HINSTANCE handle_;
  42 };
  43 }  // namespace
  44
  45 expected<DynamicTracingLibraryHandle> DynamicallyLoadTracingLibrary(
  46     const char* shared_library, std::string& error_message) noexcept try {
  47   const auto handle = LoadLibrary(shared_library);
  48   if (handle == nullptr) {
  49     error_message = "An error occurred: " + GetLastErrorAsString();
  50     return make_unexpected(dynamic_load_failure_error);
  51   }
  52
  53   std::unique_ptr<DynamicLibraryHandle> dynamic_library_handle{
  54       new DynamicLibraryHandleWindows{handle}};
  55
  56   const auto make_tracer_factory =
  57       reinterpret_cast<OpenTracingMakeTracerFactoryType**>(
  58           GetProcAddress(handle, "OpenTracingMakeTracerFactory"));
  59
  60   if (make_tracer_factory == nullptr) {
  61     error_message =
  62         "An error occurred while looking up for OpenTracingMakeTracerFactory "
  63         ": " +
  64         GetLastErrorAsString();
  65     return make_unexpected(dynamic_load_failure_error);
  66   }
  67
  68   if (*make_tracer_factory == nullptr) {
  69     error_message =
  70         "An error occurred while looking up for OpenTracingMakeTracerFactory. "
  71         "It seems that it was set to nullptr.";
  72     return make_unexpected(dynamic_load_failure_error);
  73   }
  74
  75   const void* error_category = nullptr;
  76   void* tracer_factory = nullptr;
  77   const auto rcode = (*make_tracer_factory)(
  78       OPENTRACING_VERSION, OPENTRACING_ABI_VERSION, &error_category,
  79       static_cast<void*>(&error_message), &tracer_factory);
  80   if (rcode != 0) {
  81     if (error_category == nullptr) {
  82       error_message = "failed to construct a TracerFactory: unknown error code";
  83       return make_unexpected(dynamic_load_failure_error);
  84     }
  85     const auto error_code = std::error_code{
  86         rcode, *static_cast<const std::error_category*>(error_category)};
  87     if (error_message.empty()) {
  88       error_message = error_code.message();
  89     }
  90     return make_unexpected(error_code);
  91   }
  92
  93   if (tracer_factory == nullptr) {
  94     error_message =
  95         "failed to construct a TracerFactory: `tracer_factory` is null";
  96     return make_unexpected(dynamic_load_failure_error);
  97   }
  98
  99   return DynamicTracingLibraryHandle{
 100       std::unique_ptr<const TracerFactory>{
 101           static_cast<TracerFactory*>(tracer_factory)},
 102       std::move(dynamic_library_handle)};
 103 } catch (const std::bad_alloc&) {
 104   return make_unexpected(std::make_error_code(std::errc::not_enough_memory));
 105 }
 106 END_OPENTRACING_ABI_NAMESPACE
 107 }  // namespace opentracing