Fixed coverity in acl_hal_mmd.cpp: Resource leak (RESOURCE_LEAK)

mmd_libraries were not closed after execution, which causes memory leaks. But mmd_libraries cannot be closed trivially since closing the library invalidates the symbol return by dlsym(), which means calling the function further down is undefined behaviour.
To solve this issues, I added a `dl_wrapper_t` vector as a global initialized vector that would be deallocated when closing the runtime library. This vector would contain all the opened libraries that would be closed by the destructor of `dl_wrapper_t` once the vector deallocates.

Author: haoxian2

src/acl_hal_mmd.cpp

@@ -16,6 +16,8 @@
 #include <cstring>
 #include <fstream>
 #include <iostream>
+#include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 #ifdef __linux__
@@ -188,8 +190,6 @@ unsigned acl_convert_mmd_capabilities(unsigned mmd_capabilities);
 const static size_t MIN_SOF_SIZE = 1;
 const static size_t MIN_PLL_CONFIG_SIZE = 1;
 
-std::vector<acl_mmd_dispatch_t> internal_mmd_dispatch;
-
 // Dynamically load board mmd & symbols
 static size_t num_board_pkgs;
 static double min_MMD_version = DBL_MAX;
@@ -434,14 +434,26 @@ static void *my_dlsym(void *library, const char *function_name,
 }
 
 static void my_dlclose(void *library) {
-  acl_assert_locked();
 #ifdef _WIN32
   FreeLibrary((HMODULE)library);
 #else
   dlclose(library);
 #endif
 }
 
+struct acl_mmd_library {
+  struct deleter {
+    void operator()(void *library) { my_dlclose(library); }
+  };
+
+  using pointer = std::unique_ptr<void, deleter>;
+
+  pointer ptr;
+  acl_mmd_dispatch_t dispatch;
+};
+
+static std::vector<acl_mmd_library> internal_mmd_dispatch;
+
 cl_bool l_load_board_functions(acl_mmd_dispatch_t *mmd_dispatch,
                                const char *library_name, void *mmd_library,
                                char *error_msg) {
@@ -572,7 +584,7 @@ cl_bool l_load_single_board_library(const char *library_name,
       return CL_FALSE;
   }
 #endif
-  auto *mmd_library = my_dlopen(library_name, &error_msg);
+  acl_mmd_library::pointer mmd_library{my_dlopen(library_name, &error_msg)};
   if (!mmd_library) {
     std::cout << "Error: Could not load board library " << library_name;
     if (error_msg && error_msg[0] != '\0') {
@@ -583,16 +595,16 @@ cl_bool l_load_single_board_library(const char *library_name,
   }
 
   auto *test_symbol =
-      my_dlsym(mmd_library, "aocl_mmd_get_offline_info", &error_msg);
+      my_dlsym(mmd_library.get(), "aocl_mmd_get_offline_info", &error_msg);
   if (!test_symbol) {
     // On Linux, for custom libraries close the library (which was opened
     // locally) and then reopen globally. For Windows, there is no option (i.e.
     // it is always global)
 #ifdef __linux__
-    my_dlclose(mmd_library);
+    mmd_library.reset();
     ACL_HAL_DEBUG_MSG_VERBOSE(
         1, "This library is a custom library. Opening globally.\n");
-    mmd_library = my_dlopen_global(library_name, &error_msg);
+    mmd_library.reset(my_dlopen_global(library_name, &error_msg));
     if (!mmd_library) {
       std::cout << "Error: Could not load custom library " << library_name;
       if (error_msg && error_msg[0] != '\0') {
@@ -601,17 +613,20 @@ cl_bool l_load_single_board_library(const char *library_name,
       std::cout << "\n";
       return CL_FALSE;
     }
+    // FIXME mmd_library goes out of scope at the end of this function. How is
+    // this custom library used and where should the handle be stored?
 #endif
   } else {
     if (load_libraries) {
-      auto result =
-          l_load_board_functions(&(internal_mmd_dispatch[num_boards_found]),
-                                 library_name, mmd_library, error_msg);
+      auto result = l_load_board_functions(
+          &internal_mmd_dispatch[num_boards_found].dispatch, library_name,
+          mmd_library.get(), error_msg);
       if (result == CL_FALSE) {
         std::cout << "Error: Could not load board library " << library_name
                   << " due to failure to load symbols\n";
         return result;
       }
+      std::swap(mmd_library, internal_mmd_dispatch[num_boards_found].ptr);
     }
     ++num_boards_found;
   }
@@ -1134,7 +1149,7 @@ void l_close_device(unsigned int physical_device_id,
   return;
 }
 
-static acl_mmd_dispatch_t *get_msim_mmd_layer() {
+static std::optional<acl_mmd_library> get_msim_mmd_layer() {
 #ifdef _WIN32
 
   const char *acl_root_dir = acl_getenv("INTELFPGAOCLSDKROOT");
@@ -1159,7 +1174,7 @@ static acl_mmd_dispatch_t *get_msim_mmd_layer() {
       ipa_simulator ? mmd_lib_name_ipa : mmd_lib_name_aoc;
 
   char *error_msg = nullptr;
-  auto *mmd_lib = my_dlopen(mmd_lib_name, &error_msg);
+  acl_mmd_library::pointer mmd_lib{my_dlopen(mmd_lib_name, &error_msg)};
   typedef acl_mmd_dispatch_t *(*fcn_type)();
   if (!mmd_lib) {
     std::cout << "Error: Could not load simulation MMD library "
@@ -1168,17 +1183,17 @@ static acl_mmd_dispatch_t *get_msim_mmd_layer() {
       std::cout << " (error_msg: " << error_msg << ")";
     }
     std::cout << "\n";
-    return nullptr;
+    return {};
   }
-  auto *sym = my_dlsym(mmd_lib, sym_name, &error_msg);
+  auto *sym = my_dlsym(mmd_lib.get(), sym_name, &error_msg);
   if (!sym) {
     std::cout << "Error: Symbol " << sym_name
               << " not found in simulation MMD library ";
     if (error_msg && error_msg[0] != '\0') {
       std::cout << "(message: " << error_msg << ")";
     }
     std::cout << "\n";
-    return nullptr;
+    return {};
   }
 
   // Now call the function. Ignore the Windows cast to fcn pointer
@@ -1187,10 +1202,15 @@ static acl_mmd_dispatch_t *get_msim_mmd_layer() {
 #pragma warning(push)
 #pragma warning(disable : 4055)
 #endif
-  return ((fcn_type)sym)();
+  acl_mmd_dispatch_t *mmd_dispatch = ((fcn_type)sym)();
 #ifdef _MSC_VER
 #pragma warning(pop)
 #endif
+
+  auto library = std::make_optional<acl_mmd_library>();
+  std::swap(library->ptr, mmd_lib);
+  library->dispatch = *mmd_dispatch;
+  return library;
 }
 
 ACL_HAL_EXPORT const acl_hal_t *
@@ -1255,11 +1275,11 @@ acl_mmd_get_system_definition(acl_system_def_t *sys,
   if (use_offline_only == ACL_CONTEXT_MPSIM) {
 
     // Substitute the simulator MMD layer.
-    auto *result = get_msim_mmd_layer();
-    if (!result)
+    auto result = get_msim_mmd_layer();
+    if (!result) {
       return nullptr;
-    else
-      internal_mmd_dispatch.push_back(*result);
+    }
+    internal_mmd_dispatch.push_back(std::move(*result));
 
     ACL_HAL_DEBUG_MSG_VERBOSE(1, "Use simulation MMD\n");
     num_board_pkgs = 1;
@@ -1269,7 +1289,7 @@ acl_mmd_get_system_definition(acl_system_def_t *sys,
     internal_mmd_dispatch.resize(num_board_pkgs);
     ACL_HAL_DEBUG_MSG_VERBOSE(1, "Board MMD is statically linked\n");
 
-    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[0];
+    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[0].dispatch;
 
     dispatch.library_name = "runtime_static";
     dispatch.mmd_library = nullptr;
@@ -1345,7 +1365,7 @@ acl_mmd_get_system_definition(acl_system_def_t *sys,
   sys->num_devices = 0;
   num_physical_devices = 0;
   for (unsigned iboard = 0; iboard < num_board_pkgs; ++iboard) {
-    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[iboard];
+    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[iboard].dispatch;
 
     dispatch.aocl_mmd_get_offline_info(AOCL_MMD_VERSION, sizeof(buf), buf,
                                        NULL);
@@ -1417,7 +1437,7 @@ int acl_hal_mmd_try_devices(cl_uint num_devices, const cl_device_id *devices,
                                 // names might get cached by various routines
 
   for (unsigned iboard = 0; iboard < num_board_pkgs; ++iboard) {
-    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[iboard];
+    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[iboard].dispatch;
 
     dispatch.aocl_mmd_get_offline_info(AOCL_MMD_BOARD_NAMES,
                                        MAX_BOARD_NAMES_LEN, buf, NULL);
@@ -1487,7 +1507,7 @@ int acl_hal_mmd_try_devices(cl_uint num_devices, const cl_device_id *devices,
   physical_device_id = 0;
 
   for (unsigned iboard = 0; iboard < num_board_pkgs; ++iboard) {
-    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[iboard];
+    acl_mmd_dispatch_t &dispatch = internal_mmd_dispatch[iboard].dispatch;
 
     dispatch.aocl_mmd_get_offline_info(AOCL_MMD_BOARD_NAMES,
                                        MAX_BOARD_NAMES_LEN, buf, NULL);